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Junkers Ju.287

 

ju287-1


In 1943 the German Junkers company was given the task of designing a heavy bomber that would be faster than any contemporary Allied fighter. A swept-wing planform was essential to reach the speed required, and to overcome the disadvantages of a backward-swept wing, the Junkers design team proposed a wing swept forward. In theory such a wing should have the same effect as one swept back in reducing the effective thickness-to-chord ratio, but would have the highest lift coefficient at the root, decreasing outboard. The wing tips would thus be the last to stall, with aileron control available up to this point. An additional advantage of a forward-swept wing was that by freeing the centre portion of the fuselage of wing spars, it facilitated the provision of the large weapons bay called for in the bomber specification, around the centre of gravity.


To test such a wing full scale Ju 287-Vl was produced, under supervision of  Hans Wocke. To save time and money this aircraft utilised the fuselage of a Heinkel He 177A, the tail of a Ju 388 and nose wheels salvaged from a crashed Consolidated B-24 Liberator. The forward-swept wing, however, was representative of that of the intended bomber.


Power was provided by four Junkers Jurno 004B turbojets, two being attached to the sides of the fuselage nose and two being mounted under the wing. Two Walter 501 rocket units provided boost for take-off.


A forward-swept wing is structurally unstable; it reacts to increase the loads. As speed increased the forces eventually exceed the strength of the wing. To compensate for this divergence problem, as it is called, forward-swept wings have to be very strong in torsion to prevent any twisting that would lead to catastrophic loads.


An indication of the severity of this problem is that on the Ju 287-V1, to preserve the structural integrity of the wing, the main landing gear did not retract into the wing, but was fixed, the wheels being enclosed in fairings.


Seventeen test flights were made by the Ju 287-V1, the first one at Brandis, near Leipzig, on 16th August 1944, in the hands of Flugkapitan Siegfried Holzbaur. The flights proved the aerodynamic advantages of the wing planform; wing tufts confirmed the progressive wing stall from the root to the tip. Lateral control at low speeds was good. However, the trials also proved some of the problems predicted. Two of the most serious were a tendency for the aircraft to Dutch roll in reverse, and for the aircraft to increase g inadvertently during a turn, when the pilot was attempting a steady turn.


Despite the problems, work started on the definitive bomber, the Ju 287-V2, and final assembly was under way when the factory was seized by advancing Russian troops. The incomplete bomber was transferred to the Soviet Union, together with Hans Wocke and other key members of the Junkers design team, where it was completed and test-flown in 1947.

 

ju287-2

 

 

Ju 287 V-1
Max speed: 404 mph
 
Ju 287 V3
Engines: 6 x 800kg BMW 003A-1 turbojets
Max take-off weight: 21520 kg / 47444 lb
Empty weight: 11920 kg / 26279 lb
Wingspan: 20.11 m / 65 ft 12 in
Length: 18.6 m / 61 ft 0 in
Wing area: 58.3 sq.m / 627.54 sq ft
Max. speed at 16,400 ft: 856 km/h / 532 mph
Ceiling: 12000 m / 39350 ft
Range: 2125 km / 1320 miles
Crew: 4

 

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