POWER PLANT: Pratt & Whitney R-2800-77 ‘Double Wasp’ radial engine, rated at 2,800 hp
PERFORMANCE: 460 mph at 30,000 ft
COMMENT: The Republic P-47N was the last Thunderbolt variant to be produced. It was designed as an escort fighter for the Boeing B-29 Superfortress bombers flying raids on the Japanese home islands. Increased internal fuel capacity and drop tanks had done much to extend the Thunderbolt’s range during its evolution, and the only other way to expand the fuel capacity was to put fuel tanks into the wings. Thus, a new wing was designed with two 50 U.S. gal fuel tanks. The redesign proved successful in extending range to about 2,000 miles, and the squared-off wingtips improved the roll rate. The P-47N entered mass production with the uprated R-2800-57 engine, with a total of 1,816 built. The very last Thunderbolt to be built, a P-47N-25, rolled off the production line in October 1945. Thousands more had been on order, but production was halted with the end of the World War II in August 1945.
POWER PLANT: Four Junkers Jumo 004B-1 turbojet engines, rated at 950 kp each
PERFORMANCE: 347 mph at 19,685 ft
COMMENT: The Ju 287 was intended to provide the Luftwaffe (German Air Force) with a bomber that could avoid interception by outrunning enemy fighters. The swept-forward wing was suggested as a way of providing extra lift at low airspeeds, necessary because of the poor responsiveness of early turbojet engines at the vulnerable times of takeoff and landing. A further structural advantage of the forward-swept wing was that it would allow for a single massive weapons bay forward of the main wing spar. The first prototype was intended to evaluate the concept, and was assembled from the fuselage of a Heinkel He 177, the tail of a Junkers Ju 388, main undercarriage from a Junkers Ju 352, and nose wheels taken from crashed Consolidated B-24 ‘Liberator’, all of which were fixed to lower weight and complexity, and equipped with spats to reduce drag. Two of the Junkers Jumo 004 turbojet engines were hung in nacelles (pods) under the wings, with the other two mounted in nacelles added to the sides of the forward fuselage. Flight tests began on 16 August 1944, with the aircraft displaying extremely good handling characteristics, as well as revealing some of the problems of the forward-swept wing under some flight conditions. The most notable of these drawbacks was ‘wing warping’, or excessive inflight flexing of the main spar and wing assembly. Tests suggested that the warping problem would be eliminated by concentrating greater engine mass under the wings. This technical improvement would be incorporated in the subsequent prototypes. The production version of the Junkers Ju 287 was intended to be powered by four Heinkel-Hirth HeS 011 engines, but because of the development problems experienced with that engine, the BMW 003 was selected in its place. The second and third prototypes, V2 and V3, were to have employed six of these engines, in a triple cluster under each wing. Both were to feature the all-new fuselage and tail design intended for the production bomber, the Ju 287A-1. V3 was to have served as the pre-production template, carrying defensive armament, a pressurized cockpit and full operational equipment.
Work on the Ju 287 program, along with all other pending German bomber projects (including Junkers’ other ongoing heavy bomber design, the piston-engined Junkers Ju 488 came to a halt in July 1944, but Junkers was allowed to go forward with the flight testing regime on the V1 prototype. The wing section for the V2 had been completed by that time. Seventeen test flights were undertaken in total, which passed without notable incident. Minor problems, however, did arise with the turbojet engines and the RATO booster units, which proved to be unreliable over sustained periods. This initial test phase was designed purely to assess the low-speed handling qualities of the forward-swept wing, but despite this the V1 was dived at full jet power on at least. After the seventeenth and last flight in late autumn of 1944, the V1 was placed in storage and the Ju 287 program came to what was then believed to be its end. However, in March 1945, for reasons that are not entirely clear, the 287 program was restarted, with the RLM issuing a requirement for mass production of the jet bomber (100 airframes a month) as soon as possible. The V1 prototype was taken out of storage and transferred to the Luftwaffe evaluation center at Rechlin, but was destroyed in an Allied bombing raid before it could take to the air again. Construction on the V2 and V3 prototypes was resumed at the Junkers factory near Leipzig, where they were captured by Soviet troops and brought to the Soviet Union including the Junkers design team. Redesigned in its original work number EF 131 the V3 aircraft flew for the first time in 1947 (Ref.: 24).
POWER PLANT: Six Junkers Jumo 004B-1 turbojet engines, rated at 950 kp each
PERFORMANCE: 534 mph
COMMENT: The Junkers EF 131 was, in essence, a hybrid airframe built from the components of the Junkers Ju 287 V2 and V3 of the Luftwaffe’s radical forward-swept-wing jet bomber. The V2 was nearly complete at the time of its capture by Soviet forces in 1945, and was taken into Red Air Force hands under military intelligence supervision along with the skeletal airframe of the barely-started V3. The V3 was to have been the first Ju 287 to be made to pre-production model specifications, and the eventual EF-131 was almost identical to it in terms of overall design. The airplane was completed and briefly test flown in the Soviet zone of occupied Germany, before being dismantled and transported to GOZ-1 (Gosoodarstvenny Optnyy Zavod – state experimental plant), at Dubna near Moscow. OKB-1 at GOZ-1 was formed with Dr. Baade as the chief designer, and a very talented team of German engineers seconded by the Soviet government. Extreme pressure was applied to get the aircraft ready to appear in the 1947 Aviation Day fly-past at Tushino airfield, but several factors combined to prevent the EF-131 from appearing. Flight testing in the USSR began on 23 May 1947, at the LII airfield, after the airframe had been strengthened. The first flight resulted in the port undercarriage collapsing due to a bolt failure, subsequent flight tests revealed major deficiencies such as nose wheel shimmy and tail surface vibration. Rectification of the defects caused many delays but the worst delays were caused by bureaucracy when it was decreed that foreign workers could not work at the LII airfield. The aircraft sat at LII over the winter but the harsh conditions caused the deterioration of rubber components and wiring, which required lengthy repairs. Preparations for resuming flight tests were almost complete in June 1948 when Ministry of Aircraft Industry ordered that further work on the EF-131 be discontinued. The Junkers EF-131 had become obsolete as newer Soviet-built engines with better performance became available (Ref.: 24).
POWER PLANT: One BMW VI 7,3 Z liquid-cooled engine, rated at 750 hp
PERFORMANCE: 205 mph
COMMENT: The Heinkel He 51 was a single-seat biplane which was produced in a number of different versions. It was initially developed as a fighter, it was also developed as a ground-attack aircraft and a floatplane.
In 1931, Heinkel Aircraft Company developed the Heinkel He 49, officially an advanced trainer in fact it was a fighter. The first prototype flew in November 1932, and was followed by two further prototypes with a longer fuselage, and a revised engine. The type was ordered into production for the still secret Luftwaffe as Heinkel He 51, the first pre-production aircraft flying in May 1933. Deliveries started in July of the next year.
The He 51 was a conventional single-bay biplane, with all-metal construction and fabric covering. It was powered by a BMW VI engine, with an armament of two machine guns mounted above the engine. The He 51 was intended to replace the earlier Arado Ar 65, but served side-by-side with the slightly later Arado Ar 68. The He 51 was outdated the day it entered service, and after an initial run of 150 production fighters, the design was switched into the modified He 51B, with approximately 450 built, including about 46 He 51B-2 floatplanes. With begin of WW II the Heinkel He 51B-2 was only used in a role as trainer (Ref.: 24).
POWER PLANT: One BMW VI 6.0 liquid-cooled engine, rated at 660 hp
PERFORMANCE: 150 mph at sea level
COMMENT: The Heinkel He 60 was a reconnaissance floatplane designed for the German Kriegsmarine (German Navy) to be catapulted from warships of the 1930s.
The Heinkel He 60 was designed as a single-engined biplane of mixed wood and metal construction with fabric covering. Its single bay wings were of equal-span and had significant stagger.
The first prototype flew early in 1933 and proved to be underpowered with its 660 hp BMW VI engine. The second prototype had a more powerful version of the BMW engine, but this only marginally improved its performance and was unreliable, so production aircraft reverted to the original engine. Of conventional configuration, the He 60 was a sturdy aircraft, designed to be capable of operating on the open sea. As a result, it was always somewhat underpowered for its weight, which made handling sluggish and the aircraft vulnerable to enemy fire. Attempts were made to solve its lack of power by fitting one aircraft with a Daimler-Benz DB 600 engine, but engines were not available for production.
Initial deliveries of the He 60 were to Kriegsmarine training units in June 1933. From 1934, the major production version, the He 60C began to be delivered to the shipboard floatplane units of the Kriegsmarine, operating from the catapults of all German cruisers. It also saw action with Spanish Nationalist forces during the Civil War.
In 1939 it was replaced as a shipboard aircraft first by the Heinkel he 114 in service, then soon after by the Arado Ar 196, but it remained in service with several coast reconnaissance Staffeln (squadrons) when WW II began. It had been withdrawn from front-line service by 1940, but returned to use following Germany’s invasion of the Soviet Union in 1941, being used for coastal patrol work in the Baltic and Mediterranean Seas. All He 60s were removed from service by October 1943 (Ref.: 24).
POWER PLANT: One Nakajima Ha-44 radial engine, rated at 2,450 hp
PERFORMANCE: 442 mph at 39,370 ft (estimated)
COMMENT: In mid-1942, the Imperial Japanese Army Air Force wanted to obtain a high-altitude fighter fitted with a pressure cabin and capable of reaching a top speed of 497 mph and having a maximum range of 1,850 miles. As these performance requirements were rather stringent, the Koku Hombu decided to instruct Tachikawa to proceed with the design of the aircraft designated Ki- 94 while they placed a contract with Nakajima for another high-altitude fighter, the Ki- 87, with less stringent range requirements.
The initial aircraft was a large twin-boom monoplane with two engines mounted in tandem driving four-blade tractor and pusher propellers. But it was judged that the design was too complex and in 1943 Tachikawa submitted a new proposal to meet the same requirements as the competitive Nakajima Ki-87. The new aircraft was a single-engine high-altitude fighter of conventional design with laminar-flow wing and featuring a pressure cabin mounted in the fuselage behind the wing trailing edges. The aircraft was to be powered by a fan-cooled turbo-supercharged 2,400 hp Nakajima radial engine driving a six-blade propeller. This design was approved by the Koku Hombu, and the aircraft was designated Ki-94-II (the scrapped earlier Ki-94 design was named the Ki-94-I). An order was placed for one static test airframe, three prototypes, and eighteen pre-production aircraft. Only two prototypes were built in the event; the first was equipped with a single 2,541 hp Nakajima Ha-219 (Ha-44) engine, driving a four-blade propeller because the six-blade one was not ready. The second prototype was to be fitted with a six-blade propeller. The war’s end however stopped the construction of the second prototype and also found the first prototype still being readied for its intended maiden flight, the Ki-94-II never taking to the air (Ref.: 1, 24).
POWER PLANT: One Focke-Wulf T.1 radial turbojet engine, rated at 600 kp
PERFORMANCE: 515 mph at 29.530 ft
COMMENT: The Focke-Wulf 190TL was one of the earliest jet projects of the Focke-Wulf Company. First design studies began in 1941 on the basis of a standard Focke-Wulf Fw 190 fighter then in production. The original BMW 803 radial piston engine was replaced by a Focke-Wulf T. 1 turbojet engine. This comprised a two-stage radial compressor, an annular combustion chamber and a single-stage turbine. The exhaust passed through an annular outlet streaming around the surface of the fuselage. Further work on this project was cancelled in 1942.
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