All posts by Marko P.

Messerschmitt Me 163A Komet

Weimar and Nazi Germany, WW2, , , ,

Nazi flag 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

Heinkel He 112

Weimar and Nazi Germany, WW2, , ,

Nazi flag Nazi Germany (1935)
Fighter – 66 to 100 Built

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 Luftwaffe
An alternate livery of the Luftwaffe He 112
He 112 in Romanian Service
He 112 in Romanian Service
He 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.

 

Lublin R-XVI

Poland, WW2, , , ,

Polish Flag 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.

 

 

 

Nakajima Ki-115 Tsurugi

Empire of Japan, WW2, , , , , , ,

 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
Empty Weight 3,616 lbs / 1,640 kg
Maximum Takeoff Weight 6,440 lbs / 2,880 kg
Maximum Speed 340 mph / 550 km/h
Cruising speed 186 mph / 300 km/h
Range 745 miles / 1,200 km
Crew Pilot
Armament
  • Bomb load up to 1,760 lbs (800 kg)

Gallery

Illustrations by Ed Jackson

Another Ki-115 Tsurugi in Natural Metal with 500kg Type 92 Bomb
Ki-115 Tsurugi in Green with 500kg Type 92 Bomb
Ki-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

 

 

 

Yakovlev Yak-4

Soviet, WW2, ,

USSR flag USSR (1939)
Light Bomber – 90 to 100 Built

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.

Yak-4 Specifications
Wingspans 45 ft 11 in / 14 m
Length 33 ft 4 in / 10.18 m
Wing Area 316.4 ft² / 29.4 m²
Engine Two M-105  hp engines
Empty Weight 10,050  lbs / 4,560 kg
Maximum Takeoff Weight 13,481 lbs / 6,115 kg
Climb Rate to 5 km In  6.5 minutes 
Fuel load 1,120 litres (244 gallons)
Maximum Speed  332 mph / 535 km/h
Cruising speed 284 mph  / 458 km/h
Range 460  miles / 740 km
Maximum Service Ceiling 31,824 ft / 9,700 m
Crew Pilot and the rear gunner. 
Armament
  • Two 7.92 mm (.30 caliber) machine guns 
  • 400 to 900 kg (880 to 1.980 lbs) bombs

Gallery

Illustrations by Ed Jackson

Yak-4, 118th Independent Reconnaissance Aviation Regiment, Northern Fleet, 1943
Yak-4, Riga, Latvia, June 1941
Yak-4, 314th Reconnaissance Aviation Regiment, 1941
Yak-4, Grodno, Belarus, June 1941
Yak-4 from the 314th Reconnaissance Aviation Regiment, Babruysk, Belarus, June 1941

Credits

  • Written by: Marko P.
  • Edited by: Stan L. & Henry H.
  • Illustrations by Ed Jackson

Sources

  • D. Nešić (2008), Naoružanje Drugog Svetskog Rata SSSR, Beograd
  • B. Gunston and Y. Gordon (1977)Yakovlev Aircraft Since 1924, Putnam Aeronautical Books.
  • Y. Gordon, D, Khazanov (1999) Soviet Combat Aircraft, Midland Publishing
  • Y. Gordon, D, Khazanov and S. Komissarov (2005) OKB Yakovlev, Midland
  • G. Sarhidai, H. Punka and V. Kozlik. (1996) Hungarian Air Forces 1920-1945, Hikoki Publisher

 

Arado Ar 234A Blitz

Weimar and Nazi Germany, WW2, ,

Nazi flag 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.

Ar 234 V4 Specifications
Wingspans 46 ft 7 in / 14.2 m
Length 38 ft 2 in / 11.65 m
Height 12 ft 6 in / 3.8 m
Wing Area 284 ft² / 26.4 m²
Engine Two Junkers 004 A-0 turbojet
Empty Weight 10,740 lbs / 4,250 kg
Maximum Takeoff Weight 19,180 lbs / 8,700 kg
Fuel Capacity 3,800 l
Maximum Speed 472 mph / 760 km/h
Range 930 miles / 1,500 km
Maximum Service Ceiling 36,090 ft / 11 km
Crew One Pilot
Armament
  • None

Gallery

Illustrations by Ed Jackson

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.

Credits

  • Written by Marko P.
  • Edited by Stan L. & Ed J.
  • Illustrations by Ed Jackson
  • D. Nešić (2008), Naoružanje Drugog Svetskog Rata Nemačka Beograd
  • D. Mondey (2006). The Hamlyn Concise Guide To Axis Aircraft OF World War II, Bounty Books.
  • J. R. Smith and E. J. Creek (2006) Arado 234 A, Chevron Publishing
  • R. P. Bateson, Profile 215 ARADO Ar 234 Blitz
  • M. Griehl (2012) X-Planes German Luftwaffe Prototypes 1930-1945, Frontline Book
  • Jean-Denis G.G. Lepage Aircraft Of The Luftwaffe 1935-1945, McFarland and Company.
  • D. Donald (1998) German Aircraft Of World War II, Blitz Publisher

Messerschmitt P.1101

Weimar and Nazi Germany, WW2, ,

Nazi flag Nazi Germany (1944)
Jet Fighter – 1 Incomplete Prototype Built 

The P.1101 prototype after the war [Wiki]


During the war, German scientists and engineers managed to develop and build a number of jet powered aircraft, several of which went on to see combat. What is generally less known are the large number of experimental jets that were proposed and prototyped. These designs utilized a great variety of engines, airframes, and weapons. One of these unfinished projects was the Messerschmitt P.1101 jet fighter.

Need for a New Jet Fighter

Line drawing of the P.1101 [Luftarchiv]
During the war, the Germans introduced the Me 262, which had the honor of being the first operational jet fighter in the world. While it provided better performance than ordinary piston powered aircraft, it was far from perfect. The greatest issues were that it was expensive to build, required two jet engines, and could not be built in sufficient numbers. The German Air Ministry (Reichsluftfahrtministerium; RLM) wanted a much simpler and cheaper design powered by a single engine. They issued a competition for a new jet fighter ,code named 1-TL-Jäger, during July 1944 for all available aircraft manufacturers. Some of the requirements listed were that it would be a single seater, have a maximum speed of 1000 km/h (620 mph), an endurance of at least one hour, armor protection for the pilot, make use of the Heinkel HeS 011 engine, and had an armament that had at least two 30 mm (1.18 in) MK 108 cannons. During a meeting with the leading German aircraft manufacturers held in September 1944, Messerschmitt presented the P.1101designed by Waldemar Voight.

The Messerschmitt P.1101 Development History

Drawing of the P.1101 before a number of design changes were introduced. [Luft46.com]
Messerschmitt’s engineers and designers began working on designing a single engined jet aircraft at the start of 1943. Two projects, P.1092 and P.1095, were both powered by a single Jumo 004 jet engine, but, as the Me 262 was entering full production, their development was largely suspended. These projects were shelved until the RLM competition in 1944. Seeing a new opportunity, Messerschmitt presented drawings of a new project named P.1011, which was influenced by the previous projects. It had an all-metal fuselage construction and was powered by one HeS 011 engine with the air intakes placed on the wing’s roots. It also had a V-tail.

Following the meeting with the RLM officials in September, some changes were made to the P.1101’s overall design. Instead of two air intakes, a single one in the nose was to be used. This also necessitated the redesigning of the cockpit, which was moved back. In addition, the rear V-tail was replaced with a standard fin design. At this early stage, the possibilities of using this aircraft for other purposes were still being explored. Beside the standard fighter, other roles which were considered were night fighter and interceptor. On 10th November, the owner of the company, Willy Messerschmitt, issued orders to begin working on the first experimental prototype. To speed up the developing time, it was proposed to reuse the already produced components of the Me 262. The Me 262 fuselage, wings design and construction were to be copied.

End of the Project

The P.1101 prototype was only partially completed in early 1945. It appears that, despite Messerschmitt’s attempts to complete this project, the RLM simply lost interest. Messerschmitt’s other projects, like the P.1110 and P.1111, showed greater potential than the P.1101. This, together with the fact that the promised engine never arrived, meant that the single incomplete prototype was put into storage at the Messerschmitt Oberammergau research center. It remained there until the war’s end, when it was captured by American forces.

Technical Characteristics

Side view of the P.1101. This picture was taken at the Messerschmitt Oberammergau base. [Luftarchiv]
The P.1101 was a single seater, jet engine-powered mixed construction fighter. The lower parts of the all-metal fuselage were designed to house the jet engine. In the front of the fuselage, a round shaped intake was placed. To the rear, the fuselage was additionally reinforced to avoid any damage due to the heat of the jet exhaust. The underside of the fuselage was to have a skid to help better land during an emergency.

While it was originally intended to be powered by the HeS 011 engine, the power plant was never supplied and the Jumo 004B was to be used as a replacement. The main fuel tank, with a capacity of 1,100 liters (290 gallons), was placed just behind the cockpit. Only a mock-up engine was ever installed in this aircraft, so it was never tested properly, even on the ground. Due to this, it is unknown what the P.1101’s overall flight performance would have been. Some sources give rough estimates, such as that it could have reached 890 km/h (550 mph) at sea level and up to 980 km/h (610 mph) at higher altitudes. Of course, these are only estimations contingent on the fact that the plane had no other problems during operational flight. In addition the general ability to test flight characteristics in the transonic-supersonic range were extremely crude at this point.

Close up view of the P.1101’s large front air intake for the jet engine. The markings painted on it were probably added by the Americans after the war. [Luftarchiv]
The wing’s were made of wood materials. The prototype would have a completely innovative feature, namely the sweep angle of the wings could be adjusted at different angles ranging between 35° and 45°. The rear vertical and horizontal tail assembly was also made of wood.

The P.1101 had a retracting tricycle-type landing gear. It consisted of one forward mounted and two mid-fuselage wheels. All three retracted rearwards into the fuselage. The cockpit had a round shaped canopy with good all around vision.

The basic armament configuration consisted of two MK 108 cannons with 100 rounds each. These were placed in the front lower part of the fuselage. There were proposals to increase the firepower by adding two more MK 108 cannons, and the use of experimental air-to-air missiles was also considered. As the prototype aircraft was built to test overall flight performance, no armament was ever installed.

Rear view of the tail assembly. [Luftarchiv]

In American Hands

The restored P.1101 in America. [Pinterest]
Advancing American soldiers reached the Messerschmitt Oberammergau base during April (or May) 1945. The single P.1101 was found there and, for some time, left open to the elements. The Bell Aircraft Chief Designer Robert Woods came to know of the existence of this aircraft. Once he had a chance to examine it, he organized for it to be shipped back to America for further study. It would be restored and used as testing mock up aircraft. The Bell aircraft design bureau paid great interest to the variable wing design. Working from the P.1101, they would eventually develop the Bell X-5, one of the first operational aircraft that could change the position of its wings during flight.

The Bell X-5 aircraft, which was heavily influenced by the German P.1101 design [WIki]

Conclusion

While incorporating the innovative feature of variable swept wings, the P.1101 was another victim of the chaotic state Germany was in at the end of war. Whether this aircraft could have performed its role is unknown, and while it never flew for the Germans, it helped the Americans develop the Bell X-5 after the war which incorporated the same variable wing design.

P. 1101 Specifications
Wingspans 27 ft / 8.24 m
Length 30 ft 1 in / 9.13 m
Height 9 ft 18 in / 2.8 m
Wing Area 170 ft² / 15.8 m²
Engine One Jumo 004B or one HeS 011
Empty Weight 5,725 lbs/ 2,600 kg
Maximum Takeoff Weight 8,950 lbs / 4,060 kg
Fuel Capacity 1,100 l / 290 Gallons
Estimated Maximum Speed 610 mph / 980 km/h
Estimated Cruising speed 550 mph / 890 km/h
Crew 1 pilot
Armament
  • Two 108 MK cannons
Messerschmitt P.1101 Prototype
Initial P.1101 Design prior to changes

Credits

  • Article by Marko P.
  • Edited by Stan L. and Henry H.
  • Illustrated by Carpaticus
  • D. Nešić, (2008). Naoružanje Drugog Svetsko Rata-Nemačka. Beograd.
  • D. Monday. (2006). The Hamlyn Concise Guide To Axis Aircraft Of World War II, Bounty Books.
  • D. Sharp (2015) Luftwaffe Secret Jets of the Third Reich, Mortons Media Group
  • M. Griehl (2012) X-Planes, Frontline Books
  • R. Ford (2000) German Secret Weapons of World War Two, MBI Publishing
  • Jean-Denis G.G. Lepage (2009) Aircraft of the Luftwaffe 1935-1945, McFarland and Company
  • J. R. Smith and A. L. Kay (1972) German Aircraft of the Second World War, Putnam
  • http://www.luft46.com/mess/mep1101.html

Modli J.M. 8

Cold War, Yugoslavia, , , ,

Yugoslavia flag Yugoslavia (1939-1950)
Trainer – 2 Prototypes

The Modli-8 in use with the Yugoslav Aviation after the war. www.paluba.info

The Modli J.M. 8 was designed in the Kingdom of Yugoslavia, built by the Independent State of Croatia (NDH), and after World War II, operated by the Federal People’s Republic of Yugoslavia (FPRY). It was an inexpensive training aircraft that would be used in this role up to 1950.

The Beginning

The story of the Modli J.M. 8 began in 1938, when an aircraft engineer from the 1st Air Force Regiment (stationed at Novi Sad), Josip Modli, finished work on a new light training aircraft design. He originally intended to design and build a single seat trainer that was cheap and simple to manufacture by using mostly wood. He also intended to gain the interest of amateur aviators and aeroclubs with a low price. The J.M. 8 designation comes from the initials of the designer’s name. Due to its small size and low price, it earned the nickname Komarac/komaрац (Mosquito).

The following year, Modli actually began building this aircraft. He reused the small 18 hp engine taken from a damaged French HM.14 Pou du Ciel (Nebeska Vaš/Небеска Ваш in Serbian). Four had been bought from France in 1935 but, due to construction problems, their use was limited and all were damaged during test flights. One was tested at Novi Sad, where the 1st Air Force Regiment was stationed.

Modli reused the engine from a damaged HM.14 Pou du Ciel for his first prototype. Four of these small aircraft were bought from France. www.vazduhoplovnetradicijesrbije.rs

At that time, word of his design and work reached the Yugoslavian Air Force Headquarters. Headquarters then instructed (or ordered, depending on the sources) aircraft engineer Tišma, who was co-owner of the Albatros aircraft manufacturer from the cit of Sremska Mitrovica, to contact Modli. After short negotiations, Tišma and Modli reached an agreement that Albatros should finish the construction of the J.M. 8.  If the design received any mass production orders, Modli agreed to provide Albatros with a license for its production.

The J.M. 8 was completed in early 1941, with testing scheduled to begin in March. Due to bad weather, Albatros’ main airport at Ruma was flooded during March and early April, so no tests flights were conducted. During the outbreak of the April War (Axis invasion of Yugoslavia), all finished and partially constructed planes from Albatros were loaded on a train on the 10th of April. Because of the great confusion due to the outbreak of war and the lack of documentation, the fate of this train and its cargo is unknown to this day.

After the end of  the April War, the Serbian Air Force Commission made estimates of all unpaid pre-war designs, including the Modli J.M. 8, in order to arrange for future payments for military contracts. The commission, after analysis of the Modli J.M. 8 documentation, concluded that the aircraft did not meet any military requirements and was suitable for civilian use only.

Technical Characteristics 

The Modli J.M. 8 was designed as a single engined, high wing, mixed construction (but mostly wood) training aircraft. Its fuselage had a simple design made of plywood. The high wings and the rear tail were made of a wooden structure covered with fabric. For better flight controls, Modli used two modified Gottingen 426 longerons. The wings were connected to the fuselage with three “N” shaped metal bars on both sides and with two additional ones in the centre. The tail had a large rudder and elevators made of wood.

It was powered by the two cylinder Aubier & Dunne 18 hp engine. The engine compartment was covered with duralumin. The two-bladed propeller was made of walnut. A fuel tank with a capacity of 16 liters was placed in the center of the wing.

The Aubier & Dunne 18 hp engine was reused for the first prototype. Source: www.vazduhoplovnetradicijesrbije.rs

The landing gear was fixed, but was equipped with rubber shock absorbers for greater comfort and control during  landing. There was no rear wheel, being instead equipped with a small skid and shock absorber.

The pilot’s cockpit was fully open with a small windshield at the front. The cockpit had a simple design and was equipped with basic controls and instrumentation. These flight instruments included an airspeed indicator, fuel level, tachometer, and altimeter. As the first prototype was never adequately tested, details about its flying performance are not known.

During World War II

After the Yugoslavian capitulation, its territories were divided between the Axis forces. The Germans created the Independent State of Croatia (Nezavisna Država Hrvatska) puppet state. Despite promises of sending military equipment, weapons and aircraft, the NDH was mostly supplied with older or captured equipment. The NDH aviation industry was heavily dependent on supplies from Germany and Italy, as it lacked any major production capacity or industrial development, meaning domestic production was not possible. The only attempt at domestic production was with the Modli aircraft.

In 1941, Modli joined the new NDH Air Force with the rank of Flight Captain as a flight school instructor. He immediately began working on his second prototype, now simply called Modli-8. Unlike his first prototype, the second one was powered by a stronger four-cylinder Praga-B giving 40 hp. As this engine was too strong for the prototype, its power was reduced to just 20 hp. For the landing gear, two smaller rear wheels from a German Me-109 were reused. The Modli-8 was also shorter in comparison to the first prototype by 0.94 ft (15 cm).

In 1943 Modli was transferred to the technical workshop of the 1st Air Base in Zagreb, where he continued to develop his plane. In 1944, the Modli-8 was completed and introduced to NDH operational service according to authors T. Lisko  and D. Čanak. Unfortunately, they do not give more information on its service history. According to authors B. Nadoveza and N. Đokić on the other hand, noted that Modli deliberately delayed the production of the Modli-8 and it was never fully completed for use by the NDH.

On 26th October 1944, Josip Modli fled to Slovenia at the helm of a Bücker Bü 131 “Jungmann” in hopes of joining the Yugoslav Communist Partisans. Meanwhile, his assistants and friends in Zagreb hid the Modli-8 prototype in the attic of an old shed. Due to the chaos and confusion caused by the war, it was easy to hide the small and lightweight prototype. The Modli-8 would survive the war intact.

The Modli-8 was the only NDH domestically-built aircraft during the War. These two pictures may be the only ones of the Modli-8. Source: www.paluba.infok

In NDH service, the Modli-8’s lower fuselage, wings, and tail were painted in silver. The upper part of the fuselage and vertical stabilizer was blue. The wings struts were painted in red, while the middle of the fuselage wore a red stripe on both sides with a white outline. There were NDH markings with a large “JM8” painted on the tail. The color scheme would remain the same after the war but the NDH marking would be replaced with the Communist Star.

After the War

After the collapse of the NDH and the German forces in Yugoslavia, Modli, now Captain in the Yugoslav People’s Army, moved his prototype from Zagreb to Skopje, where it was completed in an army workshop. Modli himself flew the prototype during the summer of 1945. Surprisingly , he did not report this flight to his superiors and an alarm was raised, with several fighters launched to intercept him. Modli was lucky, as this incident did not affect his military career. The Modli-8 was, by order of Air Force Command, moved to Belgrade for further tests. The aircraft proved to be a good design, as it was easy and pleasant to fly according to test pilot Vasilije Vračević. There were some issues with the sensitivity of the large rudders and elevators during flight. For take off, it only needed a very short 170 m (558 ft) runway, and could land on a 125 m (410 ft) airfield. The maximum speed was around 100 km/h 223 mph at an altitude of 1 km.

The Modli-8 was then given to Aircraft Center Vršac, where it was used for training and propaganda flights. It was used operationally up to 1950, when it was removed from Army service. During its operational service, the Modli-8 was also used as a glider trainer. Under the right conditions it could be used as a glider with the engine shut off, which was useful for glider training.

Josip Modli later (date unknown) designed a two-seater version named Modli-9, but it was never fully completed. Both the Modli-8 and the unfinished 9 were given to the Croatian Technical Museum (Zagreb)  after the death of Josip Modli in 1974.

Production and Modifications

Despite being cheap, easy to build, and pleasant to fly, the Modli-8 was never adopted for military or civilian service. The first prototype was never fully tested due to the outbreak of the war and was lost (precise fate unknown). The second prototype was built during the war and was in use up to 1950. Despite the good feedback for its flight performance from the military, the Modli-8 was rejected for production, mostly due to the recent adoption of the BC-3 Trojka.

Modli J.M.8 – First prototype powered with Aubier & Dunne engine, lost in WW2.

Modli-8 – Second prototype powered by Praga-B engine and with other minor improvements, in service until 1950.

Modli-9 – Two-seater version, never fully completed.

Conclusion

Despite the few number of built aircraft, the Modli J.M. 8 had a small but interesting development history, changing owners several times. It had the honor of being the only aircraft built in Croatia during World War II. Despite its simplistic nature, it saw extensive use as a trainer after the war.

Operators

  • Kingdom of Yugoslavia – One built prototype
  • Independent State of Croatia (NDH) – Constructed one prototype but never tested
  • Federal People’s Republic of Yugoslavia (FPRY) – Operated the Modli-8 up to 1950.

Modli-8 (second prototype) Specifications
Wingspans 31 ft 2 in / 9.5 m
Length 19  ft 7 in / 6 m
Height 6 ft  / 1.85 m
Wing Area 36.25 ft² / 11.05 m²
Engine One four cylinder Praga-B 40 hp engine
Empty Weight 474 lbs / 215 kg
Maximum Takeoff Weight 705  lbs / 320 kg
Fuel Capacity 16 l
Climb Rate to 1 km In 10 minutes
Maximum Speed at 1 km 223 mph / 100 km/h
Take of run 558 ft / 170 m
Landing run 410 ft / 125 m
Range 124 mi / 200 km
Maximum Service Ceiling 5578 ft / 1,700 m
Crew 1 pilot
Armament
  • None

Gallery

Illustrations by Carpaticus

Modli Croatia
Modli Yugoslavia

Sources:

  • T. Lisko  and D. Čanak (1998), The Croatian Air Force In The WWII, Nacionalna i sveučilišna knjižnica, Zagreb
  • Vojislav V. Mikić, (2000) Zrakoplovstvo Nezavisne države Hrvatske 1941-1945, Vojno  istorijski institut Vojske Jugoslavije
  • B. Nadoveza and N. Đokić (2014), Odbrambena Privreda Kraljevine Jugoslavije, Metafizika Beograd.
  • Nebojša Đ.and Nenad M. (2002), IPMS Yugoslavia and Yugoslavian Aviation Special Interest Group Bulletin No 1-4, 

 

 

Focke-Wulf Fw Triebflügel 

Weimar and Nazi Germany, WW2, , ,

Nazi flag Germany (1944)
Experimental VTOL Fighter – Paper Project

The bizarre looking Focke-Wulf Triebflügel fighter design. [luft46.com]
During the war, German aviation engineers proposed a large number of different aircraft designs. These ranged from more or less orthodox designs to hopelessly overcomplicated, radical, or even impractical designs. One such project was a private venture of Focke-Wulf, generally known as the Triebflügel. The aircraft was to use a Rotary Wing design in order to give it the necessary lift. Given the late start of the project, in 1944, and the worsening war situation for Germany, the aircraft would never leave the drawing board and would remain only a proposal.

History

During the war, the Luftwaffe possessed some of the best aircraft designs and technology of the time. While huge investments and major advancements were made in piston engine aircraft development, there was also interest in newer and more exotic technologies that were also being developed at the time, such as rocket and jet propulsion. As an alternative to standard piston engine aircraft, the Germans began developing jet and rocket engines, which enabled them to build and put to use more advanced aircraft powered by these. These were used in small numbers and far too late to have any real impact on the war. It is generally less known that they also showed interest in the development of ramjet engines.

Ramjets were basically modified jet engines which had a specially designed front nozzle. Their role was to help compress air which would be mixed with fuel to create thrust but without an axial or centrifugal compressor. While this is, at least in theory, much simpler to build than a standard jet engine, it can not function during take-off. Thus, an auxiliary power plant was needed. It should, however, be noted that this was not new technology and, in fact, had existed since 1913, when a French engineer by the name of Rene Lorin patented such an engine. Due to a lack of necessary materials, it was not possible to build a fully operational prototype at that time, and it would take decades before a properly built ramjet could be completed. In Germany, work on such engines was mostly carried out by Hellmuth Walter during the 1930s. While his initial work was promising, he eventually gave up on its development and switched to a rocket engine insead. The first working prototype was built and tested by the German Research Center for Gliding (Deutsche Forschungsinstitut für Segelflug– DFS) during 1942. The first working prototype was tested by mounting the engine on a Dornier Do 17 and, later, a Dornier Do 217.

The Dornier Do 217 was equipped with experimental ramjets during trials. [tanks45.tripod.com]
The Focke-Wulf company, ever keen on new technology, showed interest in ramjet development during 1941. Two years later, Focke-Wulf set up a new research station at Bad Eilsen with the aim of improving already existing ramjet engines. The project was undertaken under the supervision of Otto Ernst Pabst. The initial work looked promising, as the ramjets could be made much cheaper than jet engines, and could offer excellent overall flying performance. For this reason, Focke-Wulf initiated the development of fighter aircraft designs to be equipped with this engine. Two of these designs were the Strahlrohr Jäger and the Triebflügel. The Strahlrohr had a more conventional design (although using the word conventional in this project has a loose meaning at best). However, in the case of the Triebflügel, all known and traditional aircraft design theory was in essence thrown out the window. It was intended to take off vertically and initially be powered by an auxiliary engine. Upon reaching sufficient height, the three ramjets on the tips of the three wings would power up and rotate the entire wing assembly. It was hoped that, by using cheaper materials and low grade fuel, the Triebflügel could be easily mass-produced.

A model of the Triebflügel. This is how it may have looked if completed. [Wiki]

The Name

Given that these ramjet powered fighter projects were more a private venture than a specially requested military design, they were not given any standard Luftwaffe designation. The Triebflügel Flugzeug name, depending on the sources, can be translated as power-wing, gliding, or even as thrust wing aircraft. This article will refer to it as the Triebflügel for the sake of simplicity. 

Technical Characteristics  

Given that the Triebflügel never left the drawing board, not much is known about its overall characteristics. It was designed as an all-metal, vertical take-off, rotary wing fighter aircraft. In regard to the fuselage, there is little to almost no information about its overall construction. Based on the available drawings of it, it would have been divided into several different sections. The front nose section consisted of the pilot, cockpit, and an armament section for cannons and ammunition, which were placed behind him. Approximately at the centre of the aircraft, a rotary collar was placed around that section of the fuselage. Behind it, the main storage for fuel would be located. And at the end of the fuselage, four tail fins were placed. 

A drawing of the Triebflügel’s interior. [luft46.com]
This aircraft was to have an unusual and radical three wing design. The wings were connected to the fuselage while small ramjets was placed on their tips. Thanks to the rotary collar, the wings were able to rotate a full 360o around the fuselage. Their pitch could be adjusted depending on the flight situation. For additional stability during flight, the tail fins had trailing edges installed. The pilot would control the flying speed of the aircraft by changing the pitch.  Once sufficient speed was achieved (some 240 to 320 km/h (150 to 200 mph)), the three ramjets were to be activated. The total diameter of the rotating wings was 11.5 m (37  ft 8  in) and had an area of 16.5 m² (176.5 ft²). 

This unusual aircraft was to be powered by three ramjets which were able to deliver some 840 kg (1,1850 lb) of thrust each. Thanks to ramjet development achieved by Otto Pabst, these had a diameter of 68 cm (2.7 ft), with a length of less than 30 cm (0.98 ft). The fuel for this aircraft was to be hydrogen gas or some other low grade fuel. The estimated maximum speed that could be achieved with these engines was 1,000 km/h (621 mph). The main disadvantage of the ramjets, however, was that they could not be used during take-off, so an auxiliary engine had to be used instead. While not specifying the precise type, at least three different engines (including jet, rocket, or ordinary piston driven engines) were proposed.

In the fuselage nose, the pilot cockpit was placed. From there the pilot was provided with an overall good view of the surroundings. The main issue with this cockpit design wass the insufficient rear view during vertical landing. 

Close up view of the Triebflügel landing gear assembly. [Secret Jets of the Third Reich]
The landing gear consisted of four smaller and one larger wheels. Smaller wheels were placed on the four fin stabilizers, while the large one was placed in the middle of the rear part of the fuselage. The larger center positioned wheel was meant to hold the whole weight of the aircraft, while the smaller ones were meant to provide additional stability. Each wheel was enclosed in a protective ball shaped cover that would be closed during flight, possibly to provide better aerodynamic properties. It may also have served to protect the wheels from any potential damage, as landing with one of these would have been highly problematic. Interestingly enough, all five landing wheels were retractable, despite their odd positioning.  

The armament would have consisted of two 3 cm (1.18 in) MK 103s with 100 rounds of ammunition and two 2 cm (0.78 in) MG 151s with 250 rounds. The cannons were placed on the side of the aircraft’s nose. The spare ammunition containers were positioned behind the pilot’s seat.

Final Fate

Despite its futuristic appearance and the alleged cheap building materials that would have been used in its construction, no Triebflügel was ever built. A small wooden wind tunnel model was built and tested by the end of the war. During this testing, it was noted that the aircraft could potentially reach speeds up to 0.9 Mach, slightly less than 1,000 km/h. The documents for this aircraft were captured by the Americans at the end of the war. The Americans initially showed interest in the concept and continued experimenting and developing it for sometime after. 

In Modern Culture 

The Triebflügel taking off in the movie. [marvelcinematicuniverse.fandom.com]
Interestingly, the Triebflügel was used as an escape aircraft for the villain Red Skull in the 2011 Captain America: The First Avenger movie.

Conclusion

The Triebflügel’s overall design was unusual to say the least. It was a completely new concept of how to bring an aircraft to the sky. On paper and according to Focke-Wulf’s engineers that were interrogated by Allied Intelligence after the war, the Triebflügel offered a number of advantages over the more orthodox designs. The whole aircraft was to be built using cheap materials, could achieve great speeds, and did not need a large airfield to take-off, etc. In reality, this aircraft would have been simply too complicated to build and use at that time. For example, the pilot could only effectively control the aircraft if the whole rotary wing system worked perfectly. If one (or more) of the ramjets failed to work properly, the pilot would most likely have to bail out, as he would not have had any sort of control over the aircraft. The landing process was also most likely very dangerous for the pilot, especially given the lack of rear view and the uncomfortable and difficult position that the pilot needed to be in order to be able to see the rear part of the aircraft. 

The main question regarding the overall Triebflügel design is if it would have been capable of successfully performing any kind of flight. Especially given its radical, untested and overcomplicated design, this was a big question mark. While there exist some rough estimation of its alleged flight performances, it is also quite dubious if these could be achieved in reality. The whole Triebflügel project never really gained any real interest from the Luftwaffe, and it is highly likely that it was even presented to them. It was, most probably, only a Focke-Wulf private venture.

Triebflügel Estimated  Specifications
Rotating Wing diameter 37  ft 8  in / 11.5 m
Length 30 ft / 9.15 m
Wing Area 176.5 ft² / 16.5 m²
Engine Three Ramjets with 840 kg (1,1850 lb) of thrust each
Empty Weight 7,056  lbs / 3,200 kg
Maximum Takeoff Weight 11,410 lbs / 5,175 kg
Climb Rate to 8 km In 1 minute 8 seconds
Maximum Speed  621 mph / 1,000 km/h
Cruising speed 522 mph  / 840 km/h
Range 1,490  miles / 2,400 km
Maximum Service Ceiling 45,920 ft / 14,000 m
Crew 1 pilot
Armament
  • Two 3 cm MK 103 (1.18 in) and two 2 cm (0.78 in) MG 151 cannons

Gallery

A rendition of how the Triebflugel may have looked had it been built. Illustration by Pavel ‘Carpaticus’ Alexe.

Credits

  • Article by Marko P.
  • Duško N. (2008)  Naoružanje Drugog Svetsko Rata-Nemačka. Beograd.
  • D. Sharp (2015) Luftwaffe Secret Jets of the Third Reich, Dan Savage
  • Jean-Denis G.G. Lepage (2009) Aircraft of the Luftwaffe 1935-1945, McFarland and Company  
  • J.R. Smith and A. L. Kay (1972) German Aircraft of the Second World War, Putham  
  • http://www.luft46.com/fw/fwtrieb.html 

 

Yakovlev Yak-2

Soviet, WW2

USSR flag USSR (1939)
Ground attack bomber – 100 Built

The Yak-2. Source: Y. Gordon, D, Khazanov Soviet Combat Aircraft

During his career, Alexander Sergeyevich Yakovlev designed a number of successful aircraft, his most famous being his single engine fighters. But his first proper military aircraft project, the Yak-2, would be so poorly designed that it was practically useless. Nevertheless, thanks to Yakovlev’s good standing with Stalin, this aircraft would be put into production, albeit in small numbers, and would see limited action during World War Two.

The No-22 and BB-22 projects

While being involved in civil aviation, Yakovlev wished to pursue military contracts., Yakovlev actually wanted to gain a proper military contract. He estimated that the best way to do this was to impress Stalin himself. To do so, he set on designing the fastest plane in the Soviet Union. Having no previous experience in designing military aircraft, this was no easy task. Nevertheless, he soon began working on a two-engined mixed construction aircraft named simply the No.22 (but also known as the Ya-22). When the prototype was complete and flight tested it reached a maximum speed of 567 km/h (352 mph). This design would first be presented to the Soviet Spanish Civil War hero Yakov Smushkeviche, who was also the Chief of the Soviet Air Force. Yakov was highly impressed with this aircraft and informed Stalin about its performance. Stalin agreed and gave a green light for its future development.

In May of 1939, for further testing and evaluation, this prototype would be given to the Nauchno Issledovatelysii Institut (NII VVS). There, the aircraft was evaluated by a commission consisting of Chief engineer Holopov, test pilot Shevarev, and navigator Tretyakov. They managed to reach a maximum speed of 567 km/h (352 mph) without any problems. The commission also suggested that, with an improved cooling system and with new propellers, the maximum speed could be increased up to 600 km/h (372 mph).

When Yakovlev began working on the No.22, he did not seriously consider in which role it should be used. Military officials would decide the aircraft would be used as a light bomber, a use that both Yakovlev and Stalin would agree with. The plane would be renamed BB-22  (Blizhnii Bombardirovshchik, short range bomber) to fit its new role.

 

The BB-22 prototype, Source: Source: Y. Gordon, D, Khazanov Soviet Combat Aircraft

While at first glance the BB-22 showed to be capable of racing at high speeds, its use in military aviation would prove to be highly problematic. The core of this problem lay in the fact that this aircraft was designed with the main purpose of reaching the highest possible speed, with little thought for military adaptation. Very shortly, the BB-22 began showing the first signs of being an inadequate design. While being tested, it was noted that the engine was prone to overheating. During one test flight, the pilot attempted to reach 7,000 m (23,000 ft) which the designers claimed that it could reach in 8 minutes. In reality, the pilot needed more than half an hour due to constant engine overheating problems. Other issues were also noted, like the inadequate fuel system and wheel brakes.

In the meantime, Air Force officials were discussing the BB-22’s performance and if it should have been put into production. Nearly two months earlier, Yakovlev had already made first steps for the BB-22’s production without their knowledge, despite no official order being given. While military officials were still discussing the BB-22, he had already given copies of the design to GAZ’s Plant No.1. In June 1939, the Council of Soviet People’s Commissars officially gave orders to put the BB-22 into production. The first production aircraft was completed by the end of 1939, and thanks to the political machinations of its designer, made its first flight in February 1940. Production of the aircraft was subsequently delayed. By the end of 1939, of the planned 50, only one was built. Despite these problems, the Soviet Defence Committee issued orders for 580 new aircraft to be built.

 

Work on the Yak-2

Despite the best attempts of Soviet Air Force officials to cancel the BB-22 project, they were hindered by two facts. First was the fact that Stalin personally showed significant interest in its development. Secondly, Yakovlev was appointed as the Deputy People’s Commissar for aircraft production. As a result, the aircraft’s production could not be interrupted. In November 1940, the name of the aircraft was changed to Yak-2, as it was common practice in the Soviet Union to name the aircraft after their designers

By March 1940, after numerous tests and attempts to improve this aircraft, it simply proved to be unusable due to many mechanical flaws. These included the engine overheating, poor flight stability, problems with hydraulics, insufficient quality of bolts that held the wings etc. In total, over 180 faults were reported. The situation was so bad that the Directorate of the Soviet Army Land-based Aviation actually demanded the cancellation of any further work on the Yak-2. On the other side, GAZ No.1 plant officials (who were responsible for the production of this aircraft), along with their test pilots who had flown on this plane, urged its production in order to stay in Yakovlev’s graces. There were plans to produce the first series of 21 aircraft that would be ready by May 1940. After numerous complaints about the Yak-2’s performance, Stalin ordered that the whole situation be investigated. To avoid any kind of guilt, Yakovlev simply blamed the GAZ No.1 production plant for the Yak-2’s poor quality. Ultimately, only 100 Yak-2s would be built and given to the Air Force for operational use.

 

Yak-2 side view. Source: Pinterest

Technical characteristics

The Yak-2 was designed as a twin-engined, mixed-construction low-wing light bomber. The frontal part of the fuselage was made of duralumin. The central part of the fuselage, which was integrated into the wings, was made of wood. The rear part of the fuselage consisted of a welded steel tube frame that was covered with fabric. This rear part could be, if needed (for repairs for example), be separated from the remainder of the aircraft.

The Yak-2 was powered by two Klimov M-103 960 hp liquid cooled engines. The two engines were placed in wing nacelles, on each side of the central fuselage.

op view of the Yak-2. The two engines could be clearly seen. Source: Wiki

The Yak-2 had standard retractable landing gear units, which consisted of two larger frontal wheels and one smaller to the rear. All three retracted to the rear, with the frontal two retracting into the engine nacelles. While, initially, the aircraft had only one large frontal landing wheel on each side, the majority would be built with twin-wheels on each side.

Unusually, the wings were built using only a single large piece. This greatly limited the possibility of transporting this plane by rail. The wings were built using two metal spar structures which were covered with plywood skin. At the rear of the fuselage, the twin-finned tail was positioned.

While it was based on the BB-22, unlike it, the Yak-2 received a modified canopy with both crew members being placed in it. The pilot was placed in front, while the navigator/rear gunner was placed behind him. This arrangement provided easier crew communication.

The Yak-2 had a crew of two, with the pilot placed to the front and the navigator/machine gunner to the rear. Source: Pinterest

The armament of this aircraft consisted of two rear positioned 7.62 mm (0.3 in) machine guns. These were placed in a small cupola that could be raised higher up to provide better covering fire. There was a provision for an internal bombing bay that could hold 400 kg (880 lbs) of bombs. In addition, the aircraft could carry up to 100 kg (210 lbs) bombs in external bomb racks

In combat

Despite its obvious mechanical unreliability, the Yak-2 would be allocated for operational service. The first group of 25 aircraft were initially allocated to the Kharkov Military District. Due to many mechanical problems, they could not be used for flying. Even at this time, there were still attempts to somehow improve the Yak-2’s overall performance, with minimal results. When the aircraft was fully equipped with military equipment, such as radio, weapons, and full fuel load, the flight performance dropped dramatically. For example, the maximum speed was reduced to 399 km/h (247 mph). In addition, the Yak-2 struggled to reach heights of 8,100 m (26,500 ft), which were some 2,800 m (8.800 ft) lower than those reached during prototype testing.

When the war with the Germans broke out, some 75 Yak-2s were allocated to the 136th Bomber Regiment located in Kiev and the 316th Reconnaissance Regiment in the western district. Their use was quite limited, as most were destroyed on the ground by the German Air Force. At least one was shot down by friendly aircraft fighters.

 

The majority of Yak-2s were destroyed on the ground by the German Air bomb raids. Source Y. Gordon, D, Khazanov and S. Komissarov OKB Yakovlev, Midland
Some did survive the initial German Air raids but would be lost in the following weeks. Here, a group of three Yak-2s on their way to bomb German positions can be seen. Source: Y. Gordon, D, Khazanov and S. Komissarov OKB Yakovlev, Midland

Proposed versions

Despite its generally poor performance of the Yak-2, there were some attempts to reuse this aircraft for other purposes. These included the BPB-22 short-range bomber, R-12 reconnaissance, I-29 escort fighter, Yak-2KABB ground attack aircraft, and a trainer version.

The BPB-22

The GAZ. No.81 production plant, on its own initiative, tried to develop a short-range dive bomber based on the BB-22. For this proposal, they equipped one aircraft with the newly developed M-105 engines and added dive brakes. The first flight test made in October 1940 was disappointing and the project was canceled.

R-12 reconnaissance

Based on elements from No-22 and the Yak-2, a reconnaissance aircraft named R-12 was to be developed. This aircraft was to be powered by 960 hp M-103 engines. In the end, nothing came of this project.

Yak-2KABB

This was a ground attack prototype equipped with bombs, two 20 mm (0.78 in) cannons, and two machine guns placed under the fuselage. It also received a new modified cockpit design. The aircraft was tested in a series of evaluation flights and was generally considered to be a good design. The outbreak of the war stopped any further work on this aircraft.

The experimental Yak-2KABB. Source: Y. Gordon, D, Khazanov and S. Komissarov OKB Yakovlev, Midland

I-29

The I-29 was a heavy escort fighter that was to be armed with two 20 mm (0.78 in) cannons. While work on this aircraft continued up to 1942, it would ultimately be canceled.

A trainer version

One Yak-2 was built as a dual-control trainer aircraft. While it was tested in March 1941, nothing came from this project. It is not known if this version ever received any official designation.

Production

Being an unsuccessful design, the actual production run was limited. The Yak-2 was produced by the GAZ No.1 production plant, which built around 25 aircraft. The Moscow Aircraft factory No.81 produced some 75 Yak-2s which were slightly improved in quality but, otherwise, were the same. By the time production ended, only around 100 aircraft were built.

  • No-22/BB-22 Prototype – The first prototype built during the summer of 1939, which served as a base for the Yak-2
  • Yak-2 – Main production version
  • Yak-2KABB – A ground attack prototype
  • BPB-22 – Short-range bomber, one prototype built
  • R-12 – Reconnaissance version proposal
  • I-12 – Escort fighter proposal
  • Trainer Aircraft – One prototype of a dual-control trainer version was built but was not accepted for service

Conclusion

While it managed to achieve extraordinary speed during the prototype phase, in the military role, the Yak-2 proved to be a disappointing design. Once it was fitted with armament and other equipment, its performance dropped dramatically. This, together with other design problems, ultimately led to the cancelation of this project after only 100 built aircraft.

Specifications –  Yak-2 Specifications
Wingspan 45 ft 11 in / 14 m
Length 30 ft 7 in / 14 m
Wing Area 316.4 ft² / 29.4 m²
Engine Two M-103 960 hp engines
Empty Weight 9,390 lb / 4,260 kg
Maximum Takeoff Weight 12,410 lb / 5,630 kg
Fuel Capacity 600 liters
Maximum Speed 310 mph / 500 km/h
Cruising Speed 255 mph / 410 km/h
Range 560 mi / 900 km
Maximum Service Ceiling 28,545 ft / 8,700 m
Crew One pilot and one navigator/gunner
Armament
  • Two 7.92 mm (0.3 in) machine guns
  • 400 to 500 kg (880 to 1100 lbs) bombs

Gallery

Yak-2 (BB-22) – 316th RAP Lt.I.M.Agarkov. South-West Front – July-August 1941
Illustration by Ed Jackson

 

  • D. Nešić (2008), Naoružanje Drugog Svetskog Rata SSSR, Beograd.
  • B. Gunston and Y. Gordon (1977)Yakovlev Aircraft Since 1924, Putnam Aeronautical Books.
  • Y. Gordon, D, Khazanov (1999) Soviet Combat Aircraft, Midland Publishing.
  • Y. Gordon, D, Khazanov, and S. Komissarov (2005) OKB Yakovlev, Midland.