Junkers Ju 287

Junkers Ju 287
	; Side view of the Ju 287 V1 (August 1944)
Type:	Four- or six-engine bomber
Design country:	German Empire
Manufacturer:	Junkers aircraft and engine works Dessau
First flight:	August 8, 1944
Commissioning:	Never put into service
Production time:	Was never mass-produced
Number of pieces:	2 prototypes

First Ju 287 prototype (Ju 287 V1) shortly before completion in Brandis in May 1944

Model of the Junkers Ju 287

The Junkers Ju 287 was a heavy medium to long-range bomber with a new type of negative swept wings. It was propelled by four or six jet engines .

The first of two completed prototypes made its maiden flight in 1944. A third prototype was in the early stages of construction at the end of the war. After the war, attempts were briefly continued in the Soviet Union.

development

When the first jet engines became available in Germany in 1942, the Reich Aviation Ministry (RLM) demanded the development of a bomber aircraft for medium and long-haul flights that would be far superior to Allied fighters in terms of speed. In early 1943, Junkers began developing such a bomber under the direction of technical director Heinrich Hertel and project manager Hans Wocke .

Wind tunnel model of the EF58, a very early preliminary design for the Ju 287

At around the same time, tests at the German Research Institute for Aviation (DVL) had been completed, which showed the advantages of swept wings compared to straight wings in the high-speed range . The swept wings caused no shock waves at high near-sound speeds, which were just as doomed for the American Bell X-1 as the Soviet BI-1 . Similar tests had also been carried out at Junkers , here with negative, i.e. forward-swept, wings. Compared to the positive swept wing, Junkers saw some advantages in the negative swept wing, which is why this was included in the development of the new bomber. The negative sweep has the advantage that the boundary layer does not migrate to the wing tip. In the case of positive swept wings, boundary layer fences were later installed to prevent the boundary layer from migrating and the resulting loss of lift.

The negative swept wing was initially planned as Project EF 116 for a relatively small, twin-engine photo reconnaissance aircraft. In September 1943, the project and thus the wings to be used were modified for the somewhat larger EF 122 bomber project. Junkers received the official construction contract together with the type designation Ju 287 in December 1943. In February 1944 the company received the information that two test models V1 and V2 are being procured for 3.3 million Reichsmarks and a further 18 pre-series models worth 20.5 million Reichsmarks should. In May 1944, however, the order was reduced to the two prototypes and six pre-production aircraft.

Arrangement of engines, start-up rockets and landing gear of the Ju 287 V1 (model)

In order to be able to test these new wings quickly, an improvised test vehicle was built with the Ju 287 V1 from parts of various existing aircraft types. The fuselage and cabin came from a Heinkel He 177 , the tail unit from a Ju 388 , the rigid aerodynamically lined landing gear from a Ju 352 and the two nose wheels from captured US American Consolidated B24 “Liberator” bombers.

Since the planned Jumo 004C were not yet available, the Ju 287 V1 was equipped with four Junkers Jumo 004 B-1 jet engines, each with 8.83 kN (around 910 kp) static thrust. Two engines each were hung on the side walls of the fuselage bow and under the center wing. In addition, four 1200 kg Walter 501 start -up rockets were installed under the engines, which were dropped after the start. Initially, the proposal to equip the machine with six BMW 003 A was also discussed .

The first flight with captain Siegfried Holzbaur took place on August 8, 1944 at the Waldpolenz airfield in Brandis near Leipzig , as the runways at the Junkers factory in Dessau turned out to be too short. At that time the aircraft was certified as having good flight characteristics. It reached a flight speed of 370 km / h. A total of 17 starts were reportedly carried out (only eleven occupied), the last on September 18th. The aircraft was then transferred to the Rechlin air force test site , mainly to carry out aerodynamic studies.

The flight characteristics and performance of the Ju 287 V1 proved to be excellent from the start.

Contours of a Ju 287 V2 with a fuselage of the Ju 288 and a 2x1 engine

Parallel to the tests, the V2 prototype was built with a new fuselage and retractable landing gear. Initially, two Junkers jet turbines, each with a thrust of 28.5 kN (around 2900 kp), were planned. Since these, like Heinkel HeS 011 engines, were not yet available, six BMW 003 engines combined into triplets with 7.8 kN thrust each were provided under the wings (triangle arrangement), which, however, was less favorable due to strong surface vibrations Maintenance options and low ground clearance proved problematic.

For the third prototype, the Ju 287 V3, the proven arrangement of the V1 with two engines on the fuselage and four under the wings was used. The V3 was given the hull of the Ju 288 with a pressurized cabin for a crew of three. The chassis was retractable into the fuselage. The rear armament was remotely controllable from the cockpit.

All work on the Ju 287 was stopped in September 1944 and the V1 and V2 parked in camouflage. In March 1945, however, the lock was lifted again and the construction of 75 machines for fighting ships at great distances was planned. However, the end of the war came before that.

The two damaged prototypes and other parts later made it to the Soviet Union , where two more aircraft were built and one of them was also completed. The Soviets then moved the engineering staff to Podberesje in the USSR, where the machines were tested under the designation EF 131 and EF 140 (including two modified Rolls-Royce-Nene engines ).

Apparently the tests were stopped in 1948 and the concept of negative wing arrowhead was not pursued any further. The reasons for this were vibrations of the wing tips and a pitching up of the wing tips. These bent upwards and uncontrollably increased the angle of attack on the outer wing. Since the angle of attack determines the lift and the pitching moment of a wing, this made it difficult for the pilot to control the aircraft.

Years later, developers of this aircraft constructed the jet airliner 152 in the German Democratic Republic and the VFW 614 and HFB 320 in the Federal Republic of Germany , the latter also with a negative wing sweep.

Junkers projects

A successor to the Junkers Ju 87 was developed under the designation Ju 287 by the end of 1942 . After the project was abandoned, the number 287 was reassigned.

A series of studies based on the Ju 287 were carried out at Junkers under the name EF for the jet engines under development.

EF 122: Wind tunnel model to investigate the optimal engine arrangement. Including with engines on the wings, as implemented later on the VFW 614 .
EF 125: Planned further development of the Ju 287 with only two jet engines under the wings.
EF 131: Further development of the Ju 287. A first test model was planned for early 1946; a total of three test machines should initially be built.

After Dessau was taken by Soviet troops, work was continued under their supervision from the summer of 1945, initially there and later in the Soviet Union. Six Jumo 004 B / C or BMW 003 A-1s were planned as engines, obviously again in the triangle arrangement.

Technical specifications

Parameter	Ju 287 V1
crew	1 pilot and 1 copilot
length	18.30 m
span	20.11 m
height	6.0 m
Wing area	58.30 m²
Wing extension	6.9
payload	approx. 3,000 kg
Empty mass	12,510 kg
Max. Takeoff mass	19,974 kg
Wing wing loading	215 kg / m²
Marching speed	511 km / h
Top speed	558 km / h
Service ceiling	approx. 11,000 m
Range	2,100 km
Max. Flight duration	4 h 10 min
Engines	4 × jet engines Junkers Jumo 004 B-1 "Orkan" with 8.83 kN static thrust each (approx. 910 kp)

literature

Horst Lommel: Junkers Ju 287. The world's first jet bomber and other swept wing projects . Aviatic, Oberhaching 2003, ISBN 3-925505-74-1 .
Manfred Franzke: Junkers Ju 287. The jet bomber of the Luftfwaffe and successor models EF 131 / EF 140. In: Airplane profiles. No. 65. Unitec, Stengelheim 2020.
Wolfgang Wagner: Hugo Junkers aviation pioneer - his aircraft . In: German aviation . No. 24 . Bernard & Graefe, Bonn 1996, ISBN 3-7637-6112-8 .
Heinz J. Nowarra : The German Air Armament 1933-1945 . Bernard & Graefe, Bonn 1998, ISBN 3-8289-5315-8 .
Tony Wood, Bill Gunston: The Air Force . Salamander Books Ltd., England 1977.

Web links

Commons : Junkers Ju 287 - Collection of pictures, videos and audio files

image
Detailed presentation with many pictures and sketches (French)

Individual evidence

↑ FlugRevue October 2009, pp. 100-103, high-tech in a hail of bombs - Junkers Ju-287
↑ Weekly report of the Rechlin testing center for the week from 6 to 12 August 1944
^ RLM: V-Muster-Programm, November 1942
↑ JFM AG: Appendix I of the supervisory and administrative board meeting of JFM AG on May 15 and 16, 1942
^ JFM AG: Quarterly report for the supervisory board of JFM AG - January – March 1942