Empire of Japan (1945) Kamikaze Aircraft – 105 Built
The Ki-115 suicide aircraft [Combat Workshop via Pinterest]
Throughout 1945, it was becoming clear to Japanese Army Officials that an Allied invasion of the Japanese mainland was growing ever more likely. Seeing as their navy and airforce had been mostly destroyed, they needed new weapons to fight off a probable Allied attack on Japan. Among these new weapons were Kamikaze aircraft, with many older designs having already been used in this role. However, some Kamikaze aircraft were to be specially designed for such a role, being cheap and able to be built quickly and in great numbers. One such aircraft was the Ki-115 Tsurugi (Sabre) which was built in small numbers, and never used operationally.
History
Rear view of Ki-115 suicide aircraft [ijaafphotos.com]Following the extensive loss of men, materiel, and territory during the fighting in the Pacific, the Japanese Army and Navy were in a precarious situation, especially as there was a great possibility of an Allied invasion of their homeland. Unfortunately for them, the Japanese fighting forces on the ground, in the air, and on the sea were mostly mere shadows of their former selves, unable to prevent the rapid Allied advance across the Pacific. This was especially noticeable after the costly Japanese naval defeat during the Battle of Leyte Gulf in October 1944 and later Battle of Okinawa which ended in July 1945.. The desperation, or better said fanatical refusal to accept that the war was lost, led to the development and use of Kamikaze (divine wind) tactics. This name was taken from Japanese history, the term arose from the two typhoons that completely destroyed the Mongol invasion fleets.
Essentially, the Kamikaze were Japanese pilots that used their own explosive-laden aircraft as weapons, and sought to crash into important targets, such as Allied warships. This term also entered widespread use to designate all Japanese suicide craft used in this way. During the war, these tactics managed to sink over 30 Allied ships and damage many more.
Allied anti-aircraft fire was often concentrated in order to prevent Kamikaze attacks. But, despite this, Japanese aircraft would often get through. [Wiki]The suicide attacks were mostly carried out using any existing aircraft that was operational, including older trainers and obsolete aircraft. Kamikaze are a subject with a great deal of nuance and can be difficult to understand through a conventional lens. However, supplies of these aircraft would inevitably become limited and their previous usage meant fewer would be serviceable compared to newer, more expensive models. Thus, the Japanese Army wanted a specially designed Kamikaze aircraft that could be produced in great numbers. These aircraft needed to have a simple construction and use as little of dwindling material stockpiles as possible.
On 20th January 1945, the Japanese Army contacted the Nakajima aircraft manufacturer with instructions to design and build such an aircraft. The basic requirements included a bomb load up to 800 kg (1,760 lbs). It had to be able to be powered by any available radial engine in the range of 800 hp to 1,300 hp. The maximum speed desired was 515 km/h (320 mph). Construction and design had to be as simple as possible. They also wished to speed up the whole development and production process and also to reduce the need for skilled labor. It was especially emphasized that the undercarriage had to be jettisonable, not retractable. It was not expected for the aircraft to fly back, so a retractable landing gear was not needed and this would make the production and design process somewhat quicker.
First Prototype
The job of designing this aircraft was given to Engineer Aori Kunihiro. He was supported by engineers from Ota Manufacturing and the Mitaka Research Institute. While Nakajima received the contract in January 1945, it only took two months to complete the first prototype. In March 1945, this prototype was presented to the Japanese Army and then put through a series of tests. Almost immediately, a series of faults with the design were noted. This was not surprising given that the whole design process lasted only two months. During running on the ground, the fixed and crude undercarriage was difficult to control. The pilot’s poor frontal visibility further complicated matters. This was unacceptable even for skilled pilots, while less experienced pilots would have had great difficulty in successfully operating it on the ground. The Army rejected the prototype and requested a number of modifications to be done.
The Ki-115 first prototype. [ijaafphotos.com]The Ki-115 cockpit was positioned in the middle of the fuselage and offered the pilot limited forward vision when on the ground. [Wiki]
Technical Specifications
The Ki-115 was designed as a low-wing mixed construction suicide attack aicraft. The front fuselage, containing the engine compartment, and the central part were built using steel panels. The engine compartment was held in place by four bolts and was specially designed to house several different potential engines. Eventually, the Japanese chose the 1,130 hp Nakijama Ha-35 14 cylinder radial piston engine. It had a fixed-pitch three blade propeller. In order to help reach its target quicker, two small auxiliary rocket engines were placed under each wing.
The wings were built using all-metal construction with stressed skin. The rear tail unit was built using wood and was covered by fabric. The cockpit was placed in the upper centre of the fuselage. It was semi-open, with a front windshield.
As requested, the Ki-115 prototype had a fixed and jettisonable undercarriage. It had a very simple design, using simple metal tubes with no shock absorbers. While two wheels were used in the front, a tailskid was used at the rear. The fixed undercarriage tested on the prototype proved to be highly ineffective. All later produced aircraft were instead equipped with a simple and easy to build shock absorber.
Ki-115 side view [ijaafphotos.com]The armament consisted of a bomb load of up to 800 kg (1,760 lbs). This included using either a single 250 kg (550 lb), 500 kg (1.100 lb) or 800 kg (1.760) bomb. The bomb was not to be dropped on the enemy, but instead be detonated once the aircraft hit its target. Beside the bomb, no other armament was to be provided on the Ki-115.
The Ki-115 was initially meant to be supplied with a fixed undercarriage, which proved to be problematic. Production aircraft were instead provided with simple shock absorbers. [ijaafphotos.com]
The Fate of the Project
Once the prototype was back in Mitaka Kenkyujo (where the prototype was built), the engineers began working on improving its performance. The redesigned undercarriage, which incorporated a simple shock absorber, was completed by June 1945, by which time a series of test flights were done. By August 1945, some 104 Ki-115 aircraft were ready. Two Ki-115s were given to Hikoki K.K., where the Japanese Navy Air Force was developing its own suicide attack aircraft. By the war’s end, none of the Ki-115s built would be used in combat.
Surviving Aircraft
The Ki-115 planes were later captured by the Allies, and nearly all were scrapped. Surprisingly, two Ki-115s have survived to this day. One can be seen at the Pima Air & Space Museum. This aircraft is actually on loan from the National Air and Space Museum. The second aircraft is currently located in Japan. Not wanting to potentially damaged tis aircrafts on the side of caution no restoration attempts are planned for the near future.
The surviving Ki-115 at the Pima Air & Space Museum. [Wiki]A picture of the second surviving aircraft taken during the 1980’s in Japan. [hikokikumo.net]
The Ki-115b Proposal
In order to further improve the aircraft’s performance and reduce cost, the Ki-115b version was proposed. This included replacing the all-metal wings with ones built of wood. These new wings were larger and had to be equipped with flaps. To provide the pilot with a better view, his cockpit was moved to the front. Due to the end of the war, nothing came from this proposal.
Production and Modifications
The Ki-125 was built in small numbers only, with some 104 production planes plus the prototype. These were built by the two Nakajima production centres at Iwate (22 aircraft) and Ota (82 aircrafts). The production lasted from March to August 1945.
Ki-115 prototype – Tested during early 1945.
Ki-115 – In total, 104 aircraft were built, but none were used operationally.
Ki-115b – Proposed version with larger wooden wings, none built.
Only 105 Ki-115 aircraft, including the prototype, were ever built. [ijaafphotos.com]
Conclusion
Luckily for the Japanese pilots, the Ki-115 was never used operationally. It was a simple and crude design which was born out of desperation. If the Ki-115 was ever used in combat, it would have likely presented an easy target for enemy fighters and suffered from poor reliability due to its cheap construction.
Ki-115 Specifications
Wingspan
28 ft 2 in / 8.6 m
Length
28 ft 1 in / 8.5 m
Height
10 ft 10 in / 3.3 m
Wing Area
133.5 ft² / 12.4 m²
Engine
One 1,130 hp Nakijama Ha-35 14 cylinder radial piston engine
Another Ki-115 Tsurugi in Natural Metal with 500kg Type 92 BombKi-115 Tsurugi in Green with 500kg Type 92 BombKi-115 Tsurugi in Natural Metal with 500kg Type 92 Bomb
Credits
Written by: Marko P.
Edited by: Stan L. & Henry H.
Illustrations by Ed Jackson
Sources
R. J. Francillon (1970) Japanese aircraft of the Pacific war, Putham and Company
D. Nešić (2007) Naoružanje Drugog Svetskog Rata Japan, Tampoprint
D.Mondey (2006) Guide To Axis Aircraft Of World War II, Aerospace Publishing
Nazi Germany (1940)
Jet Powered Bomber & Reconnaissance Aircraft – 8 Prototypes Built
The Ar 234 A V6 (GK+IW) prototype. [Warbirdphotographs]
Following a request from the German Ministry of Aviation (Reichsluftfahrtministerium – RLM), in 1940, German aircraft manufacturer Arado began working on a new multi-purpose jet powered plane. Arado’s work would lead to the development of the advanced and sophisticated Ar 234 aircraft. During 1943, a small series of eight prototypes would be built and used mainly for testing, but some saw operational service.
History
During the spring of 1940, Arado was contacted by RLM officials with a request to design a completely new multi-purpose jet aircraft to be used for bombers and for reconnaissance duties. This aircraft was to be powered by new jet engines which were under development by Junkers and BMW. Interestingly, besides the request that it should be able to reach the British naval base at Scapa Flow in Northern Scotland, no other performance requirements were specified. The sources do not specify the precise base of operation for these reconnaissance missions. Geographically, the closest territories under German control were south Norway and Denmark, although it is possible that these aircraft would have had to operate from air bases in the occupied territories in Western Europe, either from France, the Netherlands or Belgium. This would require an estimated range of over 900 km. In essence, the RLM gave Arado free reign in terms of the overall design and its performance. If the prototypes built were satisfactory, an initial order for 50 aircraft was to be given.
Work on this new design was given to engineer Rüdiger Kosin, as Arado’s Technical Director, Walter Blume, was uninterested in this project. When work started, it received the Arado Erprobungs (experimental) 370 designation. During the initial phases, there were several different proposals about the number of crewmen, wing size, weapon configuration and the number of engines. After nearly a year, in October 1941, the first proper project, designated the E 370/IVa, was completed. This proposal was mainly intended to be used as a reconnaissance aircraft and was to be equipped with camera equipment. It was to be powered by two BMW P 3302 turbo jet engines. The armament was quite modest and consisted of only one 13 mm MG 131 machine gun. As this aircraft was to operate from short-length airfields, the designers came up with the idea to use a wooden retractable skid for landing, which was to be mounted beneath the fuselage.
E 370/IVa drawings. [Smith & Creek, Arado 234 A]
The project was presented to RLM officials in late October of 1941. They were satisfied and gave permission for the production of 50 aircraft. During the evaluation, it received the 8-234 designation. Unfortunately for Arado, the head of the RLM Technical Department, Ernst Udet, committed suicide just a few weeks later. He was replaced by Erhard Milch, who was more interested in aircraft that were already being produced rather than the proposed Arado project. This without a doubt affected the earlier mentioned initial production order, as the initial order for 50 seems to disappear from record. Despite this setback, work on the E 370 continued. During early 1942, some modifications to the fuselage were made with the aim of increasing its size and strength. The unusual skid undercarriage was replaced by a retractable wheeled bogie system.
In February 1942, Erhard Milch visited the Arado company. He was presented with the drawings and calculations for the improved E 370 model. He was generally impressed with what he saw, and gave his permission for the construction of a wooden mockup. The order would be increased to six prototypes in the following month. The aircraft was to take off using a small three wheel dolly. After the aircraft was in the sky, the dolly was jettisoned and landed with the help of a parachute, meaning it could be used again. In addition, the idea of using a retractable skid undercarriage was reintroduced. If needed, jettisonable Walter HWK auxiliary rocket take-off engines could be attached under the wings. Throughout 1942, many additional modifications and changes were made to the design. Great attention was given to the testing of different engine types and configurations.
By the end of 1942, the number of prototypes to be built was once again increased to 20. The first seven aircraft were to be powered by Jumo 004 engines, with prototype V8 powered by four BMW 003 engines, and V9 through V14 with two BMW 003 engines. The remaining aircraft were to be powered by four BMW 003 engines. The first prototype was meant to be built by November 1943, with the last in October 1944. Surprisingly, these 1942 plans actually started to be completed early, with the first 3 prototypes ready by August 1943. Thanks to this, it was possible to run the first test trials even earlier than anticipated.
Work on the First Prototypes
Work on the construction of the first prototype began in late 1942. During this time, the name was changed to Ar 234. Progress was slow due to problems with the delivery of the Jumo 004 engines, which only arrived in February 1943. These engines were tested and immediately proved to be problematic, as they failed to achieve the promised 850 kg (1879 lbs) thrust. Once fitted with these engines, the first prototype, Ar 234 V1, was used for static ground testing and taxiing trials. No flight was initially accepted due to the short runway at Brandenburg, where the prototype was built. For this reason, the prototype was moved to a Luftwaffe airfield at Munster. During July 1943, this aircraft was mainly used for ground tests. In late July, there was an accident when one of the Jumo engines caught fire. The damage was minor and was quickly repaired. On 30th July, Ar 234 V1 made its first test flight piloted by Horst Selle. The flight was successful, with no problems with the aircraft. The dolly, on the other hand, was lost when the parachute failed to properly open. In early August, there were again problems with the same engine. To avoid any potential threat to the aircraft, it was simply replaced by an engine taken from Ar 234 V3, which was under construction. On 9th August, another test flight was undertaken. During this flight, Selle reached a speed of 650 km/h (400 mph) without any problems. The dolly was once again lost, similarly to the first one. Additional changes were made to the position of the parachute on the dolly, which proved to be the solution to this problem. The V1 prototype would be lost in an accident where the pilot overshot the landing field and crash landed on 29th August. While the aircraft was not repaired, parts of it were reused for testing other equipment.
The Arado 234 V1 first prototype. This particular aircraft would be lost in an accident where the pilot overshot the landing field and crash landed on 29th August 1943. [Warbirdphotographs] V1 during the third test flight, during which the dolly parachute release system was successfully tested. [Luftwaffephotos]
The V2 prototype was completed in late August 1943. There were some issues with the engine, which had to be replaced. The aircraft was otherwise trouble-free. It was moved to Alt Lonnewitz, where it was mainly used for engine testing. In late September 1943, V3 made its first flight. While, initially, it was to be equipped with a pressurized cabin and an ejector seat, this was never implemented.
In early October 1943, the V2 prototype, with its pilot, Selle, were lost in a fire. This accident prompted the Germans to introduce automatic fire extinguishing systems on all of the Ar 234 prototypes, including later ones. Another change was introducing ejection seats to avoid any further pilot casualties. Due to this accident, there were some delays in the Ar 234 project. Testing continued in November, when V3 was piloted by Walter Kroger. On the 21st of November, the V3 aircraft was transferred to Insterburg to be presented to Adolf Hitler, together with other experimental jet aircraft, like the Me 262 and Me 163. Hitler was highly impressed and even gave orders that some 200 aircraft be built during 1944. During this time, V4 was also flight tested. Both V3 and V4 were used until June 1944 for various roles, including crew training, after which they were removed and replaced with later Ar 234 B versions. By the end of 1943, V5, fitted with Jumo 004 B-0 engines. was introduced.
During early 1944, two Arado 234 aircraft would be tested with a four engine configuration. The idea was that the use of four smaller engines would provide similar performance to the larger ones. V8 was powered by two pairs of BMW P.3302 engines. V6 (which was built later than V8) was tested with four BMW 003 engines placed in four separate wing-mounted nacelles. During a routine flight of V6 at the start of June 1944, all four engines stopped working only 17 minutes after take-off. The pilot was forced to conduct an emergency landing of the plane, after which it caught fire and was heavily damaged, rendering it a complete loss. After this accident, and due to many other engine problems with both versions, all further work on the multi-engined Ar 234 A was discontinued. These would later serve as the basis for the Ar 234 C version instead.
V6 powered by four BMW 003 engines placed in four separated wing cowlings. [Luftwaffephotos] V6 after a forced landing in June 1944, shortly before the engines began to burn. This accident and problems with the engines put an end to the development of the multi-engined Ar 234 A version. [Warbirdphotographs] V8 was powered by four BMW P.3302 engines placed in pairs. [Warbirdphotographs]
Technical Characteristics
The Arado Ar 234A (as they were designated later on) prototypes were designed as all metal, high-wing turbojet-powered experimental reconnaissance planes. Their fuselages had a semi-monocoque design with a flat top. The wings consisted of two main spars, each with 29 ribs. They were covered with metal stressed skin. Each wing was connected to the fuselage by four bolts. If needed, these could easily be taken off and removed. At the rear, there was a more or less conventional tail unit.
The Ar 234 was used to test a number of different engines. The first 4 prototypes were powered by two Jumo 004 A-0 engines, which had 840 kg (1,850 lbs) of thrust. V5 and V7 used Jumo 004 B-0 engines which provided 900 kg (1,980 lbs) of thrust. The 3.8 m (12 ft) long engines (both types had the same size) were attached to the wings using three bolts. V6 and V8 were powered by four engines which were able to achieve 800 kg (1,760 lbs) of thrust. As the Ar 234 was intended to be used for reconnaissance operations, a large fuel capacity was important. One 1,800 liter fuel tank was placed behind the cockpit, with a second 2,000 liter tank in the rear of the fuselage. With this fuel load the Ar 234 had an operational range of 1,500 km (930 miles). To assist with take-off, the Ar 234 could be equipped with small Walter 109-500 type rocket engines. These had a run time of 30 seconds and could generate 500 kg (1,100 lbs) of thrust. After the Ar 234 was in the air, the rocket motors would be jettisoned and would land on the ground using small parachutes.
The Ar 234 did not have conventional landing gear, but instead used a three wheel 640 kg (1,410 lbs) jettisonable take-off assist dolly. The Ar 234 pilot could control this dolly by using the rudder, which was connected to hydraulic brakes on the dolly. Once in flight, the dolly would detach and then fall back to Earth using a parachute, and could thereafter be reused. Initially, it was discarded during flight, but this proved to be problematic. After some redesign work, the moment of release was changed to just after take-off. There was no risk of the dolly impacting the fuselage in midair, as the parachute pulled it away from the aircraft. When the Ar 234 had to land, it would use the retractable hydraulically operated skid under the fuselage. The engine nacelles were also provided with smaller skids to avoid any damage to them and to provide better stability during landing. The V3 prototype tested in early 1944 used a drag parachute during landing. This proved to be successful and was later implemented as standard from the B series on.
The smaller front wheel on the jettisonable dolly was fully steerable to help during airfield taxiing and take-offs [Warbirdphotographs] Close up view of the large sliding skid. [worldwarphotos.info] Ar 234 during landing. A fuselage skid along with smaller skids placed under the engine nacelles were used instead of wheels. Later versions of the Ar 234 incorporated a conventional wheeled landing gear. [Warbirdphotographs]
The pilot’s cockpit was fully glazed, which provided excellent all around visibility. To enter the cockpit, the pilot used a small hatch placed atop the cockpit. This was not a great design feature as, in an emergency, the pilot could not easily escape the plane. In order to protect the pilot from enemy fire from the rear, a 15 mm thick armor plate was installed behind his seat. Behind this protective armor plate, three oxygen tanks were placed. The instruments were placed on two smaller panels to the left and right of the pilot.
A few Ar 234s were equipped with two Rb 50/30 cameras. These were placed behind the rear fuel tank. These could cover a wide area of 10 km (6 mile) at an altitude of 10 km (33,000 ft).
There were initial plans to arm the Ar 234 with a 13 mm machine gun for self defence. Due to the experimental nature of the Ar 234 A version, no actual armament would actually be installed.
Operational Service
In May 1944, Conny Noell of the Luftwaffe experimental Versuchsverband unit requested that at least two Ar 234 airframes be used for experimental reconnaissance operations after examining the prototypes. The request was accepted and the V5 and V7 aircraft were allocated for this task. Besides the camera equipment, virtually nothing else was changed on these two aircraft.
For the testing of these aircraft, two pilots were chosen, Horst Götz and Erich Sommer. At the start of June 1944, the V5 prototype was tested by Götz during a short 30 minute long flight. He later wrote, after the war “The take-off procedure was not very complicated. First, I engaged the starter, then fed petrol into the combustion chamber until, at approximately 6,000 rpm, I made the gradual change to J2 kerosene. The engines were then reved up to their maximum 9,000 revolutions. After take-off, I throttled the engine back to cruising speed. It was a completely new flying experience. Only a slight whistling noise in the cockpit could be heard. The take-off dolly had functioned quite normally. It was really wonderful”.
Four days later, Sommer also tested this aircraft and gave a similar positive assessment of its overall performance. More flights were undertaken in the following days without major problems. While piloting the V5 prototype during a routine take-off, Götz’ wheeled takeoff dolly release mechanism failed, with the assembly remaining stuck to the aircraft’s landing skids. He immediately tried to land back at the airfield. Despite the dangerous maneuver, he managed to land in a nearby potato field, with minimal damage to the plane.
Around this time, the two test pilots were informed that no prolonged or high-altitude flights had ever been attempted by the Ar 234 prototypes, mostly due to a lack of pressurized cockpit. For this reason, Sommer decided to personally test the Ar 234’s performance at altitude. In late June 1944, he made the first high altitude flight, which lasted over an hour and fifteen minutes at an altitude of 11 kilometers (36,000 ft). During a dive, he managed to reach a speed of 590 km/h (367 mph). A few days later, he made another similar flight that lasted over two hours, during which he managed to cover a distance of 1,435 km (890 miles). When the test flights were completed, both pilots gave positive feedback and evaluations about the performance of the planes and recommended their immediate production.
Following the Allied invasion of German occupied France in 1944, the experimental unit was ordered to move its two aircraft and equipment by train to Juvincourt, in France, by the end of July. Due to delays with the delivery of necessary parts, mostly due to Allied air raids, V7 was finally ready to take to the sky on the 2nd of August. V7’s first operational mission was to take photographs of the Allied landing beaches and the 10 km (6 mile) wide inland strip . The flight was a success, without any problems. The Ar 234’s cameras managed to take nearly 400 photographs of the Allied invasion force, which provided the Germans with vital information about the strength and numbers of the enemy. With this single flight, Sommer managed to achieve what the remaining Luftwaffe reconnaissance units failed to do in two months. During August, some 7 reconnaissance flights were undertaken by the two Ar 234 aircraft. Following the rapid Allied advance, they had to be relocated to Belgium. While V7, piloted by Sommer, arrived without any problems, Götz was less fortunate. During the flight, he was hit by friendly anti-aircraft fire. While damaged, Götz managed to fly up to Oranienburg. But his bad luck for that day was not yet over. His landed Ar 234 aircraft was struck from behind in a ground collision by a Focke Wulf Fw 190 which was attempting a take-off, completely destroying V5. Ironically, the first German operational jet powered aircraft, and the first in the world, was shot down by the Germans and then destroyed by a German fighter plane!
Sommer was stationed with his aircraft at Volkel in Holland until the 5th of September, when it was relocated to Rheine base. On the 10th, Sommer performed a reconnaissance flight over the Thames Estuary but, without direct orders, continued up to London. The next morning, he was informed that, due to this action, he was to be arrested and court martialed. Sommer immediately contacted Götz and explained the situation to him. Götz immediately took action and, after persuasions and threats, managed to get the charges against Sommer dropped. After the war, they both found out who demanded Sommer’s arrest. It was the chief of the V-2 program, Hans Kammler, who had feared that the pictures of London would prove the failure of his rocket program.
Part of the damage suffered by V5 during the forced landing and after being hit by ground anti-aircraft fire, shortly before being hit by an Fw 190 taking off. [Smith & Creek, Arado 234 A]
Sommer made at least four more reconnaissance flights with Ar 234 V7 before it was finally replaced with a B version, which was essentially just a copy of the previous version but with a wider fuselage and a more conventional completely retractable wheeled landing gear. After this, V7 was mainly used for crew training before being damaged during a take-off accident on 19th October 1944. After it was repaired, Götz made a flight to Oranienburg, where the plane was removed from service.
Production
Of the Arado 234 A series, only 8 aircraft were ever produced, as they were used for experimentation of various equipment and engine units.
V1 (TG+KB) – Badly damaged during a harsh landing.
V2 (DP+AW) – Was lost in a flight accident.
V3 (DP+AX) – Was presented to Hitler, who authorized the Ar 234 production. Used for various testing until July 1944.
V4 (DP+AY) – Similar to the V3 prototype, used up to June 1944 mainly for crew training, when it was removed from service.
V5 (GK+IV) – The first aircraft to be used operationally, but was lost when damaged by friendly ground-based anti-aircraft fire.
V6 (GK+IW) – Heavily damaged during a landing accident and caught fire soon after.
V7 (GK+IX/ T9+MH) – Used operationally until October 1944, when it was damaged in a take-off accident. Written off as a complete loss.
V8 (GK+IY) – Tested with a four engine configuration, but proved to be highly problematic.
Conclusion
While only a small number of Ar 234A planes were built, they proved to be successful designs. During the initial development phase and in their experimental use in service, no major issues were noted. The major drawback was the insufficient quality of the engines and the use of a jettisonable takeoff dolly. Following the success of the Ar 234 A, the development and production of the B and C versions was approved.
V1, the first prototype, made its first test flight piloted by Horst Selle at the end of July 1943. It would eventually be lost in an accident when the pilot overshot the landing field and crash landed on 29th August 1943. Ar 234 V5 was the first aircraft of the small production series to be used operationally during the Allied Liberation of France in 1944. It would be lost after a series of unfortunate circumstances culminated with a ground collision with a Focke Wulf 190 which was attempting a take-off. Ironically, the first German operational jet powered aircraft, and the first in the world, was shot down by the Germans and then destroyed by a German fighter plane! V5 was fitted with Jumo 004 B-0 engines. V6 was tested with four BMW 003 engines placed in four separate wing-mounted nacelles. During a routine flight at the start of June 1944, all four engines stopped working, forcing the pilot to conduct an emergency landing of the plane. After this, the plane caught fire and was heavily damaged, rendering it a complete loss.
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 PrototypeInitial 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
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 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 CroatiaModli 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,
United States of America (1945)
Observation Scout Floatplane – 10 Built
XOSE-1 taking off. Notice it is painted in the wartime colors. [axis-and-allies-paintworks.com]The XOSE-1 was an observation float plane built by the Edo float company during World War II and was intended to be a possible replacement for the OS2U Kingfisher. Before being built, the type seemed promising and ten prototypes were ordered. Although development was slow, the aircraft would finally fly after the war had ended. Testing showed the design was riddled with flaws and, with the end of the war making the observation floatplane obsolete and unnecessary, the XOSE-1 program was cancelled.
History
Photo of the mockup XOSE-1.
Before America had entered the Second World War, it was realized that many assets in the United States arsenal were outdated to some degree. Many aircraft were unable to compete with their contemporaries around the world. One such piece of equipment would be the ship launched floatplane. A concept that originated in the 1920s and 1930s, it involved the use of small floatplanes that were carried aboard large warships and could be deployed via catapults for a number of tasks to assist their mothership. These missions included long range scouting, spotting for the warships’ main guns and also providing anti-submarine protection using depth charges or torpedoes. Most of America’s larger warships were equipped with catapults at the time for this purpose. The dedicated ship-based floatplanes the United States Navy (USN) operated at their entrance to the war was the aging Curtiss SOC biplane and the Vought OS2U Kingfisher. The latter would soon replace the former and would enter widespread service after the Attack on Pearl Harbor. Although the Kingfisher was just entering service, the search for a modern seaplane that would eventually replace the aircraft began. The new type was expected to carry out the same duties as its predecessor but also be able to effectively protect itself if needed. The OS2U only had one .50 caliber machine gun for offense, which wasn’t very helpful when against newer fighters. The first and most prominent aircraft that would rise to meet this role would be the Curtiss SC Seahawk, but it would not be the only type that would be built. In fact, a competitor would come from a little known company called Edo.
The Edo Aircraft Company is not a company often mentioned in history regarding the Second World War. The company was founded in 1925 by Earl Dodge Osborne, with the name being an acronym of his own name. Despite being rarely discussed among historians, Edo was immensely crucial to the war effort for the USN. Edo was a primary producer for aluminum floats before the war and would be the main producer for the floats on Navy floatplanes, like the OS2U. It was estimated that up to 95% of floats used on USN aircraft were built by Edo. Not only was Edo responsible for the production of the floats, they were also known for adapting said floats for use on the aircraft that would use them. Edo had become known for their work on floats, but they worked on a handful of their own floatplane designs in the years before WWII had started. However, this was around the time the company was created in 1925, and aircraft design had changed drastically since then. Given their background and knowledge with designing and fitting floats, the USN requested that the Edo company should attempt to design their own modern floatplane for the ship-based observation role. Eager to attempt building a modern aircraft, Edo eagerly accepted the request. On January 11th, 1944, they would begin work on their floatplane, which would be called the XS2E-1.
Frontal view of an XOSE-2 or XTE-1. The two were visually identical from the outside. [axis-and-allies-paintworks.com]The preliminary design of the XS2E-1 was deemed acceptable by the Navy and an order for ten prototypes was made. The XS2E-1 would be a two seat design with a Ranger V-770-8 engine. The engine mount and cowling would also both be designed by Ranger (this company would become Fairchild after the war.) Additionally, a Westinghouse 19 turbojet was to be installed in the rear of the aircraft to offer increased thrust for evasion or to give chase to an enemy aircraft. This would make the aircraft a mixed powerplant type. Another order for eight more units was made some time after the first order, but an exact date is unknown. On March 16th, 1944, the USN opted to change the floatplane’s design. The Westinghouse 19 turbojet that was planned for the project was experiencing its own difficulties in development.
When the XS2E-1 was drafted, the turbojet, due to its development, had become much heavier than what Edo was expecting. Due to this weight increase and a high demand for the jet engine on other aircraft projects, it was removed from the XS2E-1. This caused a weight problem in the aircraft’s design, as it no longer had the additional thrust needed to operate with its then-current weight. Edo changed the aircraft’s design drastically to make the XS2E-1 lighter. A significant revision done was the removal of the second seat, making the aircraft a smaller, single-seater aircraft. This, however, meant all the work the 2nd crewmen was intended to do was now transferred to the pilot, which would include operating the radar system in addition to flying and observing.
A frontal shot of an XOSE-1 demonstrating its folding wings. [axis-and-allies-paintworks.com]After the loss of the turbojet and the switch to a single seater design, it was decided to change the aircraft’s role to an Observation Scout floatplane. Another reason for the change was that, developing parallel to the XS2E-1, was the Curtiss SC-1 Seahawk mentioned earlier, an aircraft that was meant to fill the Scout role for the USN. Finding that developing two aircraft with the same role was redundant, the USN authorized the role change on the XS2E-1. With the new role, the XS2E-1 was redesignated as the XOSE-1. Not long after the role and design change, a full-scale wooden mockup of the new XOSE-1 was built and an inspection was held on November 24th, 1944. An early criticism of the design was linked to the removal of the second seat, as would-be operators complained the intense workload was too much to put onto the pilot. A variant was soon conceived, the XOSE-2, which would address this workload issue by reintroducing the second seat for another crewman. This second crewmen would be tasked with operating the onboard radar system and performing observation duties. An order for two XOSE-2s to be built, as well as for a derivative of the XOSE-2 that would be a dual-control training version, soon followed after conception of the two-seat variant. The trainer would be named the XTE-1. Progress on the program overall was slow up to this point, but Edo had added many innovative features to the design to improve its performance.
Side view of an XOSE-1 taking off. [axis-and-allies-paintworks.com]The war came to an end before the XOSE-1 could take flight. The end of the war saw most of the projects the USN was working on be terminated immediately, as there was no purpose in developing them anymore. The XOSE-1, however, was saved from this fate, as the USN allowed the floatplane to continue development after the end of the war. The XOSE-1’s first flight took place on December 28th of 1945, only a few months after the war had ended. Since there was no urgency to press this new type of aircraft to the frontlines anymore, funding to the program was cut and work slowed down in accordance. The XOSE-2 version finally flew on September 24th, 1947, two years after the war was over. Two XOSE-2s were built. It is unknown exactly when the first XTE-1 was completed and flew, but two of this type were built as well. Originally, during its debut, the XOSE-1 was painted in the standard blue-on-the-top-white-on-the-bottom that mid war USN aircraft used, but would later be colored in the dark blue that late/post-war Navy aircraft were painted in.
Rear view of an XOSE-1 with the floats detached and the wheels attached instead. [axis-and-allies-paintworks.com]Despite being a company that had only built a handful of planes two decades prior, the XOSE-1 was very promising from the outset, but problems soon began to arise during testing. The XOSE-1 experienced trouble with the Ranger built engines. The two seater XOSE-2 experienced many more problems and major changes had to be implemented in the design. Some remedies to the problems included increasing the height of the tailfin and the addition of a ventral strake below the tail to help with stability. Stability issues were found to be caused by the two seater’s larger canopy installed on the largely unmodified fuselage. By the time the stability issues were resolved, it was almost for naught, as the aircraft program was going nowhere.The shipborne floatplane type itself was beginning to show its obsolescence compared to newer technology. Exactly when the program ended or the whereabouts of the ten XOSE built are unknown, as details about the program during this time are sparse. It is unknown if the XOSE-1 was ever even tested from a ship, as many warships postwar would have their catapults removed. Most of the testing was done via land or sea takeoff, with wheels attached to the floats or a landplane conversion where the floats were replaced with a conventional landing gear. The type would be slowly replaced by ship-based helicopters, an idea that had begun during the Second World War and expanded upon thereafter. The era of the scout floatplane, especially shipboard ones, was over. It is most likely all of the XOSE-1s and its derivatives were scrapped before 1950, as all shipboard seaplane squadrons had been disbanded in 1949.
Design
An Edo XOSE-1 in flight [axis-and-allies-paintworks.com]The Edo XOSE-1 was a single-seat floatplane design of all metal construction. It’s floatation was provided by one large aluminum float under the hull, and two smaller aluminum floats on the wingtips. This layout was used on almost every USN floatplane. In addition to floats, the aircraft was also able to be launched via catapult aboard a ship. An optional wheeled undercarriage was also available for ground based takeoffs.
The body of the aircraft would be constructed of metal and would contain 135 lbs (61 kg) of armor. The overall weight of the aircraft would be 5,316 Ib (2411.3 kg) standard and 3,973 Ib (1802 kg) empty. The fuselage would have a length of 31 ft 1 in (9.5 m) and a height of 14 ft 11 in (4.5 m). The XOSE and its variants had a unique construction that allowed many parts of the aircraft to be easily accessible for maintenance.
A rear view of an XOSE-1 with its wings folded back. [shu-aero.com]The Edo XOSE-1 and all of its variants were equipped with the Ranger V-770-8 inline engine that gave it a top speed of 188 mph (302 km/h), a cruising speed of 111 mph (178.6 km/h) and a stall speed of 61 mph (98.2 km/h). The aircraft would have a climb rate of 1,350 ft/min (411.5 m/min) and a maximum service ceiling of 22,300 ft (6797 m). The XOSE-1 would also have a range of 600 mi (965.6 km).
The cockpit would allow protection for the pilot, as the canopy was bulletproof. The canopy was one piece and would slide down and behind the cockpit for easy movement in. On the XOSE-2/XTE-1, the cockpit would be lengthened to accommodate the additional crewman, who would do observation and radar tasks. The canopy on the two seater versions would be two parts and the forward segment would slide back over the rear section.
Fuel would be stored in the fuselage in self-sealing fuel tanks. The tail section of the aircraft would be of metal construction as well. The only differences between the two versions were on the two seaters, in which the tail of the aircraft had to be extended height-wise and a vertical strake beneath the tail was added. Both of these changes helped in the stabilization of the two seaters. The wings of the aircraft were also constructed of metal and would have a wingspan of 37 ft 11 in (11.6 m). The wings would utilize a unique feature for some of its control surfaces. The flaps, that extended outwards from the folding line, would retract automatically if enough water impacted them. This was put in place to prevent damage to these flaps. Additionally, there were retractable slats on the leading edge of the wings to increase drag. The wings themselves could be folded inward for easy storage aboard ships or hangars. Interesting to note, the wings had a manual folding system instead of a hydraulic system most aircraft at the time had.
For armament, the XOSE-1 was equipped with two M2 .50 caliber machine guns as standard. Two hardpoints were equipped on the wings that could allow the XOSE-1 to carry two 350 Ib depth charges or two 50 gallon drop tanks. Additionally, two emergency rescue racks could also be carried on the underside for air to sea rescue missions. A single hardpoint could also be used to carry a radar pod. There is also mention of the XOSE-1 having smoke projectors as well. The two-seat XOSE-2 would lose one of the M2 machine guns and only carry a single gun. The XTE-1 variant would be completely unarmed, given it was only a trainer.
Conclusion
With the Edo XOSE-1 program being terminated, this would be the last time Edo would build an aircraft all on their own. However, Edo would propose a very interesting concept to the US Navy in the 1950s for an amphibious fighter similar to the Convair F2Y Sea Dart. However, this type would never be built.
Variants
XS2E-1 – Initial design of the XOSE-1. The XS2E-1 was a two seater and mounted a larger engine as well as a Westinghouse J19 jet engine. This design was changed and became the XOSE-1.
XOSE-1 – Single seat reconnaissance floatplane. The XOSE-1 had two .50 Cal M2 machine guns mounted in the wings and two hardpoints for depth charges. 6 were built.
XOSE-2 – Two seat version of the XOSE-1. The E-2 version would have a radar operator, a lengthened canopy, and only a single .50 cal for defense. Two were built.
XTE-1– Tandem control version of the XOSE-1. This version would be unarmed and would be used for training purposes. Two were built.
Operators
United States of America – The XOSE-1 and its variants were only tested by the United States Navy.
Edo XOSE-1 Floatplane Specifications
Wingspan
37 ft 11 in / 11.6 m
Length
31 ft 1 in / 9.5 m
Height
14 ft 11 in / 4.5 m
Wing Area
237 ft² / 22 m²
Engine
520 hp (387.7 kW) Ranger V-770-8 Inline Engine
Propeller
2-blade Hamilton Standard constant-speed propeller (9ft / 2.7m diameter)
Powerplant Ratings
Horsepower output
Altitude
Take Off
550 hp
Sea Level
Normal
(Approx. 84% Throttle)
500 hp
800 ft / 244 m
Fuel Capacity
120+58 US Gal / 454+219 L
Weights
Empty
3973 lb / 1802 kg
Gross
5316 lb / 2411.3 kg
Maximum
6064 lb / 2750.6 kg
Climb Rate (at sea level)
1,350 ft / 411.5 m per minute
Maximum Speed
188 mph / 302.6 kmh
Cruising Speed
111 mph / 178.6 kmh
Stalling Speed
61 mph / 98.2 kmh
Range
600 mi / 965.6 km
Maximum Service Ceiling
22,300 ft / 6797 m
Crew
1 pilot
Armament
2x 12.7x99mm / .50 cal Browning AN/M2 machine guns
Edo XOSE-1 in Standard Wartime ColorsEdo XOSE-1 with the additional ventral stabilizers addedA view showcasing the retractable flaps on the engine.
Two Edo XOSE-1s in flight together [shu-aero.com]A side view of the XOSE-1 in flight A side view of the XOSE-1 in flight. [axis-and-allies-paintworks.com]Rear view of an XOSE-2 or XTE-1. [axis-and-allies-paintworks.com]
Credits
Article written by Medicman11
Edited by Stan L. and Ed J.
Illustrated by Ed Jackson
Jane’s All the World’s Aircraft 1947
Norton, Bill. American aircraft development of WWII : special types, 1939-1945. Manchester: Crécy Publishing Ltd, 2016. Print.
Wagner, Ray. American combat planes of the 20th Century : a comprehensive reference. Reno, NV: Jack Bacon & Co, 2004. Print.
With the development of new designs for the Italian Air Force, the need for a more advanced reconnaissance aircraft became apparent. Italians mostly used older biplanes for this role, which was far from a perfect solution, and thus a new design was needed. For this reason, one Re.2000 would be rebuilt and tested as a reconnaissance aircraft. Despite an initial order for serial production, only a few prototypes were ever built.
History
Officine Meccaniche Reggiane SA (Reggio Emilia in Northern Italy) was a WWI-era aircraft manufacturer. After the war it was not involved in any significant aircraft production or design work. Large scale production only began during the thirties, when Reggiane became a subsidiary of the much larger aircraft manufacturer Caproni, which was led by the well known engineer Gianni Caproni. Thanks to him, Reggiane was aided by Caproni’s larger and well qualified aircraft design department. Reggiane and Caproni were involved with several experimental pre-war designs, like the Ca.405 Procellaria and P.32bis, in addition to the licensed production of the S.M.79. In 1938, the development of the Re.2000 began with a request from the Italian Aviation Ministry (Ministero dell Aeronautica) under the codename “Programme R.” This was intended to upgrade the Italian Air Force (Regia Aeronautica) with new and modern designs.
Despite the time and resources involved in development, the resulting Re.2000 would not be adopted for the Italian Air Force. It would see service in countries like Sweden and Hungary in some numbers. Due to the demand for long range fighters and shipboard versions, a small number was adopted for service by the Italian Air Force. From the small number of Re.2000s seized by the Italian Air force, most were from the Series II and III. At least one was used as a base for the experimental two-seat Re.2003 version.
The Re.2003
In early 1941, Italian Air Force officials placed an order for a two-seater reconnaissance aircraft. Reggiane responded by simply reusing the already produced Re.2000 in order to speed up development and to streamline a potential production run. One Re.2000 (MM.478) was modified by adding an additional seat behind the pilot.
The prototype was completed very quickly, and by July it was ready for its first test flight. The test flight was carried out by Captain Francesco Aggelo. The flight was considered successful, but certain modifications were required. These include redesigning the rear observer’s cockpit and the installation of camera equipment. Once these modifications were made, the test flights were resumed in November 1941 with two new pilots.
The Re.2003 seems to have fulfilled all requirements that were demanded. On the 16th of December 1941, an official order for the production of 200 Re.2003 was placed at Reggiane. Production was to commence before September 1942.
Reggiane engineers and designers began working on an improved second prototype in 1942, based on the Re.2002 (MM.12415). The decision to use the Re.2002 was probably based on the fact that it was put into production and was in (very limited) use during the war. In addition, while the Re.2000 was being produced for the export market, it was not adopted for Italian aviation use. Simply put, production in larger quantities was not possible.
Technical Characteristics
The Re.2003 was originally based on the Re.2000, and for this reason, the cosmetic and structural differences were minimal. The Re.2003 was a low wing, mixed construction, but mostly metal, two-seater reconnaissance plane. The fuselage consisted of a round frame covered with aluminum sheets held in place by flush-riveting. The Re.2003’s wings had a semi-elliptical design, with five spars covered with stressed skin. The wings were equipped with fabric-covered Frise type ailerons. The tail had a metal construction, with the controls surfaces covered with fabric. The fuel was stored in the wings, but the precise quantity is not known.
The landing gear system was unusual. When it retracted backward, it rotated 90° (a copy of the Curtiss type) before it moved into the wheel bays. For better handling when landing, the landing gear mechanism was provided with hydraulic shock absorbers and pneumatic brakes. The smaller rear wheel was also retractable and could be steered if needed.
The Re.2003’s engine was the stronger Piaggio P.XI bis RC.40, which had around 1025 hp. Due to being used in limited test flights, precise engine performance is not clear. Author Jonathan Thomson noted that the maximum speed was around 471 km/h (293 mph). The first prototype had the Re.2000’s original engine cowling. The second prototype had a more aerodynamically-shaped cowling, as it was based on the Re.2002.
The most obvious difference was the larger canopy. The front pilot canopy section was more or less the same as the Re.2000. The rear section was somewhat larger in order to provide the observer with a better view. In addition, two small glass windows were added on both sides of the fuselage sides for the observer.
Side view of the Re.2003. Below the rear cockpit, the two small windows placed to provide the observer with a better view of the surroundings can be seen. Source: www.vvsregiaavions.com
The main armament was not changed and consisted of two Breda-Safat 12.7 mm ( 0.5 in) heavy machine guns. The machine guns were placed in the top of the front cowling and fired through the propeller arc. For each machine gun, a provision of 300 rounds was provided. The machine guns could, depending on the combat situation (lack of ammunition, for example), be fired together or individually. The Re.2003 was also tested with a bomb load of 500 kg (1100 lb) placed on the ventral rack.
Operational Use
The Re.2003 first prototype was used by the 1st Gruppo Reserve Aerea (Reserve 1st Air Group), possibly from late 1942 up to the Italian capitulation in 1943. It was then captured by the Germans, who used it as a trainer aircraft. This aircraft, while in German hands, was stationed at the Caproni-Taliedo airfield. Its final fate is unknown.
To make the development of the new Re.2003 fast and easy, Reggiane simply reused the Re.2000 and later Re.2002 for this purpose. While it had a short operational life, it appears that no major problems were encountered during its development and that it could fulfill the designated role as a reconnaissance plane. Source: www.vvsregiaavions.com
Cancellation of the Project
The following year, due to the rapid military deterioration of the Italian Air Force, the need for more advanced fighters had greater priority over other projects. Work on the Re.2003 was slow and, by late 1942, little progress had been made. The second prototype’s development was also proceeding at a slow pace. It made its first test flight in October 1942. Some historians note that the second prototype was never fully completed. In order to increase the production of fighter designs, Reggiane was asked to stop the development of the Re.2003, and instead focus on the production of fighter planes. Only the two prototypes were ever built.
Re.2003 first prototype (MM.478) – One prototype built and used in a limited role. Re.2003 second prototype (MM.12415) – Based on the Re.2002, one built.
Operators
Italy – Operated the first prototype during the war.
Germany – Captured one prototype in 1943. It was used as a trainer plane.
Conclusion
Due to the Re.2003’s short development life, it is not known if it could have fulfilled the purpose the Italian Air Force officials had intended for it. It appears that no major problems were encountered during its development, so there is no indication it had any problems fulfilling its role as a reconnaissance plane. However, without ever being properly tested in real combat conditions, this will never be known.
Re.2003 Specifications
Wingspan
36 ft 1 in / 11 m
Length
26 ft 5 in / 8 m
Height
10 ft 4 in / 3.15 m
Wing Area
220 ft² / 20.4 m²
Engine
One Piaggio P.XI RC.40bis, 1025 hp
Maximum Takeoff Weight
7,210 lbs / 3,270 kg
Maximum Speed
293 mph / 471 km/h
Range
447 miles / 720 km
Crew
Pilot and observer
Armament
Two 0.5 in (12.7 mm) heavy machine guns
Bomb load of 1,100 lb ( 500 kg) bombs.
Gallery
The Re.2003 Prototype – Illustration by Carpaticus
Sources:
D. Nešić (2008) Naoružanje Drugog Svetsko Rata-Italija. Beograd.
M. Di Terlizzi (2002) Reggiane RE 2000 Falco, Heja, J.20, Instituto Bibliografico Napoleone.
J. W. Thompson (1963) Italian Civil And Military Aircraft 1930-1945, Aero Publisher
G. Cattaneo (1966) The Reggiane Re.2000, Profile Publication Ltd.
J. F. Bridlay (1972) Caproni Reggiane Re 2001 Falco II, Re 2002 Ariete and Re 2005 Sagittario, Profile Publications
The modified Yakovlev EG prototype in flight. (Yakovlev OKB) Colorization by Amazing Ace
The EG (also known as the Yak-M-11-FR-1, Sh or Yak-EG) was a prototype helicopter designed in 1946 by the Yakovlev OKB. The EG was designed with a coaxial rotor configuration and had an ambitious performance estimation. Through manufacturer testing, it was revealed that the EG had very undesirable handling characteristics and excessive vibrations when the helicopter reached around 20 mph (30 km/h). These flaws caused the cancellation of the EG project and the completed prototype was converted to an aerosani in 1955 and donated to a farm in the Kazakh SSR. The Kamov OKB would later go on to develop the coaxial rotor configuration further.
History
Lessons of the Second World War showed the world the importance of adopting and developing modern technologies. Throughout the war, autogyros and helicopters became increasingly relevant with several countries’ militaries and saw a dramatic increase in development. The Soviet Union had a very limited selection of these machines during the war, and looked to develop this technology and expand their arsenal. In 1946, the esteemed Yakovlev OKB initiated a project for an experimental coaxial rotor helicopter design. The project was given the nickname of “EG”, for “Experimental Helicopter” (Экспериментальный Геликоптер / Eksperimentahl’nyy ghelikopter). When the task of designing the EG was first announced to the design team, a flabbergasted staff member exclaimed “Shootka?” (шутыш), which roughly translates to “Are you kidding?”. This then led the EG to unofficially be referred to as the “Sh”, a running joke in the design team. Another designation which referred to the EG was “Yak-M-11FR-1”, which referred to the engine that the helicopter would use. The origin of this designation is unknown, but it does not appear to be official.
A detailed cutaway drawing of the modified Yakovlev EG prototype. (Yakovlev OKB)
Responsibility over the project was given to chief designer S.A. Bemov, with I.A. Erlikh as his aide. The EG was envisioned as a coaxial rotor configuration while powered by a 5-cylinder air-cooled Shvetsov M-11FR-1 radial engine producing 140 hp. When the initial design was completed in early 1947, the design team built a flying scale model of the EG to prove the viability of the coaxial rotor design. The scale model was given the designation of ED 115, with the digits referencing OKB-115, the plant designation for Yakovlev OKB.
The modified prototype Yakovlev EG sits on the Yakovlev OKB’s premise with it’s rotor fins folded. (Yakovlev OKB)
After verifying the EG’s design, construction of the actual prototype commenced. The prototype was completed sometime in the summer of 1947 and was promptly subjected to manufacturer’s trials. The EG prototype performed 40 tethered flights (total of 5 hours flight time) before being authorized to perform the first free flight test on December 20, 1947. Through extensive testing, it was revealed that the center of gravity was too far to the rear, which led the team to remove the tail and tailskid and relocate the oil tank behind the cockpit. In early 1948, the M-11FR-1 engine was removed, replace by an experimental M-12 radial engine, a development of the M-11. The first test flight with this engine was conducted on April 9th, but the engine proved troublesome and forced the team to refit the M-11FR-1 engine. Flight tests continued until July 8, 1948, with a total of 75 free flights conducted (total of 15 hours flight time).
Despite the EG showing relatively decent results, it suffered from excessive vibration, loss of stick force and phugoid instability once the machine approached 20 mph (30 km/h). This severely restricted the EG’s practicality and thus warranted the project’s cancellation. The coaxial rotor design configuration was given to Kamov OKB to further develop, while the Yakovlev OKB moved onto more conventional helicopter configurations. A second prototype was in construction but was never completed and was scrapped when the program was canceled. The sole completed prototype was preserved at the Moscow Aviation Institute for a couple of years before being converted to an aero-sleigh by students between 1954 and 1955. The converted sleigh was then donated to a farm in the Kazakh SSR and the fate beyond that is unknown. Photos of this new conversion do not exist. Though ultimately ending up as a failure, the EG was an important stepping stone in Soviet helicopter development and was quite special in the sense that it was the Yakovlev OKB’s first helicopter design.
Design
The original configuration of the Yakovlev EG with a horizontal tail, tail bumper and endplate fins. (Yakovlev OKB)
The Yakovlev EG was a coaxial rotor helicopter powered by a 5-cylinder air-cooled Shvetsov M-11FR-1 radial engine producing 140 hp. The engine drove co-axial two-bladed rotors using a transmission system which featured a centrifugal clutch, a 90-degree gearbox and a cooling fan. Fuel tanks were placed under the gearbox while the oil tank was next to the engine. The rotors (made of laminated pine and hardwood) spun in opposite directions at 233 rpm. Both collective and cyclic pitch control was provided through the rotor’s fully articulated hub mount. The EG’s fuselage consisted of simple welded steel tubes which had D1 duraluminium skin all around except for the engine compartment. The rear fuselage, which was covered with fabric, gradually tapered off to form a fin which was accompanied by a horizontal stabilizer supplemented by two endplate tips. The tail and the horizontal stabilizer would be removed later on in the test phase due to the offset center of gravity. The EG had a non-retractable tricycle landing gear with vertical shock absorber struts. The glazed cockpit compartment could house two pilots, which would enter through doors on either side of the fuselage.
Operators
Soviet Union – The Yakovlev EG was designed with the intent of serving the Soviet Union. The EG was evaluated by Yakovlev OKB but was deemed to be unfit for service due to the excessive vibration and loss of stick control and phugoid instability when the helicopter reached speeds around 20 mph (30 km/h).
146 mi / 235 km – Estimation based on 58 mph / 93 kmh Top Speed
Hover Ceiling
820 ft / 250 m
Flight Ceiling
8,860 ft / 2,700 m – Estimated*
* – Testing never exceeded 590 ft / 180 m
Crew
1x Pilot
1x Co-Pilot
Gallery
Side View Profile of the Yakovlev EG by Ed JacksonA desktop model of the Yakovlev EG. This model does not have the tail components presented. (Yakovlev OKB)The modified Yakovlev EG prototype in flight. (Yakovlev OKB)A side view of the original configuration of the Yakovlev EG with a horizontal tail, tail bumper and endplate fins. (Yakovlev OKB)A side view of the modified prototype Yakovlev EG sitting on the Yakovlev OKB’s premise with it’s rotor fins extended. (Yakovlev OKB)
Nazi Germany (1939)
Experimental jet-engine powered aircraft – 2 prototypes and 1 mockup
The He 178 has the honor to be the first aircraft that made it to the sky solely powered by a jet engine. It was mainly designed and built to test the new jet engine technology. Two would be built, of which the first prototype made its maiden flight in late October 1939, just weeks after the start of the Second World War.
A photograph of the He 178 taken during its first test flight. Source: airwar.ru
Early German jet engine development
The leading German scientist in jet engine development was Hans Joachim Pabst von Ohain. He began working on jet engine designs during the thirties, and by 1935 managed to patent his first jet engine while working at the University of Göttingen. The following year, the director of this University, seeing the potential of the Hans Joachim jet engine, wrote a letter to Ernst Heinkel (the owner of the Heinkel aircraft manufacturer). Ernst Heikel was very interested in the development of jet-powered aircraft, seeing they had the potential of achieving great speed and range. After a meeting with Hans Joachim (17th March 1936), Ernst immediately employed him and his team (led by a colleague named Max Hahn) to work for his company.
In 1936, Hans Joachim and his team began building the first working prototype jet engine, using hydrogen gas as the main fuel, the HeS 1 (Heinkel-Strahltriebwerk 1). The HeS 1 was not intended as an operational engine, but for testing and demonstration purposes only. It was built and tested in early 1937, and was considered successful, so the research continued. The HeS 2 was the second test jet engine that initially used hydrogen gas fuel, but this would be changed to gasoline fuel. While this engine had some issues, it helped Hans Joachim and his team in gaining important experience in this new technology.
In September 1937, a series of modifications were made in order to improve its performance. By March 1938, the third HeS 3 jet engine was able to achieve 450 kg (1,000 lbs) of thrust during testing, much lower than the estimated 800 kg (1,760 lbs). Further modifications of the HeS 3 jet engine would lead to an increase of only 45 kg (100 lbs) of thrust.
Experimenting with the HeS 3 engine mounted on the He 118
In May (or July depending on the source) of 1939, testing of the improved HeS 3A engine began. At the same time, field testing done by attaching this engine to a piston-powered aircraft was being planned. For this reason, an He 118 was equipped with this auxiliary test jet engine. The He 118 was Heinkel’s attempt to build a dive bomber, but the Junkers Ju 87 was chosen instead. Having a longer undercarriage, the He 118 was able to mount the jet engine without any major problem. In order to keep the whole flight testing a secret, the tests were scheduled to start early in the morning.
Drawing of the He 118 equipped with the experimental HeS 3A jet engine. An improved version of this engine would later be mounted in the He 178. Source: www.fiddlersgreen
The pilot chosen for this test flight was Erich Warsitz. When the He 118 reached the designated height using the piston engine, the pilot would then activate the auxiliary jet engine. During this flight, the He 118 powered by the HeS 3A jet engine managed to achieve 380 kg (840 lb) of thrust. More test flights were carried out with the modified He 118 until it was destroyed in a fire accident during landing. Despite this accident, the final version of the HeS 3B jet engine was intended to be mounted in the Heinkel designed He 178 aircraft. While this engine was far from perfect and did not manage to achieve the designer’s expected thrust, Ernst Heinkel urged its installation in the He 178 as soon as possible.
The He 178 history
Interestingly, the whole He 178 development began as a private venture. It was also under the veil of secrecy and the RLM (Reichsluftfahrtministerium), the German Aviation Ministry, was never informed of its beginning. Ernst Heinkel gathered the designers and technical directors to reveal to them ’…We want to build a special aircraft with a jet drive! The RLM is not to know anything about the 178. I take full responsibility!..’
Heinkel was possibly motivated by a desire to get an early advantage over the other German aircraft manufacturers. The main competitor was the Junkers Flugzeugwerke, which would also show interest and invest resources in developing this new technology.
While Hans Joachim was in charge of developing the proper jet engine, work on the He 178 airframe was led by the team of Hans Regner as main designer and Heinrich Hertel, Heinrich Helmbold, and Siegfried Günter as aircraft engineers. The first He 178 mockup was ready by the end of August 1938. Ernst Heinkel was, in general, satisfied with the design, but asked for some modifications of the cockpit and requested adding an emergency escape hatch door for the pilot on the starboard side. The following year, both the He 178 airframe and the HeS 3B jet engine were ready, so the completion of the first working prototype was possible.
Technical characteristics
The He 178 was designed as a shoulder wing, mixed construction, jet engine-powered aircraft. As it was to be built in a short period of time and to serve as an experimental aircraft, Ernst Heinkel insisted that its overall construction should be as simple as possible. It had a monocoque fuselage which was covered with duralumin alloy. The wings were built using wood and were sloping slightly upwards. The wing design was conventional and consisted of inboard trailing edge flaps and ailerons. The rear tail was also made of wood. The pilot cockpit was placed well forward of the wing’s leading edge.
The jet engine used initially was the HeS 3B, but this was later replaced with a stronger HeS 6 jet engine. The He 178 jet engine was supplied with air through a front nose Pitot-type intake, then through a curved shaped duct which occupied the lower part of the fuselage, leading directly to the engine. The exhaust gasses would then go through a long pipe all the way to the end of the fuselage. At the developing stage, there were proposals to use side intakes but, probably for simplicity’s sake, the nose-mounted intake was chosen instead. The He 178 fuel tank was placed behind the cockpit.
The He 178 was to be equipped with a retractable landing gear with two larger wheels in the front and a small one at the rear. All three landing gear legs retracted into the aircraft fuselage. For unknown reasons, this was not adopted early on and many test flights were carried out with landing gear in the down position. One possible explanation was that the Heinkel engineers may have left it on purpose. They probably wanted to have the landing gear down in order to be able to land quickly if the engine failed.
First test flights
The first He 178 V1 prototype was completed by June 1939, when it was transported to the Erprobungsstelle Rechlin (test center). Once there, it was presented to Adolf Hitler and Hermann Göring. Interestingly, prior to the flight testing He 178 V1, another Heinkel innovative rocket-powered aircraft, the He 176 was demonstrated. On 23rd June 1939, the He 178 pilot Erich Warsitz performed a few ground test runs. During this presentation, the He 178 was not taken to the sky, mostly due to the poor performance of the HeS 3A jet engine.
Following this presentation, He 178 V1 was transported back to the Heinkel factory in order to prepare it for its first operational test flight. The first He 178 test flight was achieved on 27th August 1939 at the Heinkel Marienehe Airfield near Rostock. At this stage, the pilot, Erich Warsitz, was instructed by the Heinkel engineers not to fly this aircraft at high speeds, mostly due to the fixed undercarriage. In addition, the HeS 3B could only provide enough thrust for only six minutes of effective flight. During this flight, there was a problem with the fuel pump but, despite this, the pilot managed to land with some difficulty but nevertheless successfully.
While there are only a few photographs of the He 178 V1 prototype, this was taken during its maiden flight on the morning of 27 August 1939. Source: airwar.ru
The flight is best described by the pilot’s own words. ‘…As the aircraft began to roll I was initially rather disappointed at the thrust, for she did not shoot forward as the 176 had done, but moved off slowly. By the 300-meter mark, she was moving very fast. The 176 was much more spectacular, more agile, faster, and more dangerous. The 178, on the other hand, was more like a utility aircraft and resembled a conventional aircraft …In this machine, I felt completely safe and had no worries that my fuel tanks would be dry within a minute. She was wonderfully easy to hold straight, and then she lifted off. Despite several attempts, I could not retract the undercarriage. It was not important, all that mattered was that she flew. The rudder and all flaps worked almost normally, the turbine howled. It was glorious to fly, the morning was windless, the sun low on the horizon. My airspeed indicator registered 600 km/h, and that was the maximum Schwärzler had warned me. Therefore, I throttled back, since I habitually accepted the advice of experienced aeronautical engineers. The tanks were not full and, contrary to custom, I did not want to gain altitude for a parachute jump should things go awry. It was supposed to be a short flight. At 300 to 400 meters altitude I banked cautiously left – rudder effect not quite normal, the machine hung to the left a little, but I held her easily with the control stick, she turned a little more and everything looked good.
After flying a wide circuit my orders were to land at once, this had been hammered into me, but now I felt the urge to go round again. I increased speed and thought, ‘Ach! I will!’ Below I could see the team waving at me. On the second circuit – I had been in the air six minutes – I told myself ‘Finish off!’ and began the landing. The turbine obeyed my movement of the throttle even though a fuel pump had failed, as I knew from my instruments and later during the visual checks. Because the airfield was so small for such flights I was a little worried about the landing because we did not know for certain the safe landing speed: we knew the right approach, gliding and landing speeds in theory, but not in practice, and they did not always coincide. I swept down on the heading for the runway. I was too far forward and did not have the fuel for another circuit. Now I would have to take my chances with the landing, losing altitude by side-slipping. I was flying an unfamiliar, new type of aircraft at high speed near the ground and I was not keen on side-slipping. It was certainly a little risky, but the alternative was overshooting into the River Warnow. Such an ending, soaking wet at four on a Sunday morning, appealed less. The onlookers were horror-struck at the maneuver. They were sure I was going to spread the aircraft over the airfield. But the well-built kite was very forgiving. I restored her to the correct attitude just before touching down, made a wonderful landing, and pulled up just short of the Warnow. The first jet flight in history had succeeded! …’’ Source: L. Warsitz (2008) The First Jet Pilot The Story of German Test Pilot Erich Warsitz.
An interesting fact is that pilot Erich Warsitz managed to be the first man that flew on both a rocket-powered (He 176) and a jet-powered (He 178) aircraft in history.
Heinkel’s attempt to gain the support of the Luftwaffe
During the following months, Hans Joachim tried to improve the HeS 3B jet engine, which would lead to the development of the HeS 6. This jet engine managed to achieve a thrust of 1,300 lb (590 kg), but due to the increase in weight, it did not increase the He 178’s overall flight performance.
As the He 178 was built as a private venture, Heinkel’s next step was to try obtaining state funding for further research from the RLM. For this reason, a flight presentation was held at Marienehe with many RLM high officials, like Generaloberst Ernst and General Erhard Milch. During the He 178 V1’s first attempt to take off, the pilot aborted the flight due to a problem with the fuel pumps. During his return to the starting point, a tire burst out. The pilot, Erich Warsitz, lied to the gathered RLM officials that this was the reason why he aborted the takeoff.
After a brief repair, Erich Warsitz managed to perform several high-speed circuits flights. During the presentation flight, Erich Warsitz estimated that he had reached a speed of 700 km/h (435 mph), which was incorrect, as later turned out… Interestingly, even at this stage, the He 178 was still not provided with the retractable landing gear. The RLM officials were not really impressed with the He 178’s performance, and for now, no official response came from them.
This was for a few reasons. The Luftwaffe had achieved great success during the war with Poland, which proved that the piston-powered engines were sufficient for the job. In addition, Hans Mauch, who was in charge of the RLM’s Technical Department, as opposed to the development of jet engines. He was against the development of jet engines by any ordinary aircraft manufacturer. Another problem was the He 178’s overall performance. During the test flights, the maximum speed achieved was only 595 km/h (370 mph). Hans Joachim calculated that the maximum possible speed with the HeS 6 was 700 km/h (435 mph). The speed was probably affected by the landing gear, which was still deployed and not retracted.
While the RLM did not show any interest in the He 178, Heinkel would continue experimenting with it. While the He 178 did perform many more flight tests, these were unfortunately not well documented. What is known is that, in 1941, the He 178 (with fully operational landing gear) managed to achieve a maximum speed of 700 km/h (435 mph) with the HeS 6 jet engine.
The He 178’s final fate
By this time, Heinkel was more interested in the development of the more advanced He 280. In addition, the use of the HeS 3B jet engine was completely rejected, being seen as underpowered. The interest in the development of the He 178 was lost and it was abandoned. The second prototype, which was similar in appearance, but somewhat larger in dimensions, was never fitted with an operational jet engine. It was possibly tested as a glider. There was also a third mockup prototype built that had a longer canopy.
This is a wooden mockup of the third prototype. While it is somewhat difficult to spot, the front landing gear wheels are actually made of wood and not rubber. Source: airwar.ruFront view of He 178 V2. Strangely, more photographs of the second prototype survived the war than of the first prototype. Source: airwar.ruRearview from the second He 178 V2 prototype. Source: airwar.ruThis is the second V2 prototype which was to be powered by the HeS 6 jet engine but was never equipped with it. Source: Source: airwar.ru
The He 178 V1 was eventually given to the Berlin Aviation Museum to be put on display. There, it was lost in 1943 during an Allied bombing raid. The fate of the second prototype is unknown but it was probably scrapped during the war. While no He 178 prototypes survived the war, today we can see a full-size replica at the Rostock-Laage Airport in Germany.
An He 178 replica can be seen at Rostock-Laage Airport in Germany. Source: Wiki
Conclusion
Today, it is often mentioned that the He 178 was Germany’s lost chance to get an edge in jet-powered aircraft development. What many probably do not know is that the He 178 was not designed to be put into production, but to serve as a test aircraft for the new technology. We also must take into consideration that the jet engine technology was new and needed many years of research to be properly used. While Germany would, later on, operate a number of jet aircraft, they were plagued with many mechanical problems that could never be solved in time. Regardless, the He 178 was an important step in the future of aviation development, being the first aircraft solely powered by a jet engine
Heinkel He 178 (HeS 6 jet engine) Specifications
Wingspan
23 ft 7 in / 7.2 m
Length
24 ft 6 in / 7.5 m
Wing Area
98 ft² / 9.1 m²
Launch Weight
4.405 lbs / 2.000 kg
Engine
One HeS 6 jet engine with 590 kg (1,300 lb) of thrust
Maximum speed
435 mph / 700 km/h
Cruising speed (when towed)
360 mph / 580 km/h
Crew
Pilot
Armament
None
Gallery
Illustration’s by Ed Jackson
He-178 V1
He 178 V2
Sources
C.Chant (2007), Pocket Guide Aircraft Of The WWII, Grange Books
D. Nešić (2008), Naoružanje Drugog Svetskog Rata Nemačka Beograds
Jean-Denis G.G. Lepage (2009), Aircraft Of The Luftwaffe 1935-1945, McFarland & Company Inc
M. Griehl (2012) X-Planes German Luftwaffe Prototypes 1930-1945, Frontline Book
T. Buttler (2019) X-Planes 11 Jet Prototypes of World War II, Osprey Publishing
L. Warsitz (2008) The First Jet Pilot The Story of German Test Pilot Erich Warsitz Pen and Sword Aviation
By the middle of the Second World War, the Germans were losing control of the skies over the occupied territories. Even the Allied air attacks on Germany itself were increasing. In an attempt to stop these raids, the Blohm und Voss company presented the Luftwaffe with a new project which involved using cheap gliders in the role of fighters. While a small series would be tested nothing came from this project.
The Bv 40 was designed as a cheap, armed, and armored fighter glider. This is the first prototype (PN + IA) which was lost on its second test flight. Source: https://www.flugrevue.de/klassiker/kampfgleiter-blohm-voss-bv-40/
History
By 1943, the German Luftwaffe (air force) was stretched to limits in an attempt to stop the ever-increasing number of Allied air attacks. The Allied Bombing campaign particularly targeted German war industry. During this time, there were a number of proposals on how to effectively respond to this ever-increasing threat. Proposals like the use of a large number of relatively inexpensive fighter aircraft, that were to be launched from larger aircraft, were considered with great interest. One proposal went even further by suggesting the use of an inexpensively modified glider for this role. This idea came from Dr. Ing Richard Vogt who was the chief designer at Blohm und Voss.
In mid-August 1943, Dr. Ing Richard Vogt handed over the plans of a cheap and easy to build (without the use of strategic materials which were in short supply) glider that could be built by a non-qualified workforce to the German Ministry of Aviation (Reichsluftfahrtministerium – RLM). The pilots intended to fly this glider were to be trained in basic flying skills only. The initial name of this Gleitjäger (glider fighter) was P186 which would later be changed to Bv 40. After receiving the initial plans the RLM responded at the end of October 1943 with a request for six prototypes to be built. The number of prototypes would be increased to 12 December 1943 and again to 20 in February 1944. If the project was successful, a production order of some 200 per month was planned.
One of the few built prototype is preparing for a test flight. Source: https://www.flugrevue.de/klassiker/kampfgleiter-blohm-voss-bv-40/
Design
The Bv 40 was designed as a partly armored and armed, mixed construction, fighter glider. Its 0.7 m (2ft 3 in) wide fuselage was mostly constructed using wooden materials, while the cockpit was provided with armored protection. The front armor of the cockpit was 20 mm (0.78 in) thick, the sides were 8 mm (0.31 in), and the bottom 5 mm (0.19 in) thick. Additionally, the cockpit received a 120 mm thick armored windshield.
The wings and the tail unit were also built mostly using wooden materials. The rear tail had a span of 1.75 m (5ft 9in). For towing operation, the Bv 40 was provided with a jettisonable trolley that was discarded once the Bv 40 was in the air. Once it was back to the airbase it was to land using a skid.
What is interesting is that in order to have as small a size as possible, the cockpit was designed so that the pilot had to be in a prone position. While a pilot prone positioned design offered advantages like being a smaller target and having an excellent view at the front, it also caused some issues like a bad rearview. While this design was tested in Germany (like the Akaflieg Berlin B9 for example), it was never implemented. Inside the cockpit, there were only basic instruments that were essential for the flight. In addition, due to the high altitude that it was supposed to operate, the pilot was to be provided with an oxygen supply system and a parachute. The side windows had sliding armored screens with integral visor slots that could offer extra protection.
Close up view of the small pilot cockpit. Source: https://www.flugrevue.de/klassiker/kampfgleiter-blohm-voss-bv-40/
The armament of this glider consisted of two 3 cm (1.18 in) MK 108 cannons. These were placed in the wing roots with one on each side. This was serious firepower which could cause a huge amount of damage to the target it hit. Due to its small size, the ammunition loadout was restricted to 35 rounds per cannon. The ammunition feed system was quite simple; it consisted of a rectangular ammunition feed hatch placed in the middle of each wing. Inside the wings, an ammunition conveyor chute was placed to guide the rounds directly to the cannons. There was also a secondary option which included the use of one cannon together with the ‘Gerät-Schlinge’ 30 kg (66 lb) towed guided bomb. This bomb was to be guided by the Bv 40 toward the enemy bombers and was then detonated at a safe distance. In practice, during testing, this proved to be almost impossible to achieve success.
The front view of the Bv 40. Note the towing cable and the release mechanism just behind it. The pilot was beside he armored cockpit also protected by a 120 mm thick armored windshield. The large box with the round capcel (marked as number 5) is the compass housing. Source: https://www.flugrevue.de/klassiker/kampfgleiter-blohm-voss-bv-40/
Other weapon systems were also proposed. For example the use of R4M rockets placed under the wings. There was also a proposal to use the Bv 40 in the anti-shipping role by arming it with four BT 700 type torpedoes or even using 250 kg (550 lbs) time-fused bombs. Due to the extreme weight increase, this was never possible to achieve.
How should it be used?
In essence, the glider was to be towed by a Me-109G to a height of around 6 km before being released. Once released, it was to engage incoming enemy bombers with its two 3 cm (1.18 in) cannons. If circumstances allowed, a second attack run was to be launched. After the attack, the pilot simply guided the glider to the nearby airbase. It was hoped that the small size and armored cockpit would be the pilot’s best defense.
Testing of the Prototypes
Once the first prototype (marked PN+UA) was completed in early 1944, the first test flight made at Hamburg-Finkenwerder was unsuccessful as it was not able to take-off from the ground. A second more successful attempt was made on the 6th (or 20th depending on the source) May 1944 at Wenzendorf. Despite being intended to have an armored cockpit, the first prototype was tested without it. It appears also that during the maiden flight it was towed by another unusual Blohm und Voss design: the asymmetrical Bv 141. But according to most sources, the Me-110 was to be used, which seems more plausible. After the first flight, some modifications to the jettisonable undercarriage were made. On the 2nd June 1944, the first prototype was lost during a crash landing.
The Bv 40 small size is evident here. Source: Pinterest
A few days later the second prototype (PN+UB) made its first test flight. During a dive, it managed to reach a speed of 600 km/h (370 mph). Its final fate is unknown but it was probably scrapped. The third prototype never took off from the ground as it was used for static structural tests. The fourth prototype (PN+DU) was lost during its first test flight but the precise date is unknown. The fifth prototype (PN+UE) made its first test flight on 6th July 1944, but its fate is also unknown. The last prototype (PN+UF) was tested with a new fin section and made its maiden flight on the 27th of July 1944.
During these test flights, the Bv 40 was able to achieve a flight speed of up to 650 km/h (404 mph). During dive testing, the following speeds at different altitudes were achieved: 850 km/h (528 mph) at 4,000 m (13,120 ft), 700 km/h (435 mph) and an astonishing 900 km/h (560 mph) at 5,000 (16,400 ft). Nevertheless, the results of the test flight appear to have been disappointing due to Bv 40’s poor overall flight performance.
The Bv 40 interior of the pilot cockpit. The Pilot was placed in a prone position. While this arrangement was tested on some German aircraft design in practice it was never implemented. Source: https://www.flugrevue.de/klassiker/kampfgleiter-blohm-voss-bv-40/
Rejection of the Project
Once the project was properly revised by the RLM officials, the obvious shortcomings of the Bv 40 became apparent. The Bv 40 was simply deemed too helpless against the Allied fighter cover. In addition, when the report of the first few prototypes was studied, it became clear even to the RLM that the Bv 40 was simply a flawed concept and so it decided to cancel it in mid-August 1944. The next month the Allies bombers destroyed the remaining 14 Bv 40 which were in various states of production.
Not wanting to let their project fail, the Dr. Ing Richard Vogt and the Blohm und Voss designers proposed to mount either two Argus As 014 pulsejets or two HWK 109-509B rocket engines under its wings. Nothing came from this as the Me-328 and Me-163 proved to be more promising (these ironically also ended in failure). There was even a proposal to modify the BV 40 to be used as a Rammjäger (ram fighter) which was never implemented.
Production
Despite initial requests for the production of 200 such gliders only a small prototype series would be built by Blohm und Voss during 1944.
Bv V1 – Lost during its second test flight.
Bv V2 – Fate unknown.
Bv V3 – Used for static testing.
Bv V4 – Lost during it’s first flight.
Bv V5 – Flight tested but final fate unknown.
Bv V6 – Tested with modified fin section.
Bv V7-V20 – Lost during one of many Allied bombing raids on Germany.
Operators
Germany – While testing was conducted on a small prototype series no production order was given.
The Bv 40 side view. Source: http://www.histaviation.com/Blohm_und_Voss_Bv_40.html
Conclusion
The Bv 40 on paper had a number of positive characteristics; it was easy to make, could be available in large numbers, was cheap, well-armed and it did not need skilled pilots. But in reality, the poor performance, lack of a power plant, low ammunition count, and its vulnerability to Allied escort fighters showed that this was a flawed concept. This was obvious even to RLM officials who put a stop to this project during 1944.
The Bv 40 drawings. The small rectangles in the middle of the wings are ammunition feed openings. Source: http://www.warbirdsresourcegroup.org/LRG/luftwaffe_blohm_und_voss_bv40.html
Gallery
Illustration by Ed Jackson
Blohm und Voss Bv 40
Blohm und Voss Bv 40 Specifications
Wingspan
25 ft 11 in / 7.9 m
Length
18 ft 8 in / 5.7 m
Height
5 ft 4 in / 1.63 m
Wing Area
93.64 ft² / 8.7 m²
Empty Weight
1.844 lbs / 830 kg
Launch Weight
2.097 lbs / 950 kg
Climb rate to 7 km
In 12 minutes
Maximum diving speed
560 mph / 900 km/h
Cruising speed (when towed)
344 mph / 550 km/h
Maximum Service Ceiling
23,000 ft / 7,000 m
Crew
Pilot
Armament
Two 3 cm (1.18 in) MK 108 cannons
Or one 3 cm (1.18 in) MK 108 cannon and a glider bomb
Sources
J. Miranda and P. Mercado (2004) Secret Wonder Weapons of the Third Reich: German Missiles 1934-1945, Schiffer Publishing.
R. Ford (2000) Germany Secret Weapons in World War II, MBI Publishing Company.
Jean-Denis G.G. Lepage Aircraft Of The Luftwaffe 1935-1945, McFarland and Company.
M. Griehl (2012) X-Planes German Luftwaffe Prototypes 1930-1945, Frontline Book.
D. Herwig and H. Rode (2002) Luftwaffe Secret Projects, Ground Attack and Special Purpose Aircraft, Midland.
Nazi Germany (1942)
Amphibious Multipurpose Transport – 1 Incomplete Mockup Built
The 1:10 model of the Ar 233. [Dan Sharp]The Arado Ar 233 was an amphibious passenger transport seaplane designed in 1942, a time when it seemed Germany would soon complete its conquest of Europe and conclude the Second World War. Intended for civilian use after the war, the development of the Ar 233 was cancelled due to the deteriorating war situation for Germany in 1944. As the project was deemed low priority, much of the Ar 233’s advanced design work was done in the German Military Administration in France by the Société Industrielle Pour l’Aéronautique (SIPA) aircraft firm located within the Northern German administrative zone. The Ar 233 never materialized, but an incomplete mockup was constructed along with a 1:10 scale model. The incomplete mockup, along with blueprints and notes, were captured by the Free French Forces shortly after the Liberation of France. However, the Ar 233 was not further developed by the French, unlike quite a few of the German aircraft projects undertaken and captured in France. Relatively unknown and often overlooked, the Ar 233 is an interesting obscure project to provide an alternate-history post-war Germany with a suitable transport plane.
History
A cutaway drawing of the Ar 233 in its passenger configuration. [Dan Sharp]The first couple years of the Second World War appeared to have been going firmly in favor of Germany. Most of Western Europe had been conquered by then, and the Wehrmacht was making steady progress in its advance eastwards to conquer the Soviet Union. Despite recently declaring war on the United States, a distant economic powerhouse, Germany still seemed confident in its path to triumph. This feeling was prominent amongst the Germans throughout the initial years of the war. As such, some aircraft firms began to make preparations for post-war German civil aviation early in 1940, in accordance with a request made by the Reichsluftfahrtministerium (RLM / Ministry of Aviation). A few examples of aircraft designed for future German civil use are the Focke-Wulf Fw 206 and Blohm & Voss BV 144. The Arado firm was not exempt from partaking in civil aircraft design and responded with a two engine float plane design.
Designed as a passenger transport, the project began around August within the Arado firm bearing the designation “E 430”. Two variants were originally envisioned, a Bramo 323 R2 powered seaplane model capable of transporting ten passengers and a smaller Argus Ar 204 powered amphibian floatplane (capable of operating from land and water) able to transport eight passengers. According to the RLM, the project officially began in October 1942, but this was likely when it was submitted or approved to the RLM. Work on the project most certainly began in August due to the amount of preliminary steps required. This is further backed up by interviews with former French aircraft designers. As the German mainland’s industry was mostly reserved for military production, the industry of occupied France (German Military Administration in France) seemed like an acceptable place to offload this low priority project. As such, the Arado firm made arrangements for the German-controlled French Société Industrielle Pour l’Aéronautique (SIPA) aircraft firm to assist in the design and production of the E 430. The SIPA firm was founded by Émile Dewoitine in 1938 after his previous firm Constructions Aéronautiques Émile Dewoitine was nationalized. It would appear that, between October and December of 1942, the E 430 project gained the designation Ar 233.
In addition to the update in nomenclature, the smaller As 204 powered E 430 “Amphibium” was cancelled in favor of the ten passenger seaplane. However, the amphibious characteristic of the former was integrated into the Ar 233. Soon after, the French SIPA firm began work on producing a full-scale mockup. The SIPA factory in Île de la Jatte, Neuilly-Sur-Seine, West of Paris, was responsible for the the mockup while the other office at 27/29 Rue Dupont (also in Neuilly-Sur-Seine) and the Dewoitine Design office in 11 Rue de Pillet-Will in Paris were responsible for other work. By Christmas Eve of 1942, it would appear that a large portion of the mockup was completed as the Arado firm released a brochure advertising the Ar 233 which featured images of the mockup. The brochure made mention of four projected Ar 233 variants which included the original passenger airliner, a flying ambulance, a private luxury touring aircraft, and a cargo transport. The French effort in the design work and mockup construction went unrecognized, as all French involvement in the project were omitted from the brochure. However, close examination of a few photos in the brochure shows some of the equipment labelled in German and French.
A wind tunnel model of the Ar 233. The bulge beneath the wing is a extendable float. [Dan Sharp]Further on, it would appear that a 1:10 scale model of the Ar 233 was constructed along with a set of propellers. They were tested separately until May 1943 apparently, when they were paired together and sent to the Nationaal Luchtvaart Laboratorium (NLL / National Aviation Laboratory) facility in Amsterdam, Occupied Netherlands. Other than this model, not much more work appeared to have been done on the Ar 233. This was likely due to the disaster at Stalingrad, when the German 6th Army suffered a catastrophic defeat, and Germany’s ensuing effort to focus on their military industry. Nonetheless, the project remained stagnant for the remainder of 1943 and was finally cancelled in 1944 in favor of military aircraft. When the Allied forces and Free French Forces liberated France, it seems that the mockup and quite a lot of notes and design prints were captured. It does not appear that the French furthered the Ar 233 project after the war unlike quite a lot of the other German projects conducted in France, such as the Heinkel He 274 bomber or Blohm & Voss BV 144 airliner.
A rear view of the Ar 233 mockup which shows the port side entrance hatch. [Dan Sharp]In the end, the ill-fated Ar 233 did not progress beyond the mockup and wind tunnel testing stage, although the project was meant to be a capable amphibious seaplane which could operate in all weathers including the extremes in the North Pole and the Tropical regions. The aircraft also had the luxury of being operable from both land and sea. This also would allow the aircraft to operate in underdeveloped regions which did not have adequate airfields. It also would have made emergency landings safer as calm water surfaces would allow for less dangerous landings compared to rough land terrain.
Design
The incomplete Ar 233 mockup in the workshop of the French firm SIPA, near the outskirts of Paris. [Dan Sharp]The Ar 233 was an amphibious seaplane intended to be powered by two 9-cylinder air-cooled Bramo 323 MA radial engines producing 968 hp each. Each engine would be driven by a three blade propeller which would be started electrically via an onboard generator. The generator would also power the onboard radio systems (FuG X P, FuG 101 and FuBl II F) and a fan to provide ventilation. The Ar 233’s crew consisted of a pilot and a radio operator, though a co-pilot could join the crew. The Ar 233 had four variants which would have the passenger capacity vary. For ease of transport, the Ar 233 was designed so that it could be taken apart and transported via the railroad system.
A rear view of the Ar 233 mockup’s cockpit which shows the pilot and copilot’s seat. Note the hatch in the middle which gives access to the forward passenger luggage compartment. [Dan Sharp]The pilot’s compartment consisted of three seats for a pilot, a co-pilot or passenger and a radio operator. An extra set of controls could be installed for a co-pilot in longer range flights or to train pilots. The cockpit could be accessed via a ladder that folded to the underside of the wing. The side windows in the cockpit could be opened by sliding them forward, while the forward windows could be dropped forward to the bow section. An emergency manual pump was located next to the co-pilot’s seat that could be used to remove water. Visibility from the cockpit appears to be inadequate due to the lack of downwards visibility. Rear visibility also seems to be lacking.
The fuselage of the Ar 233 was a ship-hull shaped in order to allow floating on water surfaces. The fuselage was divided into several sections which, in order from front to end, were the nose wheel compartment, forward baggage compartment, pilot’s cockpit, landing gear hatch, passenger compartment, rear baggage compartment and a washroom fitted with a toilet. Lighting in the passenger compartment was provided by ceiling lights which were powered by a generator. Two air ventilation fans were also provided, with one above the entrance and the other in the land gear shaft. The left side of the fuselage had a door which allowed passengers to enter. The entrance door opened both upwards and downwards, with the latter being able to act as a platform. An emergency exit was provided on both sides, as the middle window in the fuselage could open. The tail of the Ar 233 was designed so that it curved upwards in order to protect the control surfaces by preventing unnecessary contact with the water.
A three-view drawing of the Ar 233 along with it’s basic dimensions. [Dan Sharp]In the passenger airliner configuration, the aircraft could carry eight passengers and two crew members. The seats provided in the passenger compartment were fitted with armrests, side tables, seatbelts, lamps and small luggage nets. The luxury touring configuration only allowed four seats (including the pilot). It would also have had two extra 400 L fuel tanks near the wing edge to extend the range. The cargo transport configuration would carry no passengers and had all seats in the passenger compartment removed for cargo. Any cargo would be loaded through hatches on the fuselage side and would have equipment to secure cargo in flight. In the ambulance configuration, beds could be fitted in the passenger compartment for the wounded.
There would be two wheeled landing gears which would be extendable from the side of the hull for land-based operations. Each one of these wheel measured at 39.96 x 14.96 in / 1,015 x 380 mm. These landing gears, when retracted, remained above the waterline and were hydraulically operated. The nose wheel (width measured at 33.74 x 12.79 in / 875 x 325 mm) sat at the front of the aircraft and could retract into a watertight compartment that could expel excess water with compressed air. If needed, a crewmember could climb above the nose compartment and lift the lid on top to perform maintenance. It was also provided with a locking mechanism. Additionally, the nose wheel’s suspension strength allowed it to perform takeoff and landings at altitudes up to 4,900 ft / 1,500 m.
The Ar 233 was designed so that it could be transported via rail. This blueprint drawing shows the transport configuration. [Dan Sharp]The “V” shaped gull wings that sat on top of the fuselage provided a suitable platform for the engines and propellers, as it allowed them to be mounted at a safe distance from the water. Just behind the engine cowls were a set of hydraulically extended floats for assistance with landing on water. The fuel tanks for the engines were located in the wing leading edge in three “densely riveted” containers. These fuel tanks would be refilled by climbing on top of the cockpit via an access ladder. In addition, hydraulically operated flaps were provided to aid the Ar 233 in landing. These flaps were designed to yield in rough water conditions to reduce damage.
In terms of excess equipment, the Ar 233 could carry a fog horn, rubber dinghy, boat hook, towing gear, ropes, detachable sun canopy, emergency food and water, emergency tools, both ground and sea anchors and various other materials.
Variants
E 430 (Bramo 323 R2) – Original design concept which saw a dedicated seaplane powered by two Bramo 323 R2 radial engines and capable of transporting ten people. This design was further developed by incorporating the amphibious characteristic of the E 430 “Amphibium”. This design was later improved upon and bore the designation Ar 233.
E 430 Amphibium (Argus Ar 402) – Original design concept developed beside the E 430 which saw a scaled down variant powered by Argus Ar 402 engines and capable of carrying eight passengers. This variant could be operated from land and water due to it’s amphibious characteristics. This variant was cancelled but its amphibious design was carried onto the E 430.
Ar 233 (Commercial Airliner) – Commercial airliner design based on the original E 430 design which would be capable of carrying ten people. A pilot and radio operator were part of the crew which allowed for eight passengers. In addition, a co-pilot could be in the crew at the expense of a passenger. Two baggage compartments (located in the hull in front of the cockpit but behind the nose wheel and behind the passenger compartment) and a toilet compartment (located behind the rear baggage compartment) were provided for the passengers. Powered by two 9-cylinder air-cooled Bramo 323 MA radial engines.
Ar 233 (Luxury Touring Aircraft) – Luxury touring variant intended for sightseeing in remote areas. This variant featured four seats (including the pilot). This variant had the choice of carrying two extra fuel tanks at 400 L each in the outer wings. The envisioned range was 1,120 mi / 1,800 km. This variant also had the choice of implementing an additional set of controls for a co-pilot. It is not known if this variant would retain the two baggage compartments and toilet. Powered by two 9-cylinder air-cooled Bramo 323 MA radial engines.
Ar 233 (Cargo Transport) – Cargo transport variant which saw the removal of the passenger compartment equipment for cargo. The aircraft in this configuration appeared to been capable of carrying up to 2,200 lb / 1,000 kg of cargo. The cargo would be loaded from doors on the side of the fuselage with equipment provided to secure the cargo. The two baggage compartments and toilet were definitely removed for space. Powered by two 9-cylinder air-cooled Bramo 323 MA radial engines.
Ar 233 (Flying Ambulance) – Flying ambulance variant which envisioned the possibility of placing four beds in the passenger compartment either for the wounded or for the passengers. This variant was mentioned as the E 430 Flying Ambulance in the Ar 233 brochure, which shows the variant still maintained the original designation. It is not known if this variant would retain the two baggage compartments and toilet. Powered by two 9-cylinder air-cooled Bramo 323 MA radial engines.
Operators
Nazi Germany – The German Arado design firm was the original designer and intended to develop the Ar 233 for use with Lufthansa, the Luftwaffe and other organizations. The project was cancelled in 1944 after Allied forces liberated France.
German Military Administration in France – The SIPA firm under German control was responsible for partially designing and building the Ar 233. All three of SIPA’s facilities appeared to have been working on the project.
Free France – The Free French Forces captured the intact Ar 233 mockup as well as notes and drawings after the Liberation of France, but they did not continue development of the project and presumably scrapped the mockup.
Arado Ar 233 (Commercial Airliner)
Wingspan
77 ft 9.07 in / 23.70 m
Length
68 ft 5.65 in / 20.87 m
Height
21 ft 5.87 in / 6.55 m
Wing Area
807.29 ft² / 75.00 m²
Engine
2x 9-cylinder air-cooled Bramo 323 MA radial engine (986 hp / 735 kW)
Propeller
2x electrically started three-blade propeller
Propeller Diameter
11 ft 5.79 in / 3.50 m
Wheel Width
34.45 x 12.79 in / 875 x 325 mm – Nose Wheel
39.96 x 14.96 in / 1,015 x 380 mm – Fuselage Wheels
Arado Ar 233 – Artist Conception of the Military VersionArado Ar 233 – Artist Conception of the Passenger Version
A blueprint sketch showing how the main landing gear operated. [Dan Sharp]The radio operator’s position which is located behind the cockpit. All the equipment mockups are labeled in French and German. [Dan Sharp]A blueprint sketch showing extension of the forward nose. [Dan Sharp]A blueprint sketch showing the fuel tank arrangement of the Ar 233. [Dan Sharp]Inside view of the incomplete tail section of the mockup. [Dan Sharp]The nose section of the Ar 233 mockup. A tow ring is visible at the tip of the aircraft while two labels above it shows where the landing lights would be positioned. [Dan Sharp]A closeup of the cockpit is shown. The seats are removed and the forward baggage compartment can be seen. [Dan Sharp]A partial view of the Ar 233 mockup’s passenger compartment which shows two very comfortable looking seats. [Dan Sharp]A blueprint sketch shows the wing floats extended. [Dan Sharp]Credits
File No. IV-7 & V-16 Aircraft – Paris Zone (CIOS, Rep. Item No. 25). (1945).
Wasser-Land-Flugzeug Ar 233. (1942). Arado Flugzeugwerke.
Empire of Japan (1945)
Yugoslavia (1939-1950)
United States of America (1945)
Kingdom of Italy (1941
USSR (1946)
