World War 2 saw the airplane rise to even greater importance than in the first World War. Air superiority became a crucial component of battlefield operations and air forces were massively expanded during the conflict.The Allied and Axis sides of the war developed enormous war machines, capable of developing and rolling out unprecedented numbers of advanced new military equipment in rapid response to changing conditions on the battlefield, as well keeping up with the technological advances of adversaries.
High altitude bombing raids and night fighting were hallmarks of the War for Europe, whilst aircraft carrier battles pitched the American and Japanese fleets against one another. The technology of the day was pushed to it’s limit with the use of superchargers in aircraft engines, the introduction of radar, and the rapid development of the jet engine by the war’s end.
The period ended as the Nuclear Age and subsequent Cold War were ushered in by the tremendous and tragic blows to Japan’s wearied people.
Nazi Germany (1943) Rocket Powered Fighter – 10 Built
The first operational Me 163 prototype. [luftwaffephotos.com]During the Second World War, the Luftwaffe experimented with a number of unorthodox designs. This included a handful of rocket-powered aircraft, like the Me 163. This particular aircraft was created thanks to the somewhat unexpected combination of two different projects. One was the airframe designed by Alexander Martin Lippisch, and the second was the rocket engine developed by Helmuth Walter. Following the testing of the first prototypes, a small series of some 10 aircraft were built that were mainly used for testing and training.
Alexander Martin Lippisch and Helmuth Walter
The history of Me 163 was closely related to the work and design of aircraft engineer Alexander Martin Lippisch and rocket development pioneer Helmuth Walter. Lippisch was somewhat unorthodox in his aircraft design work, to say the least. He was quite interested in the development of gliders and later aircraft that were either completely lacking a tail unit or of an all-wing configuration.
In 1921, Lippisch, together with a colleague, participated in the formation of the so-called Weltensegler GmbH (World Glider Ltd.) company. At that time, the Germans were prohibited from developing and building military aircraft. The Germans worked around this prohibition by instead focusing on gliders and civilian aircraft which if needed would be quickly converted for military use, and conducted secret experiments. While glider development may seem like a waste of effort, it actually provided the Germans with an excellent foundation on which they managed to develop the Luftwaffe during the 1930s, becoming a formidable force at the start of the war. In 1925, Lippisch joined Rhön Rossitten Gesellschaft RRG, where he soon began working on his first glider. It was named Storch I, and incorporated his unusual all-wing design.
Over the years, Lippisch also became interested in rocket technology. With assistance from Fritz von Opel, Lippisch managed to build a rocket-assisted glider. This contraption was flight tested in June 1928. This was actually the first-ever rocket-assisted flight in the world. While initially successful, the glider crash-landed, and caught fire. The plane would be lost in the accident.
This accident did not prevent Lippisch from experimenting with rocket-powered all-wing gliders. He focused his work on a powered version of his Storch V glider. For this project, he used an 8 hp DKW engine. His work was successful and he managed to find investors who were willing to provide funds for the project. This led to the development of the Delta I all-wing aircraft during the late 1920s, and it was followed by Delta II, III, and IV.
Lippisch Delta I prototype. [aviastar.org]Following this, Lippisch joined the Deutsche Forschungsinstitut DFS, where he worked as an engineer. There, he developed a series of new glider designs, like the DFS 40. In 1938, the work of Helmuth Walter came to his attention. Walter was a young scientist who was highly interested in rocket propulsion. He managed to gain military funding, which greatly helped in his work. In 1937, he even managed to gain attention from the Reichsluftfahrtministerium RLM (German Air Ministry). The RLM formed a Sondertriebwerke (Special Propulsion System Department) with the aim of experimenting with rocket engines in the aircraft industry. While this department was mainly focused on developing rocket engines for short take-off assistance, Walter desired a more prominent role in rocket propulsion. He intended to develop a rocket engine that could replace standard piston engines. Walter managed to develop such an engine, named Walter TP-1, which was fueled by the so-called ‘T-Stoff’ (hydrogen peroxide) and ‘Z-Stoff’ (water solution of either calcium or sodium permanganate). His engine design would be tested in 1939 on the He 176. However, the final results were disappointing and the engine did not go into production.
The DFS 194 predecessor
Lippisch and his design team began working on a new project incorporating the Walter rocket engine. Initially, the project was designated simply as Entwurf X (Design X), before being changed to 8-194 and finally DFS 194. Work on the prototype came to a temporary halt as the DFS lacked proper production capabilities to finish the aircraft. To keep the project going, the RLM instructed Messerschmitt to provide the necessary manpower and production support.
Given the small chance of progression in the DFS and in order to increase the speed of the project, Lippisch and his team moved to Messerschmitt’s base at Augsburg at the start of 1939. He also tried to negotiate with Heinkel for the production and development of the DFS 194 project, but nothing came of this. At Augsburg, Lippisch and his team worked in Messerschmitt’s newly formed Department L (which stands for Lippisch).
The DFS 194 prototype served as the base for the future Me 163. [nevingtonwarmuseum.com]The first calculations were promising, as the plane would be able to reach a speed of 550 km/h (342 mph). Once completed the DFS 194, was transported to the secret German rocket test center at Peenemunde-West Airfield during the summer of 1939. During ground tests, it was noted that the engine installation was poorly designed and too dangerous to be actually flight tested. Instead, it was decided to use the design as a glider. Surprisingly, despite this huge setback, production orders for three prototypes were given. Initially, these were designated simply as Lippisch V1, V2, and V3, but would be renamed to Me 163A V1 to V3. This was mainly done to mask the true purpose of this aircraft, as this was the name given to an older, rejected Bf 163 Messerschmitt reconnaissance aircraft project.
The Me 163A Prototype Series
The RLM was not satisfied with the general design of the engine compartment initially tested on the DFS 194. They requested that for further Me 163 development, it would need to be substantially changed. In addition, the engine was to be replaced with the Walter R II-203 engine. This engine was to have a manually regulated thrust ranging from 150-750 kg of thrust (330-1,650 lbs). The engine compartment was also to be completely redesigned in order to have easy access to the main components for maintenance.
Following the start of the Second World War in September 1939, the work on the Me 163 slowed down but still went on. The first unpowered flight by the Me 163 V1 prototype, in some sources marked as V4, (KE + SW) was carried out during early 1941. This prototype was towed by a Bf 110 heavy fighter. Once at a sufficient altitude, the V1 was released. During the test flight, the pilot, Heini Dittmar, managed to reach a speed of some 850 km/h (528 mph) during a dive. While this was a great starting point for the project, Hitler, following military victories in Poland and in the West, ordered that funds for such projects be reduced. In the case of the Me 163, this meant that only two more additional prototypes were to be built.
Side view of the Me 163 V1 (V4).[luftwaffephotos.com]In May 1941, a wooden mock-up of a Me 163 was completed, which was then transported to the Walter Werke. Once there, it was to be equipped with the R II-203 engine. Once the first prototype was fully completed and equipped with this engine, the first tests were carried out at Peenemunde-West in August 1941. The test pilot was once again Heini Dittmar. After a series of test flights that lasted from August to September 1941, the Me 163 prototype showed promising results. The pilot managed to reach top speeds of 800 km/h (500 mph). At this time, the second V2 prototype was also equipped with a rocket engine and used in various test flights. Ernst Udet, Director-General of the Luftwaffe, was highly impressed with its performance. He even gave orders that an additional 8 prototypes were to be built, bringing the total to 13 at this time.
Once the prototype was equipped with the R II-203 engine, the first tests were carried out in August 1941. These proved to be highly successful, which led to an increase in interest for the Me 163 project. [Spate & Bateson]At the start of October, Heini Dittmar said that, in order to fully test the Me 163’s flying performance, the fuel load had to be increased. On his personal insistence, the V3 (CD + IM) prototype, was fully fueled. This is according to W. Spate and R. P. Bateson (Messerschmitt Me 163 Komet). Other sources like M. Griehl (X-Planes German Luftwaffe Prototypes 1930-1945) this aircraft was described as being the V8 prototype instead. On the 2nd of October 1941, he took to the sky, initially towed by a Bf 110. At an altitude of 3,960 meters (13,000 ft), Dittmar activated the engine. After reaching a speed of 965 km/h (600 mph), he lost control of the aircraft as the result of compressibility effects. The prototype began a rapid descent toward the ground. He then switched off the engine, which enabled him to regain control, after which he landed safely on the ground. Later analysis of the flight indicated that Dittmar managed to reach a speed of 1002 km/h (623 mph). As the whole project was undertaken under great secrecy, this success was not published at the time.
The Me 163 in the middle was the aircraft that Heini Dittmar flew when he reached a speed of 1002 km/h (623 mph). [Spate & Bateson]Following these events, the Me 163 project got a temporary boost in prominence, with Herman Goring himself placing great interest in it. Ernst Udet additionally placed an order for 70 new Me 163 airframes together with engines for the B version in October 1941. A month later, things changed dramatically for Me 163 after Udet committed suicide. His replacement, Erhard Milch, was less interested in unconventional aircraft designs, like the Me 163. Work on the project nevertheless continued.
A breakup with Messerschmitt
While the Me 163 project was underway, relations soured between Willy Messerschmitt and Lippisch. Messerschmitt personally disliked the Me 163, partly due to its unique overall design, but also given that he was not involved in its development. By 1943, Lippisch left Augsburg and moved to Vienna. While not physically present in the design bureau, he tried to maintain contact with the Me 163 development team at a distance.
In the meantime, Messerschmitt was unwilling to be involved in the Me 163 project, under the excuse that his company was already overburdened with the production of other aircraft. For this reason, the production of further Me 163 aircraft was instead given to Klemm Leichtflugzeugbau, a relatively small aircraft company owned by Hans Klemm.
Production of the A-0 series
While the V1 prototype was mainly used for initial testing, the V2 would serve as a base for the A-0 series. An initial order for ten A-0 aircraft was previously given to Messerschmitt, but only seven were completed. The remaining three aircraft were actually completed by the Klemm factory. These were all completed from 1941 to 1942. The number of prototypes built is not clear in the sources. The numbers range from 1 to 8 prototype aircraft. According to S. Ransom and H.H. Cammann (Jagdgeschwader 400), while three prototypes were meant to be built initially, not all met the requested specifications, except one, which received the V4 designation. Author M. Griehl (Jet Planes of the Third Reich) on the other hand noted that the V4 was the first prototype. He explained that the previous three prototypes were actually related to the initial Bf 163 reconnaissance project that was rejected.
In-Service
Of the 10 built Me 163 A-0 planes, not all were equipped with fully operational engines. A number of them were instead operated as unpowered gliders. This version was not intended for combat operations and was mainly used for crew training and further experimentation.
At the end of November 1943, the V6 aircraft was lost in an accident with the loss of the pilot. In another accident at the end of 1943, another pilot died when the engine stopped working during a takeoff. While the pilot tried to turn back for a landing, having limited control, the aircraft hit a ground station radio antenna before hitting the ground and exploding. It was discovered in an investigation that the undercarriage dolly bounced off the ground much higher than usual, and struck the aircraft, damaging the rocket engine. Some prominent pilots, like Hanna Reitsch, actually had the chance to flight-test the Me 163 aircraft. At least one aircraft was still operational by February 1945 and was used for testing the 55 mm R4M rockets by Erprobungkommando 16.
Me 163A at Peenemunde, 1943. [Ransom & Cammann]At least one Me 163A survived up to February 1945. It was used by Erprobungkommando 16 (Eng. testing or evaluation-coomand) in Silesia to test the 55 mm R4M rockets. This unit had the primary function of testing and examining the newly built Me 163 and helping in the development and improvement of its overall design. Besides these, no other armament was installed on the Me 163 A series. Source Source: W. Spate and R. P. Bateson Messerschmitt Me 163 Komet
Technical Characteristics
The Me 163A was a high-speed, rocket-powered, swept-wing, short fuselage, mixed-construction tailless aircraft. The Me 163A fuselage was built using metal, divided into three sections, the front cockpit, central fuel tank, and the aft engine compartment.
The wooden wings had a very simple design consisting of two spars covered in thick fabric. If needed, the wings could be detached from the fuselage for transport. At the wings’ trailing edges ailerons were placed, which the pilot during flight used for pitch and roll. The wing area was 17.5 m² (57.4 ft²). The tail did not have the standard horizontal stabilizers, instead of having a single large vertical stabilizer. Despite this, no major problems during flights were ever noted on the Me 163A.
For the pilot to enter the cockpit he was provided with a ladder placed on the left side of the aircraft. The cockpit canopy opened upwards. Overall visibility was poor, and later versions would have an improved canopy. While it did offer some improvements for the pilot’s line of sight, it would not resolve the overall poor visibility of the aircraft. Given that the Me 163A was based on a DFS 194 glider, it was equipped with minimal instrumentation needed for the aircraft to be flown.
View of the Me 163A’s cockpit interior. [Spate & Bateson]The Me 163A was powered by a single HWK R II 203 rocket engine, which gave 750 kg (1,650 lb) of thrust. The main fuel consisted of a mix of T and Z Stoff. These two chemicals were highly reactive, volatile, and prone to explosion. To avoid this, extensive preparation and security measures were necessary. The maximum speed this engine achieved was some 850 km/h (530 mph). This high speed was achieved to some extent thanks to the aircraft’s low weight. The empty weight was 1,140 kg (2,513 lbs) while the maximum takeoff weight was 2,200 kg (4,850 lbs).
Interestingly, in order to save weight, the Me 163 did not have a conventional landing gear unit. Instead, during take-off, it was provided with a specially designed two-wheel dolly. It would be jettisoned upon take-off. When landing on the airfield, the Me 163 used a retractable skid located beneath the fuselage.
Despite the A series having not been designed to have any weapon systems, at least one Me 163A was tested with the installation of the 5.5 cm (2.16 in) R4M air-to-air rockets.
Production Versions
DSF 194 – Prototype whose further development led to the creation of the Me 163
Me 163 Prototype Series– Prototype aircraft
Me 163A-0 – 10 Pre-production aircraft built
Conclusion
The Me 163A series, despite its unusual appearance and overall design, proved to be a rather successful aircraft. It had some shortcomings, mostly regarding its dangerous fuel load. Upon completion of successful testing, order for the Me 163B version was given.
Me 163A Specifications
Wingspans
8.85 m / 29 ft 3 in
Length
5.25 m / 17 ft 2 in
Height
2.16 m / 7 ft 8 in
Wing Area
17.5 m² / 57.4 ft²
Engine
One HWK R II 203 rocket engine with 750 kg (1,650 lbs) of thrust
Empty Weight
1,140 kg / 2,513 lbs
Maximum Takeoff Weight
2,200 kg / 4,850 lbs
Maximum Speed
850 km/h / 530 mph
Crew
1 pilot
Gallery
Me 163A – Illustrated by Carpaticus
Credits
Written by Marko P.
Edited by by Ed Jackson & Henry H.
Illustrations by Carpaticus
Sources
D. Nešić (2008) Naoružanje Drugog Svetsko Rata-Nemcaka. Beograd.
W. Spate and R. P. Bateson (1971) Messerschmitt Me 163 Komet , Profile Publications
M. Ziegler (1990) Messerschmitt Me 163 Komet, Schiffer Publishing
M. Emmerling and J. Dressel (1992) Messerschmitt Me 163 “Komet” Vol.II, Schiffer Military History
E. T. Maloney and U. Feist (1968) Messerschmitt Me 163, Fallbrook
S. Ransom and H.H. Cammann (2010) Jagdgeschwader 400, Osprey publishing.
D. Donald (1990) German aircraft of the WWII, Brown Packaging books ltd
D. Monday (2006) The Hamlyn Concise Guide To Axis Aircraft OF World War II, Bounty Books.
M. Griehl (1998) Jet Planes of the Third Reich, Monogram Aviation Publication
M. Griehl (2012) X-Planes German Luftwaffe Prototypes 1930-1945, Frontline Book
He 112 the unsuccessful competitor of the Bf 109. [luftwaffephotos.com]Prior to the Second World War, the German Luftwaffe was in need of a new and modern fighter that was to replace the older biplane fighters that were in service. While four companies responded to this request, only the designs from Heinkel and Messerschmitt were deemed sufficient. The Heinkel He 112 was an especially good design that offered generally acceptable flight characteristics and possessed a good basis for further improvements. While it was in some regards superior to the Messerschmitt, ultimately it would not be accepted for service, and only 100 or so aircraft would be built. These would be mainly sold abroad, with those remaining in Germany used for various testing and evaluation purposes.
History
By the early 1930s the Heinkel company was a well-established aircraft manufacturer. It was rapidly expanding, mostly thanks to the export of some of its aircraft designs. The Heinkel company also had a good relationship with the German Air Ministry RLM (Reichsluftfahrtministerium RLM), which entered a series of different aircraft production contracts with Heinkel.
At this time the German Air Force was in the process of a huge reorganization, and the development of new military aircraft. Quite of interest was the development of a new fighter aircraft that would replace older Arado Ar 68 and Heinkel He 51 biplanes that were in service. For this reason, in May 1934 the RLM issued a competition for a new and modern fighter plane that could reach speeds of 400 km/h (250 mph) at an altitude of 4,000 meters (19,685 feet). Initially, three companies were contacted, including Arado, Focke-Wulf, and Heinkel. Interestingly, and somewhat ironically as it later turned out, Messerschmitt, a relatively small company at that time, was also contacted by the RLM.. All four companies were to build three prototypes of their design, which were to be tested before a final decision was to be made.
Arado and Focke-Wulf completed their prototypes, the Ar 80 and Fw 159 respectively, by the end of 1934. The Heinkel He 112 and Messerschmitt Bf 109 prototypes took a bit longer to complete, which was completed in September 1935. The He 112’s design was greatly inspired by the He 70 passenger plane, which would later be modified for military purposes. Heinkel engineers used the He 70’s the overall design as the basis for the He 112, mainly regarding its wings and the fuselage construction.
The inspiration for the He 112 was the He 70. While the He 70 had good general performance it would not be employed by the German in any major military role. [Wik]Once all four companies submitted their designs, evaluation trials were carried out at the German test centers located at Rechlin and Travemunde starting in October of 1935. After some initial testing, both the Ar 80 and Fw 159 experienced too many mechanical breakdowns and even crashes, which ultimately led to both being rejected. The He 112 and Bf 109 on the other hand proved to be more promising designs. Interestingly due to shortages of domestically built engines, both aircraft were initially powered by Rolls-Royce Kestrel engines.
The He 112 V1 (D-IADO) was powered by a 695 hp Rolls-Royce Kestrel Mk. II engine during trials. Once the aircraft was completed, it was first flight-tested by Heinkel’s own test pilot Gerhard Nitschke. While he gave a generally positive review of its performance, he also noted the aircraft’s drag was a bit higher than expected. However, given that its overall performance was deemed sufficient for the competition, Heinkel decided to proceed with the project. This prototype arrived at the designated test center of Travemunde by the end of 1935. During a series of flight tests, the maximum speed achieved was 466 km/h (290 mph).
The He 112 V1 first prototype, used for the trials held at Rechlin and Travemunde. [luftwaffephotos.com]It was clear that the RLM would never accept an aircraft powered by a foreign engine. The Heinkel engineers began working on the second prototype that was to be equipped with a domestically built engine. The V2 (D-IHGE) was powered by a 640 hp Junkers Jumo 210C liquid cooled engine. The first test flight was made in November 1935 by another Heinkel test pilot Kurt Heinrich. The V2 was more or less just a copy of the first prototype.
Construction of Additional Prototypes
During the series of test flights, the performance of the two competitors was quite similar, with some minor advantages between them. In the case of the Bf 109, it was slightly faster, while the He 112 had lower wing loading. In addition, the He 112 had a better design and safer landing gear unit.
As the V2 was flight tested at Heinkel, the initial results of the competition began to arrive. The Heinkel engineers were keen on finding a way to overcome the Bf 109’s slightly faster speed. So the Gunter brothers began to redesign the V2 wings. Walter and Siegfried were at that time, probably Heinkel aircraft designers (for example the He 51 biplane is one of their designs.). Their calculation showed that a reduction in the wing profile would provide an additional boost to the maximum speed by at least 24 to 29 km/h (15 to 18 mph). This modification reduced the overall size of the wings, but led to another problem. Namely, the wing loading exceeded that of the RLM commission requirement. Given that the aircraft speed was increased, Heinkel officials deemed that it was a necessary compromise that would not affect the general rating of the aircraft.
The V2 prototype reached the Travemunde test center sometime in early 1936. In February 1936 the V1 and V2 prototypes were moved to the Rechlin Testing Center. In early March, a series of dive tests were carried out. In one of these, the V2 was seriously damaged, luckily the pilot survived the crash. After a few weeks of repairs with Heinkel, the aircraft was quickly put back to use. But in another landing crash, it was completely destroyed and listed as irreparable. Once again the test pilot managed to escape without any injury. This accident, while it did not prevent Heinkel’s involvement in the new fighter competition, it certainly affected the commission’s opinion on the He 112 at least to some extent.
The last of the prototypes intended for the competition was the V3 (D-IDMO). While initially, it was more similar to the first prototype, it received the wing modification implemented on the V2. Additional changes include increasing the rear tail unit size, adding a new radiator, installation of three (or two depending on the source) 7.92 mm MG 17 machine guns. In addition, it would later receive a new enclosed cockpit with a sliding canopy.
Side view of the V3 (D-IDMO) prototype. [luftwaffephotos.com]
Further Competition Developments
Despite the series of improvements to their He 112 design, the tide was slowly but surely turning toward the Bf 109. The RLM commission was getting somewhat frustrated with Heinkel’s constant changes to the design, and the previously mentioned crash did not help matters. In March, it was already being discussed to proclaim the Bf 109 as a winner. The Germans were also informed by the Abwehr intelligence service that the British were developing and preparing for the production of the new Spitfire. RLM officials were simply not willing to risk taking a chance on an aircraft design that could not quickly be put into production, as the Bf 109 was.
While the He 112 project would have ended there, thanks to Heinkel’s strong political connections, an extension of the trials was agreed to. Both companies were to build additional 15 0-series aircraft to be used for testing. The production was to commence in October 1936 with the last aircraft to be completed by May the following year.
Heinkel’s first completed aircraft, which was included in the previously mentioned contract, was actually a He 112 V4 (D-IDMY) prototype which was ready in June 1936. The V4 received a new and stronger 680 hp Jumo 210D that was equipped with a supercharger. In addition, it had an open cockpit, besides which it was in essence a copy of the V3. Possibly anticipating the contract for additional aircraft, Heinkel began working on additional airframes in advance. This led to the completion of the V5 (D-IIZO) and V6 (D-IQZE) prototypes in July of 1936. The V6 was intended as a replacement for the lost V2 aircraft. This aircraft was powered by a Jumo 210C engine. The last aircraft of the prototype series was the V8 (D-IRXO) powered by a Daimler DB 600A engine. It was primarily intended to serve as test aircraft. All of these previously mentioned prototypes were to serve as the forerunners of the He 112 A-0 series.
The V4 prototype before it received any markings. [luftwaffephotos.com]Following more test flights by numerous Luftwaffe pilots, the Bf 109 was receiving more and more positive reviews from pilots that had the opportunity to fly them. The Bf 109, while proving to have excellent flying performance, was also cheaper and easier to build than the He 112. Given the fact that the Germans were attempting to accelerate the production of the new fighter, this was seen as a huge advantage over the He 112.
In late 1937 Ernst Udet, who was at that time the director of the RLM technical development sector, visited the Heinkel company Marienehe Test Site. There he informed Heinkel that his He 112 was rejected as a fighter. Possibly to compensate for the huge investment in the fighter project, Heinkel company was permitted to export the He 112.
Heavy Fighter Role
Parallel with the development of the first fighter aircraft, the RLM was also interested in the so-called Zerstorer (heavy fighter). This aircraft was to be armed with cannons and machine guns. Heinkel proposed that the V6 be armed with a 2 cm MG C/30L cannon placed in the centerline of the engine. According to D. Bernard the V6 was designated for further testing, under real combat conditions, and would be sent to Spain at the end of 1936. It would be lost there in a landing accident in July 1937. Ernst Heinkel was likely dissatisfied with this outcome, as Messerschmitt once again triumphed as its Bf 110 would be accepted for this role.
The A and B series
Despite being inferior to the Bf 109, the Heinkel company continued working on the He 112, improving its design, in the hopes of gaining the attention of the RLM. The construction of the limited production He 112 A-0 series was still underway, with a total of only six aircraft (D-ISJY, D-IXHU, D-IZMY, and D-IXEU) built. The last two aircraft of the A-0 series received no registration numbers, as they were intended to be sold to Japan. The remaining four aircraft were used for various proposals. For example, the A-01 aircraft was to be used as a base for the proposed He 112 C-0 aircraft carrier modification, which was never implemented. The A-02 and A-04 were used for further flight tests. The A-03 was mainly used as an exhibit aircraft for various European aviation exhibitions, which were quite common before the war.
The A-series was built in small numbers and mostly employed for testing various equipment and design changes. [luftwaffephotos.com]The A-series was built in small numbers, as Heinkel’s attention moved to the B-0 series instead. The B-0 series was quite different from the previous version, as it introduced a number of changes and modifications. Some of which included a new cockpit design, more powerful armament, changes to the engine ventilation design, fuselage and engine cowling changes, and other modifications.. The forerunner of the B series was the He 112 V7 prototype, which included many modifications previously mentioned.
Following the unsuccessful attempt to gain the Luftwaffe’s attention Heinkel and his team of engineers began working on redesigning the He 112. The basis for the next version, the He 112B-0, the V7 (D-IKIK) was reused. It incorporated a newly redesigned wings and tail unit, and was to be powered by a 1,000 hp Daimler DB 600A engine. Heinkel officials and Hertel himself were hoping that this new version could potentially persuade RLM to reconsider the He 112. Following it was the V9 (D-IGSI), which was powered by a weaker 680 hp Jumo 210E engine. In the following months, work on the B-series was intensified with many different engines being tested (Jumo 210E, 210G etc). Ultimately meager export sales, and the RLM’s rejection of the He 112 by the start of 1939 forced Heinkel to finally terminate the project.
The B-series was in many aspects a complete redesign from the previous series. Including the introduction of a new tail unit, and part of the fuselage, to name a few [luftwaffephotos.com]
Rocket Engine Tests
Prior to the Second World War, the Germans were quite interested in the experimentation and the development of rocket technology. Various tests conducted by Dr. Wernher von Braun were carried out at the Kummersdorf-West test centers. While this research eventually led to the creation of the infamous V-2 rocket, the development of rocket engines that were intended to possibly be installed in aircraft is often overlooked. Ernst Heinkel was quite a supporter of this project and even donated a number of aircraft to be used as testbeds for the potential new engine. He even donated a few pre-production series He 112 for this research.
A rocket engine was installed in the rear of the fuselage, with the engine nozzle being placed just beneath the tail unit. During the first ground test, the engine exploded, destroying the aircraft (He 112 A-01) in the process. Another He 112 V3 aircraft was outfitted with the rocket engine and was being prepared to conduct its first test flight. As the pilot was approaching this aircraft, the rocket engine exploded again. Somewhat miraculously the pilot survived with no major injuries. While again the aircraft was lost, another aircraft that was built as a replacement would receive the same markings.
The V3 prior to the start of testing. Which would spectacularly explode shortly after the picture was taken. [luft46.com]Von Braun requested another aircraft which Henkel provided, this was the He 112 V8. During these trials it received a slightly altered designation V8/U. The plane was to ascend on its own piston engine. Then at a certain height, it was to fire the rocket engine wich was placed to the rear of the fuselage for a 30-second burst. This flight test was carried out in April 1937 and was more than successful. During the short burst, the plane reached a speed of 460 km/h (286 mph). The He 112 V8 was returned to Heinkel but two more aircraft (H7/U and A-03) would be donated for the rocket research program. The V8 would be eventually sent to Spain in 1937 and its final fate is unknown. Thanks to the He 112, the German rocket engine program gained a huge boost, which would eventually lead to the He 176 and later Me 163.
Technical Characteristics
The He 112 was an all-metal single-engine fighter. The monocoque fuselage consisted of a metal base covered by riveted stress metal sheets. The wing was slightly gulled, with the wingtips bending upward, had the same construction as the fuselage with a combination of the metal construction covered in stressed metal sheets.
During its development life, a great number of different types of engines were tested on the He 112. For the main production version, He 112 B-2, the 700 hp Jumo 210G liquid-cooled engine was used. With this engine the maximum speed achieved was 510 km/h (317 mph). For the Jumo engine, an all-metal three blade variable pitch propeller was used. The He 112 had a fuel capacity of 101 liters in two wing mounted tanks, with a third 115 liter tank placed under the pilot seat
The landing gear were more or less standard in design. They consisted of two larger landing wheels that retracted into the wings, and one smaller wheel placed at the rear. The He 112 landing gear was wide enough to provide good ground handling and stability during take-off or landing.
The pilot cockpit received a number of modifications. Initially, it was open with a simple windshield placed in front of the pilot. Later models had a sliding canopy that was either partially or fully glazed.
While the armament was changed during the He 112’s production, the last series was equipped with two 7.92 mm MG 17 machine guns and two 2 cm Oerlikon MG FF cannons. The ammunition load for each machine gun was 500, with 60 rounds each for the cannons. If needed, two bomb racks could be placed under the wings, with one per side. Each could carry one 10 kg anti-personnel bomb. For the acquisition of targets, the pilot used the Revi 3b gun sight.
Brief Service with the Luftwaffe
Despite losing to the Bf 109, Heinkel was permitted, after some lobbying from Ernst Heinkel himself, to send one He 112 to Spain for combat evaluation. Once it reached Spain during the end of 1936, the He 112 was allocated to the Experimental Fighter Unit 88 which was part of the Condor Legion. In Spain, it was mostly used against ground targets. One of its greatest successes happened during an attack on the Republican-held Cesena train station. The pilot, Obereutnant Balthasar, made three attack runs in which he managed to destroy an armored car and a tank. The aircraft would be lost in a landing accident that happened in July 1937. Two more prototypes would be sent to Spain during 1938, the V8 and V9. The V8 was heavily damaged during initial trials and spent some four months in repairs. The V9 had a better service life, as it was used in a number of ground attacks. Both aircraft would be returned to Germany by the end of 1938.
Only a small number of He 112 (less than 20) saw limited service with the Luftwaffe in 1938 [luftwaffephotos.com]In 1938 a possible conflict with Czechoslovakia and the Western Allies, France, and the United Kingdom over the dispute caused huge concern in the RLM. The Luftwaffe was simply not ready for open war, as it was not yet fully equipped. For this Reason, the RLM instructed that all available aircraft be relocated to the Luftwaffe to temporarily boost their readiness numbers. An unknown number of He 112 B, taken from the Japanese purchase order, were temporarily pressed into service. These were allocated to the IV./JG 132 station at Oschatz. In November they relocated to Mahrish-Trubau. Once the crisis was over, the aircraft were replaced with the Bf 109. The pilots that had the chance to fly them gave a generally positive review of their flying performance.
Export Attempts
As mentioned earlier, the He 112 was permitted to be exported abroad if there were any interested customers. This order was officially given at the end of January 1938. A number of countries such as Austria, Japan, Romania, and Finland showed interest, but only a few actually managed to procure aircraft.
Negotiation with Austria
During November 1937 an Austrian delegation visited Heinkel with a desire to enter into a purchase agreement for acquiring 42 He 112B aircraft. Due to lack of funds, this order was reduced to 36 at the start of 1938. Eventually, nothing came of this as the Germans simply took over Austria in March 1938.
In Japanese Hands
At the end of 1937, a Japanese delegation made a contract with Heinkel for purchasing 30 He 112B’s. If these proved to be satisfactory, an additional order for 100 would be placed. This order included 2 He 112 A-0, 6 B-0, and 21 B-1 and the V11 prototype. After a series of tests, the Japanese were not impressed with the He 112 and did not accept it for service. The experimental He 112 C aircraft carrier version was also sold to Japan, according to D. Bernard.
J. R. Smith and A. L. Kay provide a completely different story. According to them, Japan expressed an interest in buying 30 He 112B-0 aircraft, with the first group of 12 aircraft arriving in Japan in 1938. While the remaining 18 were to arrive soon after, the Sudeten crisis changed the plan. The Germans were preparing for a potential war with Czechoslovakia and needed every possible aircraft. So they requisitioned the aircraft intended for Japan. Once the crisis was over, Heinkel offered to ship these delayed aircraft to Japan, which rejected the offer. The Japanese were disappointed with the He 112 B-0 performance and decided to cancel the purchase. The sources also conflicted with each other if the He 112 in Japanese service ever saw action.
In Spain
Some three He 112 were tested during the Spanish civil war. Thanks to this, Francisco Franco’s forces had some insight into the He 112’s performance. Based on this, Spain initially asked for 12 aircraft. The order would be eventually increased to 18 aircraft. Interestingly, Spanish pilots managed to shoot down an Allied P-38 that likely accidentally entered the Spanish air space while flying the He-112B-0 in 1943.
He 112 in Spain’s service. [luftwaffephotos.com]
In Romania
Romania initially asked for 24 aircraft, with the order later increased to 30 He 112 aircraft. These arrived from June to October (or September) 1939. The Romanian He 112 would be used during 1941 against the Soviet Union. The following year, all would be allocated for pilot training.
Romanian He 112 even saw service against the Soviet Forces during 1941. [luftwaffephotos.com]
Hungary
The last nation that operated the He 112 was Hungary. In September 1937 a delegation from Hungary visited Heinkel where they inspected the He 112. This delegation was satisfied with what they saw and ordered 36 aircraft, but also showed interest in a licensed production. Ultimately the RLM rejected this offer and only one aircraft ever reached Hungary.
Other Unsuccessful Negotiations
Prior to the war, Heinkel organized a series of demonstrations of the He 112B to various interested European air forces. These include Yugoslavia, The Netherlands, Finland, Turkey, and Switzerland. While many of these parties were interested, for various reasons, chiefly budget constraints, nothing came of these negotiations.
Production
The production numbers of the He 112 are not clear and vary widely depending on the source. According to F.A.Vajda and P. Dancey the production run was as follows with 3 in 1935, 11 in 1936, 13 in 1937, 30 in 1938, and 46 in 1939 for a total of 103 aircraft. Author D. Berliner mentioned a number of 66 aircraft being built. Author Duško N. gave a number of 68 aircraft of all versions being built. D. Bernard gave us a number of 98 aircraft. While C. Chants mentioned a number of 110 aircraft.
Prototype and Production Versions
He 112 V1-V – Prototype series used for testing of various engines and overall design
He 112 A – Planed main production version, which was not adopted
He 112 B – Extensively modified versions of preceding models
He 112 B-1 – Equipped with a Jumo 210E engine
He 112 B-2 – Equipped with a Jumo 210G engine
He 112 B-3 – Proposed version powered by a Daimler DB 601A engine, none built
He 112 C – A proposed aircraft carrier version, only one prototype was built and sold to Japan
He 112 E – Intended as an export version, based on the B series
He 112 U – Propaganda aircraft, which was actually based on the He 100
Operators
Germany – Briefly operated a small number of the He 112
Japan – Operated some 12 to 30 aircraft mainly for testing
Spain – Operated less than 20 He 112 aircraft
Romania – Purchased some 24 to 30 He 112, which saw combat action against the Soviet Union
Hungary – Purchased one He 112
Austria – Planned to acquire 42 He 112, but nothing came from this as it was annexed by Germany.
Conclusion
The He 112 during its brief service life was shown to be a good fighter aircraft. It proved to be a worthy competitor to the Bf 109. It’s quite difficult to pinpoint the exact circumstances that ultimately led to its downfall. Sources often mention that one of the main reasons was political involvement, which favored Messerschmitt. Political quarrels in Germany often influenced decision to adopt aircraft during the war. This factor was surely at play when the fate of the He 112 was decided. But a more practical answer was simply that the Bf 109, while shown to have good flying performance, was also cheaper and easier to build than the He 112. Given that at that time, the Luftwaffe was in the middle of a huge reorganization and rearmament effort, conditions certainly favored the Bf 109. The He 112’s constant design changes did not help either.
He 112B-2 Specifications
Wingspans
29 ft 10 in / 9.1 m
Length
30 ft 2 in / 9.22 m
Height
12 ft 7 in / 3.82 m
Wing Area
180 ft² / 17 m²
Engine
One 700 hp Jumo 210G liquid-cooled engine
Empty Weight
3,570 lbs / 1,620 kg
Maximum Takeoff Weight
4,960 lbs / 2,250 kg
Climb Rate to 6 km
In 10 minutes
Maximum Speed
317 mph / 510 km/h
Cruising speed
300 mph / 484 km/h
Range
715 miles / 1,150 km
Maximum Service Ceiling
31,170 ft / 9,500 m
Crew
1 pilot
Armament
Two 20 mm cannons and two machine guns 7.92 mm machine guns
Illustrations by Godzilla
He 112 as seen during its brief service with the LuftwaffeAn alternate livery of the Luftwaffe He 112He 112 in Romanian ServiceHe 112 in Romanian ServiceHe 112 v5 as it was tested by Japan
Credits
Written by Marko P.
Edited by by Ed Jackson & Henry H.
Illustrations by Godzilla
Sources
Duško N. (2008) Naoružanje Drugog Svetsko Rata-Nemаčaka. Beograd.
D. Monday (2006) The Hamlyn Concise Guide To Axis Aircraft OF World War II, Bounty Books.
D. Berliner (2011) Surviving fighter aircraft of World War two, Pen and sword
F.A.Vajda and P. Dancey (1998) German aircraft industry and production 1933-1945, Airlife Publishing Ltd.
J. R. Smith and A. L. Kay (1990) German Aircraft of the Second World War, Putnam
D. Bernard (1996) Heinkel He 112 in Action, Signal Publication
R.S. Hirsch, U, Feist and H. J. Nowarra (1967) Heinkel 100, 112, Aero Publisher
C. Chants (2007) Aircraft of World War II, Grange Books.
A P-51B undergoes testing at a Lockheed reassembly plant in Liverpool, UK. December 1943. [National Archives]Initially developed to provide an export alternative to the P-40 for France and the UK, North American’s P-51 would prove to be a superb aircraft that would rank among the most decisive weapons of the Second World War. With its streamlined airframe and highly efficient cooling system, the aircraft would reach new heights when equipped with the far more advanced Packard Merlin engine. Though its early years would prove troublesome, it would solve long standing issues regarding the lack of long range bomber escorts, and achieve a level of performance beyond its Axis contemporaries.
Interwar Fighter Developments
The Merlin powered P-51’s share the distinction of being among the most successful fighter aircraft ever developed, but also having one of the convoluted development paths of any mass production fighter. While the aircraft would make its first flights in 1943, it had its roots in the late interwar period where many of the technologies it incorporated were first established.
US interwar fighter development saw rapid technical advancement, but a comparatively small build up of planes. Here an XP-40 undergoes wind tunnel testing, the design would go through a number of changes that would result in the P-40. [This day in Aviation]The general environment of interwar fighter development for the US Army Air Corps was one of high theoretical advancement, but comparatively slow practical development. While major milestones were made in regards airframe and powerplant design, there was considerably less urgency to develop and mass produce fighters for use by the Air Corps. This was mostly a result of an isolationist foreign policy, which limited availible resources, and to a lesser degree, a desire within the Air Corps to focus on bomber procurement. While the development of new fighters was limited, the Air Corps had great freedom in procuring aircraft for testing purposes. While funding was still limited, they were allowed to procure up to 14 examples of an aircraft through their budget before they would need to petition Congress for additional funding. While a large build up of the Air Corps during this period was a financial and political impossibility, it would prove sufficient for exploring aircraft design and development. This environment would exist into the late 1930’s as the political situations in both Europe and Asia destabilized, and subsequently, the order was given to continue the development of the XP-38, XP-39, and XP-40 into new fighters for use with the Air Corps (Ethell 9).
While these aircraft were being prepared for service, vital new developments were being made in regards to airframe design. At the National Advisory Committee for Aeronautics (NACA) offices at Langley field, efforts had been made to produce airfoils which could achieve laminar flow. In short, this effect is characterized by minimal disruptions to the airflow of the surfaces of the wings and adjoining fuselage. In the context of fighter aircraft, this allowed for a much lower drag coefficient, which would permit better acceleration and would lessen the instability encountered at higher Mach numbers. They would achieve this by June of 1938 when an airfoil displayed laminar flow characteristics in wind tunnel tests (Ethell 10).
Europe Ablaze
The escalation to and the outbreak of hostilities in Europe would completely dispense with the interwar malaise and saw the US begin a massive arms build up. The most notable shift in policy was President Franklin Delano Roosevelt’s call for 50,000 aircraft in January of 1940. The resulting surge of orders would end up leaving most US aircraft manufacturers at capacity, and though they would satisfy domestic demand, the fulfillment of export orders was not a priority. This represented a serious issue facing the Allies in Europe. At the outbreak of the war, the French and British air forces were still largely in the process of expanding and modernizing. While they both possessed examples of modern fighter aircraft, such as the Dewoitine D.520 and Supermarine Spitfire Mk.I’s respectively, they also employed a large number of outdated aircraft in comparison to the better equipped German Luftwaffe. The expedient solution to this problem seemed to be to purchase aircraft abroad, and the US was by far the best source.
To this end British and French interests were served by the British Purchasing Commission. While they had decided on the ideal candidate being the Curtis-Wright P-40, they found the at-capacity firm unwilling to compromise its contracts to the US Army. They were soon negotiating with other firms for P-40’s which would be manufactured under license, and by 1940 had placed as many orders as they could. It was clear to all parties involved that any of the larger firms that were involved in US rearmament would be unable to deliver any sizable number of aircraft to the Allies. In January of 1940, Oliver Echols, in charge of Air Corps procurement, would suggest to the Purchasing Commission to approach a manufacturer that lacked any major contracts involved with US rearmament (Ethell 10).
This suggestion would see the British Purchasing commission returning to older offers from firms that they had turned down the previous year. The most important of these would be North American Aviation. North American had earlier proposed to build P-40’s under license for the Allies, though the offer was given little consideration (Ethell 10). They were likely turned down over their relative inexperience in the field of fighter aircraft, having previously built advanced trainers, like the AT-6 Texan, and the crude NA-50 and NA-68 export fighters. In spite of this, and finding few options among other US aircraft manufacturers, the British Purchasing commission would once again approach North American. This time however, North American was given the option to either produce license-built P-40’s, or instead to design a new aircraft with the aid of research data acquired from Curtiss-Wright on the XP-46 fighter prototype. NAA’s small, but enthusiastic team would choose the latter, and prepared to design a new fighter built around the Alison V-1710 engine.
Enter North American
North American’s greatest claim to fame before the Mustang was the AT-6, arguably the best advanced trainer of its day. [Wikimedia]By the standard’s of most US industries of the time, North American Aircraft was a fledgling company, though one with great promise. It was originally formed as a holding company in 1929 to purchase stock in other aviation concerns, and was later incorporated under General Motors’ General Aviation branch. As a holding company, North American would gather a considerable amount of resources in these early years, of particular note was the firm’s acquisition of Fokker. In 1934, as a result of new regulations on air mail carriers, General Motors was required to divest itself of North American, which then became an independent firm. Thereafter, North American incorporated its parent company, General Aviation, and continued under the direction of its president James H. ‘Dutch’ Kindelberger (O’Leary 9). He would subsequently take the company west in 1936 where they would open a new facility at Mines Field, California. Prior to the war they would develop the O-47 reconnaissance and observation aircraft, which had begun under General Aviation, and the AT-6 advanced trainer, which was among the most successful designs of its type. They would also produce a set of unsuccessful export fighters which were altogether unimpressive. With this in mind it’s understandable North American was initially passed over, they were in fact, inexperienced in fighter development and their only real foray into that field was a disappointment. However, when the British Purchasing commission returned to the company in 1940, they found the firm more than ready to meet their needs. Their contract was worked out for 400 planes at a price no higher than $40,000 dollars a unit, and spare parts in the amount of 20% of the value of the aircraft.
The first step in developing the new fighter was purchasing the most recent data on fighter design from Curtiss-Wright’s XP-40 and XP-46 prototypes, and acquiring the new breakthrough aerofoil designs recently developed under NACA (Ethell 10, 11). This information was made available to the design team headed by Edgar Schmued, a German born aeronautical engineer who had previously been a GM field service manager for their Brazil branch. The work soon began on a new fighter under the designation NA-50B, later changed to NA-73, under a common and straightforward design strategy. Schmued would work to build a plane that would excel by incorporating all of the most recent developments in fighter design to produce an aircraft that was both cutting edge, yet conventional (Douglas 252). The Curtiss-Wright prototypes were a starting point that was quickly surpassed, with engineer and aerodynamicist Ed Horkey considering the prototypes too dated for use on the new project, and the data was discarded (Forsyth 13). This came as somewhat of a blow considering they were forced to pay about $50,000 for the test data. The same cannot be said for the data acquired from NACA.
Edgar Schmued would join North American through its parent company’s acquisition of Fokker. He would lead the team responsible for designing the Mustang which would be developed continuously through the Second World War. [alchetron]Horkey would come across NACA’s research through a confidential release for American industrial use, and was convinced that it would make an excellent addition to the new fighter’s design. NAA would send a representative to collect the data from NACA at Langley Field, and they would go on to receive minor technical support. While the design did not possess true laminar flow characteristics, it did drastically reduce drag and improve the performance of the aircraft (Ethell 11). Further streamlining was achieved through the mounting of a low drag, centerline radiator which incorporated the work of British scientist, Dr. F.W. Meredith. This divergent-convergent duct was capable of using the heat ejected by the radiator to actually produce thrust and offset some of the speed loss incurred by drag incurred by the radiator’s air scoop (Douglas 252).
Great care was taken to build the prototype in good time. The NA-73X, would make use of a number of components from North American’s AT-6 trainer, including its landing gear, hydraulics, and electrical systems. Remarkably, the construction of the prototype was completed on the 102nd day of the project, but it would have to wait another 20 days for its Allison V-1710-39/F3R engine (Marshall & Ford 94). The supply of Allison engines at the time was constrained, and resulted in the project having to delay its deliveries to the British. Despite this, the fast pace of the program, and the fall of France would see the British order another 320 aircraft before the prototype even flew. With the program approaching testing, the British were awaiting the results and readying their own test pilots to become acquainted with the new plane. The prototype was first flown by American test pilot Vance Breese on the 20th of October, 1940. It would go on to make several more test flights before having to be repaired after an accident with test pilot Paul Balfour. The accident was a result of pilot error, who failed to switch over from an empty fuel tank, and as such the incident did not reflect poorly on the design itself (Marshall & Ford 151). As the sleek new fighter was taking shape, the British Purchasing Commission would notify NAA that the aircraft’s RAF designation was to be the ‘Mustang’ in a communique sent in December 1940 (O’Leary 24).
This prototype NA-73 was delivered to the US Air Corps for testing, though they would not place orders for Mustangs until a later date. [This day in aviation]Among the last modifications to the NA-73 regarded its armament, fuel capacity, and reinforcement of its wings. Several proposals for its armament were considered, but for the British Mustang they installed a pair of .50 caliber guns in the nose cowling with another two .30 caliber guns in each wing. With these last additions made, the British soon received several of the new aircraft, which now bore the more familiar title of Mustang. The first, AG345, would be put through tests to find any issues from the transition from the NA-73. Several issues arose over the stiffness in the ailerons, power surges in dives, and overheating. These were subsequently addressed, though more drastic changes were needed in the case of the engine, which required installing a new carburetor scoop, and altering the scoop for the radiator (Marshall & Ford 165). The culmination of these new changes would result in the finalized Mustang Mk.I, and a second development prototype, NA-83.
While the aircraft’s development was proceeding at a rapid pace for the British, the USAAC would show very little initial interest in the Mustang. The aircraft the USAAC had dubbed the XP-51 was largely overshadowed by other developments and comparatively little effort was made to conduct exhaustive tests on the XP-51 prototypes at Wright Field to correct their faults. Their interest in the aircraft would be piqued only after the U.S. entrance into the second World War.
Mustang Mk. I
In British service the Mustang would take a different developmental path than what was proceeding in the United States. While the British were receiving their Mustang fighter aircraft, the US had been forced to develop the aircraft into a dive bomber, the A-36, as funds for fighter development had been expended for 1942. In the case of the RAF, the Mustang Mk. I went into service as soon as was practicable and saw their first squadrons, numbers 161 and 613, receive supplies of the new aircraft in April of 1942. They would first be employed as reconnaissance aircraft before later taking on more dangerous work during Operation Jubilee in which they undertook offensive recon sorties over the raid area in Dieppe, France. Beyond this they would be subsequently used to fly nuisance raids and fighter sweeps across the low countries. Its long range, high speed, and effective armament were used to great effect over these areas as they harassed rail and road communications, while also remaining quite capable against enemy fighters wherever they were encountered (Ethell 24, 25). Even by this early mark, the once uncertain contract they signed with North American had already paid off.
It was during this period that the aircraft’s faults and strengths would make themselves evident. The nose mounted guns were troublesome and complicated maintenance; they were often removed from operational planes and were eliminated from the succeeding models of the aircraft. The radiator still presented teething issues, as under certain conditions the oil could freeze over and would fail to circulate, and eventually cause the radiator to boil over. Visibility too would become an issue, as the canopy frame of the cockpit severely restricted the pilot’s view. However despite its faults, the plane was fast, possessing good acceleration and a high top speed that made it capable of outrunning all fighters in the theater at sea level (Ethell 24).
The Mustang Mk.I would prove an exceptional fighter with the RAF, if at first, a little rough around the edges. [wikimedia]While the radiator issues would be addressed and a new bubble canopy was developed, another, more serious drawback of the design would require far more resources to address. The Allison engines that the early Mustangs were equipped with were considerably lacking when it came to high altitude performance due to their single stage, single speed superchargers. While the aircraft received good marks for its low altitude performance from pilots in the RAF, above the 15,000ft the Allison V-1710 suffered considerable power loss. Though this was by no means surprising, it represented an area where performance could be significantly improved. At higher altitudes the aircraft was outpaced by both contemporary models of the Fw 190 and Bf 109. At low altitudes, it was made somewhat redundant by the RAF’s new Hawker Typhoon, which both flew faster at low altitudes and was better armed. It wasn’t long until the idea arose to fit the Mustang with an engine possessing better high altitude performance, a combination that might well produce an exceptional fighter that was as capable at high altitude as it was down low (Douglas 253).
The first major step toward this came on April 29, 1942, when Wing Commander Ian Campbell-Orde invited one of Rolls Royce’s test pilots, Ronald W. Harker, to test the new aircraft. Harker was impressed by its performance and he believed that if the aircraft was fitted with the new Merlin 61, it would be able to outpace a similarly equipped Spitfire by a considerable margin (Marshall & Ford 215). The Merlin 61 was the obvious choice for many reasons, chief of which was its two stage, two speed supercharger which stood to offer the plane exceptional high altitude performance. To this end, a Mustang Mk.I was provided to Rolls Royce at Hucknall to undergo the necessary modifications. By the beginning of June 1942, the British had correctly projected that the Mustang’s top speed would be increased to 430mph at an altitude of 25,000ft, which was roughly twice as fast as the Allison powered Mustang at that altitude (Douglas 254). When the test aircraft was complete the results were quite impressive, as during a fly off between a Spitfire Mk. IX and a Mustang, both fitted with Merlin 61’s, the Mustang quickly outpaced the Spitfire.
Across the Atlantic, a parallel development began underway after a study of the Mustang’s combat debut with the RAF. The new United States Army Air Force, no longer constrained by funding, rushed to acquire supplies of the Mustang, and sought to re-engine the fighter to improve its high altitude performance. To this end, two P-51’s were set aside for conversion. By the early half of the Summer of 1942, both British and American Mustang experiments were underway. While the Mustang was previously seen as a side project which was never a wholly American or British effort, it was by then extremely clear that the design had tremendous potential and the development of which was of immense importance to the Allies.
Shoeing the Mustang
Orders for various Mustang types for the USAAF would begin in 1942, including this P-51 armed with four Hispano 20mm cannons. These orders were quickly overshadowed by developments to get the Packard engine into the aircraft. [Wikimedia]Re-engining the Mustang was by no means an easy task, as the Merlin was considerably heavier than the Allison and required a larger cooling system. To achieve this, the radiator was reworked, with the oil cooler moved apart from the radiator matrix to a forward position, and the ducting of the entire scoop assembly being redesigned. Earlier aerodynamic and buffeting issues caused by the radiator intake were also resolved by moving the scoop out of the boundary layer under the fuselage. The resulting set up would also achieve the earlier described Meredith effect, which produced thrust that offset the drag caused by the scoop (Marshal & Ford 97, 219). Additionally, the carburetor’s intake duct was moved beneath the nose which also necessitated lowering the wing to accommodate the lower cowl.
In addition to higher cooling requirements, the new Merlin engine weighed 350lbs more than the Allison and would mount a larger, heavier propeller, which would represent a significant shift in weight. To compensate, 61lbs of ballast was added, the primary fuselage longerons were strengthened, and the wings were strengthened and moved lower and forward. These changes would also help to compensate for the stronger vortex generated by the propeller and the greater forces generated by the improved ailerons (Marshall & Ford 219). The new engine and the subsequent operations would also result in some yaw instability. Adding a fin ahead of the horizontal stabilizer seemed an adequate solution, but it would not be undertaken until far later.
While the testing for most of these modifications was done through a variety of converted air frames, the prototype that brought them all together was the XP-51B, which first flew on October 1, 1942. The importance placed on this aircraft was considerable, as several months prior, a large order for 1200 P-51A’s was placed by the US government on the provision that their production could be switched for P-51B’s, given advanced notice (Marshall & Ford 230).
The first of two XP-51B’s would be ready in October of 1942, however, a long and difficult development process would delay serial production until the summer of the following year.[Thisdayinaviation]The XP-51B would prove promising but it was troubled by radiator issues which would remain with the aircraft through January of 1943. These were tracked down to a chemical reaction which was found to be degrading the coolant tubes, and was resolved by a lacquer liner. There were also air flow issues within the radiator, which were solved through moving its aftercooler core to improve airflow through the scoop. The prototype’s last major issue was the tendency for its air scoop to produce loud, and worrying, vibrations at high speed. Resolving the problem once again required them to change the geometry of the scoop (Marshall & Ford 258, 311). This was solved by the aforementioned modification that moved it out of the boundary layer below the wing, and further improved as the depth of the gutter was increased and the inlet size was reduced (Matthews 7).
Most of the issues with re-engining the P-51 involved its cooling systems and air scoop, which were revised several times. [NACA]All of the production models of the Merlin powered P-51’s would fly with engines produced under license by Packard. It was a matter of good fortune that Packard was already engaged in the mass production of their version of the Merlin engine prior to the demand for the engine for the new Mustangs. Packard had built its first V-1650-1’s, a license built Merlin 28, in August of 1941 which were later destined for use in Canadian built Avro Lancasters, DeHavilland Mosquitos, and the updated Curtis Wright P-40F (Marshall & Ford 176). Changing production to suit the needs of the P-51B would however not be easy, and matters were made worse by a general strike at the main plant which, alongside slow development at Wright Field, made for considerable delays. Some of the supply issues would be addressed as the new Mustangs would receive the first priority in terms of supplies, superseding the P-40F and L, and denying its use on the P-38. However, beyond these were the predictable teething troubles, and combined with the less predictable hurdles, they saw widespread deployment of the P-51B delayed considerably. Packard would go on to supply North American with engines, however they would never fully be able to meet the massive demands of both the United States and Great Britain (Marshall & Ford 347).
My Kingdom for a Horse
While development on the Merlin powered P-51’s proceeded, the USAAF had formulated and launched a strategic bombing campaign dedicated to destroying industries vital to the German war effort. The theoretical foundations of this strategy had been set in the interwar era and were initially seen as a means to expand the Army Air Corps into a force with greater autonomy. Many early interwar theorists, such as Maj. Harold George, would describe a vague ‘economic web’ that could be destroyed and force an industrial and morale collapse, but in 1943 these theories were put to the test. The practical details of the campaign were laid out at the Allied conference at Casablanca. There a series of targets was decided upon, but later altered to a plan that favored targeting aircraft and submarine production, in addition to ball bearing plants (Overy 45, 305). However, the main concern for USAAF bombing operations was that thus far, all daylight strategic bombing campaigns had ended in failure after formations of unescorted bombers were shredded by fighters.
The USAAF bombing campaign against Germany began in earnest in early 1943, it was based on a number of untested theories which planners hoped would bring an early end to the war. [National Archives]Since before the war, it was commonly believed among the Air Corps senior officers that a formation of well armed bombers was capable of defending itself from whatever threats it might face. This assertion would be disproven, as even the small raids against targets in France and the low countries sustained casualties that made consistent raids impossible. In early 1943, the next step of the campaign would be far more ambitious, moving on to targets deeper within Germany itself. The need for a long range escort fighter had already become apparent before this point, and work was underway to produce external fuel tanks for existing fighters, but the offensive would be continued without a fighter aircraft able to accompany raiders for the full duration of their missions.
Throughout the summer and autumn of 1943, the USAAF would launch numerous raids against targets in Western Germany, though the bombers could only be escorted over the low countries by P-47’s and P-38’s. It wasn’t long until these range limitations were understood, and soon after, exploited by the Luftwaffe. Wherever Luftwaffe fighters were untroubled by Allied fighters, they were free to make use of their most effective anti-bomber tactics.
Generalmajor Adolf Galland’s prescribed method of attack for single engine fighters was to make head on, or oblique, attacks from slightly above the bomber formation, carried out by at least a Schwarm, or two pairs of fighters (Marshall & Ford 267). This achieved two things, it increased the closure rate to reduce the likelihood of being hit by defensive gunners, and it was from this position that both the pilot and copilot of the bomber were most vulnerable. In the absence of escort fighters, Luftwaffe pilots would be able to regroup, fly ahead of the formation, climb, and repeat the attack. The lack of escort fighters also meant the Luftwaffe was safe to employ its two engined fighters against bomber formations, which with their heavier armaments, were much better equipped to bring down bombers. Over time their tactics grew even more complex as dedicated aircraft, typically Ju 88’s, were tasked with shadowing bomber formations to pass their altitude, course, and speed to flak and fighter control services.
Many Luftwaffe aircraft would be re-equipped to take on heavy bombers, like this Bf 109G-6 with its underwing 20mm gun pods. [Bundesarchiv]Prior to the arrival of the P-51’s, the USAAF had two suitable fighters for the purposes of escorting bombers at high altitude, the P-38 and P-47. While they had the high altitude performance, they did not have the range to reach deep into the continent. The issue would be partially resolved through the addition of external fuel tanks, which had been discussed at a conference with the Material Division at Wright Field in March of 1942 (Ethel 51). Work however, was slow and the 108 and 75 gallon drop tanks were not delivered in large numbers until the end of summer, 1943. These tanks would allow the shorter ranged P-47 to be able to cover bombers over their flight over the low countries, and the P-38, over the Rhineland. It should also be noted that the escort range was considerably lower than the maximum combat range of the aircraft, as the planes flew in a zig-zag pattern overhead so as not to out pace the bombers. Supplies of larger volume fuel tanks which would take the fighters further into German air space would not be available until the spring of the following year. External fuel tank development and procurement had been mismanaged by Army Air Force leadership who were still largely convinced that the bomber’s defensive capabilities were adequate. Had there been a greater supply, and larger volume tanks initially available, the P-47 and P-38 could have escorted bombers over most of Germany. To make matters worse, the P-38, which by then handled the most important leg of the trip, was troubled by a number of technical issues. While the P-38 possessed good high altitude performance, an exceptional climb rate, and a heavy armament, it was handicapped by a cockpit that pilot’s rated the worst of any US fighter in service and had flying characteristics that made it difficult for pilots to aggressively pursue Luftwaffe aircraft (Dean 164). The large, twin engine Lightning also had an unmistakable appearance, such that Luftwaffe pilots would almost always spot and identify the Allied plane before Lightning pilots could do likewise. With this benefit, Luftwaffe pilots were typically the ones who dictated the engagement, and would depart when conditions were unfavorable. On the defense they would have another advantage, both the Fw 190A and the Bf 109G were capable of out maneuvering the P-38 in high speed dives. The P-38 encountered severe compressibility issues at speeds significantly lower than those encountered on the two German fighters (Marshall & Ford 441). Thus, while the P-38 was capable of performing long range escort missions, its pilots would be forced to employ more conservative tactics than those used in the P-47.
By the start Autumn of 1943, USAAF planners were hoping to accelerate their progress on Operation Pointblank. This plan would see bombers raid targets that were vital to the German aviation industry in order to achieve air supremacy over Western Europe before an invasion of the continent. While losses for these raids were still extremely high, it was hoped that dispatching a larger force capable of inflicting serious damage would make it worth it. On August the 17th, the 8th Air Force prepared for its largest raid yet, with 376 B-17’s dispatched to attack the ball bearing works, at Schweinfurt, and a Messerschmitt factory, at Regensburg. Both of these facilities were located deep within Germany and most of the journey would see the B-17’s outside the area where they could be escorted. To compensate for this, the flight over Regensburg would continue over the Alps and into Allied controlled Tunisia. It was hoped that flight over the Alps would prove easy, and in the case of the Schweinfurt force, they believed that the German fighter squadrons would still be on the ground refueling after their first attacks while the bombers made their return. Both would be met with disaster as the Luftwaffe would hit both forces after their escort fighters turned for home, and the Luftwaffe fighters had taken to the air again as the Schweinfurt raiders made the return trip.
The bombers of the USAAF flew in staggered formations in order to maximize the the defensive capabilities of the aircraft. These tactics alone proved totally inadequate to protect bomber formations from fighters and were revised several times to compensate for flak. [National Archives]Of the 376 bombers to leave England, 60 would be shot down, 176 were damaged, and 30 remained in North Africa where they awaited repairs at the overburdened facilities in Tunisia. Losses in combat and written off airframes amounted to 31% of the dispatched force; in contrast the Germans lost only 28 fighters (Overy 340, 341). Following the disaster, the 8th Air Force would carry out raids only where there was full escort cover and the next deep incursion into German airspace would only be conducted in the spring of the following year. The winter of 1943 would spell uncertainty for the campaign, as it was clear that for all intents and purposes, much of German industry lay beyond striking range. With this limitation threatening to seriously cut back the USAAF’s campaign, they would request that Lockheed, Republic, and North American increase the internal fuel capacity of their fighters, and hoped that a suitable long range escort would materialize.
Leaving the Stable
Col. Charles McCorkle, 15th AF with pilots. The P-51B proved the solution to the problems plaguing the ailing strategic air campaign. [National Archives]As a result of the pressure to produce new, long range fighters for the escalating campaign in Europe, the first P-51B’s were produced before the prototype had gone through its testing and modification cycles. The first plane, a P-51B-1, was completed March 31, 1943 and would include several features that would later be found unsound on prototype. As a result, these initial planes would have to be altered accordingly and would have many parts that were non-interchangeable with later models (Marshall & Ford 316). In addition to reworking the air scoop and radiator, they would also have their ailerons modified, both to improve their effectiveness and to remove a steel diaphragm which would interfere with the plane’s magnetic compass. Most importantly, the decision was made that the aircraft would incorporate an additional 85 gallon fuselage fuel tank which would provide the aircraft with phenomenal range.
With this new aircraft, the USAAF would finally possess what they had been searching for. With the addition of the new internal fuel tank, the aircraft would be capable of deep incursions into German airspace, and it would deliver on what was promised back in the spring of 1942. They were excellent fighters, especially at high altitude. The early P-51B’s would use the Packard V-1650-3 engine, a license production of the British Merlin 61, which produced 1410 hp at 29,300 ft and 1630 hp at 16,400ft at War Emergency Power (P-51 operation manual 31). This engine would later be replaced with the Packard V-1650-7 in later models of the aircraft, which was geared for better performance at medium altitude. These engines, combined with the low drag fuselage and laminar designed wings would provide the aircraft with a superb climb rate, a high top speed at altitude, and exceptional high speed maneuverability.
While the aircraft had taken a largely completed form with the P-51B-5 and P-51C-1, it would be continuously modified in the field and on the production line, throughout its service with the air force. The most notable of these changes were the additions of a fuselage tank, booster motors for its ammunition belts, a vertical fin extension, and field retrofits for a perspex canopy dubbed the Malcom Hood. However, only the 85 gallon fuel tank would be a universal addition.
The fuselage tank would enable the P-51B’s to reach much of central Europe from England, but it was not present in the first deliveries of the aircraft, as was the case with the 59 P-51B’s active in England at the end of November 1943. The installation kits were first sent out in September of 1943, and the tank was later incorporated into the production run with the first long range P-51B being accepted by the Army in December of the same year (Marshall & Ford 393, 407).
The next addition to the aircraft was intended to solve a major issue with the plane’s machine guns, which were found to be prone to jamming when the pilot pulled turns of over 1g. This issue was a result of the canted position of the guns in the wings which put stress on the ammunition belts. The ideal solution was to reposition the guns, but seeing as that would necessitate a considerable redesign, engineers would instead work in a stop gap measure in the form of boost motors for the ammunition belts. These were issued as kits like the fuel tank, though unlike those for the fuselage fuel tank, they were issued in more limited numbers and the issue persisted well into 1944 (Ethell 64).
The Mustang had long had a tendency to yaw in the opposite direction of a roll, which affected its handling since its earliest models, and this was made significantly worse when fuel was carried in the fuselage tank. Despite the problem being an evident and considerable inconvenience, its solution wouldn’t materialize until much later. Eventually, it was decided to fit the aircraft with a fin extending from its vertical stabilizer, along with adding reverse rudder boost tabs. However, these kits arrived very late, having begun production in April of 1944, and later incorporated into the design of late P-51C’s and the subsequent P-51D (Marshall & Ford 306).
The Malcom Hood provided far better visibility than the earlier ‘birdcage’, and was added to a number of P-51B’s based in Northern Europe. [National Archive]Many long standing issues revolved around the ‘birdcage’ canopy of P-51 since the aircraft’s inception, and as was the case with the engine, an improvement was found in British service. With the RAF, many Mustangs received a new frameless bubble canopy. This canopy vastly improved visibility, especially to the rear of the aircraft, which was virtually non-existent from within the birdcage, and it could be drawn back on landing and take-off. Dubbed ‘Malcom Hoods’ after their manufacturer, a plexiglas works named Robert Malcom Ltd. they were subsequently sought after by the USAAF for use with their P-51’s in Europe.
Breaking the Stalemate
The new P-51B’s would make their first major debut with the 8th Air Force in early 1944, though the introduction was not as smooth as had been hoped. Squadrons reported a number of issues with the new aircraft, which included high altitude fuel transfer failures with external tanks, glycol reserve tanks that leaked and froze, radiator corrosion and coolant leaks, radios and spark plugs failing, and excessive oil loss (Marshall & Ford 425). However the USAAF hadn’t the time to immediately resolve these teething issues, and with these problems passed along to the manufacturer and Air Force maintenance services, the P-51’s would soon play a key role in the escalating bomber offensive.
Through the winter of 1943, both the day and night bombing campaigns were facing withering losses which spelled serious trouble for maintaining the pace of operations over Europe. With less than one thousand bombers stationed in England, the USAAF would lose 200 in September alone (Douglas 326). In the face of these losses, the Combined Bomber Offensive was failing to carry out the Pointblank directive, which aimed to cripple the Luftwaffe before an invasion of Europe was conducted. During this period the Luftwaffe had actually built up the strength of its fighter force and had reorganized and improved its defenses into a centralized command structure. To make matters worse, the head of RAF’s Bomber Command, Arthur Harris, would ignore orders to attack German industries involved in aircraft production. Instead, he would order Bomber Command to continue to carry out an ineffective area bombing campaign of Germany’s cities believing it would bring an end to the war without the need for an invasion (Overy 343, 344). It was under these bleak circumstances that the US’s Eighth and Fifteenth Airforces were tasked to cripple the Luftwaffe and establish air superiority over much of Europe before the invasion, now only a few months away. However, they would soon see a change in leadership and the delivery of new equipment that would put them on the path to controlling the skies over Europe.
Escort fighters typically flew a few thousand feet above their charges when they weren’t independently seeking the enemy. They weaved back and forth over the bombers in order to not speed past them. Here a flight of four P-51’s flies overhead at roughly 30,000 ft. This tactic declined in use when the relay system came to prominence. [National Archives]In December of 1943, the USAAF established a joint strategic air command to consolidate their bomber forces over both the European and Mediterranean theaters, and drive them towards a unified objective. With Gen. Spaatz in command of all strategic bomber forces, and Maj. Gen. James Doolittle in command of the Eighth Airforce in England, the USAAF would now have clear strategic direction, and more aggressive leadership. Doolittle would take a pivotal role in revising the existing strategy into one which proved instrumental in undermining, and dismantling the Luftwaffe in the coming weeks. Crucially, he recognized the inadequacy in trying to undermine the Luftwaffe’s fighter strength solely through targeting the production of new aircraft. To hold to this existing, overly conservative strategy was hopeless, and the invasion of France was scheduled for five months after he took office. Targeting the factories alone wasn’t enough, and thus Doolittle would give the order for returning escort fighters to perform fighter sweeps and seek out enemy planes in the air and on the ground (Overy 361). Among the first and most important moves was to create a more effective relay system for the fighters, further increasing the time they could spend over enemy territory.
By the start of 1944, Maj. Gen. Kepner, 8th Air Force, would also play a major role in implementing this new strategy, as he officially untethered the Eighth’s fighters from the bombers and allowed them to seek out the enemy at their discretion. The P-51 would play a pivotal role, as its excellent high altitude performance and range meant it was able to take up the last position of the fighter relay, and was more than a match for whatever it found. Beyond the existing penetration, target, and withdrawal relay positions, the P-51 was also able to take up a fourth mission. These units would perform sweeps 50 to 70 miles ahead of the bomber formation and attack German fighters as they were climbing, assembling, or transiting towards the bomber formation. Their efforts were greatly aided by British signals intelligence services that provided the assembly points for the Luftwaffe’s fighter groups (Marshall & Ford 425, 425; Overy 362).
This change in tactics would have immediate and profound impacts as they began to be widely implemented in February and March of 1944. The first major achievement of the new strategy were the widespread losses inflicted on the twin engined fighter forces, which had earlier proven themselves as potent anti-bomber weapons. Against the new long range fighters, they were almost defenseless, and were withdrawn in March (Overy 366). Similar effects were felt throughout the Luftwaffe’s fighter forces, which thanks to the new P-51’s, were left without any safe haven. Whenever the bombers were over Germany, their escort fighters could make their appearance. While the new strategy often meant that the bomber formations were often less protected, this was counterbalanced in that it placed the German fighters on a defensive footing. The days of Luftwaffe fighters leisurely climbing alongside a formation before diving at it head on were over, now whenever they reached a formation they were forced to conduct hit and run attacks, or face off against the escorts.
Luftwaffe attrition escalated as airfields that were once ignored were now periodically harassed by fighters that attacked transiting and grounded aircraft. Doolittle did all he could to promote these attacks, and would allow for the destruction of aircraft on the ground to count towards a pilot’s ace status (Marshall & Ford 423). These attacks would prove costly to the USAAF, but well worth it as Luftwaffe operational losses for all aircraft increased sharply and it robbed them of the ability to train new pilots in secure airspace. This shift in strategy and subsequent success would prove instrumental to the USAAF in the following months, as their responsibilities were soon to broaden when the Allies landed in France.
When equipped with external fuel tanks, the P-51B could operate over any part of Germany. This proved disastrous for the Luftwaffe as transiting aircraft and those on the ground were now vulnerable, no matter how far they were from Allied air bases. [National Archive]While the Eight and Fifteenth air forces were still occupied with the task of destroying the Luftwaffe in the air and on the ground, they would soon be given additional missions. The most unexpected of which came in the form of Operation Crossbow, which called upon the Eighth Air Force to disrupt Germany’s use of the new V-1 bomb from coastal bases. Then came the task long awaited, which called upon the Eighth to begin the preparations for Operation Overlord. To meet these new objectives, the Pointblank raids were accelerated, culminating in ‘Big Week’ in February of 1944.
Between the 19th and the 26th, the Eighth and Fifteenth air forces would fly roughly 6,200 sorties against 18 aircraft assembly plants and two ball bearings plants, at a loss of 247 bombers and 28 fighters. Undoubtedly steep, but sustainable in comparison to the Luftwaffe which lost roughly one third of its single engine fighters (Overy 369). The success of the raids themselves was difficult to judge, as fighter production still increased, though at a significantly reduced rate which saw a shortfall of roughly 38.5 percent (Overy 370). During these operations the P-51 would provide the USAAF deep penetration cover and perform strafing attacks against German airfields. However, there weren’t enough long range escorts for full coverage until the summer of 1944. The situation was further complicated when all P-51B’s were grounded between the 10th through the 15th of March in order to address structural issues with the aircraft’s engine mounts, wings, and tail. These were subsequently resolved by replacing the retaining bolts for the engine, reinforcing the tail empennage and ammunition doors, and installing landing gear locks to prevent their uncontrolled release at high speed (Marshall & Ford 442, 446). These issues would however not present a long term obstacle during the early months of 1944 as the tempo of operations and list of targets grew in the following months.
With the major push against the German aviation industry mostly over, the USAAF would soon set its sights on two major targets, rail communications across much of Northwestern Europe, and Germany’s oil industries. The first was an immediate necessity for the success of Operation Overlord, crippling German strategic mobility was essential for an invasion which would require considerable time after the first landings to build up a force on the continent. The formalities were worked out in March when the Transportation Plan was decided upon. It would fortunately have the support of RAF Bomber Command, as Harris’s evident failure to end the war on his terms would see him temporarily divert his force into supporting the preparations for the invasion of France. The subsequent offensive against fuel production would start far less formally. Spaatz was convinced of its necessity, but due to the months it would need to take effect, he was at first unable to convince his superiors to divert resources to it. However, in a matter of weeks, he was able to argue for its necessity under the Pointblank Directive and was then allowed to conduct attacks against Germany’s synthetic fuel industry whenever resources permitted (Overy 371).
Between the now crippling fuel shortage and marauding allied fighters, the Luftwaffe soon found themselves completely overwhelmed by the autumn of 1944. Here a P-51 lines up on an He 177 heavy bomber, as the one beside it continues to burn. [National Archives]With these new policies in place, the Luftwaffe would be thoroughly disrupted as a result of Spaatz’s strategy, and Doolittle and Kepner’s tactics. The USAAF would end up inflicting punishing losses on the Luftwaffe in the air, disrupting the manufacturing of new aircraft, and eventually causing chronic fuel shortages that severely limited their ability to conduct large scale operations of any kind. In this, the P-51 would prove essential with its exceptional high altitude performance, and its endurance that could take it anywhere over Germany.
In many ways, the bombing of factories alone was a largely ineffective means of inflicting serious damage to the German war economy, as many industries proved to be exceedingly resilient. Fighter production proved a particularly difficult target, as apart from the later targeted aero engine industry, production and final assembly plants could be dispersed and were largely safe from raiders. When fighter production was further streamlined and resources were diverted to support it, Germany would end up vastly expanding fighter production during the period in which those industries were the most frequently raided (Zeitlin 59). This was, however, was achieved only by reducing the rate of modifications and improvements, and transferring resources away from the production of bombers. In comparison, the later targeting of fuel production and rail transportation proved key, as the inability to reliably move material by rail combined with chronic fuel shortages proved a fatal military and economic obstacle. As a result, establishing air supremacy over Western Europe before Operation Overlord was as much an achievement of long range fighter operations as it was of the bombers. The Luftwaffe could sustain itself when aircraft deliveries did not meet expectations, but it quickly found itself struggling when it lost scores of pilots and found itself hard pressed to train new ones once they had lost control of the skies over Germany.
Pre-war military theorists envisioned fleets of bombers destroying vital war industries with the near pin-point accuracy they achieved in controlled tests. The reality of the campaign revealed this as hopelessly optimistic when even the most accurate raids resulted in large amounts of collateral damage. [National Archives]In the end it must also be said that the civilian costs of the raids were steep, and while the Eight and Fifteenth Airforces were not involved in a campaign directed against the civilian populace, as was the case with Bomber Command and the USAAF elsewhere, the technical limitations of the time meant that bombs frequently fell on civilian areas. Even under ideal circumstances, the dimensions of a bomber formation were larger than their targets and it was physically impossible to strike factories, railyards, and refineries without causing significant damage to the surrounding area. The realities of the campaign would also prove worse than predicted. Targets were frequently obscured by bad weather and smoke generators, and formations typically took heavy anti-aircraft fire on the approach. As a result, bombs were often released by the best estimate from the bomb sight or at the direction of a ground mapping radar system (Overy 347). Even outside of Germany, the civilian costs of these operations were heavy as the Allied air forces carried out the transportation plan. In France alone, between March and June of 1944, French officials placed the figure of civilians killed by Allied bombing at 25,266 (Overy 574).
The 4th Fighter Group ‘Debden Eagles’
When the US entered the Second World War, few American airmen had any combat experience, with the notable exceptions being volunteer airmen in service with foreign armies. The Debden Eagles were one such group, having volunteered to serve with the RAF and entered service in late 1940 and 1941. While they were among the few Americans fighting against Nazi Germany at the time, they had garnered a somewhat unfortunate reputation as glory-seekers and primadonnas thanks to their unique position (Bucholtz 6). Their tendency of excessive overclaiming of victories during this period would prove particularly irritating to their superiors. With the US entry into the war, the Eagle squadrons, and their Supermarine Spitfires, were subsequently integrated into the USAAF.
Capt. Donald Willis, an Eagle Squadron pilot alongside a Spitfire Mk V, late 1943. [National Archives]The RAF’s 70th, 121, and 133 Eagle Squadrons would become the 334th, 335th, and 336th Squadrons of the 4th Fighter Group on the 12th of September 1942. These units flew Spitfire Mk IX’s and within the month were supporting the nascent bomber offensive which was targeting installations in France. The start of this effort went poorly, when only one aircraft out of a twelve plane flight returned, the rest having been lost to enemy fighters, harsh weather conditions, or having run out of fuel in the short range fighter. Thankfully for the Group, this would be their worst day of the war. Despite this setback, the unit saw its first major mission carried out on the 20th of October in the Calais area escorting B-17’s carrying out a high altitude raid. This would be the first major bomber operation carried out under escort and was met with success. Their Spitfires would prove a very capable fighter aircraft, but their short range rendered them unable to conduct escort missions far beyond the English Channel. In any case, this wouldn’t prove much of an issue, as for the rest of the year as they would mostly conduct fighter sweeps across the low countries and provide convoy cover (Bucholtz 9). However, with the changing of the year, the 4th would exchange their venerable Spitfires for new P-47’s.
The 4th FG flew their Spitfires in combat for the last time on April 1st, 1943, after which they completed the full transition to P-47C’s. This change was not viewed favorably, as most of the unit’s pilots disliked the considerably heavier Thunderbolt (Marshall & Ford 340). The changeover had little initial impact on operations, and the squadron was largely involved in the same missions as before. However, the group would later accompany bombers on deeper raids into Europe thanks to newly issued external fuel tanks for their P-47’s. They would use these new 200 gallon fuel tanks on an escort mission into Ghent on July 25th and soon after their first foray into Germany airspace over Westhoff-Emmerich. It should be noted that these fuel tanks were a rare piece of equipment at the time and the 4th only had them thanks to the efforts of Lt. Col. Cass Hough of the 8th Fighter Command’s technical section. They were, unfortunately, as troublesome as they were vital, often failing to transfer fuel above 20,000, and were later withdrawn as British made paper 108 gallon tanks became more available (Marshall & Ford 411).
Despite their complaints, the 4th FG’s veteran pilots would master their new planes and had put them to good use. In a battle defending a formation of B-17’s over the city of Utrecht, the 4th FG was credited for the destruction of nine enemy aircraft at the cost of one of their own, with the pilot having bailed out over the occupied Netherlands (Bucholtz 16). With their P-47s, the 4th would take up an important supporting role in the escalating bombing offensive, one which saw their longer ranged P-47s making more flights into the German frontier. This tempo and the 4th’s change in command under the more aggressive Lt. Col. Don Blakeslee would see the unit become among the most successful in the entire USAAF.
Col. James Matthew Blakeslee would lead the 4th FG from January to November 1944, after which he remained on the ground after several high profile pilots of the USAAF had been lost in a short period of time. He is pictured here receiving the Distinguished Service Cross from Supreme Allied Commander in Europe, Dwight Eisenhower. [National Archives]Lt. Col. Blakeslee was made C.O. of the 4th with the turn of the year, and in addition to bringing new, more aggressive tactics to the table, he would work to ensure his unit was re-equipped with the new P-51. Blakelsee would meet personally with General William Kepner and argue that his squadron would be the best candidate for refamiliarization with the new plane as their experience with the similarly-engined Spitfire would make for an easier transition. Kepner was convinced, and subsequently put the 4th FG at the top of the list for P-51’s. The schedule for the transition was harsh as they continued to fly combat missions in their P-47’s while also familiarizing themselves with the new aircraft. The process was time consuming and they would not make their operational debut with their new planes until February 28, 1944 (Marshall & Ford 432). These Mustangs would nearly double the combat range of the unit, and the pilots favored them over their older P-47’s, but they experienced a variety of harsh teething issues and mechanical failures.
While the conversion was taking place, the 4th would be committed to Doolittle’s more aggressive strategy against the Luftwaffe, with the aim to achieve aerial supremacy over Western Europe before the invasion of France. As such their independent actions increased, and on January 31, 1944, they would join the 355th FG in bombing the Luftwaffe’s airfield at Gilze-Rijen (Marshall & Ford 425). In many ways this mission bore some similarity to the fighter sweeps they had conducted since they had flown with the RAF, but it would mark a first in that direct assaults on Luftwaffe airfields would then become more commonplace. Among the last major actions the unit would perform with its P-47s was its support of ‘Big Week’.
Their first combat mission in the new planes was fairly uneventful, on February 28, when flying as escorts for a formation of bombers attacking a V-1 launch site they encountered no enemy aircraft but strafed a Ju 88 on their way home. They would claim their first aerial kills two days later during a bomber withdrawal support mission near Frankfurt where they claimed two enemy fighters (Bucholtz 38). The following day the unit would help achieve a major milestone, the first fighter escort operation to Berlin and back. The operation would prove anything but easy, as deteriorating weather conditions saw most of the aircraft involved turn back. However, elements of the 3rd Bomb Division would press on, supported by the 4th, 55th, 354, and 363rd FG’s. The 4th would engage a formation of roughly 60 Fw 190’s and Bf 110’s northeast of Wittenberg in the day’s first encounter with the enemy. They claimed five victories but suffered one loss from enemy fire, and another as a result of a radio failure which made navigation across a storm in the English channel impossible. The pilot was later forced to ditch his aircraft in France after a failed attempt to reach neutral Spain (Marshall & Ford 439, Bucholtz 39).
Capt. Don Salvatore Gentile was among the leading aces in the 4th FG. He was credited with 21 aerial and 6 ground victories, though his combat service ended after a botched aerobatics stunt in front of assembled members of the press. He was grounded and went on a tour to raise war bonds, later becoming a test pilot. [National Archives]Perhaps the most exciting encounter that day was experienced by Capt. Don Gentile and Lt. John Godfrey, both aces in the 4th. The two pilots were unable to join the rest of their flight as a result of extremely poor weather, but proceeded with their mission regardless. En route the weather would clear, and reveal a flight of roughly 50 Do 217 night fighters, pressed into service as daylight bomber destroyers, and dozens of Fw 190’s which were preparing to attack a nearby formation of USAAF bombers. The pair would decide to attack, in order to disrupt the enemy formation and prevent them from engaging the nearby bombers from an advantageous position. Gentile and Godfrey dove on the night fighters, damaging one and sending the group diving in an effort to escape. The engagement turned into utter chaos as the single-engined fighters joined in. In the confusion, the pair of aces would claim one enemy aircraft in a series of defensive fights that eventually saw them make their escape through the clouds. Flying on instruments and practically lost, they made their way back to England by their intuition, landing at RAF Hurn (Bucholtz 40).
The unit would return to Berlin on March 6 in support of a massive 8th Air Force operation. Favorable weather conditions would allow the 8th to dispatch a force of 730 bombers against a series of targets in and around the German capital, where they would meet the Luftwaffe in the largest air battle of the war up to that point. The 4th, led by Col. Blakeslee, would be tasked with escorting the bombers, which would prove a difficult undertaking, with the sheer number of opponents forcing the group to disperse into individual flights and sections to expand their coverage. The unit would be credited for the destruction of 15 enemy aircraft of the 45 claimed by P-51’s that day, in exchange for five losses. In comparison, P-47 units were credited with 37 kills for 5 losses, and P-38 units brought down three units at the cost of three of their own. It should also be noted the P-38’s comprised the minority of the fighters, while there were roughly twice as many P-47’s as there were P-51s. The USAAF would claim a total of 83 ‘confirmed’ enemy aircraft with the Luftwaffe having recorded the loss of 75 fighters (Marshall & Ford 439; Bucholtz 43, 45). The majority of these kills were twin engine and night fighters pressed into daylight service. This engagement, while not representing a distinct turning point, did demonstrate a noticeable shift in the war over Germany. Of the 672 bombers that proceeded with the mission, 69 failed to return, and 6 were written off. These were certainly heavy losses, but were a fraction of the nightmare that the Allies were facing in the summer and autumn of the previous year. Beyond that, Luftwaffe losses were mounting both in the sky and on the ground, and the use of its heavier, twin engined bomber destroyers had become untenable in the face of agile new opponents.
D-Day
During the first day of Operation Overlord, most fighter units were dedicated to countering a Luftwaffe response that never came. Several would go on to attack inland targets. [National Archives]Over the coming weeks the 4th would continue to support the bombing campaign, but in June of 1944 they would participate in something far more decisive. The group would be among the many fighter units providing top cover for the invasion of Normandy. Throughout D-Day, each of the unit’s three squadrons would operate independently and continuously until nightfall. The day began with the 334th and 335th squadrons undertaking an offensive patrol under the command of the unit’s C.O., Col. Blakeslee, between 03:20 and 09:45 over Rouen, France. The patrol found no enemy fighters and sought out targets of opportunity, in their case a pair of locomotives that they strafed with their machine guns. Their only loss was 1st. Lt. Fraser, who had lost contact with the rest of the squadron and was subsequently downed by German fighters and taken prisoner. The 336th would sortie at 06:42 to provide cover for warships shelling the landing areas, which proved uneventful (Bucholtz 84).
At 11:20, the 334th would sortie again to Rouen with one section carrying bombs. They would attack a troop train to poor effect, though an encounter with a flight of 10 Fw-190 near their airfield at Evreux proved more successful. In the ensuing battle the 334th was credited with the destruction of four enemy fighters, with the only damaged P-51 making it back home. While this confrontation was happening, the 335th had attacked the marshaling yards at Fleury. The 336th would fly for the last time that day at 13:35 conducting a fighter bomber sweep near Evraux. They would find no targets and would lose an aircraft to ground fire, with 1st Lt. Freiderick being taken as a PoW. The last mission of the day would see the 334th and 335th conduct attacks against a radar station and a road convoy near Rouen. While successful in their mission, they incurred heavy losses when elements of the unit were attacked by around 15 fighters belonging to JG 2 and JG 26 as the US fighters attacked infantry positions.
Capt. Winslow Sobanski was a Polish infantryman at the outbreak of the war, eventually finding his way to the US where he then joined one of the Eagle Squadrons. He was among those killed in action during the group’s last sortie on D-Day. Pictured here in a P-47. [National Archives]The day would prove exhausting, with pilots flying up to three missions from dawn to dusk. Between flights most of the 4th’s pilot’s would rest, usually either having coffee or trying to get some sleep in before their next mission. The different squadrons would also find themselves having vastly different experiences, with the 336th having spent most of the day covering the invasion force which the Luftwaffe hadn’t the strength to attack, and taking part in a fighter bomber sweep that found no worthwhile targets and saw one aircraft lost to flak. In comparison, the 334th and 335th spent the entire day conducting offensive sweeps which claimed a number of targets, but also saw them sustain higher casualties than any of the other US fighter squadrons over Normandy that day with ten fighters lost (Bucholtz 82, 83).
Shuttle Mission to VE-Day
Following the success of the landings, and subsequent breakout in Normandy, many of the USAAF fighter units would take on tactical missions in support of the armies in Western Europe, in addition to the ongoing strategic air campaign. However, some P-51 units were selected to participate in an escort mission in which the bombers would land at prepared airfields in the Soviet Union instead of returning to their home bases. A 45 aircraft detachment of fighters from the 4th would depart for the Soviet Union on June 20th. The mission would see them join a force of 1,000 bombers as they attacked targets in the Rhineland, and then on to Piryatin, Ukraine some seven hours away. 45 Mustangs of the 4th would make the trip, encountering some 25 enemy fighters over Siedlice, downing two, but losing one of their own. All but one of the remaining planes landed at their intended destination, with one 2nd Lt. Hofer being forced to land at Kiev after running low on fuel after pursuing enemy fighters (Bucholtz 88). However, unbeknownst to the assembled American aircraft, the formation had been trailed by a Ju 88. Soon after, a well coordinated attack by the Luftwaffe using its He 177 heavy bombers saw many of the US bombers hit, though their P-51’s were unscathed.
The P-51’s were subsequently dispersed and flew a variety of missions in the following weeks which brought them over Central Europe and the Mediterranean. They soon flew an escort mission against an oil refinery in Drohobycz, Poland on the 26th. The return leg of the mission took them to Lucera, Italy where they would support the bombing operations of the 15th Air Force. The largest of these missions would take them over Budapest to perform a fighter sweep ahead of the strike force. There they encountered 80 German and 18 Hungarian Bf 109G’s and a massive dogfight ensued. In the battle the 4th would claim eight Axis fighters at the cost of four of their own. This included 2nd Lt. Hofer who had died during a strafing attack against an airfield. (Bucholtz 89). The unit would be led back to England on the 3rd of July.
American and Soviet personnel during Operation Frantic. [National Archives]Beyond Operation Frantic the 4th settled back into the ‘usual’ operations they’d had since most of the group had left for the Soviet Union. They continued to fly deep penetration and escort missions over Germany, though by the end of the summer, Luftwaffe activity in the air had been considerably reduced. The savage war of attrition over Germany had been decisively won by the USAAF, as the Luftwaffe began to feel ever more crippling shortages of experienced pilots and fuel. Ironically, the Luftwaffe’s supplies of fighter aircraft were secure, though transporting them to airfields would prove ever more troublesome through the remainder of the war. While they had the aircraft, a subsequent USAAF campaign against rail communications across Germany would make overland transportation difficult, and ever more frequent fighter sweeps made transiting by air a very dangerous prospect.
For the remainder of the war the 4th FG remained committed to supporting the strategic bombing campaign, especially as it pertained to offensive fighter sweeps and attacks against Luftwaffe airfields. Their last victory of the war was a probable destruction of an Me 262 that was damaged over the Prague/Ruzyne airfield, with the group credited for 1,058.5 total victories against enemy aircraft, both in the air and on the ground (Bucholtz 120). They would end the war among the most successful Fighter Groups in the USAAF, having come a long way from the overly boastful volunteers that had flown against the Luftwaffe before any other Americans.
The 99th Fighter Squadron ‘The Tuskegee Airmen’
As black aviators, the men of the Tuskegee-trained squadrons would face unique challenges, having to face prejudice from their own countrymen who sought to deny them the opportunity to fight. They were initially excluded from many of the pre-war programs that turned out many of the pilots who later joined the ranks of the USAAF and US Navy. Many who ran these programs espoused the belief that they were incapable of the judgment needed for leadership, and that they had lacked ‘the proper reflexes to make a first class fighter pilot’ in the words of General Edwin J. House (Moye 102).
Their chance came with the Civilian Pilot training program in 1939, having been excluded from the program the previous year. The program was extended to a series of predominantly black colleges and universities, with the most critical being the Tuskegee Institute in Alabama. The university would build a fledgling airfield that eventually grew into an Army Air Corps training base, which proved controversial even among hopeful applicants, as in their eyes they were clearly still segregated from the rest of the Army. While the controversies flowed in the small Alabama town, the Air Corps moved to create the first black pursuit squadron, the 99th.
Col. Benjamin O. Davis would lead the 99th fighter squadron and the later 332nd Fighter group. He would go on to become a Brig. General in the newly formed United States Air Force after the war. [San Diego Air and Space Museum]The first cadets of the 99th would graduate March 7, 1942 under the command of Capt. Benjamin O. Davis. The squadron would subsequently fly within the US before its transfer to the Mediterranean in late March 1943, equipped with new P-40L’s (Moye 99). They occupied a former Luftwaffe airfield in Morocco and were to be attached to the 33rd Fighter Group after they had gotten some experience in theater. In May, the squadron would be deemed ready for service and would move to a field in Tunisia. They would see success there, but the leader of their fighter group, Col. William Moymer was immediately hostile to their presence. He failed to return the salutes of the 99th’s officers and he placed the squadron on patrol duties over secure air space. He would then openly criticize them for being ‘unaggressive’ for failing to claim victories over territory where they were unlikely to encounter enemy aircraft (Bucholtz 18, 19; Moye 101). In spite of this, the unit pushed on and would aid in the preparations for the invasion of Sicily.
The 99th’s first combat missions were fighter sweeps against enemy positions in Southern Italy, their first target being a German airfield on the island of Pantelleria on June 2, 1943. The airbase would be the site of many more attacks, including the unit’s first encounter with enemy fighters. On June 9th, six P-40’s from the 99th Squadron accompanied A-20’s to the airfield, encountering four enemy fighters. In the ensuing fight they successfully drove off the enemy aircraft, and damaged one, taking no losses of their own. A further effort was made to intercept a flight of Ju 88’s at high altitude but were unable to, as their P-40’s had their oxygen systems removed to save weight for the low altitude mission (Bucholtz 21). The pilots of the 99th were particularly enthused that in their first encounter with the enemy, they had managed to complete their mission and all returned home safely.
While they would eventually be known for their iconic red tailed P-51’s, members of the Tuskegee fighter squadrons would fly the P-40L, P-39Q, and P-47D before they were issued Mustangs. [National Archives]The squadron would be redeployed days later, partially a result of Moymer who sought to see the squadron reduced to coastal patrol duties. Instead, the 99th was transferred to the 79th Fighter Group, who’s commander, Col. Earl E. Bates, did his best to integrate the unit into the group. While they remained formally segregated, they enjoyed a far more open and professional environment than what they endured with the 33rd (Moye 103). Their first mission with the unit was on July 2 and saw them escort a flight of 16 B-25’s to their target, a German airfield in Castelvetrano, Italy. It would prove less than ideal when the B-25’s failed to line up with their target on the initial approach and had to repeat the attack, giving Axis fighters stationed nearby the time they needed to scramble. Two of the 99th’s pilots were lost in the first pass from the German fighters, but the remaining members soon regained control of the situation. In the ensuing confrontation with enemy Fw 190’s, Bf 109’s, and a Macchi 202, the 99th would claim one confirmed destruction, one probable, and two damaged aircraft. Though perhaps most importantly, none of the B-25’s they were escorting came to harm (Bucholtz 21, 22).
The coming weeks saw them mostly fly ground attack missions in support of the ongoing invasion of Italy, and met very few enemy aircraft for the remainder of the year. It was during this time that they also discovered that the Tuskegee training center wasn’t large enough to supply a sufficient number pilots to the squadron, while also supporting the construction of three additional squadrons. Their pilots resultantly flew an abnormally high number of missions due to being short handed (Bucholtz 25). This period also saw them defeat a great deal of the unfair criticism leveled against them and had largely cemented a favorable reputation within the Army Air Force. Among the most notable victories on that front was an article in Time, which had previously published an article based on Moymer’s alleged grievances with the squadron. Maj. Roberts of the 99th would be quoted “people assumed we were not producing because we were negroes…but now that we have produced, things have changed.” The 99th had also succeeded in convincing most of the 79th FG of their worth, and had garnered a great deal of respect as they moved into 1944. Many white pilots of the 79th disobeyed an order from the commander of the Air Force commander in the MTO, and held a desegregated dinner party to celebrate the anniversary of the 99th’s combat debut (Moye 104, 105).
Forming the 332nd Fighter Group
While 99th gained valuable experience over the Mediterranean, they began to rotate pilots out to train the next pursuit squadrons to form a segregated fighter group. These squadrons were the 100th, 301st, and 302nd, all of which would be formed at Selfridge Field, Michigan. Selfridge would prove a particularly dreadful post for these men, as it was here that they would face intense discrimination both by the local populace and base staff, while being a stone’s throw from the racial powder keg of Detroit. However, this would not remain their home for long, and they would soon depart for their operational assignments by the end of the year. They would join the 99th in the Mediterranean Theater of Operations in January of 1944, being equipped with a set of used P-39s. These aircraft would prove troublesome in service due to their age and condition, and as such numerous accidental losses followed, so by the early summer of 1944, Col. Davis had managed the acquisition of new P-47Ds. However, the unit would soon transition again to the newer P-51 soon after the 99th joined the rest of the fighter group in July, something the group’s veterans would resent as they felt they had been segregated again after finding acceptance within the 79th FG.
Capt. Andrew Turner aboard a P-51. The group’s transition to this aircraft vastly expanded the range and variety of operations across the Mediterranean and Central Europe. [National Archives]The group would fully transition to Mustangs by July of 1944, and would be reassigned to the 15th Air Force where they would support long range bombing operations. Their first mission in their new planes was on July 4th, where they took 40 aircraft to to escort two bomber wings, but they would encounter only a pair of Bf 109’s that made no attempt to attack the allied aircraft . Beyond this, their pace of escort missions rose and they would take part in supporting raids against Axis positions in Northern Italy and Southern France. Soon after, they would provide support for the amphibious invasion of Southern France. On August 12, All four of the 332nd’s squadrons were given specific targets, with the 99th striking radar stations in Montpelier and Sete, the 302nd attacking radar stations in Narbonne and Leucate, the 100th attacked the radar stations near Marseilles and Cape Couronne, and the 301st attacked four targets around Toulon. At the loss of three pilots, one captured and two killed, all of the targeted radar stations sustained considerable damage .
The remainder of the war saw the 332nd fly a considerable number of escort missions, including an earlier attack against the Ploesti oil fields in Romania on July 13th, 1944. It was during that mission that they had begun to cement their status as one of the most reliable escort units in the USAAF, after they dispersed a flight of eight German fighters that had attacked bombers of the 55th Bomb Wing. Their C.O., Col. Davis maintained an unwavering directive to his unit, on escort missions they were never to abandon their bombers. This didn’t sit well with some but it was accepted, in part because many felt that a failure to protect the bombers would come down harder on them than the other squadrons (Bucholtz 51, 105; Moye 102). As such, their record for defending bombers was exemplary, having lost only 27 bombers to enemy fighters from June of 1944 to April 1945. It should also be noted that 14 of these losses occurred during a single day when a failure in mission planning resulted in the bombers and their escorts failing to meet at the proper time. As the target that day was the Luftwaffe air base at Memmingen, Germany, losses were correspondingly high (Bucholtz 53, Haulman 2). This places the remaining 13 bomber losses among the other 178 escort missions they performed over ten months. This policy would however, result in the squadron having the lowest aircraft kill to loss ratio of any other P-51 squadron in the theater, however, they would still consistently outscore all of the veteran P-38 squadrons in the Mediterranean (Marshal & Ford 477).
Among their most impressive escort missions was in support of a bombing raid against the Daimler-Benz tank assembly plant in Berlin, on March 24, 1945. From the 332nd’s base in Ramitelli Italy, this was a 1600 mile round trip, the longest mission ever conducted by the 15th Air Force. 59 Mustangs of the 332nd would leave their base at 11:45 under the command of Col. Davis, though he would soon return after experiencing engine trouble and left the squadron in the command of Capt. Edwin Thomas. They would encounter some two dozen enemy fighters outside of the German capital, including a number of Me 262s. The jets would initially prove difficult to catch, and the aircraft, belonging to JG 7, would at first disengage from the bombers whenever the escorts drew close. However, several of the jets would later press their attack on the formation. In the ensuing battle 1st Lt. Earl R. Lane, Flt. Officer Joseph Chineworth, and 1st Lt. Roscoe Brown would each be credited with a confirmed kill on three downed Me 262s. On their return flight they engaged several targets of opportunity, including two trains. The success of this mission earned the unit one of their three Distinguished Unit Citations, and the personal thanks of Gen. Lawrence of the 5th Bomb Wing (Bucholtz 108, 109).
Beyond their role as escorts for the 15th Airforce’s bombers, the 332nd would be engaged in a number of fighter bomber missions across the Meditteranean and Central Europe. These missions were conducted whenever time permitted between bombing raids and would see the squadron engage a number of targets. These would include airfields and various transportation targets varying from trains to river barges. A raid on August 30, 1944 would mark the unit’s most successful day when the 332nd attacked poorly camouflaged aircraft at Grosswardein airfield, Romania. In the ensuing strafing attack, they would be credited with the destruction of 83 aircraft with a further 31 damaged, ranging from 30 Ju 88’s, to a pair of super heavy Me 323 transport aircraft (Bucholtz 66). They would mount similar attacks against Axis airfields from Romania to Hungary.
Pilot’s of the 332nd, Lt. Clarence ‘Lucky’ Lester on the right, leads the group with 3 credited victories, all claimed on the same day. [National Archives]The 332nd would end their campaign at an airfield in Cattolica, Italy, and was credited for the destruction of 111 aircraft in the air, 150 on the ground, 57 locomotives, 600 rail cars, and had flown 15,533 sorties (Bucholtz 116). It was a common myth that the squadron had never lost a bomber to enemy fighters, this being a rumor circulated by the press near the end of the war. This was not the case, but even with the failure over Memmingen, their bomber losses to fighters were half of the average and they were a considerable morale booster for the bomber crews of the 15th Airforce.
Flight Characteristics and Pilot’s Remarks
[P-51B pilot training manual]The P-51B would prove to be an excellent fighter, but one that could present some challenges to those unaware of its quirks. It shared most of its general flight and handling characteristics with its older Allison powered predecessors, though some alterations to the design would make themselves felt, and not always to the plane’s benefit or pilot’s wishes.
Overall, the Merlin Mustang’s would prove to be fast and highly maneuverable, but with more complex flight characteristics than the Allison powered models that came before. Under most flight conditions, the plane was positively stable and possessed controls that were light and responsive. This aspect had been improved from the previous models, as the P-51B would be equipped with improved internally sealed and balanced ailerons which kept control stick forces light. These were rated very well, though pilots would note they were still ‘mushy’ at low speeds. However, as the plane’s top speed increased, it was capable of pulling maneuvers that could prove hazardous to pilots. Above 4g turns where a pilot without a g-suit was partially blacked out, the stick reversal could be harsh, but the worst of its effects were eliminated by a 20lb bobweight that was incorporated into the control system later on (Dean 350, 349).
The plane’s stall characteristics were mixed, but mostly mild. A one g stall in a clean aircraft was characterized by a roll to the right which came on after rudder buffering and aileron snatching, and was easily recovered from. Pilots were generally positive about the stall warning and recovery characteristics. However, its accelerated stall behavior proved to be far less universally understood. Some pilots claimed an easy recovery after ample warning, and others claimed it came on suddenly and viciously. Its low drag wings would contribute partly to this, as with its lack of air flow disturbances, stalls could come on without much warning. In the event of a spin, recovery was achieved by throttling back and pulling up while directing the rudder in the opposite direction of the spin. A spin could be serious trouble as a typical recovery resulted in a loss of about 9,000 ft in altitude (Dean 351, 352; P-51B flight manual 80).
While the plane was certainly very capable in regards to its maneuverability, pilots would have to take great caution when performing maneuvers of any kind when the fuselage tank still contained fuel. When the 85 gallon tank still contained fuel, the plane’s center of gravity shifted considerably and induced severe longitudinal instability. Hard maneuvers with any considerable volume of fuel still in the tank would result in a stick reversal that would require the pilot to brace themselves against the movement of the stick. Failing to do so would result in a loss of control or a further tightening of the turn which could result in a high speed stall or even structural failure (Dean 347, 348). Both RAF and USAAF manuals would ban aerobatics with roughly forty or more gallons of fuel in the tank, and suggested caution once it had been reduced to 25 gallons (Pilot’s Training Manual 68, Pilots Notes 30). In service this issue was one that rarely affected the plane’s effectiveness in combat, as the long range tank was the first to be used on long patrols and escort missions and thus typically contained little or no fuel when contact with enemy aircraft was made.
On early and mid production P-51B’s, pilots would also have to be cautious of high speed snapping brought on by the aforementioned longitudinal instability while they were conducting rolls. Pilots caught unaware were often injured during this violent jolt, and rolls were restricted accordingly. The addition of a fin extension for the vertical stabilizer and reverse rudder boost tabs would largely solve this issue, and the restrictions were lifted on suitably modified aircraft (Dean 350).
Perhaps where the aircraft shined the brightest were its dive characteristics, which were achieved as a result of its low drag wings and fuselage. These granted it excellent acceleration and a higher critical mach number than most of its contemporaries. Due to the changes in air flow across an aircraft’s wings as a plane approaches the sound barrier, most aircraft would experience buffeting, and a loss of control along and total loss of lifting forces. This change in flight characteristics that results in this loss of control is known as compressibility, a phenomenon that occurs when an aircraft exceeds the speed of its critical mach number.
A visual explanation of compressibility from the P-51B’s pilot training manual, the disturbed airflow results in a loss of lifting forces on the wings and control surfaces. The P-51’s wings mitigated the worst of its effects until much higher speeds. [Pilot’s training manual]Thanks to its laminar flow airfoil, the P-51 was almost unique in its ability to remain controllable at otherwise unheard of speeds. However, in a high speed dive the P-51 would eventually experience compressibility and a pilot needed to be aware of the changing characteristics of their aircraft. In the P-51 this would first be felt through a ‘nibbling’ at the controls, afterwards by the stick ‘walking’ back and forth, and lastly by the aircraft pitching up and down with motions that grew more violent as the aircraft picked up speed (Pilot’s Training Manual 74, 75). On earlier models that lacked the vertical stabilizer extension, there was also directional instability that occurred at high speed, which required rudder correction or the plane could be sent into a spin. However with the later modifications the plane was nothing less than astounding. In diving tests from 35,000ft, pilots were able to reach mach .83 while retaining control of the aircraft, and despite the violent shaking and buffeting of the aircraft, were able to recover from the dive. In more practical conditions, control characteristics would remain normal until the aircraft was between .72 and .74 mach, after which the plane would experience escalating tuck-under, or a tendency to pull downwards airspeed increased. The maximum permissible dive speed was set at 505 mph IAS below 9000 ft, and 300 mph IAS at 35,000 ft, TAS being 539 mph (Mach .81). The maximum permissible engine RPM in dives was 3300 (Dean 341, 342, 343). Overall, the P-51B proved to be phenomenal in a dive, with only the British Hawker Tempest gaining a slight lead in tests, it being another aircraft equipped with laminar flow airfoils (Ethell 62).
Its take-off procedure was fairly typical of contemporary US fighters and required a strong right rudder deflection during take off to counteract the powerful torque from its engine. Its best climb out speed was between 160 to 170 mph IAS, which was quickly achieved after its flaps and landing gear had been retracted (Dean 341). Landing was somewhat more challenging, as the 140 mph IAS glide slope offered poor forward visibility, and little was improved as the plane came in to land at about 90 mph. It was thus fairly common for combat pilots to make tail up, level landings in order to have a better view of the landing strip before touching down. Its widely spaced gear and wide tire tread otherwise made the landing fairly easy.
While the P-51B’s possessed some truly phenomenal flight characteristics, the same cannot be said for the canopy. In US Navy evaluations the ‘birdcage’ canopy was found to result in poor all-around vision, most notably fore and aft. It was also fairly restrictive and made turning to view behind the aircraft more difficult (Dean 353). The frame itself could also not be opened on take off or landing and thus proved to be of some annoyance to pilots. This would later be solved with the addition of the ‘Malcom Hood’ which provided excellent visibility and was far less confining. The rest of the cockpit was judged to be satisfactory and capable of accommodating pilots of varying stature.
The ‘birdcage’ was unpopular as it was quite restrictive in terms of visibility, and it could not be kept open on the landing approach or takeoff. [Pilot’s Training Manual]Its armament however, was distinctly lacking and fairly unreliable. It’s armament of four .50 caliber AN/M2’s was considerably lighter than most US fighters of the time and were installed in such a way that the ammunition links were prone to deformation in high-g maneuvers. It was not uncommon for P-51B/C’s to return from their missions with several guns malfunctioning as a result of failures to feed or extract. As a gun platform, its qualities were judged as roughly the same as the P-40, and below those of the P-38 and P-47 (Dean 353).
Comparisons with American Fighter Aircraft: Early to Mid 1944
Entering service alongside the P-47 and P-38, the new P-51’s would compare very well. When it came to the P-47D, equipped with R-2800-63’s, these aircraft were in some ways complementary, and excelled in areas the other did not. Thanks to its powerful turbosupercharger, the P-47 would retain the power needed to outperform the P-51 above 25,000ft, but was significantly slower at lower altitudes. The P-47 was also less vulnerable to ground fire and thus better suited for ground attack missions. The P-51B however, outstripped the P-47D in rate of climb, linear speed, acceleration at altitudes below roughly 30,000ft, and dive performance (Ethell 70; Marshall & Ford 526). Ergonomically speaking, the P-51B was the superior aircraft, as the turbosupercharger controls of the P-47D added to the workload of the pilot.
The P-47’s Turbosupercharged R-2800 engine provided unparalleled performance above 30k feet, and it’s durability made it ideal for fighter bomber missions. It was fairly lacking in its rate of climb and acceleration at low to medium altitudes. [National Archive]When it came to escorting bombers, the P-47D and P-51B were the most effective tools at the USAAF’s disposal. Both aircraft performed superbly at and above the altitudes the bombers typically flew at, though the P-51B would prove the more vital as it could travel significantly further. By late spring 1944, external fuel tanks had been introduced that extended the P-47’s escort radius across most of Germany, however, by this time the P-51B was capable of accompanying bombers beyond Poland (Marshal & Ford 516). While the shorter range of this aircraft was often used to excuse the high bomber losses during earlier campaigns, the fact is that had they been supplied with the proper external fuel tanks, they would have been capable of deep incursions into German airspace months before the P-51 entered service.
The P-38 experienced serious reliability and performance issues due to the extremely low temperatures encountered at high altitude over Northern Europe. Its poor high altitude dive performance was also widely known, and exploited by Luftwaffe pilots. [National Archives]The older P-38J Lightning would not stack up quite as favorably against the new Mustang. While the P-38J possessed a better climb rate and acceleration, it was out-stripped in linear speed by the P-51B at all altitudes, and possessed a very low critical mach number which meant that virtually any opponent at high altitude could escape by diving away. To make matters worse, a number of technical and operational issues spelled trouble for these aircraft in the colder Northern European climate. These issues, compounded by the extremely poor cockpit and canopy of the P-38, saw Lightning squadrons fall behind Thunderbolt and Mustang squadrons in victory credits (Marshall & Ford 439, 516; Ethell 70).
While the P-38J would receive external fuel tanks that would allow it to travel to Berlin and back, it was held back by a number of factors that severely reduced its combat effectiveness. In the European Theater of Operations, the P-51B would present a clear and general improvement over the P-38s, which saw more success in other theaters with conditions that they were better suited to, namely the Mediterranean and Pacific.
German Fighter Comparison: Early to Mid 1944
Entering service near the end of 1943, the P-51B compared very well to the German Fw 190As and Bf 109Gs in service at that time. The typical Bf 109 encountered through the first half of 1944 was the Bf 109G-6 series, which possessed better firepower than those that preceded it, but was heavier, and initially slower for it. These planes were equipped with either the Daimler-Benz DB 605A, or the high altitude, DB 605AS engines, both of which were later equipped with MW-50 boost systems. In all cases the P-51B possessed the superior linear speed, but in the case of MW-50 equipped aircraft, the Mustang had a slightly lower climb rate at low to medium altitude (Marshall & Ford 526, 523; P-51 flight tests). Without the boost system, which came into widespread use in the summer of 1944, the Bf 109G-6 was considerably slower and had a clear disadvantage in top speed and climb rate at all altitudes. The disparity with the high altitude model was much narrower, though the P-51 still held an edge.
The Bf 109G-6 was the most common Luftwaffe fighter encountered by the P-51. Later versions boasted considerably higher engine power thanks to the MW50 boost system; they did not compare well to many western allied fighters prior to this. Here one prepares for a fighter bomber sortie. [Asisbiz]When it came to maneuverability, both aircraft had their own advantages, with the Bf 109 having better low speed handling and the P-51 having the advantage at high speed. The dive performance of the P-51B was far superior even at lower altitudes as the Bf 109 experienced stiffening of the elevator at high speed.
Visibility the Bf 109 was more or less on the same level of the standard ‘birdcage’ P-51B, and this would largely remain the case, as both planes would be re-equipped with improved canopies that offered better visibility. However, the cockpit of the P-51 was considerably more spacious and was further improved by the Malcolm hood. The Bf 109’s greatest strength was that it was equipped with an automatic RPM governor and mixture control that took a great deal of work off the pilot.
In terms of armament, both aircraft were comparable, with an unmodified Bf 109G-6 possessing a pair of 13mm machine guns and either a 20 or 30mm cannon, which fired through the propeller hub. Of the two, the 30mm was far less common.
Overall, the Bf 109G-6 was a somewhat dated fighter, one that had its advantages, but was generally outclassed by the new Mustang. However, upgrades like water-methanol injection, an improved vertical stabilizer, and a new canopy helped keep the aircraft competitive and staved off obsolescence. The much refined ‘Kurfurst’ series would match P-51 performance in a number of areas, but its introduction was well after the Luftwaffe had lost control of German airspace.
The P-51B would face several models of the Fw 190A, with the most up to date being the A-8. The P-51B would have considerable linear speed, climb, and high altitude dive advantages over the earlier models. The Fw 190A-8 would have the benefit of a significant boost in power to its BMW 801D-2 engine, first by means of a fuel injection system, and in the summer of 1944, they were judged robust enough to be run at higher manifold pressures and had their supercharger boost regulators overridden. These modifications allowed the engine to produce significantly more power and increased the aircraft’s top speed at all altitudes (Douglass 344). In terms of top speed, this put these two aircraft on closer footing at low altitude, and ahead of the other two American fighters. It was, however, nowhere close to offsetting the general disparities at higher altitudes. The excellent defensive characteristics of the aircraft helped to offset some of its disadvantages against the P-51, as the Fw 190A held the best roll rate in the theater, solid dive characteristics, and good rearward visibility.
The Fw 190A’s were completely outclassed at altitude by the P-51B, owing to their relatively low full throttle height. They would however, be on somewhat closer footing at lower altitudes and could hold their own against the other two American fighters. [Asisbiz]In terms of armament it was no contest, as the earlier A-6’s and A-7’s possessed a pair of either 7.92mm or 13mm machineguns respectively, and a pair of 20mm cannons. This was increased to two pairs on the Fw 190A-8. In regards to ergonomics the Fw 190A was excellent, with good visibility, clean instrumentation, and an advanced engine control system which handled RPM, manifold pressure, and mixture through the use of a single, integrated electro-mechanical computer. Its controls too were tight and responsive, if a little heavy at speed, thanks to its push rod control system. However, as was also the case with the Bf 109, its cockpit was comparatively cramped compared to the P-51.
Subsequent models of both these aircraft, the most numerous being the Bf 109G-14 and the Fw 190D-9, would largely eliminate the performance disparity at low altitude. However, at medium to high altitudes, the P-51 would still enjoy a considerable edge in top speed, dive performance, and high speed maneuverability. Only later Bf 109G’s with enlarged superchargers and better high altitude performance were close to closing the gap, with the K-4 series finally achieving high altitude parity near the very end of the war.
The Bf 109G-14 and the Fw 190D-9 would enter service in the Autumn and Winter of 1944, though they would not entirely replace their predecessors by the end of the war. [Largescaleplanes, Asisbiz]The Me 262 presented a much greater threat in the air for obvious reasons. The jet fighter possessed a top speed roughly 100 miles per hour faster than the P-51 and was the only Luftwaffe fighter capable of following it into a dive. It was, however, considerably lacking in acceleration, which presented itself most dangerously on take off and on the landing approach. While the high top speed of the jets meant that they could disengage safely from most confrontations, they were helpless if caught near taking off or landing. Thus the general strategy for defeating these aircraft was to catch them as they were returning to their bases, where Allied fighters would await them. This is not to say this was easy, as their airfields were well defended by some of the best flak units available to the Luftwaffe and they would eventually have their own dedicated fighter cover (Ethell 97, 98). Higher up the jet could prove a deadly opponent as when flown well, it was extremely difficult to catch and an experienced pilot had control over most engagements.
The Me 262 was a world first, and had many USAAF planners concerned. On paper it had the ability to wreak untold havoc on allied bomber formations, but its technical limitations and the general poor state of the Luftwaffe late in the war prevented it from operating in numbers large enough to make a major impact. [Asisbiz]In any case, encounters with the new jet fighters were fairly uncommon as they were constrained by operational restrictions owing to the temperamental nature of the new turbojet engines and the lack of a dedicated trainer for the aircraft until late 1944. They would not be seen flying against the Allies in appreciable numbers until the late autumn of that year.
Building the P-51B & C
The P-51B’s and C’s were built at plants in Inglewood, California, and Dallas, Texas, respectively. The distinction exists due to the differences in manufacturing between these two facilities, but these are functionally the same aircraft. With the exception of the earliest model, the P-51B-1, which had a different aileron design, their components were interchangeable. The main production models were equipped with the Packard V-1650-7 engine. Deliveries of these models began in February of 1944 (Marshall & Ford 253)
Production of this aircraft was complicated greatly by the breakneck pace of its procurement, which saw massive orders placed before its prototype had completed testing. As such, the aircraft that left the factories differed considerably even when they were built mere weeks apart. While all WWII fighters underwent constant modification, the level and rate of changes made to the P-51B and C were extensive and rapid. In addition to minimal changes, like changing the pilot’s seat from a wooden one to a magnesium one, in a matter of weeks the P-51B would receive an additional fuselage fuel tank, an extension to its vertical stabilizer and a rudder anti-balance tab, and an elevator control system which made use of a 20lb bob weight (Dean 329). These features would constitute a considerable challenge to work into the design without compromising the pace of production for an aircraft that USAAF planners wanted in as great quantity in the shortest possible time.
The Inglewood P-51 production line. [North American Aviation]This challenge would highlight both the greatest strengths and weaknesses in US aircraft manufacturing. Most aircraft factories in the US operated by building large batches where the design would be frozen to allow faster construction. Modifying the design meant changes to the production line, which meant slowing down or stopping. US factories operated at batch sizes of up to 1,500, compared to the British Supermarine Spitfire’s production lines which operated at or below 500. The compromise was the modification center, to which “finished” aircraft would be delivered to be fitted out to new modifications. In practice, this system was extremely inefficient and saw quality control drop significantly. It also proved to be a highly inefficient use of labor, and could represent between 25 to 50% of the total labor required to complete an aircraft. Quality control also dropped considerably as the modification center was primed to try and deliver aircraft as quickly as possible (Zeitlin 55, 59). Lastly, the centers saw a great deal of wastage of material, accumulating a much larger proportion of metal scrap from rushed fittings, and ruined parts than the production lines (O’Leary 142). The USAAF would have its Mustangs, but only at a considerable cost and of initial questionable quality.
In the end they were successful in that they delivered the P-51B in great quantities despite the rushed pace of procurement, development, and production. However, it certainly contributed to the severe teething issues experienced by the aircraft that would see it briefly grounded in March of 1944 and would trouble it for weeks later.
In all, 1,988 P-51Bs were built with the first leaving the production lines, at a very low initial rate, in the summer of 1943 with the first deliveries taking place in August, with a further 1,750 P-51C’s being built. Production of both types declined as the P-51D production began in January of 1944, with the last P-51B’s leaving Inglewood in March and P-51C production continuing for several more weeks (Dean 321).
Construction
Wings
The wing group of the P-51 was composed of each wing, bolted together at the centerline. Each wing was of a cantilever stressed skin construction and consisted of a main panel, the wingtip, the flap, and the aileron. The main panel was built up around a main forward spar and a rear spar, to which twenty one pressed ribs were attached. These spars were spliced together roughly around half their length. A self-sealing 90 gallon fuel tank was fitted at the inboard section and a bay for its .50 caliber machine guns and ammunition was found near the center. The ailerons were of a fairly heavy construction, being all metal and supported by two spars and twelve flanged ribs. They were aerodynamically balanced by a diaphragm attached to the forward edge of the aileron and sealed to the rear spar by a fabric strip. These were controlled by means of a cable, as were all of the control surfaces of this aircraft. These were equipped with trim tabs and were adjustable in flight. The flaps were all metal plain flaps that were hinged on three sealed ball bearings and were hydraulically actuated.
[Legends in their time]The landing gear was hydraulically actuated with a fully retractable tail wheel. The main landing gear were fixed to the wings by a cast magnesium supports and were equipped with multiple disc brakes connected to the hydraulic cylinder by metal tubing. The wheels were 27 inches in diameter and possessed a fairly wide tread, which helped to give the P-51 excellent ground handling.
The wings of the P-51 were designed to achieve laminar flow and used a NAA/NACA 45-100 series airfoil. It would fall short of true laminar flow as even extremely minor surface imperfections resulted in airflow disruptions that made laminar flow impossible. However, these were among the most aerodynamically advanced wings used by any fighter during the Second World War, providing extremely low drag and excellent high altitude dive performance.
Fuselage
[Legends in their time]The fuselage was composed of two main sections, both of which had a semi-monocoque construction. The main section was formed by four extruded longerons, around which the intermediate frames and stringers were connected. The upper longerons were extruded H-sections which extended from the sheet metal firewall and tapered into a T-section. The lower longerons, consisting of an H-section and U-channel, extended the full length of the main fuselage. This entire unit was made up of eight assemblies which were riveted and bolted together, these being the firewall, turnover, truss, upper deck, left and right side panels, radio shelf, web assembly, and the radiator air scoop.
The main fuselage section also contained the cockpit, the windshield being composed of a center pane of bullet resistant five pane laminated glass, with two Plexiglas windows to either side. The canopy was either a metal framed Plexiglas ‘bird cage’, or a Malcom Hood. The birdcage had panels that opened outward on the top and port side. The hood slid back across the rear of the canopy. Behind the pilot were lucite windows which enclosed the radio space. A relief tube was installed and stored beneath the seat, and proved quite useful considering the long flights that this aircraft commonly made.
Early P-51B instrumentation. [Legends in their own Time]The rear section was comparatively simple, composed of two longerons, a shelf, five formers, and three solid bulkheads. The fuselage, as with the rest of the aircraft, was skinned in Alclad. This section was reinforced after structural failures during high speed rolls in early models.
Tail Section
The tail section was affixed to the rear fuselage and consisted of the horizontal stabilizer, elevators, fin, vertical stabilizer, and the rudder. The horizontal stabilizer was a one piece assembly supported by two spars, fixed to the fuselage by four bolts, and through which the vertical stabilizer was attached. The elevators consisted of a front spar with eighteen flanged ribs, and was initially fabric skinned with Alclad leading edges before it was later entirely metal skinned. These were fastened with five sealed ball bearing hinges and each had an adjustable trim tab.
The vertical stabilizer was supported by two spars along with four ribs and a detachable tip. Extensions to the vertical stabilizer by means of a fin were added to P-51B/C’s to correct for longitudinal stability issues with a full fuselage fuel tank, and to correct certain undesirable characteristics when the aircraft was put through a roll. The rudder was fitted at the rear of the stabilizer and was supported by a single spar to which twenty flanged ribs were attached. Much of the rudder was skinned with mercerized cotton, save for the reverse edge. The rudder was fitted with a trim tab and aerodynamically balanced by means of a 16.6 lb lead weight at the tip.
Engine Section
The engine section consisted of the engine mounting and external cowl components and was bolted to the firewall. The cowl consisted of a frame made of Alclad beams to which the cowl panels fastened. This frame acts as a cradle for the engine which is mounted by a bracket through anti-vibration units. The entire section is designed to facilitate easy access to the engine through panels, and the engine mount allows for the rapid removal of the Packard engine.
[Legends in their time]
Engine
The early models of the P-51B used a Packard V-1650-3, with this engine being replaced on the production line in February of 1944 with the Packard V-1650-7. These are largely the same engine, though their superchargers were geared for optimal performance at different altitudes and thus have different maximum outputs. The 1650-3 was designed specifically for high altitude use and gave the P-51B/C a full throttle height of 29,000 feet, the 1650-7 was geared to achieve a higher engine output at a FTH of 21,400 feet (Marshall & Ford 253).
These engines had a bore of 5.40 inches, a stroke of 6 inches, a displacement of 1,649 cubic inches, a compression ratio of 6.0:1, a width of 30 inches, a height of 41.6 inches, length 87.1 inches, a frontal area of 5.9 sq. ft, and a weight of 1690 lbs. They differed in that the -3 supercharger ratios of 6.391:1 and 8.095:1, and those of the -7 were 5.80:1 and 7.35:1 (Wilkinson 125, 127). They were both fitted with a four blade Hamilton-Standard 24D50-65 or -87 hydropneumatic propeller with aluminum blades of a diameter of 11 feet and 2 inches. These blades were either 6547-6, 6547A-6, or 6523A-24 types. The engine exhaust stacks were of a stainless steel construction which had a removable exhaust shroud to keep heat from the spark plugs and to reduce drag.
Packard V-1650-7 [Pilot’s training manual, Smithsonian]Both engines used a two stage, two speed supercharger and was equipped with an aftercooler. The supercharger was automatically controlled and governed by the air pressure at the carburetor intake, which was found just below the prop spinner. The controls for the engine were conventional, requiring manual throttle and rpm adjustments.
Radiator and Cooling Systems
The engine was cooled by two separate systems, one dedicated to the engine, and the other cooled the supercharged fuel-air mixture. Both of these systems were connected through the main radiator matrix within the air scoop below the main fuselage, with the coolant flow maintained by an engine driven pump. A smaller radiator for the oil cooler was placed below and ahead of the radiator matrix for the engine and aftercooler. The radiator setup was designed to make use of the Meredith effect, which in practical terms meant that the heated air flow out of the radiator produced thrust which counteracted a large percentage of the drag incurred by the scoop. The outlet for the radiator was automatically controlled. This design was able to reduce net drag upwards of 90% and was one of the most important features which allowed the aircraft to achieve such a high top speed (Marshall & Ford 510).
[Legends in their time]The hoses for the radiator which extended through roughly two thirds of the aircraft, and the unarmored radiator, which sat at the bottom center of the aircraft, constituted the most vulnerable part of the aircraft’s design. These made the aircraft fairly vulnerable to ground fire, as the high cooling requirements of the Packard Merlin engine meant that a failure of the cooling system wouldn’t take long to put the aircraft out of action.
Fuel System
The initial models of the P-51B possessed only two 92 gallon wing fuel tanks with an 85 gallon fuselage fuel tank being included later through modification kits and was eventually incorporated into the production line. The Mustang was also capable of carrying two external fuel tanks by means of wing mounts. Fuel was drawn only from individual fuel tanks, requiring the pilot to manage up to five individual sources of fuel throughout longer flights (Pilot’s Training Manual 26).
[Pilot’s Training Manual]The inclusion of the 85 gallon fuselage tank would introduce new challenges, as the shift in weight caused by a full tank introduced severe longitudinal instability. For this reason this tank was the first to be consumed. The combined tankage was 269 gallons.
Armament and Armor
P-51B’s were equipped with four .50 caliber AN/M2 machine guns. Each inboard gun was supplied with up to 250 rounds, with the outboard weapons having 350 each. These guns were mounted at roughly 45 degree angles within the wing, which caused severe cycling issues when the guns were fired while the aircraft was pulling hard maneuvers. These issues were lessened with the addition of electric boost motors for the ammunition feed, but were not completely solved until the subsequent P-51D model. The guns were electrically heated to prevent them from locking up at high altitudes. These aircraft were typically equipped with the N-3B reflector gunsight, with later aircraft receiving K-14 gyroscopic gunsights.
[National Archives]Wing pylons allowed the aircraft to carry a payload of up to 500 pounds at either side, being either external fuel tanks or bombs. These aircraft could be made to carry rockets by means of field modification kits. Armor plates were placed ahead of the radiator header tank, at the engine fire wall, and behind the pilot.
(Dean 355-376)
Conclusion
It would take a considerable effort to develop the P-51B from its Allison engined predecessors, and even greater hurdles would have to be overcome to produce them in the quantities needed. In the end, both were achieved and the P-51B would enter large-scale operation in the Spring of 1944. In spite of its harsh teething issues, it would become among the most decisive weapons of the Second World War. With its incredible range and medium and high altitude performance, the aircraft would prove instrumental in establishing air superiority over Western Europe prior to Operation Overlord, and contesting the skies over Germany itself.
P-51B production was switched over to the D model at Inglewood in March of 1944, but the aircraft would remain in service in large numbers through the end of the war. [National Archives]Its design, while not revolutionary, was thoroughly advanced and represented a considerable leap in aerodynamics and airframe design. The P-51B would however, be only a starting point for the Packard Merlin Mustangs, as further refinements would result in the iconic, and much more widely produced P-51D.
Specifications
P-51B/C ( with Fuselage tank)
Specification
Engine
Packard Merlin V-1650-3, V-1650-7
Engine Output [V-1650-7]
1630 hp [1720 hp]
Maximum Escort Fighter Weight
11,150 lbs (2x108gal external)
Gross Weight
9,681 lbs
Empty weight
6,988 lbs
Maximum Range [External Fuel]
1350 miles [2150 miles]
Combat radius [External Fuel]
375 miles [750 miles]
Maximum speed (V-1650-7)
444 mph (75″ Hg) at 20600ft
Armament
4x .50 cal M2 machine guns, 1200 rounds of ammunition
Crew
Pilot
Length
32′ 2
Height (tail down)
12’8
Wingspan
37.03′
Wing Area
235.75 sq.ft
P-51B/C ( with Fuselage tank)
Specification
Engine
Packard Merlin V-1650-3, V-1650-7
Engine Output [V-1650-7]
1630 hp [1720 hp]
Maximum Escort Fighter Weight
5058 kg (2×409 liters external)
Gross Weight
4391 kg
Empty weight
3169 kg
Maximum Range [External Fuel]
2172 km [3460 km]
Combat radius [External Fuel]
603 km [1207 km]
Maximum speed (V-1650-7)
714 km/h (1905mm Hg) at 6279 m
Armament
4x 12.7mm M2 machine guns, 1200 rounds of ammunition
Crew
Pilot
Length
9.80 m
Height (tail down)
3.86 m
Wingspan
11.29 m
Wing Area
21.9 sq.m
(Dean, Performance Tests on P-38J, P-47D and P-51B Airplanes Tested with 44-1 Fuel., Marshall & Ford)
Maximum Level Speed
Speed at 67″ Hg, 3000 RPM
75″ Hg, 3000 RPM
No wing racks, 75″ Hg, 3000 RPM
Sea level
364 mph
380 mph
388 mph
Critical altitude low blower
408 mph at 10400 ft
411 mph at 2300 ft
422 mph at 7400ft
Critical altitude high blower
426 mph at 23900 ft
431 mph at 20600ft
444 mph at 20600ft
Aircraft Specification
Gross weight 9680lbs, P-51B-15
(V-1650-7)
*A note on fuels: The 75″ of manifold pressure figure represents the high end of performance using 150 octane fuels, these were typically only available to P-51 squadrons based in England.
Climb rate
67″, 3000 RPM
75″ Hg, 3000 RPM
Maximum at low blower
3,920 ft/min at 5600 ft
4,380 ft/min 2,300 ft
Maximum at high blower
3,170 ft/min at 19,200 ft
3,700 ft/min at 15,600 ft
Aircraft Specification
Gross weight 9680lbs, P-51B-15
Maximum Level Speed
Speed at 1701 mm Hg, 3000 RPM
1905mm Hg, 3000 RPM
No wing racks, 1905mm Hg, 3000 RPM
Sea level
586 km/h
611 km/h
624 km/h
Critical altitude low blower
656 km/h at 3169 m
661 km/h at 701 m
679 km/h at 2255 m
Critical altitude high blower
685 km/h at 7284 m
693 km/h at 6278 m
714 km/h at 6278 m
Aircraft Specification
Gross weight 4390 kg, P-51B-15
(V-1650-7)
Climb rate
1701 mm Hg, 3000 RPM
1905 Hg, 3000 RPM
Maximum at low blower
1194 meter/minute at 1707 m
1335 meter/minute 701 m
Maximum at high blower
966 meter/minute at 5852 m
1128 meter/minute at 4755 m
Aircraft Specification
Gross weight 4390 kg, P-51B-15
(Performance Tests on P-38J, P-47D and P-51B Airplanes Tested with 44-1 Fuel.)
P-51 Variants through P-51D
North American
USAAF
RAF
Engine
Armament
No. Built
Additional Notes. First delivery
NA-73X
–
–
Allison
–
1
Prototype. October 1940
NA-73, -83
XP-51
Mustang Mk I
Allison
2x .50 cal MG, 4x .30 cal MG
622
RAF, export. August 1941
NA-91
P-51
Mustang Mk Ia
Allison
4x 20mm cannons
150
‘Plain P-51’. July 1942
NA-97
A-36A
–
Allison
6x .50 cal MG, bombs
500
Dive Bomber. October 1942
NA-99
P-51A
Mustang Mk II
Allison
4x .50 cal MG
310
March 1943
NA-101
XP-51B
–
Packard
4x .50 cal MG
2 (converted)
P-51B prototype
NA-102, -104
P-51B
Mustang Mk III
Packard
4x .50 cal MG
1988
Inglewood production. Summer 1943
NA-101, -103
P-51C
Mustang Mk IIIB
Packard
4x .50 cal MG
1750
Dallas production. August 1943
NA-106 (through -124)
P-51D
Mustang Mk IV
Packard
6x .50 Cal MG
+8000
Bubble canopy. January 1944
(Dean 321)
P-51B & C Variants
P-51B & C Variants
Notes
Serial No.’s
P-51B-1-NA
Earliest production model, steel aileron diaphragms, two point aileron attachment.
43-12093 to 12492.
P-51B-5-NA
Three attachment points per aileron, non-magnetic diaphragm.
43-6313 to 6352, 43-6353 to 6752, 43-6753 to 7112.
P-51B-7-NA
B-1s and 5s which received a new fuselage fuel tank carried this designation. Aircraft often carried prior designation in practice. Converted aircraft.
–
P-51B-10-NA
Production model with fuselage tank.
43-7113 to 7202, 42-106429 to 106538, 42-106541 to 106738.
P-51B-15-NA
Engine changed to Packard V-1650-7 (previous models were converted to this engine via supercharger kits).
42-106739 to 106908, 42-106909 to 106978, 43-24752 to 106738.
P-51C-1-NT
Same as P-51B-5-NA.
42-102979 to 103328
P-51C-2-NT
C-1s which received a new fuselage fuel tank carried this designation. Aircraft often used prior designation in practice. Converted aircraft.
–
P-51C-5-NT
Same as P-51B-15-NA.
42-103329 to 103378, 42-103379 to 103778.
P-51-C-10-NT
Production model with stabilizing fin extension.
42-10818 to 103978, 43-24902 to 25251, 44-10753 to 10782, 44-10818 to 10852, 44-10859 to 11036, 44-11123 to 11152.
P-51C-11-NT
Production model.
44-10783 to 10817, 44-10853 to 10858,44-11037 to 11122.
XP-51B, 312093. The XP-51B’s were a pair of earlier Mustangs converted to use the Packard V-1650-3. Their cooling systems would prove the most troublesome, though the general teething issues these aircraft experienced were harsh and varied.P-51B-7-NA 43-6913 ‘Shangri-La’. Debden, UK 1944. Debden ,UK 1944. This aircraft was flown by Capt. Don Gentile of the 4th Fighter Group, one of the unit’s leading aces.P-51B. 325th Fighter Group. Poltava, USSR 1944. The 325th was among the units that participated in Operation Frantic, where they supported a series of USAAF raids launched from within the Soviet Union during the summer and fall of 1944.P-51B-5-NA, 43-12214 ‘Rebel Queen’. Debden, UK 1944. This aircraft was flown by Col. Don Blakeslee, Commanding Officer of the 4th Fighter Group. This aircraft is an early production P-51B which had been equipped with a Malcolm Hood bubble canopy, this modification greatly improved visibility.P-51C-10-NT ‘By Request’. Ramitelli, Italy 1944. This aircraft was flown by Col. Benjamin Davis, Commanding Officer of the 332nd Fighter Group. This is a late model which has been fitted with a fin fillet, extending from the vertical stabilizer. This addition greatly improved the aircraft’s stability in rolls and high speed dives.
B-17’s accompanied by a P-51B over England, March 1945.[National Archives]A collection of P-51’s accompany a flight of B-24s of the 8th Air Force, near England. 1944. [National Archives]The Malcom Hood bubble canopy would offer pilot’s great visibility compared to the ‘birdcage’. [National Archives]The P-51A can be easily differentiated from its merlin powered counterpart by the tube shaped carburetor intake over the nose. [wikimedia]Though most P-51B’s would be sent to Europe, some would serve in the China-Burma-India theater. Here a Mustang cruises alongside a C-47. [National Archives]Ground crew pose alongside one of their planes. [National Archives]A P-51B in the CBI theater is cleaned. This plane has had its exhaust fairing removed, a fairly common modification made in the field which some pilots believed cut down on drag. [National Archives]A P-51B comes in to land, the wide tire tread and wheel base of these planes helped give these planes good landing and ground handling. [National Archives]Ground crew pose with one of their planes, the tail fin extension as equipped to this plane helped alleviate some of the aircraft’s less desirable characteristics when it was rolled. [National Archives]Among the challenges caused by segregation for the 332nd were personnel shortages. The only available training facility at Tuskegee struggled to turn out enough pilots and ground crew to support the segregated squadrons. Mechanics and armorers were among the most affected, especially when the fighter group rapidly transitioned from P-39’s, P-47’s, and P-40’s to P-51’s over the late spring and summer of 1944. [National Archive]P-51B’s of the 325th Fighter group accompany bombers on their way to the Soviet Union during Operation Frantic. [National Archives]The success of Operation Overlord saw the redeployment of many USAAF units to the continent. These P-51’s of the 9th AF were the first to be deployed to France. [National Archives]The F-6C was a photo-reconnaissance variant that had a camera installed in the fuselage, the lens cover for which sits here just behind the radiator scoop. This model was credited with the last kill in the ETO, after downing a Fw 190 on May 8 1945 (Dean 339). [Wikimedia]
O’Leary, Micheal. Building the P-51 Mustang the Story of Manufacturing North American’s Legendary WWII Fighter in Original Photos. Specialty Pr Pub & Wholesalers, 2011.
Dean, Francis H. America’s Hundred Thousand: the US Production Fighter Aircraft of World War II. Schiffer Publ., 1997.
Douglas, Calum E. Secret Horsepower Race: Second World War Fighter Aircraft Engine Development on the Western Front. TEMPEST, 2020.
Ethell, Jeffrey L. Mustang: A Documentary History of the P-51. London: Jane’s, 1981.
Haulman, Daniel L. Nine Myths about the Tuskegee Airmen. October 21, 2011.
Marshall, James William; Ford, Lowell. P-51B Mustang: The Bastard Stepchild that saved the Eighth air force. Bloomsbury Publishing Plc. 2020. (Electronic)
Moye, J. Todd. Freedom Flyers: The Tuskegee Airmen of World War II. New York, NY: Oxford University Press, 2012.
Overy, Richard James. The Bombing War: Europe 1939-1945. London: Penguin Books, 2014.
Romania (1934) Training and Reconnaissance Aircraft – None Built
Cutout view of the IAR-H.S.300. Note the turret with the machine gun, camera and tandem controls. [Dan Antoniu]The establishment of I.A.R. (Industria Aeronautică Română) at Brașov in 1925 was a huge step forward for Romanian industry, and more importantly, the A.R.R. (Aeronautica Regală Română) Romania’s Royal Air Force. However, with the turn of the decade and rapid development of military aircraft around the world, Romanian aircraft factories, which also included S.E.T. (Societatea pentru Exploatări Tehnice) and the new I.C.A.R. (Întreprinderea de Construcții Aeronautice Românești), were lagging behind in terms of equipment and production facilities. This led to a variety of issues which pushed IAR into bankruptcy. The IAR H.S.300 was IAR’s last attempt at creating an aircraft for the ARR before drastic changes were made, both in terms of the plant’s management and the air force’s requirements and needs.
Development
With the deteriorating stability in 1930s Europe, Romania’s M.A.N. (Ministerul Apărării Naționale, Eng: Ministry of Defense) decided that all of its future aircraft had to be of all-metal construction. This caused a lot of issues with the national aircraft manufacturers, which simply did not have the equipment and facilities to produce all-metal aircraft. Similar issues plagued all Romanian industries even during the Second World War.
Between 1930 and 1933, IAR developed several competent fighter aircraft designs, but none were accepted into service due to their construction, which was part metal, part wood. This would force IAR into bankruptcy. Only a small order of 20 IAR-14 fighters was placed in early 1933, under clandestine conditions, directly from the Romanian high command to the factory.
One of the 20 IAR-14 monoplane fighters produced by IAR for the ARR in 1933. It came as a very much needed show of support to the factory, which was hemorrhaging money. [All the World’s Aircraft]Things changed, however, in 1934, when the leadership at IAR requested an investigation from the Romanian Senate. They accused the MAN of not respecting the previously signed contract, ordering 100 aircraft and 150 engines per year, and buying foreign aircraft instead. In a meeting, a MAN representative responded to the allegations with the following:
“The majority of countries on the world stage have, starting from 1930, begun to equip their own air forces with planes built entirely out of metal, offering much better performance. This also being the policy of the Ministry of Equipment of the Romanian Air Force, taking into consideration the international situation, which is deteriorating swiftly, as long as the IAR factory will continue to only build aircraft from wood or mixed wood-metal, we are not interested, and will continue to rely on imports!”
During the same period, IAR developed a handful of new aircraft, one of them being a reconnaissance, observation, and training monoplane which was proposed directly to the S.S.A. (Subsecretariatul de Stat al Aerului). The blueprints and design specifications of the aircraft were discovered by Giorge Ciocoș at the Pitești archives.
IAR-22 trainer, which is what documents claim the H.S.300 was based on [Istoria Aviației Române]IAR-23, which also has a vast amount of similarities to the H.S.300. [Airwar]The plane was directly based on the IAR-22 trainer according to the factory documents, but a close analysis shows that it borrows details from several IAR aircraft, such as the empennage, which is borrowed from the IAR-23. Several other dimensions are the same as the IAR-23, such as the tailplane. It is entirely possible that the IAR-23, which was developed in March of 1934, served as a basis or inspiration for the IAR-H.S.300, as it was developed only 4 months later, in July 1934. Curiously, the documents continue to claim that the project was based on the IAR-22, stating that the wings are from the IAR-22, while a simple comparison of drawings or photos clearly shows that they are from the IAR-23. Additionally, the wings are identical to the IAR-21, which had undergone static testing in August of 1932.
Design & Construction
In the IAR documents, the aircraft is never officially given a name, instead titled as “IAR plane for training of reconnaissance and observation equipped with Hispano Suiza 300 hp engine.” Hence, it was given the unofficial moniker IAR-H.S. 300, referencing the engine. There are 7 documents detailing the layout and construction of the aircraft, with an additional 5 schemes and drawings showing the dimensions and design.
Structural side view of the IAR-H.S.300 [Dan Antoniu]The IAR-H.S.300 was a rather small monoplane, with a wingspan of 12 meters, and a total length of 8.45 meters. Empty, the plane would weigh 989 kg, and 1,420 kg fully equipped with radio and other onboard equipment.
The wing would be made entirely out of spruce, consisting of the central frame, with a length of 3 meters, and the wings themselves, at 4.5 meters each. The wings would be built upon two wooden spars, and the wing shape made from plywood. The longerons were attached to the rest of the aircraft frame via duralumin 90 degree braces. The leading edge and central portion were wrapped with plywood, while the trailing edge and flaps were covered with cloth. The horizontal stabilizers were also of wooden construction and wrapped with cloth.
Top view of the IAR-H.S.300 with measurements. Note the shape of the wings. [Dan Antoniu]In terms of the frame, it was made out of 4 spruce longerons, attached to each other via diagonal wooden supports. The attaching points were out of duralumin, and fastened with rivets. The fuselage that wrapped around the body was made out of sheet metal in the front and around the engine, plywood around the center and cloth on the tail. The elevator had a duralumin frame, but was covered with cloth, while the vertical stabilizer was made entirely out of duralumin construction and wrapped with cloth.
Frontal view of the IAR-H.S.300, showing its wooden propeller. [Dan Antoniu]The landing gear was conventional, consisting of two wheels with brakes and shock absorbers. It was fixed and reinforced with a diagonal truss. Total weight of the landing gear would be 65 kg.
As for fuel reserves, the aircraft would’ve had two fuel tanks, one in each wing, with a capacity of 115 liters each (230 total) but there was the possibility to increase it up to 500 liters total. The oil tank had a capacity of 18 liters.
Clear side view of the IAR-H.S.300. [Dan Antoniu]As mentioned previously, the engine was a Hispano Suiza 8Fb, a 18,5 L V-8. It had between 312 to 320 horsepower at normal power, and a maximum of 337. Typical revolutions per minute were 1,800 rpm and max was 2,100 rpm. Total weight was 275 kg. First variants were developed in 1914 and would be one of the most used engines by the Entente Powers during the First World War, which Romania was a part of, but later variants remained widely used throughout the 1920s and 30s. This powerplant would theoretically allow the IAR to reach a top speed of 238 km/h at 2,000 meters. Max ground speed was 245 km/h. Landing speed was to be 92 km/h. Range was 750 km with the 230 liter configuration. Time to altitude of 3000 meters was 8 min and 30 seconds.
The Hispano Suiza 8Fb V-8 engine. [Wiki]
Crew and Equipment
As a typical observation and training aircraft, there were two seats in the plane, both equipped with steering controls. The pilot is seated directly above the wings, in an open cockpit. He sat low in the plane’s body, with only his head protruding, protected by a small windshield.
The second aviator sat right behind the wings, higher up than the pilot for better visibility. He sat in a rotating turret that had a machine gun equipped, what type is unspecified. Below him were three drums, with 100 rounds each (300 total). A standard A.T.R. 4 radio was also available. The photo camera was positioned behind the turret, but could be operated from within the turret. Although the turret allowed for enough space to maneuver comfortably, the crewmans parachute was placed in a shelf behind him, for more efficient mobility.
Faith
Ultimately, the S.S.A. rejected the IAR-H.S.300. While the Air Force did need new observation and training aircraft, its method of construction and materials used were not accepted by the MAN and MAM (Ministerul Aerului și Marinei). Despite this, the plane seemed to be adequate for its role and time, with modern radio and photography devices, a turret and a respectable engine. Had IAR been able to produce a prototype and offer improvements, such as a fully enclosed cockpit, it would have been a competitive aircraft in its role. Unfortunately, IAR was bankrupt and unable to promote its designs.
IAR-27 light bomber and reconnaissance aircraft, built in the years prior to the war, more or less out of desperation. [Airwar]The salvation of IAR came in 1936, when Poland became the only supplier to grant Romania production licenses. M.A.N. purchased licenses for the production of the Polish PZL-11 and PZL-24 aircraft, which had full metal fuselages, and were decent aircraft for their time. This required vast investments into the IAR factory, for the tooling and production facilities, and also the personnel and design bureau.
However in 1938, with war knocking at Europe’s door, the M.A.N. equipped the Romanian Air Force with whatever the factories could produce, such as the IAR-37, IAR-38, and IAR-39, which likely wouldn’t have been produced if the IAR-H.S.300 had been pushed into service and upgraded, as they were also reconnaissance and light bomber aircraft. These aircraft did not prove to be a significant upgrade, and were also built out of a combination of metal and wood, but circumstances forced M.A.N. to buy them regardless.
Conclusion
The IAR-H.S.300 was a small reconnaissance and training aircraft developed as a last ditch attempt by IAR for the Romanian Air Force. However due to its construction consisting of part metal, part wood combined with the Romanian Ministry of Defence’s reluctance to accept such planes, the project died quickly. In the end, the Romanian Air Force was forced to purchase mixed construction wood-metal planes from IAR, due to the mounting hostilities of late 30s Europe.
Acronyms and Translations
I.A.R. (Industria Aeronautică Română) Eng: Romanian Aeronautic Industry
A.R.R. (Aeronautica Regală Română) Eng: Royal Romanian air force
S.E.T. (Societatea pentru Exploatări Tehnice) Eng: Technical Exploitation Society
I.C.A.R. (Întreprinderea de Construcții Aeronautice Românești) Eng: Romanian Aeronautics Construction Company
M.A.N. (Ministerul Apărării Naționale, Eng: Ministry of Defence
S.S.A. (Subsecretariatul de Stat al Aerului) Eng: State Subsecretary of Air
MAM (Ministerul Aerului și Marinei) Eng: Ministry of Air and Navy
IAR H.S. 300 Specifications
Wingspans
12 m / 39 ft 4 in
Length
8.45 m / 27 ft 9 in
Wing Area
21.9 m² / 71.9 ft²
Engine
Hispano Suiza 8Fb V-8, 312 hp
Empty Weight
989 kg / 2,180 lb
Maximum Takeoff Weight
1,429 kg / 3,150 lb
Fuel Capacity
230 liters / 60.75 gal
Maximum Speed
238 kph / 147 mph
Time to Altitude
3,000 meters / 9,840 feet – 8 min 30 sec
4,000 meters / 13,120 feet – 13 min 0 sec
5,000 meters / 16,400 feet – 19 min 10 sec
Range
750 km / 466 miles
Crew
1 Pilot & 1 Radio Operator/Photographer
Armament
Single Machine Gun (Unspecified) 3x 100 Round Drum Magazines
Gallery
Artist Conception of IAR HS.300 – Illustration by Godzilla
Credits
Written by Pavel Alexe
Edited by Henry H., Ed Jackson, & Stan Lucian
Illustration by Godzilla
Special thanks to Dan Antoniu and Eng. L. C. Tascau
Poland (1939) Transport and Ambulance Aircraft – 7 Built
The Lublin R-XVI. Source: Wiki
Following a request for a new passenger transport aircraft, the Plage and T. Laśkiewicz aircraft manufacturer developed the Lublin R-XVI. While it was not accepted for production, it would be built in a small series as a successful ambulance aircraft and used up to the Second World War by the Poles.
History
During early 1929, the Polish P.L.L airline, with the assistance of the Ministry of Transport, opened a contest for a new four-passenger transport plane. This aircraft was to be powered by a 220 hp Wright/Škoda radial engine. This contest was heavily influenced by the Polish Department of Aeronautics, which favored domestic manufactures. Aircraft manufacturer Plage and T. Laśkiewicz from Lublin (hence, all their products were named after that city) responded with the R-XI. Ultimately, this contest ended in failure, as none of the proposed aircraft proved satisfactory.
New specifications for a second contest were issued by the end of 1930. This time, Plage and T. Laśkiewicz presented a new model, the Lublin R-XVI design by Jerzy Rudlicki. While being based on the previous R-XI, there were a number of changes, like separating the cockpit from the crew compartment and changing the wing design. The novelty this aircraft introduced was the use of chrome-molybdenum tubes for the structure, a first in Poland, which reduced the weight.
When the prototype was completed, it was flight tested by Wladyslaw Szulczewski in February 1932. In the following months, the R-XVI was tested with different payloads. During these flights, the maximum speed achieved was around 194 km/h (120 mph). During 1932, the R-XVI was used mostly for postal service by the P.L.L. While the R-XVI proved to be satisfactory, its competitor, P.W.S., was chosen instead as the winner of this competition.
A New Role
Although they lost the competition, Plage and T. Laśkiewicz were instead contacted by the Medical Aviation Research Centre in cooperation with the Polish Red Cross. They were interested in the R-XVI plane and asked for certain modifications. These included adding space for two stretchers and a doctor, along with storage for additional medical equipment. This implementation was approved by the Ministry of Transport and the prototype was to be modified for this role. The aircraft was then renamed to R-XVIB, with the SP-AKP registration. Beside the changes to the interior passenger compartment, the fuselage was strengthened. These modifications were completed by the spring of 1933, when the aircraft was flight tested again.
Front view of the converted R-XVIB prototype aircraft. Source: Wiki
At the International Congress of Military Medicine in Madrid
This aircraft was presented to the VIIth International Congress of Military Medicine and the IInd International Congress of Medical Aviation, which was held in Madrid in 1933. Its crew consisted of the pilot, Zygmunt Janicki, mechanic Leon Zamiara and doctor Maj Kazimierz Michalik. The R-XVIB had the honor of being the first medical aircraft in the history of these Congresses to actually directly arrive by air. It also proved to be the best medical aircraft design present. The R-XVIB even won the first prize, the Raphael Cup, by beating the Spanish Trimotor and French Potez 29. When the Polish crews returned, they managed to fly the distance of 5,730 km (3,560 miles) without any problems.
Production Orders
Following the R-XVIB’s success in Spain, Plage and T. Laśkiewicz received production orders for one more prototype and five operational planes. The new prototype was completed during 1934. It was slightly different in comparison to the first aircraft. The most obvious change was the redesigned fuselage, improving the pilot’s visibility and using new types of landing wheels fitted with brakes and shock-absorbers. All aircraft were completed and put into service by the end of 1934.
Technical Specifications
The R-XVI was designed as a high-wing, single-engine, mixed construction transport/ambulance aircraft. The fuselage was built using chrome-molybdenum metal tubes and then covered with fabric. The one-piece wings were built using two spars which were covered by plywood. The wings were connected to the upper part of the fuselage by four bolts. The tail construction was the same as the fuselage, with a combination of steel tubes and fabric.
The R-XVI was powered by a 220 hp Škoda J-5, a nine-cylinder air-cooled radial engine, built under license after the J-5Wright Whirlwind engine. It was fitted with a two-blade fixed wooden propeller. The fuel load was stored in an aluminum tank (257 liters) which was placed in the upper part of the fuselage between the the wings.
The R-XVI high wing design and the fixed landing gear are evident in this photograph.. Source: Airwar.ru
The cockpit was placed at the front of the fuselage. To enter this position, the pilot was provided with a door. The crew compartment had room for four seats and one additional optional seat for a mechanic, if needed during the flight. There was a huge door for the passengers on the starboard side, with an additional smaller door for the luggage compartment on the port side. In the case of the later ambulance version, the crew compartment was redesigned to include two stretchers, placed one above the other. It was also equipped with shock-absorbing mounts for a more convenient flight for the patients. To bring the patients inside the plane, a large door was placed on the starboard side. On the opposite side, there was a door for the medical attendant. The interior of the medical version was provided with a first aid kit, washstand with running water, and lights.
The R-XVIB, which was designed as an ambulance aircraft, had specially designed folding doors to bring the patients inside the plane. Source Airwar.ru
The fixed landing gear consisted of two wheels. These were provided with vertical shock absorbers and brakes. If needed, there was an option to replace the landing wheels with skis. The original prototype had a small tail wheel, which was replaced on the later production model with a tail skid.
In Service
While not a combat aircraft, all R-XVIs were still operational by the time of the German invasion (1st September 1939) of Poland. By the time of the war, they were primarily used for wounded evacuation. While their final fate is unknown, they probably fell victim to the German air force.
Production and Modifications
The R-XVI was built in limited numbers for the Polish Red Cross. Besides the two prototypes, 5 additional aircraft were built.
R-XVI – Original proposed passenger aircraft prototype, later served as the base for ambulance version.
R-XVIB – Modified ambulance version, 6 aircraft were built (including a prototype).
Conclusion
While not accepted in its original role, the R-XVI would still see service as a medical aircraft used by the Polish Red Cross. In this role, they proved to be satisfactory and a small series of 5 aircraft was built. Their final fate sadly is not known and none survived the war.
Lublin R-XVIB Specifications
Wingspans
49 ft / 14.9 m
Length
33 ft 1 in / 10 m
Height
8 ft 7 in / 2.96 m
Wing Area
328 ft² / 30.5 m²
Engine
One 220 hp Wright Whirlwind (Škoda) J-5 nine-cylinder radial engine
Empty Weight
2,535 lbs / 1,150 kg
Maximum Takeoff Weight
3,590 lbs / 1,630 kg
Fuel Capacity
257 liters
Climb Rate to 1 km
In 6 minutes 30 seconds
Maximum Speed
118 mph / 190 km/h
Cruising speed
104 mph / 168 km/h
Range
479 miles / 800 km
Maximum Service Ceiling
14,635 ft / 4,600 m
Crew
Pilot and Medical Crew
Armament
None
Gallery
Illustrations by Carpaticus
Credits
Written by Marko P.
Edited by by Stan L. & Henry H.
Illustrations by Carpaticus
Sources
C. Chant. (2007) Pocket Guide aircraft of the WWII – 300 of the world’s greatest aircrafts, Grange books.
J. B. Cynk (1971) Polish Aircraft 1893-1939, Putham and Company
B. Belcarz and R. Peezkowski (2001) White Eagles: The Aircraft, Men and Operations of the Polish Air Force 1918-1939, Hikoki Publications
J. Koniarek Polish Air Force 1939-1945, Signal Publication.
Empire of Japan (1945) Kamikaze Aircraft – 105 Built
The Ki-115 suicide aircraft [Combat Workshop via Pinterest]
Throughout 1945, it was becoming clear to Japanese Army Officials that an Allied invasion of the Japanese mainland was growing ever more likely. Seeing as their navy and airforce had been mostly destroyed, they needed new weapons to fight off a probable Allied attack on Japan. Among these new weapons were Kamikaze aircraft, with many older designs having already been used in this role. However, some Kamikaze aircraft were to be specially designed for such a role, being cheap and able to be built quickly and in great numbers. One such aircraft was the Ki-115 Tsurugi (Sabre) which was built in small numbers, and never used operationally.
History
Rear view of Ki-115 suicide aircraft [ijaafphotos.com]Following the extensive loss of men, materiel, and territory during the fighting in the Pacific, the Japanese Army and Navy were in a precarious situation, especially as there was a great possibility of an Allied invasion of their homeland. Unfortunately for them, the Japanese fighting forces on the ground, in the air, and on the sea were mostly mere shadows of their former selves, unable to prevent the rapid Allied advance across the Pacific. This was especially noticeable after the costly Japanese naval defeat during the Battle of Leyte Gulf in October 1944 and later Battle of Okinawa which ended in July 1945.. The desperation, or better said fanatical refusal to accept that the war was lost, led to the development and use of Kamikaze (divine wind) tactics. This name was taken from Japanese history, the term arose from the two typhoons that completely destroyed the Mongol invasion fleets.
Essentially, the Kamikaze were Japanese pilots that used their own explosive-laden aircraft as weapons, and sought to crash into important targets, such as Allied warships. This term also entered widespread use to designate all Japanese suicide craft used in this way. During the war, these tactics managed to sink over 30 Allied ships and damage many more.
Allied anti-aircraft fire was often concentrated in order to prevent Kamikaze attacks. But, despite this, Japanese aircraft would often get through. [Wiki]The suicide attacks were mostly carried out using any existing aircraft that was operational, including older trainers and obsolete aircraft. Kamikaze are a subject with a great deal of nuance and can be difficult to understand through a conventional lens. However, supplies of these aircraft would inevitably become limited and their previous usage meant fewer would be serviceable compared to newer, more expensive models. Thus, the Japanese Army wanted a specially designed Kamikaze aircraft that could be produced in great numbers. These aircraft needed to have a simple construction and use as little of dwindling material stockpiles as possible.
On 20th January 1945, the Japanese Army contacted the Nakajima aircraft manufacturer with instructions to design and build such an aircraft. The basic requirements included a bomb load up to 800 kg (1,760 lbs). It had to be able to be powered by any available radial engine in the range of 800 hp to 1,300 hp. The maximum speed desired was 515 km/h (320 mph). Construction and design had to be as simple as possible. They also wished to speed up the whole development and production process and also to reduce the need for skilled labor. It was especially emphasized that the undercarriage had to be jettisonable, not retractable. It was not expected for the aircraft to fly back, so a retractable landing gear was not needed and this would make the production and design process somewhat quicker.
First Prototype
The job of designing this aircraft was given to Engineer Aori Kunihiro. He was supported by engineers from Ota Manufacturing and the Mitaka Research Institute. While Nakajima received the contract in January 1945, it only took two months to complete the first prototype. In March 1945, this prototype was presented to the Japanese Army and then put through a series of tests. Almost immediately, a series of faults with the design were noted. This was not surprising given that the whole design process lasted only two months. During running on the ground, the fixed and crude undercarriage was difficult to control. The pilot’s poor frontal visibility further complicated matters. This was unacceptable even for skilled pilots, while less experienced pilots would have had great difficulty in successfully operating it on the ground. The Army rejected the prototype and requested a number of modifications to be done.
The Ki-115 first prototype. [ijaafphotos.com]The Ki-115 cockpit was positioned in the middle of the fuselage and offered the pilot limited forward vision when on the ground. [Wiki]
Technical Specifications
The Ki-115 was designed as a low-wing mixed construction suicide attack aicraft. The front fuselage, containing the engine compartment, and the central part were built using steel panels. The engine compartment was held in place by four bolts and was specially designed to house several different potential engines. Eventually, the Japanese chose the 1,130 hp Nakijama Ha-35 14 cylinder radial piston engine. It had a fixed-pitch three blade propeller. In order to help reach its target quicker, two small auxiliary rocket engines were placed under each wing.
The wings were built using all-metal construction with stressed skin. The rear tail unit was built using wood and was covered by fabric. The cockpit was placed in the upper centre of the fuselage. It was semi-open, with a front windshield.
As requested, the Ki-115 prototype had a fixed and jettisonable undercarriage. It had a very simple design, using simple metal tubes with no shock absorbers. While two wheels were used in the front, a tailskid was used at the rear. The fixed undercarriage tested on the prototype proved to be highly ineffective. All later produced aircraft were instead equipped with a simple and easy to build shock absorber.
Ki-115 side view [ijaafphotos.com]The armament consisted of a bomb load of up to 800 kg (1,760 lbs). This included using either a single 250 kg (550 lb), 500 kg (1.100 lb) or 800 kg (1.760) bomb. The bomb was not to be dropped on the enemy, but instead be detonated once the aircraft hit its target. Beside the bomb, no other armament was to be provided on the Ki-115.
The Ki-115 was initially meant to be supplied with a fixed undercarriage, which proved to be problematic. Production aircraft were instead provided with simple shock absorbers. [ijaafphotos.com]
The Fate of the Project
Once the prototype was back in Mitaka Kenkyujo (where the prototype was built), the engineers began working on improving its performance. The redesigned undercarriage, which incorporated a simple shock absorber, was completed by June 1945, by which time a series of test flights were done. By August 1945, some 104 Ki-115 aircraft were ready. Two Ki-115s were given to Hikoki K.K., where the Japanese Navy Air Force was developing its own suicide attack aircraft. By the war’s end, none of the Ki-115s built would be used in combat.
Surviving Aircraft
The Ki-115 planes were later captured by the Allies, and nearly all were scrapped. Surprisingly, two Ki-115s have survived to this day. One can be seen at the Pima Air & Space Museum. This aircraft is actually on loan from the National Air and Space Museum. The second aircraft is currently located in Japan. Not wanting to potentially damaged tis aircrafts on the side of caution no restoration attempts are planned for the near future.
The surviving Ki-115 at the Pima Air & Space Museum. [Wiki]A picture of the second surviving aircraft taken during the 1980’s in Japan. [hikokikumo.net]
The Ki-115b Proposal
In order to further improve the aircraft’s performance and reduce cost, the Ki-115b version was proposed. This included replacing the all-metal wings with ones built of wood. These new wings were larger and had to be equipped with flaps. To provide the pilot with a better view, his cockpit was moved to the front. Due to the end of the war, nothing came from this proposal.
Production and Modifications
The Ki-125 was built in small numbers only, with some 104 production planes plus the prototype. These were built by the two Nakajima production centres at Iwate (22 aircraft) and Ota (82 aircrafts). The production lasted from March to August 1945.
Ki-115 prototype – Tested during early 1945.
Ki-115 – In total, 104 aircraft were built, but none were used operationally.
Ki-115b – Proposed version with larger wooden wings, none built.
Only 105 Ki-115 aircraft, including the prototype, were ever built. [ijaafphotos.com]
Conclusion
Luckily for the Japanese pilots, the Ki-115 was never used operationally. It was a simple and crude design which was born out of desperation. If the Ki-115 was ever used in combat, it would have likely presented an easy target for enemy fighters and suffered from poor reliability due to its cheap construction.
Ki-115 Specifications
Wingspan
28 ft 2 in / 8.6 m
Length
28 ft 1 in / 8.5 m
Height
10 ft 10 in / 3.3 m
Wing Area
133.5 ft² / 12.4 m²
Engine
One 1,130 hp Nakijama Ha-35 14 cylinder radial piston engine
Another Ki-115 Tsurugi in Natural Metal with 500kg Type 92 BombKi-115 Tsurugi in Green with 500kg Type 92 BombKi-115 Tsurugi in Natural Metal with 500kg Type 92 Bomb
Credits
Written by: Marko P.
Edited by: Stan L. & Henry H.
Illustrations by Ed Jackson
Sources
R. J. Francillon (1970) Japanese aircraft of the Pacific war, Putham and Company
D. Nešić (2007) Naoružanje Drugog Svetskog Rata Japan, Tampoprint
D.Mondey (2006) Guide To Axis Aircraft Of World War II, Aerospace Publishing
The Yak-4. [Wiki]Following the failure of the Yak-2, Yakovlev attempted to salvage the project. One of the attempts that saw limited production was the Yak-4. While it would be powered by a somewhat stronger engine, it too would prove to be a failure and only some 100 aircraft would be built by 1941.
The Yak-2 Failure
While the Yak-2 prototype initially had excellent flying characteristics, once it was actually fully equipped with its military equipment, its performance dropped dangerously. A large number of issues, like overheating, poor flight stability, and problems with its hydraulics, were also noted during the development phase. Despite this, some 100 aircraft would be built and some were even issued for operational use.
Yak-2 side view. [Gordon & Khazanov, Soviet Combat Aircraft]One of the many weak points of the Yak-2 was its problematic Klimov M-103 engine. The Soviet designers decided to replace this with the more powerfulr M-105 engine. Two basic designs emerged, one for a dive bomber and one for a short-range bomber. During its first test flight, the dive bomber variant proved to be so disappointing that the project was canceled. The bomber version, however, showed to be somewhat promising and the green light for its development was given.
Development History
The development of the BB-22bis (also known as Izdeliye 70bis) prototype was given to Factory No.1, and the Yak-4 designation was officially adopted only in December 1940. Engineers at Factory No. 1 started to build the prototype in early 1940 and it was completed by March the same year. This was not a new aircraft, but a modified Yak-2,serial number 1002) . That same month, Factory No.1 was instructed to produce additional prototypes for testing the aircraft’s performance by the Army, which had to be completed by the start of July 1940. The Army requested a maximum speed of 590 km/h (366 mph) at 5,000 m (16.400 ft)be , an operational range of 1,200 km (745 miles), and a service ceiling of 11,000 m (36,090 ft).
The modified Yak-2 (serial number 1002) aircraft that served as the base for the BB-22bis prototype. [Y. Gordon, D, Khazanov and S. Komissarov OKB Yakovlev ]Following the completion of the first prototype, a series of test flights were carried out. During one of the test flights, carried out on the 12th May, a maximum speed of 574 km/h (356 mph) was achieved. On 23rd May, however, there was an accident and the pilot was forced to crash land at a nearby airfield, damaging two other bombers and the prototype’s wing in the process. Given the extensive damage to the aircraft’s wing, the prototype had to be written off. Due to this and delays in production, the first two trial aircraft could not be completed before the end of 1940. Interestingly enough, these were actually produced by the Moscow Aircraft Factory No.81, which started the production of the Yak-4 during October and November 1940. At that time, the type had not yet received official approval from the Soviet Army.
The damage suffered by the first prototype during its hard landing was so severe that it had to be scrapped. [Y. Gordon, D, Khazanov and S. Komissarov OKB Yakovlev]
The two trial aircraft were given to the Army for testing on 10th December 1940. These tests were held at the end of January 1941. The results were once again disappointing, as these aircraft had worse performance than the prototype. With the added weight of equipment and fuel, the maximum speed was reduced from 574 km/h (357 mph) to 535 km/h (332 mph). The cockpit was described as being too cramped, and with the full bomb load, the plane proved to be difficult to control even by experienced pilots. The commission that examined the two aircraft insisted that the Yak-4 should not be accepted for service. In late February 1941, the Director of Factory No.81 gave a report to the Soviet People’s Commissar of the Aircraft Industry, A. Shakhoorin, that the production of the Yak-4 was to be stopped and replaced with the Yak-3. Interestingly enough, while the Yak-2 was developed by Alexander Sergeyevich Yakovlev, he did not direct the design process of the Yak-4.
Technical Characteristics
The Yak-4 was an overall copy of its predecessor, the Yak-2, but there were still some differences. The most obvious change was the introduction of new engines. The older M-103 ,960 hp, was replaced with a stronger M-105 1050 hp engine. The installation of the two new engines also introduced a number of internal improvements to the ventilation and fuel systems. New 3.1 m (122 in) long VISh-22Ye type propellers were also used on this model. The landing gear retracted to the rear into the engine nacelles, but was not fully enclosed. These consisted of two pairs of 700×150 mm wheels.
The rear parts of the fuselage were lengthened and redesigned, and it was less bulkier than the Yak-2. The cockpit was improved in order to provide the crew with a slightly better overall view. The rear gunner received a completely new pivoting canopy. He operated the TSS-1 mount armed with two 7.62 mm (.30 caliber) ShKAS types machine guns.
Rear view of the Yak-4. [Wiki]The maximum bomb load was increased to 900 kg (1,980 lbs). In addition, there was an option of mounting two 90 (20 gallons) or one 250 liter (54 gallons) auxiliary fuel tanks under each wing. There were six fuel tanks placed in the wings. These had a total capacity of 1,120 litres (244 gallons) of fuel.
A front view of the Yak-4 with its new and stronger M-105 engines. [Y. Gordon, D, Khazanov and S. Komissarov OKB Yakovlev]
In Combat
The Yak-4, together with the Yak-2, was allocated to the 314th and 316th Reconnaissance Regiments in the western district. Some were given to the 10th, 44th, 48th, 53rd, 136th and 225th short to medium range Bomber Regiments. The main problem for the units that operated the Yak-2 and Yak-4 was the slow delivery of these aircraft. For example, only a few pilots from the reconnaissance units had a chance to fly on these new aircraft. By 10th June 1941, only limited numbers of Yak-4s were available for service. A shipment of some 10 new aircraft was meant to arrive but did not due to the war’s outbreak.
Pilots from the 314th Reconnaissance Regiment performed several flights over the border with Germany just prior to the Invasion of the Soviet Union while flying Yak-4s. The Germans responded by sending the Bf 109E to intercept them, but they failed to do so. However, once the war started, the German Luftwaffe destroyed many Soviet aircraft on the ground. This was also the case with the Yak-4, with the majority lost this way. Some did survive though and offered limited resistance to the Germans. By September 1941, on the Northern front, there were still fewer than 10 operational Yak-4s. To the South, there were still some 30 or so Yak-4s which were still operational by October 1941. There is no information of the use or losses of the Yak-4 after 1942. According to Y. Gordon, D, Khazanov and S. Komissarov OKB Yakovlev , at least one Yak-4 was still operational and used by the 118th Reconnaissance Regiment in 1945.
Most of the Yak-4s were destroyed on the ground by the advancing Germans. [Y. Gordon, D, Khazanov and S. Komissarov OKB Yakovlev]The advancing Hungarians, who were supporting the Germans during the Invasion of the Soviet Union, managed to capture at least one Yak-4 aircraft during 1941. The use of this aircraft by them would be limited at best, due to the scarcity of spare parts and general poor performance.
Production
The production of the Yak-4 was only carried out at Factory No.81. The production lasted from November 1940 to April 1941. Around 90 to 100 aircraft would be built, with the last 22 Yak-4s being delivered for use by late April 1941.
Operators
Soviet Union – Operated some 90 aircraft
Hungary – Managed to capture at least one Yak-4 aircraft
Conclusion
Despite attempts to resolve a number of issues noted on the previous version, the Yak-4 in general failed to do so. The problem was the overall poor design of the original Yak-2 which offered little room for improvement. The inability to improve the aircraft to the satisfaction of the Soviet Air Force led to the cancelation of the Yak-4 project after only a small number of aircraft was built.
Nazi Germany (1940)
Jet Powered Bomber & Reconnaissance Aircraft – 8 Prototypes Built
The Ar 234 A V6 (GK+IW) prototype. [Warbirdphotographs]
Following a request from the German Ministry of Aviation (Reichsluftfahrtministerium – RLM), in 1940, German aircraft manufacturer Arado began working on a new multi-purpose jet powered plane. Arado’s work would lead to the development of the advanced and sophisticated Ar 234 aircraft. During 1943, a small series of eight prototypes would be built and used mainly for testing, but some saw operational service.
History
During the spring of 1940, Arado was contacted by RLM officials with a request to design a completely new multi-purpose jet aircraft to be used for bombers and for reconnaissance duties. This aircraft was to be powered by new jet engines which were under development by Junkers and BMW. Interestingly, besides the request that it should be able to reach the British naval base at Scapa Flow in Northern Scotland, no other performance requirements were specified. The sources do not specify the precise base of operation for these reconnaissance missions. Geographically, the closest territories under German control were south Norway and Denmark, although it is possible that these aircraft would have had to operate from air bases in the occupied territories in Western Europe, either from France, the Netherlands or Belgium. This would require an estimated range of over 900 km. In essence, the RLM gave Arado free reign in terms of the overall design and its performance. If the prototypes built were satisfactory, an initial order for 50 aircraft was to be given.
Work on this new design was given to engineer Rüdiger Kosin, as Arado’s Technical Director, Walter Blume, was uninterested in this project. When work started, it received the Arado Erprobungs (experimental) 370 designation. During the initial phases, there were several different proposals about the number of crewmen, wing size, weapon configuration and the number of engines. After nearly a year, in October 1941, the first proper project, designated the E 370/IVa, was completed. This proposal was mainly intended to be used as a reconnaissance aircraft and was to be equipped with camera equipment. It was to be powered by two BMW P 3302 turbo jet engines. The armament was quite modest and consisted of only one 13 mm MG 131 machine gun. As this aircraft was to operate from short-length airfields, the designers came up with the idea to use a wooden retractable skid for landing, which was to be mounted beneath the fuselage.
E 370/IVa drawings. [Smith & Creek, Arado 234 A]
The project was presented to RLM officials in late October of 1941. They were satisfied and gave permission for the production of 50 aircraft. During the evaluation, it received the 8-234 designation. Unfortunately for Arado, the head of the RLM Technical Department, Ernst Udet, committed suicide just a few weeks later. He was replaced by Erhard Milch, who was more interested in aircraft that were already being produced rather than the proposed Arado project. This without a doubt affected the earlier mentioned initial production order, as the initial order for 50 seems to disappear from record. Despite this setback, work on the E 370 continued. During early 1942, some modifications to the fuselage were made with the aim of increasing its size and strength. The unusual skid undercarriage was replaced by a retractable wheeled bogie system.
In February 1942, Erhard Milch visited the Arado company. He was presented with the drawings and calculations for the improved E 370 model. He was generally impressed with what he saw, and gave his permission for the construction of a wooden mockup. The order would be increased to six prototypes in the following month. The aircraft was to take off using a small three wheel dolly. After the aircraft was in the sky, the dolly was jettisoned and landed with the help of a parachute, meaning it could be used again. In addition, the idea of using a retractable skid undercarriage was reintroduced. If needed, jettisonable Walter HWK auxiliary rocket take-off engines could be attached under the wings. Throughout 1942, many additional modifications and changes were made to the design. Great attention was given to the testing of different engine types and configurations.
By the end of 1942, the number of prototypes to be built was once again increased to 20. The first seven aircraft were to be powered by Jumo 004 engines, with prototype V8 powered by four BMW 003 engines, and V9 through V14 with two BMW 003 engines. The remaining aircraft were to be powered by four BMW 003 engines. The first prototype was meant to be built by November 1943, with the last in October 1944. Surprisingly, these 1942 plans actually started to be completed early, with the first 3 prototypes ready by August 1943. Thanks to this, it was possible to run the first test trials even earlier than anticipated.
Work on the First Prototypes
Work on the construction of the first prototype began in late 1942. During this time, the name was changed to Ar 234. Progress was slow due to problems with the delivery of the Jumo 004 engines, which only arrived in February 1943. These engines were tested and immediately proved to be problematic, as they failed to achieve the promised 850 kg (1879 lbs) thrust. Once fitted with these engines, the first prototype, Ar 234 V1, was used for static ground testing and taxiing trials. No flight was initially accepted due to the short runway at Brandenburg, where the prototype was built. For this reason, the prototype was moved to a Luftwaffe airfield at Munster. During July 1943, this aircraft was mainly used for ground tests. In late July, there was an accident when one of the Jumo engines caught fire. The damage was minor and was quickly repaired. On 30th July, Ar 234 V1 made its first test flight piloted by Horst Selle. The flight was successful, with no problems with the aircraft. The dolly, on the other hand, was lost when the parachute failed to properly open. In early August, there were again problems with the same engine. To avoid any potential threat to the aircraft, it was simply replaced by an engine taken from Ar 234 V3, which was under construction. On 9th August, another test flight was undertaken. During this flight, Selle reached a speed of 650 km/h (400 mph) without any problems. The dolly was once again lost, similarly to the first one. Additional changes were made to the position of the parachute on the dolly, which proved to be the solution to this problem. The V1 prototype would be lost in an accident where the pilot overshot the landing field and crash landed on 29th August. While the aircraft was not repaired, parts of it were reused for testing other equipment.
The Arado 234 V1 first prototype. This particular aircraft would be lost in an accident where the pilot overshot the landing field and crash landed on 29th August 1943. [Warbirdphotographs] V1 during the third test flight, during which the dolly parachute release system was successfully tested. [Luftwaffephotos]
The V2 prototype was completed in late August 1943. There were some issues with the engine, which had to be replaced. The aircraft was otherwise trouble-free. It was moved to Alt Lonnewitz, where it was mainly used for engine testing. In late September 1943, V3 made its first flight. While, initially, it was to be equipped with a pressurized cabin and an ejector seat, this was never implemented.
In early October 1943, the V2 prototype, with its pilot, Selle, were lost in a fire. This accident prompted the Germans to introduce automatic fire extinguishing systems on all of the Ar 234 prototypes, including later ones. Another change was introducing ejection seats to avoid any further pilot casualties. Due to this accident, there were some delays in the Ar 234 project. Testing continued in November, when V3 was piloted by Walter Kroger. On the 21st of November, the V3 aircraft was transferred to Insterburg to be presented to Adolf Hitler, together with other experimental jet aircraft, like the Me 262 and Me 163. Hitler was highly impressed and even gave orders that some 200 aircraft be built during 1944. During this time, V4 was also flight tested. Both V3 and V4 were used until June 1944 for various roles, including crew training, after which they were removed and replaced with later Ar 234 B versions. By the end of 1943, V5, fitted with Jumo 004 B-0 engines. was introduced.
During early 1944, two Arado 234 aircraft would be tested with a four engine configuration. The idea was that the use of four smaller engines would provide similar performance to the larger ones. V8 was powered by two pairs of BMW P.3302 engines. V6 (which was built later than V8) was tested with four BMW 003 engines placed in four separate wing-mounted nacelles. During a routine flight of V6 at the start of June 1944, all four engines stopped working only 17 minutes after take-off. The pilot was forced to conduct an emergency landing of the plane, after which it caught fire and was heavily damaged, rendering it a complete loss. After this accident, and due to many other engine problems with both versions, all further work on the multi-engined Ar 234 A was discontinued. These would later serve as the basis for the Ar 234 C version instead.
V6 powered by four BMW 003 engines placed in four separated wing cowlings. [Luftwaffephotos] V6 after a forced landing in June 1944, shortly before the engines began to burn. This accident and problems with the engines put an end to the development of the multi-engined Ar 234 A version. [Warbirdphotographs] V8 was powered by four BMW P.3302 engines placed in pairs. [Warbirdphotographs]
Technical Characteristics
The Arado Ar 234A (as they were designated later on) prototypes were designed as all metal, high-wing turbojet-powered experimental reconnaissance planes. Their fuselages had a semi-monocoque design with a flat top. The wings consisted of two main spars, each with 29 ribs. They were covered with metal stressed skin. Each wing was connected to the fuselage by four bolts. If needed, these could easily be taken off and removed. At the rear, there was a more or less conventional tail unit.
The Ar 234 was used to test a number of different engines. The first 4 prototypes were powered by two Jumo 004 A-0 engines, which had 840 kg (1,850 lbs) of thrust. V5 and V7 used Jumo 004 B-0 engines which provided 900 kg (1,980 lbs) of thrust. The 3.8 m (12 ft) long engines (both types had the same size) were attached to the wings using three bolts. V6 and V8 were powered by four engines which were able to achieve 800 kg (1,760 lbs) of thrust. As the Ar 234 was intended to be used for reconnaissance operations, a large fuel capacity was important. One 1,800 liter fuel tank was placed behind the cockpit, with a second 2,000 liter tank in the rear of the fuselage. With this fuel load the Ar 234 had an operational range of 1,500 km (930 miles). To assist with take-off, the Ar 234 could be equipped with small Walter 109-500 type rocket engines. These had a run time of 30 seconds and could generate 500 kg (1,100 lbs) of thrust. After the Ar 234 was in the air, the rocket motors would be jettisoned and would land on the ground using small parachutes.
The Ar 234 did not have conventional landing gear, but instead used a three wheel 640 kg (1,410 lbs) jettisonable take-off assist dolly. The Ar 234 pilot could control this dolly by using the rudder, which was connected to hydraulic brakes on the dolly. Once in flight, the dolly would detach and then fall back to Earth using a parachute, and could thereafter be reused. Initially, it was discarded during flight, but this proved to be problematic. After some redesign work, the moment of release was changed to just after take-off. There was no risk of the dolly impacting the fuselage in midair, as the parachute pulled it away from the aircraft. When the Ar 234 had to land, it would use the retractable hydraulically operated skid under the fuselage. The engine nacelles were also provided with smaller skids to avoid any damage to them and to provide better stability during landing. The V3 prototype tested in early 1944 used a drag parachute during landing. This proved to be successful and was later implemented as standard from the B series on.
The smaller front wheel on the jettisonable dolly was fully steerable to help during airfield taxiing and take-offs [Warbirdphotographs] Close up view of the large sliding skid. [worldwarphotos.info] Ar 234 during landing. A fuselage skid along with smaller skids placed under the engine nacelles were used instead of wheels. Later versions of the Ar 234 incorporated a conventional wheeled landing gear. [Warbirdphotographs]
The pilot’s cockpit was fully glazed, which provided excellent all around visibility. To enter the cockpit, the pilot used a small hatch placed atop the cockpit. This was not a great design feature as, in an emergency, the pilot could not easily escape the plane. In order to protect the pilot from enemy fire from the rear, a 15 mm thick armor plate was installed behind his seat. Behind this protective armor plate, three oxygen tanks were placed. The instruments were placed on two smaller panels to the left and right of the pilot.
A few Ar 234s were equipped with two Rb 50/30 cameras. These were placed behind the rear fuel tank. These could cover a wide area of 10 km (6 mile) at an altitude of 10 km (33,000 ft).
There were initial plans to arm the Ar 234 with a 13 mm machine gun for self defence. Due to the experimental nature of the Ar 234 A version, no actual armament would actually be installed.
Operational Service
In May 1944, Conny Noell of the Luftwaffe experimental Versuchsverband unit requested that at least two Ar 234 airframes be used for experimental reconnaissance operations after examining the prototypes. The request was accepted and the V5 and V7 aircraft were allocated for this task. Besides the camera equipment, virtually nothing else was changed on these two aircraft.
For the testing of these aircraft, two pilots were chosen, Horst Götz and Erich Sommer. At the start of June 1944, the V5 prototype was tested by Götz during a short 30 minute long flight. He later wrote, after the war “The take-off procedure was not very complicated. First, I engaged the starter, then fed petrol into the combustion chamber until, at approximately 6,000 rpm, I made the gradual change to J2 kerosene. The engines were then reved up to their maximum 9,000 revolutions. After take-off, I throttled the engine back to cruising speed. It was a completely new flying experience. Only a slight whistling noise in the cockpit could be heard. The take-off dolly had functioned quite normally. It was really wonderful”.
Four days later, Sommer also tested this aircraft and gave a similar positive assessment of its overall performance. More flights were undertaken in the following days without major problems. While piloting the V5 prototype during a routine take-off, Götz’ wheeled takeoff dolly release mechanism failed, with the assembly remaining stuck to the aircraft’s landing skids. He immediately tried to land back at the airfield. Despite the dangerous maneuver, he managed to land in a nearby potato field, with minimal damage to the plane.
Around this time, the two test pilots were informed that no prolonged or high-altitude flights had ever been attempted by the Ar 234 prototypes, mostly due to a lack of pressurized cockpit. For this reason, Sommer decided to personally test the Ar 234’s performance at altitude. In late June 1944, he made the first high altitude flight, which lasted over an hour and fifteen minutes at an altitude of 11 kilometers (36,000 ft). During a dive, he managed to reach a speed of 590 km/h (367 mph). A few days later, he made another similar flight that lasted over two hours, during which he managed to cover a distance of 1,435 km (890 miles). When the test flights were completed, both pilots gave positive feedback and evaluations about the performance of the planes and recommended their immediate production.
Following the Allied invasion of German occupied France in 1944, the experimental unit was ordered to move its two aircraft and equipment by train to Juvincourt, in France, by the end of July. Due to delays with the delivery of necessary parts, mostly due to Allied air raids, V7 was finally ready to take to the sky on the 2nd of August. V7’s first operational mission was to take photographs of the Allied landing beaches and the 10 km (6 mile) wide inland strip . The flight was a success, without any problems. The Ar 234’s cameras managed to take nearly 400 photographs of the Allied invasion force, which provided the Germans with vital information about the strength and numbers of the enemy. With this single flight, Sommer managed to achieve what the remaining Luftwaffe reconnaissance units failed to do in two months. During August, some 7 reconnaissance flights were undertaken by the two Ar 234 aircraft. Following the rapid Allied advance, they had to be relocated to Belgium. While V7, piloted by Sommer, arrived without any problems, Götz was less fortunate. During the flight, he was hit by friendly anti-aircraft fire. While damaged, Götz managed to fly up to Oranienburg. But his bad luck for that day was not yet over. His landed Ar 234 aircraft was struck from behind in a ground collision by a Focke Wulf Fw 190 which was attempting a take-off, completely destroying V5. Ironically, the first German operational jet powered aircraft, and the first in the world, was shot down by the Germans and then destroyed by a German fighter plane!
Sommer was stationed with his aircraft at Volkel in Holland until the 5th of September, when it was relocated to Rheine base. On the 10th, Sommer performed a reconnaissance flight over the Thames Estuary but, without direct orders, continued up to London. The next morning, he was informed that, due to this action, he was to be arrested and court martialed. Sommer immediately contacted Götz and explained the situation to him. Götz immediately took action and, after persuasions and threats, managed to get the charges against Sommer dropped. After the war, they both found out who demanded Sommer’s arrest. It was the chief of the V-2 program, Hans Kammler, who had feared that the pictures of London would prove the failure of his rocket program.
Part of the damage suffered by V5 during the forced landing and after being hit by ground anti-aircraft fire, shortly before being hit by an Fw 190 taking off. [Smith & Creek, Arado 234 A]
Sommer made at least four more reconnaissance flights with Ar 234 V7 before it was finally replaced with a B version, which was essentially just a copy of the previous version but with a wider fuselage and a more conventional completely retractable wheeled landing gear. After this, V7 was mainly used for crew training before being damaged during a take-off accident on 19th October 1944. After it was repaired, Götz made a flight to Oranienburg, where the plane was removed from service.
Production
Of the Arado 234 A series, only 8 aircraft were ever produced, as they were used for experimentation of various equipment and engine units.
V1 (TG+KB) – Badly damaged during a harsh landing.
V2 (DP+AW) – Was lost in a flight accident.
V3 (DP+AX) – Was presented to Hitler, who authorized the Ar 234 production. Used for various testing until July 1944.
V4 (DP+AY) – Similar to the V3 prototype, used up to June 1944 mainly for crew training, when it was removed from service.
V5 (GK+IV) – The first aircraft to be used operationally, but was lost when damaged by friendly ground-based anti-aircraft fire.
V6 (GK+IW) – Heavily damaged during a landing accident and caught fire soon after.
V7 (GK+IX/ T9+MH) – Used operationally until October 1944, when it was damaged in a take-off accident. Written off as a complete loss.
V8 (GK+IY) – Tested with a four engine configuration, but proved to be highly problematic.
Conclusion
While only a small number of Ar 234A planes were built, they proved to be successful designs. During the initial development phase and in their experimental use in service, no major issues were noted. The major drawback was the insufficient quality of the engines and the use of a jettisonable takeoff dolly. Following the success of the Ar 234 A, the development and production of the B and C versions was approved.
V1, the first prototype, made its first test flight piloted by Horst Selle at the end of July 1943. It would eventually be lost in an accident when the pilot overshot the landing field and crash landed on 29th August 1943. Ar 234 V5 was the first aircraft of the small production series to be used operationally during the Allied Liberation of France in 1944. It would be lost after a series of unfortunate circumstances culminated with a ground collision with a Focke Wulf 190 which was attempting a take-off. Ironically, the first German operational jet powered aircraft, and the first in the world, was shot down by the Germans and then destroyed by a German fighter plane! V5 was fitted with Jumo 004 B-0 engines. V6 was tested with four BMW 003 engines placed in four separate wing-mounted nacelles. During a routine flight at the start of June 1944, all four engines stopped working, forcing the pilot to conduct an emergency landing of the plane. After this, the plane caught fire and was heavily damaged, rendering it a complete loss.
A P-61A of the 422nd NFS. (San Diego Air and Space Museum)
The Northrop P-61 was a night fighter designed to fulfill a largely overlooked gap in America’s air defenses in the years prior to its entry into the Second World War. Ambitious and groundbreaking, the P-61 would be the first fighter aircraft designed to carry a radar and was to be equipped with a state of the art remotely operated turret. However, the aircraft suffered numerous technical problems which led to many delays in its development. Despite its quirks, the plane proved to be popular with its pilots, effective in service, and far more capable in its mission than preceding American night fighters, while also proving itself effective in roles not envisioned at the time of its design.
Nascent Developments
The US Army’s night air defense services during the interwar years were perhaps their most neglected and least developed. This was in part due to the meager capabilities of the aircraft and detection systems of the time, but also general disinterest from senior leadership and, resultantly, poor funding. Despite advances in night flying instrumentation and training aids, most notably Edward Link’s ground trainer, efforts during the period to detect and intercept aircraft at night were largely futile. Success in testing was almost entirely based on the weather, as the search lights they coordinated with relied on acoustic detection, and their ability to find the enemy was largely based on luck whenever the skies were not clear. Attempts were even made to detect enemy aircraft by the weak electromagnetic waves emitted by their spark plugs, but these were met with predictably poor results. What methods they did develop were subsequently made useless by advancements in bomber design, as the new Martin B-10 was faster than most contemporary fighters, and the B-17, still in development at the time, showed even greater promise (McFarland 3, 4).
Andrew Link’s ground trainer allowed pilots to train for blind flying without actually taking to the air [American Society of Mechanical Engineers]Night fighters would prove a largely unworkable concept during the interwar years due to the crude instruments employed to find the bombers, which themselves also stood a good chance of outrunning their pursuers, however, this would soon change. The development of radar and more capable fighters would prove to be the decisive factor that would transform the practice of intercepting aircraft at night from a clumsy mission dependent more on luck than anything else, to an essential service that would grow ever more precise in its ability to detect and bring down enemy aircraft.
Lessons Abroad
The night raids during the Blitz both proved the necessity of night fighter forces and would provide the first lessons needed to found the service [Encyclopedia Britannica]Virtually all major new developments of the Air Corps’ night fighting capabilities in the years prior to the US entry into the Second World War were a result of two factors, new developments in radar and reports from observers sent to take note of the lessons the RAF were learning during the fall of France and the Blitz.
As the clouds of war drew over Europe during 1938 and 1939, it was clear that airpower would be a decisive component of any potential conflict. It was for this reason that president Franklin Delano Roosevelt massively built-up US military forces for the goal of defending both the mainland United States and its overseas military installations in 1939 and 1940. This build up had broad aims, but perhaps most importantly it saw the vast expansion of the US Army’s air power. This was to prove instrumental for those officers who wished the service to take on a much larger role in the US Armed Forces, and to finally cement their position in it, as the department had been reorganized several times during the interwar period.
They would soon see a massive leap in responsibilities as the Air Corps took up the bulk of air defense duties with the founding of the Air Defense Command in February of 1940. However, despite their eagerness to play such a major role, they also recognized their lack of experience and sought to understand the fundamentals of the modern air war in order to better fulfill this task. With the war waging in Europe, General Henry “Hap” Arnold was able to argue for the presence of US Air Corps observers overseas. In the spring of 1940, four officers were sent to London, Paris, and Berlin (Harrison&Pape 26). While these early postings were important for shaping foreign policy and building ties that would facilitate easier coordination with the RAF later in the war, they would soon become an essential source of information for Air Corps planners following the fall of France and throughout the Blitz.
It was during the Blitz that perhaps the largest gaps in US air cover would become evident, with various solutions being presented to help bridge them. Thankfully for the Air Corps observers, the Blitz would demonstrate exactly what they would need to develop to face any threat from the air. They recognized that they needed a modern air force, which could cooperate with sophisticated detection and communication networks to form a comprehensive air defense system that would leave any attacker badly mauled, day or night.
Brig. General Tooey Spaatz was the primary observer for RAF night fighting operations, and it was no coincidence that he later became Chief of the Air Corps Material Division at Wright Field. While the British night fighter services were still extremely crude at this point in the war, they presented a much better starting point for US planners than the virtually useless interwar experiments. Spaatz’s efforts largely shaped the requirements for the Air Corps’ night fighter, these being relayed to Northrop’s Chief of research, Vladimir Pavlecka, while he was at Wright Field working on another project. Alongside a set of specifications, he was told the plane would need to be a two-engined aircraft with a crew of two, a pilot and a radar operator, though the specifics of radar were not disclosed. At this time, Northrop was a new company and made for an obvious choice, as they had previously worked on an unbuilt night fighter design for the British, and were one of the only firms that were not at capacity at the time.
Soon, this new aircraft, designated the ‘Air Corps Night Interceptor Pursuit Airplane’, began to take shape. It would be powered by a pair of Whitney Double Wasp engines carried in nacelles that would be connected by a twin boom tail, and joined to the fuselage through the wings. It would carry a crew of three, a pilot, a gunner, and a radio operator who also doubled as a rear gunner. It would mount two turrets carrying four .50 caliber guns each and would be a large aircraft with a height of 13 feet and two inches (4.013 m), a length of 45 feet and six inches (13.87 m), a wingspan of 66 feet (20.12 m), it would weigh 22,654 pounds (10276 kg), and feature the new Zaparka flaps. While this proposal bore many similarities to the later XP-61 prototype, much would change as the design was revised.
While the design was promising, work was slow, and though Northrop had a prototype designed in January of 1941, it would be many months until it was ready to fly, and years before it was ready for service (Harrison&Pape 30). As a result, the aircraft would not be ready for the war to come, leaving most of the night fighting duties to stop gap designs, such as the converted A-20 bomber designated the P-70, and the British supplied Bristol Beaufort.
Clean slate, Dull chisel: A history of early American night fighting
With the attack on Pearl Harbor, the night fighter force found itself entering the war with the lessons learned from the RAF, but without adequate training programs or equipment. Compared to what existed in England, the communications and detection infrastructure was very poor, as it relied on high frequency radio sets which proved troublesome, lacked sufficient identify-friend-or-foe capability, with early warning radar set up in poor positions, and worst of all, they lacked a dedicated night fighter force.
With the help of RAF advisors, they set out to correct these faults, with the Air Defense Operational Training unit being activated March 26th, 1942. The 81st Fighter Squadron (special) was chosen on May 28th, 1942 as the first official night fighter training unit and was staffed with officers who were enthusiastic about the promise of this new mission. This unit was later placed under the new Night Fighter Department, which itself was reorganized as the Night Fighter Division and made subordinate to the Fighter Department . Their curriculum was composed on July 4th, 1942, as pilots were to be trained to a high level of proficiency in instrument flying, blind take offs and landings, night formation flying, night gunnery, pilot-radar operator interception teamwork, Ground Control Intercept (GCI), and general air defense procedures.
While this unit was extremely useful in testing and building confidence in new equipment, like the SCR 540 radar, it was hit by numerous hurdles which prevented it from turning out the number of pilots needed. This was mostly the result of a shortage of aircraft, as the relatively small number of P-70’s, DB-7’s, AT-11’s, T-50’s, and B-80’s would prove a serious bottleneck, as would the delays in getting Airborne Intercept ground trainers. This problem remained late into 1941, as the 81st was deactivated and its personnel used to form the 348th and 349th Night Fighter squadrons in October of 1941. These two squadrons would be used to train new night fighter personnel with the hope that they could build 15 squadrons by 1943. However, this training schedule was overly ambitious and hampered by insufficient supplies of equipment. Sadly, in line with much of the troubled program, night fighter pilots graduated with no fanfare or any formal ceremony. They simply signed on a line and received their wings.
Night Fighter Squadron building would continue slowly until James Doolitle would push for its accelerated development in late 1942. Doolittle, after being so impressed by RAF night fighters over North Africa, called for four new night fighter squadrons to be formed, these being the 414th, 415th, 416th, and 417th. It was not until July of 1943 that real Night Fighter Squadron development began in earnest, as more aircraft and training material became available, and the new 481st Night Fighter Operational Training Group was formed under the command of Lt.Col. Winston Kratz (Harrison&Pape 104).
Trial by Fire: Pacific
The P-70 was the USAAF’s first true night fighter. Unfortunately, in practice, the plane proved to be totally inadequate for the task. [SDASM Archives]The first night fighter deployments were to Panama and Hawaii, with the first P-70s becoming available in January of 1942. These planes were first used in improvised night fighting squadrons, like the 6th Night Fighter Squadron initially based out of Hawaii. They were, however, badly constrained by their inadequate support infrastructure and, as pilots would soon find out, the performance of their aircraft. Problems soon arose over the personnel shortages which required volunteers from signal corps officers and the enlisted maintenance crews to serve as radar operators. Problems improved very little following their move to Guadalcanal in February of 1943, where conditions were brutal.
Their objective was to try and stop the nightly raids by Japanese bombers which came over the islands to conduct nuisance raids. The P-70s were vectored onto these aircraft using the ground-based SCR 270 early warning radar without success, as the radar could provide only the azimuth to the target but not its altitude. Neither the radar crews nor pilots had much experience with GCI procedures and, combined with the meager capabilities of the P-70, the night fighters brought down few Japanese aircraft. While the night fighter crew’s living conditions improved thanks to new prefabricated shelters, their operational success did not. Their challenges were made far more difficult as the Japanese adapted to their tactics and their bombers began to fly above the P-70’s service ceiling, and went so far as to imitate American GCI operators in attempts to give faulty information to pilots (Harrison&Pape 68). P-70 crews did all they could to improve the speed and operational ceiling of the aircraft through serious modification which included installing propellers from B-17F’s and P-38 fuel pumps, though to no success.
Conditions at airfields across the Solomons were extremely poor, and made worse by occasional bombing raids [National Archives]Frustration with the P-70 even managed to motivate the squadron to modify some of the P-38s they had been supplied with in an effort to replace the P-70. This would prove difficult, as the aircraft were not equipped with radar as they were to be used in conjunction with searchlights to find their targets. Two P-38Gs were modified by Lt. Melvin Richardson and a squadron radar mechanic by adding a second seat behind the pilot and building an avionics pod for the SCR-540 out of an external fuel tank. These modified planes were much faster than the P-70s and were capable of reaching high flying Japanese bombers, however, they could not convert enough fighters. Both would receive the Legion of Merit for their ingenuity, but apart from this small victory, the 6th would lack the means to conduct their missions.
Overall, the night fighter squadron’s experiences in the South Pacific proved dismal, having neither the properly trained personnel, support elements, or even aircraft needed to effectively complete their mission. In the end, what success they did have was a result of their ingenuity and perseverance rather than specialized training or the equipment they had been issued. Each victory over the Japanese bombers was a hard-won achievement equally celebrated by the aircrews and the Marines the enemy harassed on a nightly basis.
Trial by Fire: Mediterranean
While the 6th NFS was still deployed to Guadalcanal, the 414th and the 415th left for England in March of 1943, where they would soon be retraining on Bristol Beaufighters. The switch from the P-70 was a difficult one, as between its tendency for ground looping and engine fires resulting from landing gear failure, the Beaufighter proved an intimidating plane for the US pilots. While the Beaufighter proved to be significantly faster and more agile than their old P-70s, many pilots felt uneasy flying it, and even their RAF instructors would readily admit the aircraft was among the most difficult in British service. Unlearning the habits from the P-70 was difficult, but thanks to a comprehensive program from the RAF, the challenge was soon overcome. Now proficient, the 414th and 415th left for North Africa and went into action in July of 1943 (Harrison&Pape 80).
The Bristol Beaufighter would prove an effective weapon against the Luftwaffe and Regia Aeronautica, though its handling characteristics left much to be desired [National Archives]Unlike their counterparts in the Pacific, the Mediterranean squadrons were largely successful thanks to their far superior Bristol Beaufighters, comprehensive training programs, and good technical support. Not only were they directed by far superior ground based radar systems, but these squadrons would later be the first to use the British AI Mk VIII centimetric radar sets, which, unlike the previous SCR-540, could operate at low altitudes. This radar was particularly useful, as it meant German bombers could no longer fly low to reduce the effective range of the aircraft’s radar. In November of 1943, the campaign proceeded and the two NFS’ would cover Allied convoys against the attacks of German bombers during the advance into Italy. The Germans would use a very different set of tactics compared to the Japanese, and made use of far more sophisticated equipment. As opposed to the single Japanese aircraft that often came in at around 30,000 ft (9144 m), the Germans tended to stay roughly between 10,000 and 15,000 ft (3048, 4572 m) in formations of various sizes. As opposed to the nuisance raids designed to keep the Marines from getting any rest, the Germans often sought to hit strategic targets, like harbor facilities and shipping vessels en masse. The Germans would also later employ chaff, which cluttered up radar scopes, and tail warning radar on their bombers to warn them of the approach of night fighters.
The efforts of early American night fighter squadrons in the Mediterranean would thankfully prove to be the rule rather than the exception for the air crews still to come. In the future, they would expect well trained, specialized personnel, and effective ground control radar support. However, there were still strict limitations imposed by the equipment afforded to the night fighter squadrons, in particular their aircraft which, despite their greater speed, were anything but easy to fly.
XP-61 & YP-61: trouble, frustration, and promise
The XP-61 would prove to be a promising, but troubled design that would require a lengthy redesign [This Day in Aviation]While American night fighter pilots had their first experiences in combat during 1942 and 1943, work on the new XP-61 continued. The program truly began in early 1942, after several contracts were issued. It was decided in February of 1942 that 410 aircraft would be procured with $7,136,689.56 being charged to the Defense Aide and $55,656,178.67 to Air Corps Appropriations. This contract stipulated the delivery of the first twelve to take place in April of 1943, with the final aircraft being handed over in January of 1944. However, contract negotiations saw the number of aircraft requested rise and fall significantly in the following months. In addition to deliveries to the USAAF, 50 P-61s were to be set aside for Lend Lease, though this was later dropped due to a lack of RAF interest in the aircraft (Harrison&Pape 89).
The XP-61 first flew on May 26th, 1943, but only after a long and troubled process that saw the prototype fly with different propellers than what were originally called for, a dummy turret, and without a radar. Despite these shortcomings, the prototype was initially quite promising, with the aircraft performing satisfactorily during its short preliminary flight, and its test pilot, Vance Breese, telling Jack Northrop “Jack, you’ve got a damn fine airplane!” (Harrison&Pape 89). The succeeding flights would, however, prove more troublesome ,as they soon revealed stability problems and reliability issues with the engines. These issues were tracked to the horizontal stabilizer and elevator assemblies, the short span Zap flaps, and the buildup of oil and gas in the engine crankcase. Engine failures and violent longitudinal instability soon grounded the XP-61. The stability problems were particularly troublesome, as they required redesigning much of the tail assembly of the aircraft and the addition of full span flaps in place of the Zap flaps.
Issues also arose with the use of the spoileron system on the second XP-61, which was designed to be used in conjunction with short ailerons as part of its lateral control system. The spoilers themselves were thin circular arcs that sat in grooves in the wings. These would deploy and allow the pilot remarkably good control at high speed, but their development would prove to be rather difficult. At first, they proved unstable as a result of their hinge movements, which was solved by reducing the size of the scoop. Later, serious vibration issues were found to destroy the spoilers within their wing slots. This, in turn, was found to be the result of high-speed airflow moving through the slot, and was remedied by installing plates to seal it off (Harrison&Pape 94).
In an effort to improve engine reliability, the initial Pratt & Whitney R-2800-25S engines were replaced with R-2800-10s, though this would fail to solve the problem. Despite the swap, engine failures were common in testing and it was found that cutting oil consumption resulted in oil starvation in the master cylinder, resulting in it freezing. With the rest of the articulating rods still going, the engine would work itself apart. After diagnosing the problem, the engineers at Pratt & Whitney soon resolved it with the installation of additional oil jets (Harrison&Pape 95).
These faults would see a major redesign of the XP-61, with the new model being designated the YP-61, which would act as both a prototype and pre-production model. This would incorporate a number of design modifications, including switching the tail boom’s construction from welded magnesium to aluminum alloy, the Zap Flaps being replaced by a full span trailing edge arrangement, and they would go on to incorporate the fix for the spoilerons (Dean 383). However, this would not represent an end to trouble, as the much-needed improvements in stability meant it could now be used for more demanding tests which would, in turn, uncover new faults.
As testing grew more strenuous, new problems began to arise, most notably with the fuselage. It was soon found that there were several structural weaknesses in the fuselage, with the vulnerable sections being subsequently strengthened, particularly around the canopy. The nose gear door also proved to be fairly fragile, which necessitated strengthening and having the aircraft’s 20 mm guns fitted with blast tubes to prevent the muzzle report from damaging it. It was also found that, at high speeds, the dome at the rear of the radar operator’s compartment could implode as a result of pressure difference. While this component was improved in prototyping, the problem would resurface in production models of the aircraft (Harrison&Pape 114).
At the nose of the aircraft, a new problem was found after a stopover in Arizona. In the sweltering 110-degree weather of the desert, it was found that the Plexiglas radome would deform and collapse once the aircraft was in the air, with the resulting shift in air flow causing the Lucite dome at the rear of the aircraft to blow out. While a new fiberglass dome was designed, it would not be ready well into serial production of the P-61A (Harrison&Pape 115).
The remote-controlled turret was also found to have several faults. The most immediate and concerning of these was that, while the guns were forward, the aircraft remained aerodynamically clean, but there would be intense buffeting as the turret traversed beyond 30 degrees in either direction. Following a redesign, the buffeting was mostly gone save for a far lighter effect that occurred when the turret was fully deflected to either side. In firing tests, it was found that use of the turret resulted in severe structural damage, with a similar problem being encountered with the aircraft’s 20 mm armament. In both cases, it was necessary to strengthen nearby structural elements with steel fittings, though owing to the complexity and size of the remote-controlled turret, a major redesign of the aircraft’s upper structure was required (Harrison&Pape 117, 118).
In spite of its many teething issues, the general flying characteristics earned the aircraft good marks from test pilots, exceeding Northrop’s guaranteed performance by one mile during speed tests, and was remarked upon by production project engineer Capt. Fred Jenks as follows: “The P-61 is an honest airplane. It has no mean tricks. In acrobatics such as loops, spins, Immelmanns, and fast turns, it behaves as a pursuit plane should. Its stalling gestures are near perfect.” (Harrison&Pape 121)
The YP-61, later redesignated P-61, would solve most of the issues of the troubled XP-61 and ease the transition for production models [NACA]
Britain and America on the same wavelength: Cooperation in developing the SCR-720
The Tizzard Mission
The P-61’s highly advanced air search radar was a device many years in the making, being a product of the interwar Tizard Mission, which sought to bring together US and British technical expertise for radar and radio development. It would officially become known as the British Technical and Scientific Mission, and it was not long into the war that approval was granted for the scientific material transfer to the US, which the British hoped would be reciprocated in kind by technical assistance and access to America’s electronics industries. The mission arrived in the US in September of 1940 with two gifts, a cavity magnetron, a device which allowed for the development of more advanced centimeter band radars, and an ASV Mark II surface search radar. Their audience was composed mostly of three groups, the Signal Corps, who had been struggling with the practical employment of radars for nearly a decade, microwave researchers, who were well versed on the technology but had yet to produce practical radar examples, and the US Army Air Corps, who were uninformed on technical matters but saw the promise of the technology (Brown 159, 160).
The mission got off to a good start, with the American audience suitably impressed. On the British side, they gained a great deal of information on the use of microwave techniques, and more importantly, access to larger electronics manufacturing industries and procedures. The US, on the other hand, gained access to the existing British radars and the cavity magnetron. While these advancements would have taken place eventually, the collaboration through the Tizard mission allowed rapid advancements in radar development and production in both countries. It was, of course, not without its negative consequences. Some trust in the American service-labs was lost when they gained the undeserved reputation of producing inferior equipment among the Armed Services when their interwar work was judged against the British (Brown 165, 166).
In the US, work on centimetric radar was mostly carried out through the MIT Radiation Lab, with their first goal being to produce an airborne centimeter band set (Brown 168). The benefits of a centimeter band radar over a meter band were considerable, as they would not require the use of drag inducing aerial antennas. The narrower band also meant less reflection from the ground, and while it was not yet known, they were less susceptible to jamming. In short, they represented a massive leap in capabilities over older radar sets (Brown 145).
The rooftop radar experiments above the Rad Lab were a major step in the development of practical centimetric radar [MIT Physics Department]The Rad Lab’s first centimetric radar was a 10 cm band set operated from a roof in January of 1941, with an intensive development program to follow. It was hoped that, by February, it would be mounted in a B-18 for testing, and a month following that, they hoped to have it aboard an A-20. However, many issues plagued the rooftop experiment and it was not until March that the device was transferred over to the B-18. Work would continue, and after further collaboration with the British, a new series of technology transfers would benefit both programs, with the British gaining access to a better transmitter, and the US a better receiver. Soon, the lab would produce America’s first practical centimetric Aerial intercept radar, the SCR-520. Western Electric built a few of these sets but work soon transitioned to making a lighter version for the P-61, the SCR-720 (Brown 168, 169).
SCR 720
The SCR-720/AI Mk X was comprised of a number of components, some of which were encased within pressurized canisters [Mossie.org, thisdayinaviation]The SCR-720 series was an advanced aerial intercept radar built by Western Electric and Bell Telephone Laboratories (Harrison&Pape 113). The radar operated on a wavelength of 9.1 centimeters at 3,300 megacycles, with a peak pulse power of approximately 70 kW. It had a maximum range of about 6 miles (9.65 km), which was later extended beyond 10 miles, at all azimuths between a search angle of 75 degrees to either port or starboard, with a minimum range of 300 feet (91 m). The system used a helical scan method and, in addition to the previously stated horizontal search angle, covered a total elevation of –30 degrees to +50 degrees. The device lacked provisions for IFF gear but could be used in conjunction with the SCR-729 transmitter, which was compatible with Mk III and Mk IIIG IFF sets along with beam approach beacons.
SCR-720 Radar operator’s display and controls [SCR 720 manual]The display set up was composed of two indicator boxes, a two screen display to be used by the operator, and a far simpler one screen display which was for use by the pilot. The pilot’s indicator typically went unused, as it was less precise than the rear set and was generally redundant, as the pilot would be talked onto the target by the RO. The RO’s scope consisted of a range tube on the right, and an azimuth and elevation tube on the left. The display on the azimuth scope was dependent on the settings of the range scope, as only targets within certain set ranges would appear on the scope. This range was indicated by a marker line on the range scope and could be adjusted by the RO (Survey 28). The settings of these scopes were adjusted through the control box and synchronizer in the RO’s compartment.
In service, the SCR 720 offered many benefits over previous Allied centimeter band aerial intercept radars, in particular the slightly older British AI Mk VIII. A post war survey found that, while using the SCR-720, it was harder to lose maneuvering targets on the scopes thanks to the range/azimuth display which allowed the operator to follow the target’s course. The wide coverage meant it was unlikely a rapidly descending target would be lost, the range scope made course adjustment estimates to the target easier, and the range/azimuth display made intercepts across the flight path of the night fighter easier. Overall, the SCR-720 would prove to be the most precise and advanced AI radar set of the war and would see widespread use aboard the P-61 and DeHavilland Mosquito, which carried a British production of the device designated the AI Mk X (Survey 30).
However, while the radar was the best set in its day, it was also the most complex and was said to require the knowledge and experience on the level of a masters of electrical engineering just to make one’s way around the black boxes that made up the system (Harrison&Pape 113). In service, it would prove even harder to maintain where personnel and spare parts for the system would be sparse, and many of its components would prove vulnerable to the elements. This would generally prove an issue with P-61 squadrons, as they typically lacked personnel able to fix the boxes should problems arise, and often would not have enough spares to replace faulty components. Maintenance notwithstanding, the SCR 720 was a generation ahead of the previous SCR-540 and exceeded it in every capacity except ease of repair.
SCR 720 display diagrams [Radar Survey]
Enter the Black Widow: P-61A&B
An early production P-61A [National Archives]The first P-61A rolled off the line in October of 1943 at Northrop’s plant in Hawthorne, California, with a public reveal later occurring at an Army-Navy show in Los Angeles in January of 1944. These aircraft were mostly unchanged from the last P-61 pre production aircraft, though this plane and the next 36 P-61As would be the only examples of the A model to be equipped with the remotely operated turret. The turret would be absent from the remaining 200 As and many of the succeeding B model, only to be reintroduced after a redesign (Pape 120,121).
Despite the revised model which would arrive much later in 1944, the P-61’s performance was roughly the same for its entire wartime service, with no major overall increases in horsepower or any major modifications to the airframe, apart from those to allow it to carry additional fuel and bombs and rockets for intruder and ground attack missions. Both the A and B models were powered by the Pratt and Whitney R-2800, with many early P-61As using the R-2800-10 and all aircraft beyond the P-61A-15 using the R-2800-65. Both engines produced 2000 hp, with the only major differences being their magnetos and ignition systems (Pilot’s training manual 11). Revisions to the design were gradual and often very minor between subtypes. As the P-61A matured, many new additions were made, including a new fuel system, underwing racks for bombs and fuel tanks, a water injection system, and additional oil capacity. The water injection system would boost the engine’s power about 15%, but only for brief periods and unsuitable for a lengthy climb or long-distance pursuit (P-61 training manual 12).
The P-61B would go on to extend the nose, revise the trim and hydraulic systems, alter certain instruments and displays in the cockpit, revise the heating system, alter the landing gear doors, and restore the turret (Dean 383). Much more work was done with regards the P-61C, which made use of significantly more powerful turbo-charged engines, though this aircraft did not see wartime use.
While the aircraft would mostly resemble the early prototypes, there had been more than a few major reworks of the airframe, most notably, the dropping of the ‘Zap Flaps’ for near full span types with an added lateral control system which made use of spoilerons. While these did prove troublesome in testing, the faults had been ironed out and the system worked to the satisfaction of pilots. The final configuration made use of slot covers and seals for the spoileron slots that solved the vibration problems and allowed for great lateral control for such a large aircraft while requiring little force on the part of the pilot. While this system was unconventional, pilots rapidly adapted to its use and were immediately appreciative of it, as it allowed for easily applied control at both very high and low speeds. It was particularly useful during landings, where they allowed for precise control on approach thanks to the automatic adjustment of the lateral control system with the flaps (Ashkenas 13, 14). This system was a major factor in making this fighter among the most maneuverable in the USAAF inventory, in spite of it also being the largest and heaviest.
Tough most of the aircraft’s worst issues were remedied in the prototypes, a few made it into the production models. The most glaring of these would be the plastic radome fitted to the nose of the aircraft, and the lucite tail cone at the rear, both of which would constitute fairly significant structural weaknesses. The plastic nose fitted to many of the early P-61As was weather sensitive and was prone to warping in the hot, tropical weather of the Pacific, or simply if left uncovered during a sunny and particularly hot day. The solution was painting the nose of the aircraft in a bright, reflective white paint, which raised obvious disadvantages when the aircraft was trying to stealthily pursue its targets in the dark. The lucite cone would prove more persistent and more dangerous (Harrison&Pape 115). On several occasions, these cones imploded during dives and high-speed maneuvers. While this presented little danger to the overall aircraft, the sound of rushing air through the radar operator’s position made communication between him and the pilot virtually impossible. This would be resolved later by the addition of metal reinforcement bands, though many older P-61’s would continue to fly without them.
While this was the first purpose built night fighter, in many ways, the aircraft fell short of the high hopes placed upon it, but would prove adequate for the purpose it was given. Responses to the P-61 were mixed though generally favorable, but complaints over speed and the difficulty of maintaining the SCR 720 radar persisted for all wartime models of the aircraft. Perhaps most unfortunate was that the top turret, which vastly complicated the aircraft’s design and added considerably to the aircraft’s frontal area and weight, was found to be completely unnecessary. The most immediate requests for improvement were for more powerful engines with better high-altitude performance, and for units to be supplied with more maintenance and test equipment for the SCR-720 radar, which the inadequately prepared ground crews struggled to keep in working order. While they were trained in basic maintenance and installation of the device, few had the technical skills necessary to actually repair faulty components. Neither of these would be provided in time to be of use during the war.
ETO: The 422nd and 425th Night Fighter Squadrons
French workers repair a runway at an airfield operated by the 9th AF [National Archive]The first P-61 to leave the United States was a P-61A to be evaluated by the RAF in March of 1944. This aircraft was later returned in February of 1945, as the RAF were not particularly impressed with its performance and found its maximum range to be far too low. They needed night fighters for deep penetrations into German airspace in support of the ongoing strategic bombing campaign, and the P-61 simply did not fit the requirements. While the aircraft was by all metrics a poor fit for the RAF, the language and tone surrounding the growing competition between the P-61 and DeHavilland Mosquito would become increasingly petty and hostile within certain sectors of the US War Department and the Night Fighter division.
Beyond this evaluation aircraft, three Night Fighter squadrons would be deployed to England in anticipation of Operation Overlord. These were the 422nd, which departed on March 10th, the 423rd on April 1st, and the 425th which departed May 1st. During this period, only the 425th had P-61As slated to be shipped out with them amidst general concerns regarding the availability of the aircraft. The 422nd and 423rd were still equipped with the inadequate P-70 at the time of their departures (Overlord Build Up). Supplies would thankfully become more available, with the 422nd getting their first P-61As in late May and the 423rd becoming a photographic reconnaissance squadron and would not require the aircraft (Dean 285). Both squadrons would possess a small number of aircraft, with the 425th shipping out with only nineteen aircraft, and throughout their service in the European Theater it remained the case that replacement aircraft were in short supply.
None of these P-61As were equipped with the dorsal turret, and with copious time on their hands and the feeling that a second pair of eyes looking forward would be helpful, several crews in the 425th NFS had the bright idea to move the radar operator’s position up into the now vacant gunner’s seat. Along with technical representatives from Northrop, the chief radar and engineering officers, and a Capt. Russell Glasser, who possessed a graduate’s degree in mechanical engineering, they set out to modify the aircraft. The results were spectacular, with the pilot and R/O now able to communicate in the event of intercom failure, and the resulting shift in weight changing the slightly nose up to a nose down at cruise, increasing the cruising speed between 15 and 20 mph. This change was subsequently authorized for 9th Air Force’s P-61s (Harrison&Pape 205, 206).
Ground crews prepare a P-61 for action [National Archives]It was not until July of 1944 that the European P-61s actually flew their first combat sorties, with the several months prior to this being taken up by training, including joint exercises with the RAF, and a race between the P-61A and a DeHavilland Mosquito NF Mk XVII. The latter was precipitated by a rumor that the USAAF was planning to replace the P-61 with the Mosquito.
In June, Lt. Col. Oris B. Johnson arranged for joint training with an RAF Halifax bomber squadron based at Croft, during which the Night Fighters would practice intercepting the bombers, who would in turn practice evasive maneuvers and other defensive tactics. The night fighters would be given an area to defend and would be vectored onto bombers by GCI. When they were in place to claim a ‘kill’, they flashed their navigation lights (Harrison&Pape 206). While this exercise was undoubtedly easier than what they would later be asked to do over France, it was important in building up the crew’s confidence in their abilities and equipment.
The ‘race-off’ was an event long in the making, with its roots in the War Department’s desire to purchase DeHavilland Mosquitoes for use as reconnaissance aircraft and night fighters. There were those in the department who wished to equip the Night Fighter Squadrons in the Mediterranean with Mosquitos, with the ensuing politics eventually driving a rumor that the War Department was planning to scrap the production of the P-61 in favor of the Mosquito, which were to be supplied by the UK and Canada. In any case, these proposals were impractical, as the British were extremely protective when it came to these aircraft. However, rumors soon filtered to the squadrons who were upset enough to propose a fly-off between the types. A demonstration was arranged on July 5th, 1944 at RAF station Hurn. The contenders were a P-61A and a Mosquito NF Mk XVII, with the results being that the P-61 out climbed and out turned the Mosquito between 5,000 and 20,000 feet.
The race was anything but clear cut, and it is extremely unlikely that it was just a fair competition that both sides took part in earnestly. Simply put, the RAF did not want to give the USAAF any more Mosquitoes than they absolutely had to, and were extremely motivated to throw the race. They had a great desire to ensure they were better supplied with the only night fighter in Allied service at the time that could fly long range missions into Germany. The results of the race are extremely suspicious given just how clear the P-61A’s win seemed to be in comparison to the years of evaluations which virtually always claimed that the Mosquito NF had the superior climb rate, and the P-61 had superior maneuverability. Members of the 481st NFTG who had flown planes came to the same conclusion, as did the AAF board, and even Col. Winston Kratz, director of night fighter training and a major proponent of the P-61 (Harrison&Pape 153, 156, 203). His words perhaps best sum up the event, “I’m absolutely sure the British were lying like troopers. I honestly believe the P-61 was not as fast as the Mosquito, which the British needed because by that time it was the one airplane that could get into Berlin and back without getting shot down. But come what may, the ‘61 was a good night fighter. In the combat game you’ve got to be pretty realistic about these things. (Harrison&Pape 209)”
The first real test of the P-61 in Europe came in July of 1944, when they were pressed into service against a new threat, the Fiesler 103 flying bomb or ‘buzz bomb’. The fast, unmanned weapon required the P-61 to enter a slight dive to catch them and, while they flew straight and level, they still proved a dangerous and challenging opponent. The bomb presented a small target but its massive warhead was capable of damaging a pursuer, something Capt. Tadas J. Spelis and F/O Eleutherios ‘Lefty’ Eleftherion would learn on the night of July 20th. Drawing in at 450 ft, Spelis detonated the bomb’s payload. which violently shook his plane and caused serious damage to the plane’s control surfaces and left much of the fuselage dented and perforated (Harrison&Pape 205).
Over the Channel: Autumn through Winter
P-61 crews grab lunch. Conditions for the crews of the 422nd and 425th grew basic as they operated from hastily prepared airstrips in the Autumn of 1944 [National Archives]At the end of July, the 422nd and 425th would make the trip across the channel to provide afterhours protection for the US First and Third Armies, respectively. There, both squadrons would defend the Normandy beachhead as the Allies pushed forward into France. This period would largely inform the kind of fighting they would be doing for much of the campaign, intercepting lone German bombers and the occasional night fighter acting as an intruder, while also taking on alternate support missions. Shortly after the 422nd was deployed to the Cherbourg peninsula, they intercepted several Ju 88s, Do 217s, and Ju 188s as they attempted to harass Allied forces in the area, but kills were difficult to confirm owing to the contested areas these aircraft went down in.
This period also saw the P-61’s first encounter with a German night fighter when Lt. Paul Smith and Lt. Robert Tirney intercepted a Bf 110G-4 on August 7th, 1944. While Smith and Tirney approached the enemy, they were soon spotted and found themselves in a turn fight. While the maneuverability of the P-61 allowed them to keep up with the enemy, the two planes would end up colliding. Despite the impact, both planes would end up returning home, each carrying paint from their opponent. Records show elements of the German night fighter squadrons NJG 5 and 4 had been conducting ground attack operations that night without losses (Harrison&Pape 203; Part 4 Boiten 29).
This period also saw the first use of the P-61 in the ground attack role when the 425th NFS was called to assist an attack on German forces that had broken out of Lorient. Despite their early model P-61As lacking hard points for bombs, they were able to carry out the mission thanks to the powerful cannon armament of the P-61A. They conducted strafing runs on gun positions, truck convoys, and an artillery ammunition dump at the cost of one aircraft which struck a telephone pole in a low-level attack (Harrison&Pape 204).
Following the breakout in Normandy, there was a considerable lull in interceptions of enemy aircraft and the trickle of supplies to the unit meant much of the autumn of 1944 was characterized by inactivity. From September to November, GCI directed the 422nd’s P-61s into a total of 461 chases, resulting in 282 airborne radar contacts, 174 sightings, 20 of which were positively identified as enemy aircraft, and only 7 were shot down (McFarland 28). The use of Identify Friend or Foe (IFF) appeared to be limited, resulting in a high number of interceptions of friendly aircraft, and occasional friendly fire. Air crews in the 422nd NFS believed they had been fired on several times by RAF Mosquitos, and one Mosquito of the 305 Squadron, piloted by WO. Reg Everson, had been shot down by a P-61, with his aircraft being claimed as a ‘Ju 88’ (Harrison&Pape 302, peoples war).
As the Night Fighter Squadrons moved away from the beachhead and into airfields previously held by the enemy, their supply lines grew tighter and the enemy began to develop better tactics. A scarcity of fuel even threatened to keep the 442nd on the ground, but the crisis was avoided thanks to a little ingenuity. As fuel laden B-24’s came in for their deliveries in Florennes, Belgium, they would occasionally overrun the airstrip, whereupon the aviation gasoline would be siphoned out, and then stolen by the 422nd (Harrison&Pape 267).
A P-61B is prepared to sortie, Italy 1944. [National Archives]While the Luftwaffe was less active at night during this period, their tactics had largely improved. Their typical after hours raiders became flights of bomb laden Fw 190s in the place of the lone medium bomber. The common types, the Ju 88, Do 217, Ju 87, and Ju 188, were still encountered, but were eclipsed by the more numerous 190s flying low altitude raids against Allied positions near the front line. The 190s would prove more difficult targets, as their small size made them hard to identify in the dark, and their speed and maneuverability meant they had a much better chance of slipping away from the larger night fighters. While they were harder to shoot down, the P-61 was still more than capable of breaking up their attacks and forcing them to return to base (Harrison&Pape 262).
With their superior speed and maneuverability, Fw 190 fighter bombers would prove a greater challenge for the P-61 than the usual medium bombers [Rod’s Warplanes]The lull in Luftwaffe nightly activity in the autumn and winter of 1944 meant that both British and American night fighter squadrons could shift to offensive operations, and thanks to newer models of the P-61A and B mounting additional hardpoints for fuel and bombs, they would have an exceptional tool for this task. Both the 422nd and the 425th NFS would provide a vital service to the beleaguered 101st Airborne Division at Bastogne, Belgium, where they were able to provide air cover and ground attack support, day or night, in weather that kept most planes on the ground. The nightly air battles over the Ardennes took a similar, but intensified form as the Luftwaffe mounted a desperate offensive, sortieing aircraft to attack Allied positions, drop supplies, and mounted a score of night fighter intruder missions. These intruder missions had aircraft loiter around enemy airfields and attack any aircraft attempting to take off or land.
It was during this time that one of the greatest drawbacks of the P-61 made itself well known. It was a high maintenance aircraft and replacement parts and planes were scarce. During the Battle of the Bulge, only four of the 422nd NFS’s sixteen P-61s were operational, and keeping these four planes serviceable was a round the clock effort of the highest importance. Apart from the just as limited number of A-20s, the P-61s were the only aircraft capable of flying in the terrible weather conditions of the battle. Supplies had to be found outside of the regular channels, and crews were rotated out of these aircraft that each flew up to four missions per night. Combined, the 422nd and 425th NFS claimed a total of 115 trucks, 3 locomotives, 16 rail cars, sixteen aircraft, and had disrupted Luftwaffe activities in the area (McFarland 32, 33). The actions of the 422nd would go on to earn them another Distinguished Unit citation, and a commendation from the Commanding General of the 101st Airborne at Bastogne (Harrison&Pape 293).
However, this period was also considerably more dangerous as Luftwaffe’s night fighter squadrons were also performing similar missions in the same area. While they used comparatively obsolete radars, they could still present a threat. Of the scarce P-61’s active during the Battle of the Bulge, three were lost to unconfirmed causes (Dean 286).
Spring to VE-Day
The Battle of the Bulge would mark the apex of the NFS’ activity in the European Theater. The remainder of the European campaign would consist almost entirely of ground attack and intruder missions, as fuel shortages left most of the Luftwaffe grounded. Both the 422nd and 425th would commit themselves to ‘ground work’ against the usual targets; truck convoys and rail lines, as Tactical Air Command ordered a cessation of defensive air patrols, instead focusing on general offensive operations. In this role, the P-61 proved exceptional despite the design never being intended for such use, with the initial models not even possessing bomb racks.
Most ground attack missions would be conducted the same way, though some new tactics would be introduced to take advantage of the bomb racks added to the newer models of the P-61. During the beginning of 1945, P-61s would often carry napalm to both destroy targets, and for illumination. Using the fires for illumination, they carried out attacks with a combination of bombs, and in the case of the 425th’s modified P-61s, HVAR rockets. Rail yards, locomotives, and truck convoys were favored targets, as their drivers often felt it was safe to keep their lights on. While this may seem a ridiculous use of what were among the most expensive aircraft employed during the war, the 422nd was credited with damaging or destroying 448 trucks, 50 locomotives, and 476 rail cars for the duration of their service. Perhaps more impressive were the astoundingly low loss rates suffered on these intruder missions. From October of 1944 to May of 1945, the 425th NFS flew 1,162 intruder missions with the loss of only six aircraft. Despite the inherent dangers of flying at night, these missions actually proved to be far safer than daylight sorties (McFarland 29).
VE-Day [National Archives]
Luftwaffe Opponents
The typical encounters with the Luftwaffe were with its bomber, night attack, reconnaissance, transport, and occasionally night fighter forces. Their targets ranged from frontline positions, rolling stock, to airfields, and were typically attacked by lone aircraft or small formations of light attack aircraft, such as the Fw 190F&G or obsolescent Ju 87. P-61 crews would encounter virtually all medium bomber types in service with the Luftwaffe, including the dated He 111 and Ju 88A-4. Of all the aircraft encountered, only the Me 410 proved a serious challenge to intercept. They were employed as reconnaissance aircraft and their high speed meant they were only vulnerable to the P-61 when at a disadvantage. On roughly equal footing, the Me 410 could pull away (Harrison & Pape 275).
Encounters with enemy night fighters were fairly rare, as their squadrons generally only flew ground attack missions in August against the Normandy beachhead, and much later in December, in support of the Ardennes counteroffensive. They flew Bf 110G-4s, a few of the older Ju 88Cs, and the newest German night fighter at the time, the Ju 88G. While these aircraft flew with radar that had a much more limited range than the SCR 720 and were nearly useless at low altitude, their pilots were capable of putting up a much greater fight than those of the bomber and night attack squadrons. The first encounter between a P-61 and a Bf 110G-4 resulted in the latter being able to slip away after a collision, despite holding clear disadvantages in speed and maneuverability. While most of the new pilots the Luftwaffe were supplied with at the time possessed questionable proficiency at their tasks, most green crews remained on the ground as a result of chronic fuel shortages (Part 4,Boiten 33).
On the night of December 17th, several Luftwaffe night fighter squadrons would be committed to large scale ground attack operations in support of Von Rundstedt’s offensive. These missions were conducted by several dozen aircraft at a time that searched highways, rail lines, and known Allied positions for targets. These operations achieved a level of mixed success but at an extremely high cost, as the pilots were insufficiently trained for the mission and typically encountered accurately directed anti-aircraft fire (1944 Part 5, Boiten 68). The P-61s of the 422nd and 425th would find these night fighters significantly more challenging opponents than the medium bombers and transport aircraft they usually encountered. On several occasions, the German fighters slipped away from their pursuers and claimed two, later disproven, victories against P-61s, with the war diarist of Stab NJG6 commenting the “Black Widow inferior to Ju 88 and Bf 110 in dog fighting (Part 5, Boitens 77).” However, this confidence is likely due more to survivor bias than any major technical difference between these aircraft, as several German night fighters would be lost to P-61s. In all likelihood, it was the German night fighter pilot’s confidence in undertaking aggressive maneuvers in the dark that was the most probable reason for this assessment, as the P-61 was superbly maneuverable for its size.
Over the course of this offensive, the 425th would encounter a number of German night fighters and down several of them. Between the 25th and the 29th of December, three confirmed and two probable German night fighter losses can be attributed to this squadron’s P-61s, these being Bf 110 2Z+DH of NJG 6, Ju 88G-1s of NJG4 3C+RK and 3C+ZK, and two very likely Bf 110s, 2Z+DL and 2Z+CV (1944 part 5, Boitens 79, 84, 85). Given the short period and how few P-61s were serviceable, it is safe to say that the P-61 was certainly capable of taking on these opponents. However, it should also be noted that night fighters comprised a relatively small number of kills during this time, with many more being medium bombers and Ju 52 transport aircraft.
The 422nd NFS would later rebase in Langensalza, Germany. This posting allowed P-61 crews the opportunity to get a close look at the enemy’s standard night fighter, the Ju 88G. [National Archives]
CBI: The 426th and 427th
The 426th Night Fighter Squadron was called upon by General Henry H. Arnold for the defense of the B-29s based in Chengdu, China, as per the request of the Maj. Gen. Curtis LeMay (Harrison&Pape 222). They would also be joined by the 427th NFS following the end of Operation FRANTIC and the cancelation of any further deployments of USAAF bombers in the Soviet Union. While they were sent to defend the B-29 bases, they were soon found to be almost totally unnecessary, as there were little to no Japanese aircraft active after dark in the China-Burma-India Theater. Not long after their arrival in October, 1944, they would pivot almost entirely to an offensive role, and were mostly relieved of their defensive task to search for trains and truck convoys across the theater. Several aircraft were later modified to mount 4.5 inch rockets, as was the case for their counterparts in Europe (Harrison&Pape 215). They would be met with success, as the Japanese Army was reliant on a single network of roads that ran north to south, a single major rail line, and the Irrawaddy River to move men and material across the theater. Despite the massive patrol area, they could expect to find targets at these strategic bottlenecks (McFarland 40).
A pair of P-61s look for targets by daylight over Northern Burma. Note that the tail cone has been reinforced. [National Archives]The challenges of operating in this theater largely mirrored those of the squadrons based in the Pacific, as supply lines were tight, the terrain proved difficult to construct airbases in, and the mountainous geography hampered the use of early warning radar. Fuel was particularly scarce and had to be shared with the B-29 squadrons based with them, which typically meant offensive operations were periodically called off when supplies of fuel ran out, as was a case for the 427th NFS’ detachment in China for the month of April 1945 (Harrison&Pape 236). The squadrons operated mostly dispersed across the theater as detachments, with the peak number of P-61s in the CBI being 53 in July of 1945. The number typically sat around 35 aircraft until June (Dean 386).
PTO: the 421st NFS
Many airfields across the PTO were built over coral beds which were difficult to clear and highly visible at night [National Archives]The P-61 was a godsend to the Pacific night fighter squadrons who had long been forced to rely on the inadequate P-70, and with the exception of a few field modified aircraft, radar-less P-38s. Starting from early 1944, the various night fighter squadrons in the PTO would begin receiving P-61s and phasing out their long obsolete P-70s. Unlike Europe or the Mediterranean, the operations in the Pacific would not proceed at the pace of a gradual frontline that needed to be supported but rather saw the NFS deployed to newly constructed airstrips in support of larger amphibious operations which were targeted by raiders. Conditions were poor and extremely hard on airmen and planes alike, which brought unique challenges unknown to those in the ETO. In the words of S/Sgt. Harold Cobb of the 421st NFS: “Night fighting is not glamorous, but it is specialized in every degree, especially in the seven-league-boots, island-hopping war in the Pacific. Pilots must be able to take off and land without strip lights and on fields which are so new that construction is still in progress and the Seabees are still working (Kolln 51).”
The 421st got its hands on the P-61 in April of 1944, while it was based in Wakde, New Guinea, the planes having originally been shipped to Brisbane, Australia. The impact of receiving the new planes would prove considerable, both boosting the morale of the unit and giving it a long-needed replacement for its P-70s. The overall mission of the 421st was largely the same as it was for the 6th Night Fighter squadron in Guadalcanal two years earlier, to defend against nightly nuisance raids from Japanese bombers. The Japanese had also largely improved from their earlier campaigns, as they began to seek targets of greater strategic importance which they attacked with a far greater frequency. The men of the 421st were among them and their bases at Wakde and Owi were attacked regularly, often causing casualties and destroying aircraft. These airfields being built on lightly colored ancient coral beds made them both extremely visible at night and made it extremely difficult to dig shelters (Kolln 48). The effects of high explosives were also magnified, as they propelled sharp fragments of coral through the air with every bombardment.
The squadron also faced the same challenges posed by tropical environments, often with little improvement over the conditions almost two years ago. The prepared airfields were often built under difficult circumstances and challenging geography. The Seabees often had to work with coral beds, wetlands, and jungles that proved time consuming to develop into usable airstrips, often leaving little time and resources for improving the living conditions at these airfields.
Wakde Island before it had been captured by the US. The bright coral beds that were the foundations for the airstrip made an excellent aiming point for Japanese raiders [National Archives]These conditions were also felt by the sensitive radar systems of the aircraft, especially the pressurized canisters which contained many of the system’s vital components. They had a tendency to depressurize, which resulted in electrical arcing at altitude, disabling the entire system. The 419th NFS had developed an improvised system where the electronics tanks were kept pressurized by engine-driven vacuum pumps, but it is unknown if this modification was ever taken up by any other squadrons (Harrison&Pape 149). Early models of the P-61A, which still had the plastic radome, also encountered trouble in the tropical heat and sun, as the nose of the aircraft would often soften and deform, which would impact the movement of the SCR 720’s scanner. In addition to the reflective white paint added to the nose, crews would fasten ‘sun shields’ while grounded to protect the radome in the tropical heat. As was the case with the European squadrons, supplies of replacement parts and aircraft were scarce, and in a unique twist in the Pacific, the improper packing of engines resulted in the loss of 400 R-2800s to corrosion. Combat readiness suffered as a result. The 421st considered it a ‘good day’ should six of their aircraft be operational during their operations from their later airbase at Tacloban (Harrison&Pape 241).
Conditions for the air and ground crews of the 421st were scarcely better. Harsh tropical weather, limited access to drinkable water, and disease were common in the South Pacific, with conditions only improving after redeployment to the Philippines. At Owi and Wakde, personnel had to overcome an outbreak of Typhus which claimed two, heatstroke which claimed one, and even Silicosis of the lungs which resulted in a single fatality. However, the base at Owi became perhaps the most livable thanks to the discovery of an artesian well near the unit’s bivouac area (Kolln 47,48).
In the PTO, P-61s often operated from small, busy airfields where accidents were not uncommon. This P-61 went off course on a blind landing through fog at Iwo Jima and crashed into another aircraft [National Archives]Operations over New Guinea largely proceeded the same way as they had earlier, but with far greater success thanks to their new P-61s, which meant interceptions were comparatively easy, though new Japanese tactics would periodically disrupt their success. Perhaps the most surprising of these was the deployment of radar reflecting chaff from bombers as they made their way to and from their targets. The chaff were aluminum strips that reflected radar and presented on radar scopes as a single large ‘cloud’ that could obscure the positions of aircraft. In practice, the SCR 720 did not prove very vulnerable to chaff if the pilot had already been guided toward the target, as the air search radar proved powerful enough to burn through the interference. Far off ground-based radar stations would prove more vulnerable to it, especially older models (Kolln 55). The Japanese air force would also employ new tactics against the defenders. On August 5th, the Japanese sortied several fighters along with the typical high-altitude bombers. These aircraft were picked up on radar later than the bombers to which the night fighters had already been sent against. The Japanese fighters were, however, unable to inflict much damage and their tactics were soon understood by the defenders (Kolln 50). While the 421st NFS’ P-61s were largely part of the waning war in the South Pacific, their subsequent redeployment to the Philippines would place them in one of their most active theaters of the entire war.
Tacloban
The airfield at Tacloban was muddy, overcrowded, and under constant attack during the first weeks of the US Army’s return to the Philippines [National Archives]The 421st was deployed to the airfield at Tacloban on October 31st, 1944 to provide nightly air cover for the amphibious operations in the Southern Philippines. The conditions were largely a repeat of those of the prior camps at Wakde and Owi, but the raids were far worse. What were once frequent occurrences became a daily fixture of the stay at Tacloban (Kolln 61). The airfield itself would also prove to be an extremely hazardous and ineffectual location to operate from, as would be the positions chosen for the GCI radars. Tacloban was extremely underdeveloped during the height of operations. It was without runway lights for fear they would attract Japanese bombers and the short, muddy airstrip was difficult for the heavy P-61 to operate from, with most landing attempts having to be repeated (Harrison&Pape 240). From their airfield, they were given a number of tasks which would include providing nightly air cover to invasion forces, escorting PT boats, convoy protection, and even conducting daylight patrols.
The Philippines would present a greater set of challenges to the 421st than New Guinea. For one, the aircraft and tactics used by the Japanese air forces were of a different nature entirely. While they previously worked mostly against occasional, small formations of bombers coming in at high altitudes, they now also fought against large numbers of fighters which flew continuous attacks, typically conducted at low altitudes. Coupled with poor GCI coverage of the area, the Ki-43s and A6Ms employed by the Japanese would prove an extremely difficult enemy to counter. The nightly attacks continued and many of the invasion planners became frustrated with the squadron’s inability to stop them entirely, eventually leading General Kenny to send much of the 421st to Peleliu, while the 541st Marine Air Squadron, equipped with the 565-5N, took their place at Tacloban. In the end, the 421st achieved seven kills during this time at Tacloban, and while this was a fairly significant level of success for the PTO, it was deemed unacceptable by the invasion planners (McFarland 37).
The reasons for this swap have long been debated, with claims ranging from the P-61 having insufficient range and loiter time, to the SCR-720 being unable to track more the more maneuverable Japanese fighters. In the end, however, the greatest problems faced by the squadron were its poor GCI support, its low number of serviceable aircraft which resulted from supply shortages, and the vulnerable, poorly suited airfield they had at Tacloban. The Marine night fighters who replaced them were credited with 23 kills, though most of these were during dawn or dusk missions. It does not appear that any technical failings of the P-61 were responsible for a perceived lack of performance, but rather, exceedingly poor operational conditions and biases held by the higher headquarters that placed the expectations of daylight fighters on the NFS 421st while not understanding how they would best be deployed or utilized (Kolln 72). Though most of the squadron had departed Tacloban, several planes and their associated personnel remained to ensure a smooth transition for the Marine aviators and to carry out their previous duties, though to a lesser degree.
The 421st would return at full strength to Tacloban in early January of 1945, after five weeks, and largely resumed the work they had been doing before they left. Most notably, this included the joint patrols with motor torpedo boats, especially the 7th PT boat squadron, which they had developed a good working relationship with. The P-61s would provide cover for the boats as they patrolled Surigao strait and the Ormac Bay area, with a squadron representative aboard to ensure smooth operation between the boats and their air cover (Kolln 75). Enemy air activity in the area had decreased significantly and once again took the form of periodic raids by bombers flying alone or in small formations.
The airfield the 421st returned to was vastly different from the one they had left just a few weeks prior. [National Archives]The squadron would end the war at Ie Shima, Okinawa, in July of 1945. By this point, the Japanese armed forces were in a state of exhaustion but they were still capable of launching nuisance raids against front line positions and airfields, though the frequency of these raids was low and there were two other P-61 squadrons stationed in the area. This would also mark the beginning of the replacement period of the squadron’s P-61s for P-38Ms. The 421st would spend this time performing intruder missions against targets in Kyushu, Japan, with airfields tending to be the primary targets. In this role, they developed a bombing technique with their search radars, which would be used to measure the relative distance to the target, and in conjunction with the airspeed and altitude of the aircraft, a bomb release window could be worked out. Some pilots would even add marks on their windscreens as visual aids for the technique (Kolln 89). They were, however, unable to account for its effectiveness. There was little resistance to these raids as Japan had a comparatively underdeveloped night fighter service and their night fire control for their anti-aircraft artillery was little better.
With Japan facing famine and industrial breakdowns from the blockade, the prospect of a third atom bomb with more to follow, and their last hope for conditional surrender evaporating as the Soviet Union overran their mainland colonies, the war ended and the P-61’s wartime service came to an end.
Japanese Opponents
Despite being significantly less experienced with the use of ground based and airborne radars than the Germans, Japanese aviators and mission planners consistently demonstrated the ability to develop effective countermeasures and tactics to American night fighters. Japanese signals intelligence services would prove extremely effective and were able to determine the presence of enemy night fighters in areas without radar coverage by monitoring radio transmissions, and were even able to track the position of P-61s by their IFFs (Harrison&Pape 220, 319). They would also successfully employ chaff on a number of occasions, though to decreasing effect, as the US Army began to employ more advanced centimetric search radars that were less vulnerable to it. On Iwo Jima, for instance, raiders would typically use chaff roughly thirty miles out from the island and when they departed, which had the effect of blocking the older meter band SCR-270 and reducing the range of the centimetric SCR-527 (McFarland 39). In addition to this, they would also employ seaplanes to get the attention of night fighters, and once they had drawn them away from the raider’s target, they would land on the water’s surface or return home at low altitude (Thompson 71). This tactic appeared to have been used against the P-61s of the 421st while they were at Tacloban and to good effect, as the loiter time of the P-61 was rather low and they were often forced to return home after several of these non-encounters (Harrison&Pape 234).
Variants of the Mitsubishi G4M were among the most common raiders encountered by P-61s in the Pacific [Rod’s Warbirds]In the Pacific, P-61s faced mostly medium and light bombers, though would face considerably more fighter aircraft as the war drew to a close. These aircraft employed a wider variety of tactics than those of the Luftwaffe, often to considerable success. However, they would still employ earlier tactics such as lone bomber, high altitude raids which were far less effective, as the P-61 did not have the difficulty the P-70 had in reaching high altitudes.
What they wanted but never got: The P-61C
The P-61C would be developed largely to fulfill the requests of most of the pilots who had flown P-61As and Bs. The design sought to add two major features, more powerful turbocharged engines to provide better high-altitude performance and a higher climb rate, and a set of air brakes. The air brakes would be designed by the AAF’s Wright Field staff in conjunction with Northrop. The design was first incorporated on a P-61A test aircraft, which was nearly lost after a portion of the air brake was sheared off the aircraft and nearly sent it out of control. The final design proved satisfactory and took the form of a two-part slotted panel with halves above and below either wing. These brakes also incorporated a novel system to reduce the asymmetric forces acting on the brakes. This worked by having the deployment of the lower set of brakes assisted by the raising of the top. The brake system exerted a counter force of roughly 1G when the aircraft was at high speed (Harrison&Pape 278, 281).
The engines would go through a considerably longer development period and were to be mounted on a new airframe. Initially, there was some debate on whether the engine should use either a two stage two speed supercharger, as the previous production models of the P-61 used, or a turbo supercharger. It was a new study under John M. Wild at Northrop that made the case for choosing the turbo charger, with his finding being agreed on by Wright Field’s Fighter Project Office. A CH5 turbo-supercharger was subsequently fitted to a P-61A for testing, the aircraft being redesignated the XP-61C. The XP-61C’s conversion was handled by Goodyear Aircraft out of Akron, Ohio, a firm that provided parts for Northrop. The aircraft was initially to be powered by the R-2800-77, though a production run could not be secured and a temporary installation of the R-2800-14’s were used in their place until the R-2800-73 was chosen for the production model. A parallel development that would later be designated the XP-61D made use of the R-2800-77. Cooling issues would bring an end to its development, with the P-61D being canceled as the P-61C entered production. The P-61C proved to be quite promising and a massive step above the previous models, with the aircraft’s service ceiling being raised to 41,000 ft (12497 m) and its maximum speed rising to 430 mph (692 km/h) (Harrison&Pape 279, 280). The P-61C would be the aircraft the test pilots had wanted from the outset, but would fail to make it into service fast enough to see combat.
Project Thunderstorm
Several Project Thunderstorm P-61Cs and an F-15A [NOAA]While the P-61C arrived too late to take part in the Second World War, it would go on to make major contributions to meteorological research and aeronautical safety in the post-war Thunderstorm Project. The project began with the passing of the H.R. 164 bill in January of 1945, which authorized and directed the Weather Bureau to conduct a study on the causes and characteristics of thunderstorms for aviation safety. The bill would also authorize the appropriations needed for such a study and authorized the cooperation of other departments for assistance.
The finalized research plan called for a vertical stack of five aircraft to make passes through thunderstorms as they drifted over a network of meteorological recording stations in order to document the conditions within the storm. The Army Air Force would provide several P-61Cs and its derivative, the F-15A, for this purpose, as they were designed to withstand strong maneuvering loads and were judged strong enough to quite literally ‘weather the storm’ (Roscoe 26). These aircraft would be modified for the purpose, with wartime equipment being removed and meteorological research equipment installed in its place. The aircraft were prepared at NACA’s Langley Field with the equipment necessary to monitor turbulence and vertical air currents.
The Flight Plan [Roscoe]For the tests, the planes entered thunderstorms at altitude differences of five thousand feet, with the highest aircraft being at 25,000 ft (7620 m). No storms were avoided, no matter how violent. The project first began around Orlando, Florida in 1946, before later moving to Wilmington, Ohio the following year. These locations were chosen on the basis of the frequency of thunderstorms and the nearby Air Force installations which had the radars needed to support the project. The project would see the P-61s fly through 76 storms for 1362 fly-throughs, during which they collected vital data which would help pave the way for safer air travel during the post war civil aviation boom and were used to build a foundational study for thunderstorm research (Roscoe).
The hail damaged radome of a P-61C [NOAA]
Pilot’s Remarks
Lt. Herman E. Ernst, an ace of the 422nd NFS, behind the controls of a P-61A. Note that the pilot’s radar indicator has been replaced by a compass below the gunsight [National Archives]Exhaustive tests were performed on the P-61 to determine its flight characteristics, and they were largely found to be in line with the earlier prototypes. Pilots were highly appreciative of its easy handling on takeoff and landing, along with its favorable stall characteristics. Its controls were effective up until stall condition, which itself only occurred after ample warning. Stalls themselves were relatively predictable and virtually always resulted in the nose dropping, with no tendency for either wing to drop, and no corrections being needed to prevent a roll (Dean 391).
In addition to its great stall characteristics, the P-61 would prove to be exceptionally maneuverable for a plane of its size and weight. However, given its size and with two heavy engines on the wings, its roll rate was rather poor. Tests found the aircraft could be put through all hard maneuvers save for outside loops, continuous inverted flight, spins, snap rolls, and vertical reversements. Pilot’s praise was given mostly for its extremely light controls even at high speeds, which was largely thanks to its unorthodox spoileron based lateral control system. Even at speeds of 400 mph IAS, fast aileron and spoileron movement could be affected with one finger on the control wheel, though controls were found to be ‘sloppier’ around 100 mph IAS. One pilot was so confident in the P-61’s maneuverability that he felt he could turn with the best of fighters and, in the case of the F6F, he would “be on his tail so fast it was incredible.” In addition to its maneuverability, its trimming characteristics were also very good, such that it was possible to trim the aircraft out for cruising on a single engine at 130 mph IAS. It should, however, be noted that despite this praise, pilots rated its maneuverability fair to poor, as it was compared to far lighter single engine fighters. Overall, the plane was rated very stable on all axes with good rudder and elevator effectiveness (Dean 388, 390).
Despite its size, the P-61 was capable of pulling off some very impressive aerobatics. However, regulations stipulated that acrobatics were restricted under most combat conditions. [Pilot’s manual]The P-61 also boasted excellent dive and recovery characteristics, with the book limits being set around 430 mph IAS depending on the arrangement of the aircraft, or around Mach .70. Beyond these limits, buffeting and tuck-under would occur, but the aircraft also demonstrated the ability to exceed these limits by a fair margin. One pilot would claim that he had no problems at speeds of 450 to 475 mph IAS at around 10,000 to 15,000 ft. In this case, he had achieved a true airspeed of 599 mph at Mach .83 and returned within the specified limit envelope at 512 mph TAS, Mach .70, as he reached 10,000 ft. Typically, if buffeting did occur, it was advised to exit the dive by means of a gradual pullout and with high caution should external loads be carried. Another pilot would claim that buffeting would occur far in excess of the recommended dive speed limits. The P-61 would be rated good in respects to its dive acceleration, control forces, recovery characteristics, and be ranked 8 out of 11 US fighter types in the category best stability and control in a dive (Dean 389, 390). The engine limits within dives were 30 seconds at 3090 rpm.
The P-61 was, however, not without its faults, and the most criticized and frequently voiced issues were concerning its acceleration and climb rate. These sentiments were echoed in many tests, and were most notable in rating the aircraft for takeoff, where pilots soon found themselves climbing at a disappointing rate after reducing power. Even at combat-power, the aircraft could at most manage 2500 ft/m at an altitude of 5000 ft (Dean 381). In the concluding remarks to exhaustive tests, it was the most frequently voiced complaint. While it was true many test pilots judged the aircraft somewhat unfairly against lighter single engine fighters, even its most enthusiastic testimonies were typically accompanied with remarks regarding its acceleration and climb performance (Dean 393).
The cockpit drew mixed reactions, with the general feeling being that the layout was adequate but not ideal. While most felt the layout was fair, eight of twenty-one pilots felt the arrangement was “cluttered”, with another ten remarking that they felt the pilot was seated too far from the instrument panel. This group was so displeased with the arrangement that they ended up rating P-61’s cockpit 3rd in the category “worst cockpit”. While the layout of the cockpit remained divisive, virtually all of them were displeased by the restricted visibility caused by the canopy frame (Dean 392).
The P-61B and several As would make use of the night binocular gunsight. These slid behind the pilot when not in use [P-61 Pilot’s training manual]In terms of its weaponry and its stability as a firing platform, the P-61 was well rated. Equipped with four 20 mm AN/M2 cannons and up to four .50 cal AN/M2 machine guns, the P-61 was very well armed. Despite the lack of the turret on most P-61s, the aircraft’s armament was more or less equal to its contemporaries, the Mosquito NF and Ju 88G, which both carried an armament of four 20 mm cannons. Firing stability was also good, with only one out of fourteen test pilots finding it objectionable. However, problems with the turret would impact its usefulness, as early aircraft would experience intense buffeting on the tail surfaces when the guns were set to certain positions. This problem would later be solved and the turret reintroduced to the aircraft when it was redesigned and supply bottlenecks with the B-29 were resolved (Dean 393).
Overall, the P-61 would present an aircraft with mixed, but favorable characteristics. The aircraft would be superbly maneuverable and responsive for its size and presented excellent flight characteristics at high and low speeds. In contrast, pilots were not enthused over what they judged was a poor rate of climb and cockpit layout. The 481st Night Fighter Training Group would also go on to lodge complaints about poor cockpit visibility and short combat radius (Harrison&Pape 156). While the cockpit went unchanged, the relatively limited range, of only about 1000 miles, would be later brought above 1,800 miles with the use of external fuel tanks (Dean 382).
Construction of the P-61A and B
The wings of the P-61, except for the tips, used a fully cantilever riveted, stressed skin construction with two main spars. Each wing assembly was composed of an inner panel, an outer panel, and the wingtip. The inner panel contained the engine nacelle, two fuel tanks, and a section of the flaps. This portion was the largest wing section and was fitted to the crew nacelle by means of bathtub and lug type fittings at the end of the main spars. The front section also provided one of the main air intakes for the aircraft and an outboard for the oil tank. It was constructed in two parts, forward and aft sections.
A P-61 undergoing maintenance. Its outer wing panel has been detached from the nacelle group [National Archives]The aft section was also built in two parts and it contained the wing flaps, spoilers, and ailerons. The section also contained an oil cooler and its associated exit shutter. There were six hydraulically actuated slotted flaps with a full deflection of 60 degrees. Relatively small ailerons were installed outboard of the flaps, which extended to the wing tips. To boost lateral control along with the ailerons, a series of spoilers were used and were found in trailing sections, ahead of the outer wing flaps. These were curved metal panels that extended from slots in the wings and were mechanically driven by the pilot’s control column along with the ailerons. Initially, there were also aileron and booster tabs fitted to the inboard end of the left ailerons, but these were removed on later models. The combined fuel capacity of the wing fuel tanks was 646 gallons (2445 liters).
The center fuselage was a semi-monocoque structure composed of transverse bulkheads and channel section frames, longerons at the upper and lower quarters, longitudinal bulb angle stringers, and stressed skin. It was attached to the wings by means of heavy forged fittings on both sides of the fuselage. This section contained the stations for the aircraft’s pilot, gunner, radio operator, the aircraft’s SCR-720 radar, fixed quadruple 20 mm armament, and the mechanically operated turret. The enclosures for the pilot and gunner positions were made from molded Lucite sheets and extruded metal framing, with forward sections protected by bullet resistant glass blocks. The radar nose cone was made of plexiglass on early models, before a switch to a less heat sensitive resin-impregnated fiberglass on later aircraft. The radio operator’s position was enclosed by a framework of Lucite in extruded metal frames, with a rear tail cone that was formed from two sheets of Lucite that had been cemented together and bolted to the rest of the framework. All positions had a seat with a metal pan, padded backs, safety belts, relief tubes, and hand fire extinguishers. The center fuselage was also fitted with armor plates to protect the crew and ammunition boxes. These were located behind the nose, ahead of the gunner, in front of the turret ammo boxes, and behind the radio operator. The standard crew layout on this aircraft was poor compared to contemporary night fighters. A failure of the intercom system left the aircraft combat ineffective, as each crewmember was isolated, the radar operator particularly so.
The P-61’s fuel system [Pilot’s notes]The tail booms were of a monocoque structure and connected the nacelle group to the tail group. They also housed components for communication, identification equipment, the flight control cables to the rudders, elevators, and tabs. They were connected to the nacelle groups, which were composed of a semi-monocoque structure. These carried the engine mounts, main landing gear, and fuel tanks. The engines were mounted from a built-up welded steel tube frame that was bolted to this nacelle through vibration isolators and the engine cowling panels. The cowling sections were removable in large sections and were attached to the engine by quickly-detachable fasteners to facilitate easier access to the engines. The adjustable flap segments were controlled from the cockpit and were hydro-mechanically actuated.
The tail section consisted of the horizontal stabilizer, the elevator, and two vertical stabilizers and was connected to the tail booms. The two tail sections were supported by two spanwise spars that ran through the horizontal stabilizer and had the vertical stabilizers at either end. The rudder and elevators were fabric skinned and had trim and booster tabs built into their trailing edges.
The aircraft had a tricycle landing gear arrangement, with its nose wheel housed in the center fuselage and the main gear in the nacelle group. Each main gear was supported by two steel castings which were bolted to either side of the inside of the nacelle. Landing gear loads would be handled by a shock strut which was connected to these castings by a pair of trunnions. When the gear was retracted, it was hinged on these trunnions at the castings by lockbolts which would be held in either the extended or retracted position by a mechanical latching mechanism.
Engines
The mid production P-61A and the P-61B were powered by a pair of 2000 hp class of the R-2800 Double Wasp engines. This was an air cooled, two row, eighteen-cylinder radial engine with a 5.57 inch bore and a 6-inch stroke. These engines had a maximum RPM of 2700 and a compression ratio of 6.7:1. The early A models used the R-2800-10, with the remainder of the series and the B models using the R-2800-65, both of which produced a maximum output of 2000 hp. The later R-2800-65W boosted this to 2250 using water injection, and the C used the R-2800-73 which produced 2800 hp. The A and B models were equipped with two-stage, two-speed superchargers, but the C used turbosuperchargers.
T/Sgt. M. Stetson at work on a 9th AF P-61, 1944. [National Archives]The exhaust system was a stainless-steel arrangement with the exhaust stacks distributed around the edges of the nacelle, making use of a flame dampening system used to reduce the visibility of the exhaust at night. The B model and the late A series aircraft were equipped with a water injection system. The first aircraft with this system carried 26 gallons (98 liters), good for 15 minutes, with later aircraft carrying 34 gallons (128 liters), which was enough for 20 minutes of use, though some aircraft would carry as much as 74 gallons (280 liters). Use of this system could boost engine power by up to 250 hp per engine, though only in short increments, with the suggested limit being five minutes at a time (Pilot’s manual 12). Engines with water injection were designated R-2800-65W.
The engines drove a pair of Curtiss Electric four blade constant speed, selective pitch, full-feathering propellers. The hubs were a pair of C642S with a set of 12-foot 2-inch diameter, 714-7C2-12 blades. Engine speeds between 1800 and 2300 RPM were restricted as a result of propeller vibration in that range. The props were capped by large metal spinners which enclosed the hubs and inboard prop sections.
Avionics
In addition to the SCR-720 search radar, the P-61 carried a well-developed electronics suite. This included an SCR 729 radio navigation system, an SCR 695 IFF, and an RC-36 intercom system. The P-61A and early B models were equipped with the SCR 718 radio altimeter, which was later replaced with the AN/AP1. Early models used a pair of SCR-522 radio sets which was simplified in later models by a single AN/ARC 3. In later aircraft, an AN/APS-13 tail warning radar set was also included. The navigation systems were also supplemented by a MN-26C radio compass with a MC-1206A range receiver.
The P-61’s SCR-720 air search radar was composed of six main units which were installed in a number of boxes throughout the aircraft. These were the modulator, the transmitter, the receiver, an indicator unit, the mixer, and the power supply unit. The modulator was a rotary spark gap, pressured type which produced a 4 kV pulse. The transmitter was magnetron regulated and installed in a pressurized unit. The mixer was a crystal mixer type with a soft rhumbatron switch valve. The receiver used a reflector klystron oscillator with automatic frequency control. The indicating unit used a two-tube range and azimuth elevation display set. The entire system was powered by a 1,200 watt, 115 volt, 1,600 cycle engine driven alternator (Survey 27).
Heaters
In addition to navigation, communication, and detection equipment, there were also considerable heating, cooling, and ventilation systems. On the P-61A, a series of fuel-air mixture heaters were used to provide heating for the cannons and to the crew through three ventilators. The B model decreased the number of heaters from four to just two heaters that were placed fore and aft.
Armament
Gunnery Equipment and Armament Cutaway Diagram [Pilot’s notes]The standard armament of most P-61s was a set of four fixed 20 mm Hispano AN/M2 cannons that were set in a compartment at the bottom of the central fuselage. 200 rounds of ammunition could be carried for each gun. Sighting for the gun consisted of the L-1 type gunsight on the P-61A and the LY-3N on the P-61B, with both being a reflector type lit by a sight lamp. From the B model onward, the aircraft would also carry a set of night binoculars which were a specialized gunsight for use in low light conditions.
While this aircraft is often known for its remotely controlled, quadruple .50 caliber turret, only about half of P-61s actually carried one. The turret’s machine guns were each supplied with 560 rounds, were fired simultaneously at a rate of about 800 rounds per minute, had a 360-degree traverse, and a maximum elevation of 90 degree upward from the horizontal. While the guns could be fired from any of the aircraft’s three positions, only the gunner and radio operator could direct the turret. For the pilot’s use, the guns would be locked forward by latching the turret and flipping the switch labeled “pilot” from either of the other two positions, though in the B model, the turret would automatically return to the guns forward position when not in use. The .50 caliber guns were typically fitted with flash concealing tubes in the field after pilots found it could interfere with their vision adjusted for low visibility flight. In service, the turret was almost always used by the pilot and very sparingly by the gunner against targets ahead of the aircraft. Pilots often found it unnerving to see the turret firing forward without warning from the gunner, as it could both ruin their low light vision and sometimes they misidentified the gunfire as coming from an enemy behind their aircraft. As a defensive armament, it was of little practical use, as the radar operator’s illuminated instruments screens degraded his low light vision. The turret was directed by a sighting arm which sat atop a rotating column with firing controls in the grips and fitted with an N-6 reflector sight.
The aiming system for the remotely operated turret [P-61 Pilot flight operating instructions]Several models included wing racks which were capable of carrying additional fuel tanks or bombs with a maximum weight of 1600 pounds (725.75 kg). Field modifications on some aircraft allowed for the use of rockets. (Dean 393-404)
Several P-61s of the 425th NFS were modified to carry rockets, in this case, HVARs. [Wikimedia]
Conclusion
The P-61 was a somewhat troublesome, yet effective night fighter that proved to be a capable replacement for the useless P-70 and obsolescent Bristol Beaufighter. Most of its faults, apart from the poor layout of crew, were to be expected for such a sophisticated plane still in its ‘teething period’ and supported by a modest supply chain. In the space of roughly a year, which constituted its entire combat service, most of its faults were corrected or lessened.
The aircraft served admirably across the European, Mediterranean, China-Burma-India, and Pacific theaters. P-61 pilots would encounter a variety of opponents among the Japanese and German air forces, utilizing a variety of tactics and equipment. They would prove effective against all but a handful of these combinations. Surprisingly, despite never being designed with such a use in mind, the P-61 would prove exceptional in the ground attack role. It was among the few aircraft at the time capable of carrying out attacks at night, or in poor weather. In service its greatest danger was its limited material support. This scarcity of replacement aircraft and parts would hobble operations, but the resourcefulness of ground crews often kept their squadrons from being entirely grounded. In the end, the aircraft provided effective service during their somewhat short combat tour across much of the world, in the face of inadequate material support and, at times, extremely poor conditions.
While the P-61C would never see combat, it would perform a vital role in a foundational meteorological study. Despite never being used for its intended purpose, this variant’s legacy proved to be no less important.
Specifications and Production Numbers
Type
Number Built
First Delivery
Description
XP-61
2
May-42
First prototype series
YP-61/P-61
13
Aug-43
Second prototype series, pre production
P-61A-1
45
Oct-43
Power turrets installed in first 37 planes, first production model
P-61A-5
35
–
Turret removed, R-2800-10 engine changed to R-2800-65
P-61A-10
100
–
Water injection system added
P-61A-11
20
–
Two underwing racks
P-61B-1,2,5,6,11
155
Jul-44
Extended nose, wing racks on 2,6, and 11
P-61B-10
45
–
Four underwing racks
P-61B-15,16,20,25
250
–
Turret revised and reintroduced with two and four gun versions, wing racks (two on the -16), radar gun laying on -25 with seven built
Prototype daylight fighter, 2 crew, bubble canopy, turret removed, increased fuel capacity, no radar, four nose mounted .50 caliber guns, developed from P-61B.
XP-61G
16 converted airframes
1945
P-61B-20 modified for weather recon, unarmed
All airframes were built at Northrop’s plant in Hawthorne, California
Specifications
P-61A
P-61B
P-61C
Engine
R-2800-10, R-2800-65, R-2800-65W
R-2800-65W
R-2800-73
Maximum Engine Output [boosted]
2000 hp [2250 hp]
2000 hp [2250 hp]
2800 hp
Maximum Weight
29249 lbs
39056 lbs
41138 lbs
Standard Fighter Weight
28202 lbs
29876 lbs
30068 lbs
Empty Weight
23158 lbs
24413 lbs
26418 lbs
Range [maximum external fuel]
~1000 miles [+1800 miles]
~1000 miles [+1800 miles]
–
Maximum Speed
366 mph at 20,000 ft
366 mph at 20,000 ft
430 mph at 30,000ft
Armament [turret]
4×20 mm AN/M2 [4x .50 cal AN/M2]
4×20 mm AN/M2 [4x or 2x .50 cal AN/M2]
4×20 mm AN/M2 [4x .50 cal AN/M2]
Crew
Pilot, gunner, radar operator
Pilot, gunner, radar operator
Pilot, gunner, radar operator
Length
48′ 11″
49’7″
49’7″
Wingspan
66′
66′
66′
Wing Area
664ft²
664ft²
664ft²
Specification
P-61A
P-61B
P-61C
Engine {P-61}
R-2800-10, R-2800-65, R-2800-65W
R-2800-65W
R-2800-73
Maximum Engine Output [boosted]
2000hp [2250 hp]
2000hp [2250 hp]
2800 hp
Maximum weight
13267 kg
17715 kg
18660 kg
Standard fighter weight
12792 kg
13552 kg
13639 kg
Empty Weight
10504 kg
11074 kg
11983 kg
Range [maximum external fuel]
~1609 km [~2897 km]
~1609 km [~2897 km]
–
Maximum speed
590 km/h at 6 km
590 km/h at 6 km
692 km/h at 9144 m
Armament [turret]
4x20mm AN/M2 [4x or 2x 12.7mm AN/M2]
4x20mm AN/M2 [4x or 2x 12.7mm AN/M2]
4x20mm AN/M2 [4x 12.7mm AN/M2]
Crew
Pilot, gunner, radar operator
Pilot, gunner, radar operator
Pilot, gunner, radar operator
Length
14.91 m
15.11 m
15.11 m
Wingspan
20.12 m
20.12 m
20.12 m
Wing Area
61.69 m²
61.69 m²
61.69 m²
Cruising Speeds for the P-61A&B at 28,500lbs (12927 kg)
P-61A ‘25507’, a very early A model. Only the first 37 aircraft would carry turrets before it was removed in order to correct buffeting issues and as to not compete with the B-29 program for certain components.P-61A-5 ‘Lady Gen’ 9th AF, 422nd NFS, Florennes, Belgium. 1st Lt. Paul A. Smith (Pilot) & 1st Lt. Robert E. Tierney. This particular P-61A was among the first to travel to the ETO and was flown by the first US night aces. P-61’s would eventually switch to a gloss black livery, which would eventually replace this particular plane’s olive drab and invasion stripes.P-61B ‘Midnite Madness II’, 548th Night Fighter Squadron, Iwo Jima. Stationed on Iwo Jima, aircraft of this squadron defended the recently taken island from nightly visits by Japanese raiders and reconnaissance aircraft.P-61B ‘23968’ 414th NFS, 12th Air Force, Italy with a detachment to the 422nd NFS. While two of the four MTO night fighter units were re-equipped with P-61’s and British built Mosquito’s, the other two continued to use their old Beaufighters until the end of the war.P-61C, Thunderstorm Project, USA. With their guns traded for meteorological equipment, a select number of P-61C’s would embark on a foundational meteorological and aviation safety project. While never designed for such use, the P-61 would provide data for a groundbreaking study that would reveal the effects of thunderstorms on aircraft and the behavior of the convection cells within storms, among other major scientific findings.
The R-2800-10 and R-2800-65 differed in regards to their magnetos and ignition systems. War Emergency Power with the R-2900-65W was rated for 2250 hp at 60 inches of Manifold pressure, 2700 RPM [Pilot’s operating instructions for the P-61A]Pilot’s Instrument Panel. The Pilot’s radar indicator position below the gunsight is empty [P-61 training manual]The AN/CPS-1 was a microwave early warning radar system used to great effect by the USAAF across Europe, and later the Pacific, providing P-61 crews with accurate target information. The set here was deployed in Luxembourg, where it provided support during the Battle of Bulge [National Air and Space Museum]P-61Bs patrol over the Marianas [National Archives]The addition of underwing racks would largely solve the P-61’s range issues and allow it to carry a considerable bomb load [National Archives]Members of an aviation engineering battalion add extensions to an airstrip in order to accommodate the P-61 [National Archives]A P-61 landing at Luzon, 1945 [National Archives]The radar operator worked from an isolated position at the rear of the aircraft. This would prove a major drawback of the design, as the pilot would be without radar guidance should the intercom system fail, the R/O accidentally pull the IC cable out, or if the tail cone imploded in a dive. [National Archives]Reinforcement kits were used to keep the tail cones of these aircraft from imploding in dives or high speed maneuvers [Wikimedia]A very early production P-61A of the 6th NFS in the Marianas, 1944. [National Archives]Brig. General Earl W. Barnes flew a P-61 modified for his personal use with an extra fuel tank installed in the place of its turret. Pictured here at the opening of an airfield at Middleburg Island, New Guinea. [National Archives]At -35F (-37C), engine heaters were needed to start this P-61 stationed in Alaska, 1944. [National Archives]The P-61 gave squadrons who formerly relied on the P-70 a massive boost in performance and confidence. Here, Major V. Mahr of the 6th NFS climbs into his P-61 in Saipan, July 1944. [National Archives]The XP-61E was a prototype escort fighter based on the P-61B, two aircraft were converted, but further development was canceled after the war. [Wikimedia]P-61s of the 548th NFS wait for their shift to start, Iwo Jima. [Wikimedia]A P-61 sits at Clark Field, Philippines, in August of 1945. By this point, the P-61 was being phased out by the P-38M in several squadrons. It would continue to see some use in the post war years. [National Archives]The F-15A reporter was a photo reconnaissance aircraft developed from the P-61 that went into production after the war. These aircraft would participate in the Thunderstorm Project and serve in the Korean war. [Murph’s Models]
Credits
Written by Henry H.
Edited by Stan L. and Ed J.
Illustrations by Ed Jackson
Primary Sources:
Ashkenas, I L. The Development of a Lateral Control System for Use with Large Span Flaps. No. 1015. NACA, 1946.
Pilot’s Flight Operating Instructions Army Model P-61A Airplane. (T. O. NO. 01-15FB-1). Commanding General, Army Air forces. January 15, 1944.
Pilot Training Manual for the Black Widow P-61. Office of Assistant Chief of Air Staff Training. 1944
Handbook of Operating Instructions for Radio Set SCR-720-A and Radio Set SCR-720-B. AN 08-10-181. Joint authority of the Commanding General, Army Air Forces, and the Commanding General, Army Service Force. (1943).
Northrop P61 Black Widow Pilot’s Flight Operating instructions. T.O No. AN 02-35VC-3. USAF, July 1945
Introduction Survey of Radar Part II. Air Publication 1093D Volume 1 First Edition. Air Ministry, June 1946.
Secondary Sources:
Boiten, Theo. Nachtjagd Combat Archive 1944 Part Four. Surrey: Red Kite, 2021.
Boiten, Theo. Nachtjagd Combat Archive 1944 Part Five. Surrey: Red Kite, 2021.
Braham, Roscoe R. “Thunderstorms and the Thunderstorm Project”
Brown, Louis. Technical and Military Imperatives: a Radar History of World War II. Taylor & Francis, 1999.
Dean, Francis H. America’s Hundred Thousand: the US Production Fighter Aircraft of World War II. Schiffer Publ., 1997.
Kolln, Jeff. The 421st Night Fighter Squadron in World War II. Schiffer Pub., 2001.
McFarland, Stephen Lee. The U.S. Army Air Forces in World War II: Conquering the Night: Army Air Forces Night Fighters at War. Air Force History and Museums Program, 1998.
Pape, Garry R., and Ronald C. Harrison. Queen of the Midnight Skies: the Story of America’s Air Force Night Fighters. Schiffer Publishing Ltd., 1992.
Price, Alfred. Instruments of Darkness: the History of Electronic Warfare. Greenhill, 2005.
Thompson, Warren E. P-61 Black Widow Units of World War 2. Osprey, 1998.
“WW2 People’s War – Reg EVERSON’S STORY.” BBC. BBC. Accessed August 1, 2021. https://www.bbc.co.uk/history/ww2peopleswar/stories/26/a3130426.shtml.
Nazi Germany (1944)
Parasite Interceptor – None Built
Artist’s depiction of the Sombold So 344 firing off its nose rocket. [Heinz Rodes]The Sombold So 344 was a highly specialized interceptor designed by Heinz G. Sombold to attack Allied bomber formations over Germany in 1944. The way the aircraft would attack, however, would be extremely unconventional. Being deployed from a bomber mothership, the So 344 would fly towards an approaching bomber formation and launch its entire nose cone, which was a 400 kg (882 Ib) rocket, at the enemy bombers in an attempt to destroy as many as possible. From there, the So 344 could either attack the remaining bombers or return to base and land on a skid. Work went as far as wind tunnel models for the aircraft but none would be built.
History
Towards the end of the Second World War, Germany found itself at odds on an almost daily basis against the threat of Allied bombers. While pre-existing aircraft were used to defend Germany from this threat, more and more proposals for aircraft designed to deal with enemy bombers began to emerge. A number of these projects would use extremely unorthodox or downright strange methods to attempt to destroy enemy bombers. These ranged from carrying specialized weapons to even ramming the bomber. These projects were often small in design and were made of widely available materials, like wood, to save on production costs, reserving the more important material for mainline aircraft. An aircraft produced in small numbers that followed this formula was the Bachem Ba 349 “Natter”. Although not used operationally, the Ba 349 was a small bomber interceptor that would not require an airstrip to take off. Instead, it would be launched vertically from a launch rail. After taking off, the Ba 349 would approach the Allied bombers and attack them with a salvo of rockets in the nose. With its ammo depleted, the pilot would then eject from the aircraft, with the aircraft’s engine section parachuting down and being recovered for reuse. The nose would break off for the pilot to deploy the rockets under the cone. The Ba 349 is the most well known of these projects, but many would never leave the drawing board. Many of these aircraft designs were created by large companies but a handful came from individual engineers. One such design, the Sombold So 344, would approach the destruction of enemy bombers in an entirely different, almost ludicrous way.
3-way view of the So 344 [Luft46.com]The Sombold So 344 was the idea of Heinz G. Sombold of the Bley Ingenieurbüro (Engineering Office). Bley Segelflugzeug was a sailplane manufacturer located in Naumburg, Germany. During the 1930s, they became popular for their various sailplane designs, like the Kormoran and Motor-Kondor designs. Heinz G. Sombold was an engineer at Bley. He began working on the So 344 in late 1943 and his aircraft incorporated many features of the sailplanes built by the company. At the time, the craft was only designed as a parasite escort fighter and armed with two machine guns. On January 22nd of 1944 however, Sombold would drastically change the design and purpose of the aircraft. From here, the aircraft would be designed for the destruction of enemy bombers. To fit this new role, it would use a very unorthodox weapon. The nosecone of the So 344 was a rocket filled with 400 kg (880 Ib) of explosives that could be launched by the pilot at enemy aircraft. Sombold envisioned his aircraft using its nosecone rocket against close formations of bombers, where multiple aircraft could be destroyed with one well placed explosive. American bombers would often fly in combat box formations, where the bombers would fly close together to maximize the defensive capabilities of their guns. This allowed the bombers to have ample protection from enemy interceptors, as the approaching craft would come under fire from most of the aircraft in said formation. There were earlier weapons deployed by the Germans to try and damage the closely packed formations, like the BR 21, but none would be as huge a payload as the Sombold’s nose rocket.
Rear view of the wind tunnel model
Design work on the So 344 continued through 1944, even going as far as having a ⅕ scale wind tunnel model being made and tested at the Bley facility. By 1945, work on the project was cut off, as the Bley facility had to be abandoned due to the encroaching warfront. No further work was done on the Sombold So 344 and Sombold’s fate is unknown. No other designs by Sombold are known to have existed. The 344 designation was later used for the Ruhrstahl X-4, or RK 344, air-to-air missile system.
At the top of this image is the photo of the claimed nosecone of a Sombold So 344. In actuality it is a nose section of a Wasserfall SAM. [Lower: Wiki][Upper: Luftwaffe Secret Projects 17]A photo has circulated in several books, as well online, that claims a nosecone of the So 344 was built and discovered by the Allies at the end of the war. However, this photo actually depicts the nose section of a Wasserfall surface-to-air missile. The nose of the Wasserfall easily could be confused for that of the Sombold’s, as its shape is semi-similar and both have four stabilizing fins. No So 344 was built.
Design
Photo of the 1/5 wind tunnel model of the Sombold So 344
The Sombold So 344 was a single man special attack aircraft. It was to have a short, tubular body of wooden construction. For ease of transport, the aircraft could be split into two sections. The cockpit would be located at the rear of the body, directly in front of the vertical stabilizer. The aircraft would have conventional control surfaces on its wings and stabilizers. At the ends of the horizontal stabilizers were two angled vertical stabilizers. The wings would be mid-set. For its powerplant, the So 344 would use a Walter 509 bi-fuel rocket engine. To conserve fuel, the aircraft would be deployed via bomber mothership. Once deployed, it would have around 25 minutes of fuel. To land, the So 344 would have a rounded ski built into the body, similar to how the sailplanes Bley created would land.
For its main armament, the So 344 had a massive unguided rocket as its nose cone. The nose would contain 880 Ibs (400 kg) of explosive Acetol. The rocket was triggered via a proximity fuse. For stabilization, four fins would be placed on the nose. Additionally, the So 344 would have two forward machineguns to either defend itself or attack other bombers once its payload was released.
Operations
The So 344 would be carried to an approaching bomber formation via a modified bomber mothership. Once deployed, the aircraft would move in an arc towards the bombers, coming in downwards at them from at least 3,300 ft (1,000 m) above. This height would protect the So 344 from defensive fire during its dive. When the aircraft was lined up with a group of bombers, the pilot would launch the nosecone into the middle of the formation. Given the close proximity of the bombers in formation and the explosive threshold of the nosecone, it was predicted the resulting explosion would be able to take down several bombers in one attack. After launching its nosecone, the So 344 would have some fuel left and could continue to attack the remaining bombers with two machine guns on the aircraft. When fuel was low, the aircraft would return to base via gliding, like the Messerschmitt Me 163B rocket interceptor. Once near an airfield, it used a large ski to land.
Conclusion
The So 344 was a very strange way of approaching the bomber problem over Germany late in the war. The logic behind it was not too far fetched. The aforementioned Ba 349 Natter followed a similar attack plan, approaching the bombers and firing off a salvo of rockets before the pilot bailed from the craft. A project like the So 344 was not new to Germany by that point in the war and, like most of its contemporary designs, was not produced.
Had it been produced, the So 344 would have been a very niche aircraft. The fact that the aircraft had a single shot from its rocket payload made accuracy extremely important. The aircraft also would have been a prime target for Allied escort fighters once it ran out of fuel. A bomber would also need to be modified to carry the So 344 and would be a prime target for the escort fighters once the attacker was launched. The nature of the aircraft has led it to wrongly be named a “suicide attacker” by many postwar books on the subject. In some instances, the craft is also incorrectly listed as being a ramming aircraft. It is likely the aircraft would not have impacted the war very much.
Variants
Sombold So 344 (1943)– Original planned fighter version. Armed with two machine guns or heavier armament. None were built
Sombold So 344 (1944)– The Sombold So 344 attack aircraft. Armed with a nosecone rocket which would be fired at enemy bomber formations. None were built.
Operators
Nazi Germany – The Sombold So 344 was designed for the Luftwaffe to use against Allied bombers over Germany. None of the type would be built.
Sombold So 344 Specifications
Wingspan
18 ft 8 in / 5.7 m
Length
22 ft 11 in / 7 m
Height
7 ft 1 in / 2.2 m
Wing Area
64.58 ft² / 6 m²
Engine
Walter 509 Bifuel rocket engine
Weight
2,976 Ib / 1,350 kg
Flight Time
25 minutes
Crew
1 pilot
Armament
2x machine guns
1x 880 Ib (400 kg) Nose Rocket
Gallery
Artist’s Concept of a completed So 344 with striped nosecone – By Ed Jackson
Video
Credits
Article by Marko P.
Edited by Henry H. and Stan L.
Illustration by Ed Jackson
Herwig, D. & Rode, H. (2003). Luftwaffe Secret Projects: Ground Attack & Special Purpose Aircraft. Hinckley, England: Midland Pub.