The Junkers Ju 287 was a revolutionary design for a fast jet bomber with swept-forward wings that flew in prototype form before the end of the Second World War.
Work on the basic design began at Junkers in June 1943, and was led by Hans Wocke. By the mid 1930s it was widely understood that aircraft with straight wings had a built-in speed limit, imposed by air compression at the leading edge. The eventual solution would be the swept-back wing, but that was still in the future in 1943. The Me 262 had a wing with a swept back leading edge, but a generally straight trailing edge, while the Ar 234, which made its maiden flight on 15 June 1943, had a straight wing and could go no faster than the best Allied aircraft.
It was known that a swept back wing would reduce compressibility. Dr Wocke believed that a swept-forward wing would have even more advantages. In most circumstances it would increase stability in flight, especially at low speeds. It would also mean that the central part of the wings would stall (stop providing lift) first, so the controls, on the outer part of the wings, would remain effective for longer. As a side benefit the design also gave more room for the internal bomb bay.
Wocke's timing was good. In November 1943 Siegfried Kneymeyer became Chief of Technical Air Armament at the RLM. He wanted to cancel all work on conventional bombers (apart from the Ju 88) and instead focus all efforts on high speed jet aircraft. He believed that it would be possible to produce aircraft that had a 150km/h (93mph) speed advantage over any enemy fighters, and that this would help compensate for the Allies' superior numbers.
In March 1944 Junkers were given a contract to produce a prototype of the new bomber. The first aircraft, Ju 287 V1, was to be a flying test bed produced from as many existing components as possible. The resulting aircraft used the fuselage from a He 177A, the tail from a Junkers Ju 388, the main wheels from a Ju 352 transport aircraft and the nose wheel from an American B-24 Liberator. The revolutionary wings would be the only major new component.
The V1 was to be used for low and medium speed trials to prove the basic concept, and so it was given a fixed undercarriage and was powered by four Jumo 109-004B-1 turbojets, each providing 900kg/ 1,980lb of thrust. Two of the engines were mounted under the wings, and two were placed on either side of the forward fuselage, close to the nose.
Junker's own airfield wasn't long enough to test the Ju 287, and so it made its maiden flight from Brandis airfield on 16 August 1944. Even then the aircraft needed four Walter 109-501 jettisonable rocket units, one under each wing, to help it leave the ground.
Initial flight tests were generally successful. The aircraft didn't do anything unexpected in flight, although two problems were encountered. When yawing (turning around the vertical axis), the wing on the inside of the yaw would trail slightly behind the outer wing, generate extra lift, leading to a tendency to roll. More seriously, when the aircraft was taken into a tight high-speed turn the wings flexed, tightening the turn.
After these encouraging results work began on the second prototype, with a new purpose built fuselage, tail and retractable landing gear. The V2 was to have a fuselage with a bulged and fully glazed nose, and was to have been powered by six BMW 109-003A-1 turbojets, each of 800kg/ 1,760lb thrust. This time four engines were to be mounted under the wings and two by the nose. The same engines were to be used on the A-0 pre-production and A-1 production aircraft. The engines on the wing were to be moved further forwards in an attempt to solve some of the problems with the V1.
In July 1944 Hitler issued a directive that initiated the Reichsverteidigungs programme, which focused all future development work on fighter aircraft. Limited work continued on the V2, but at a very slow pace.
In March 1945, as the Allies closed in on Germany, the RLM (German Air Ministry) decided to order the Ju 287 into production! Work resumed on the V2, and on the V3, which was to have featured a pressure cabin, a remote controlled tail gun and be capable of carrying an 8,820lb bomb load. Work also began on the B-1, which was to be powered by four Heinkel-Hirth 109-001A-1 turbojets (1,300kg/ 2,866lb thrust each) and the B-2, which was to be powered by two engines, either the Jumo 109-012 (2,780kg/ 6,130lb of thrust each) or the BMW 109-018 (3,400kg/ 7,497kg of thrust). In another sign of the unrealistic atmosphere inside the Third Reich these engines were themselves not completed.
Two months later the V1 and the V2 and a number of Junkers engineers were captured by advancing Soviet troops and taken back to the Soviet Union. Test flights resumed with the V1, while the V2 was completed but with swept back wings. It is said to have reached a speed of 620mph before the programme was halted in 1948.
Dr Wocke retained his belief in the swept-forward wing, and after the war produced the Hamburger Flugzeugbau HFB 320 Hansa executive jet using the same system.
Engine: Four Jumo 109-004B-1 turbojets
Power: 900kg/ 1,980lb of thrust
Wing span: 65ft 11 ¾ in (20.11m)
Length: 60ft 0 ½ in (18.3m)
Empty weight: 27,557lb
Maximum loaded weight: 20,000kg
Max Speed: 347mph at 19,685ft
Service Ceiling: 35,425ft
Range: 932 miles
V-3 (some estimated date)
Wing span: 65ft 11 ¾ in (20.11m)
Length: 61ft 0 ¼ in (18.6m)
Empty weight: 26,278lb
Maximum loaded weight: 47,450lb
Max Speed: 537mph at 16,400ft without bomb load
Cruising Speed: 493mph at 22,960ft
Service Ceiling: 39,360ft
Range: 1,320 miles with half bomb load, 985 miles with full bomb load
Bomb-load: 8,820lb/ 4,000kg