POWER PLANT: Four Junkers Jumo 004C-1 turbojet engines, rated at 1,020 kp thrust each
PERFORMANCE: 509 mph
COMMENT: This Blohm & Voss jet bomber project was designed to carry a great bomb load and enough fuel for long distance operations. There were four different designs, P.188.01 to P.188.04. Common to all was a rather wide fuselage center section – except for the Bv P.188.04 whose fuselage was slender – designed as an armored steel shell and located in the center of gravity. This caused a special arrangement of the landing gear in all projects with twin main wheels in tandem with an auxiliary outrigger landing gear outboard from the wings. Very unusual was the W-type layout of the wings. These had a constant 3 degree dihedral with the inner section swept back to 20 degree and then a 20 degree swept forward outer section. This was calculated to give good performance at both low and high speeds. The only drawback was excessive air pressure on the wing tips, which was to be corrected by a variable incidence system which could be adjusted through 12 degrees. An advantage of this arrangement was the fact that the fuselage was constant horizontal during take-off and landing. The crew sat in a pressured, extensively glazed cockpit. Four Junkers Jumo 004 C-1 turbojets were mounted in four single nacelles, two beneath each wing, again except for the Bv P.188.04 where two engines were combined in one nacelle on each side. Both designs of the Bv P.188.01 and Bv P.188.03 had a single fin and rudder design and an airbrake at the tail, while the Bv P.188.02 and Bv P.188.04 were of a twin fin and rudder design, with a dihedral tail-plane and the extreme tail had a remote-controlled FDL 131 Z twin 13mm machine guns firing to the rear. All these futuristic designs remained on the drawing boards (Ref.: 17).
POWER PLANT: Six BMW 003 turbojet-engines, rated at 850 kp each
PERFORMANCE: 510 m.p.h.
COMMENT: Besides four “Strahljägerprojekte I – IV” (Jet fighter projects I – IV) the BMW company worked on designs of two “Strahlbomberprojekte I and II” (Jet bomber projects I and II). Strahlbomberprojekt I was a tailless design, but in order to achieve sufficient stability a tail boom with fin was installed. Six turbojet-engines were planned, four in the wing roots and two aside the cockpit. Project not realized.
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 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).
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