Junkers Ju 287

The Junkers Ju 287 was an aerodynamic testbed built in Germany to develop the technology required for a multi-engine jet bomber.

It was powered by four Junkers Jumo 004 engines, featured an unusual and novel forward-swept wing, and apart from the wing was assembled largely from components scavenged from other aircraft.

It was one of the very few jet-propelled aircraft ever built with fixed landing gear.

The Ju 287 was intended to provide the Luftwaffe with a bomber that could avoid interception by outrunning enemy fighters.

The swept-forward wing was suggested by the project’s head designer Dr. Hans Wocke as a way of providing extra lift at low airspeeds necessary because of the poor responsiveness of early turbojets at the vulnerable times of take-off and landing.

A further structural advantage of the forward-swept wing was that it would allow for a single massive weapons bay in the best location, the centre of gravity of the plane, with the main wing spar passing behind the bomb bay.

The same structural requirement meant the wing could then be located at the best aerodynamic location, the centre of the fuselage.

Prior to the assembly of the first Ju 287, an He 177 A-5 (designated as an He 177 prototype, V38) was modified at the Letov plant in Prague to examine the technical characteristics of this single large bomb bay design.

The fixed undercarriage was used as the wing box couldn’t have cut-outs for wheel stowage which would reduce wing torsion box stiffness required for the forward sweep design.

Later prototypes with higher power engines and higher top speed would have the undercarriage stowage in the centre fuselage sides 

Two of the Jumo 004 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 in-flight 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 with under wing engines moved forward under leading edge as a mass balance. 

The 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 prototype (Junkers Ju 287 V2) would have had six engines (originally four underwing BMW 003s and two fuselage-mounted Jumo 004s, but later changed to two triple clusters composed of four Jumo 004s and two BMW 003s), and also differed from the Ju 287 V1 in having the main undercarriage struts with an inward cant, the horizontal stabilizer lowered by 30 centimetres, and light grey-coloured trouser pants for the nose wheels.

The third prototype, the Junkers Ju 287 V3, employed six BMW 003s, in a triple cluster under each wing, and featured the all-new fuselage and tail design intended for the production bomber, the Ju 287A-1, utilizing a pressurised cockpit used on the Junkers Ju 288.

The Ju 287 V4 and V5 would have served as prototypes of the Ju 287A-2 and Ju 287B-1 respectively, and the V5 and V6 were to feature tail armament and ejection seats.

The Ju 287B-1 would have had four 1,300 kg (2,900 lb) thrust HeS 011 turbojets, while the Junkers Ju 287B-2 was to employ two 3,500 kg (7,700 lb) thrust BMW 018 turbojets.

While the Heinkel turbojet was in the pre-production phase at war’s end, work on BMW’s radical and very powerful turbine engine never proceeded past three barely tested prototypes.

The final Ju 287 variant design to be mooted was a Mistel combination-plane ground attack version, comprising an unmanned explosives-packed “drone” 287 and a manned Me 262 fighter attached to the top of the bomber by a strut assembly.

The cockpit of the 287 would be replaced by a massive impact-fused warhead.

Take-off and flight control of the combination would be under the direction of the 262’s pilot.

The 262 would disengage from the 287 drone as the Mistel neared its target, the pilot of the fighter remotely steering the 287 for the terminal phase of its strike mission.

Work on the Ju 287 programme, along with all other pending German bomber projects (including Junkers’ other ongoing heavy bomber design, the piston-engined 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 components for the Junkers Ju 287 V2 had been completed by that time and were shipped to Brandis for final assembly. Seventeen test flights were undertaken in total, which passed without notable incident.

Minor problems, however, did arise with the turbojet engines and the equally experimental HWK 109-501 higher thrust (14.71 kN apiece) bipropellant Starthilfe 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 one occasion, attaining a speed in the medium dive-angle employed of 660 km/h.

To gain data on airflow patterns, small woollen tufts were glued to the airframe and the “behaviour” of these tufts during flight was captured by a cine camera mounted on a sturdy tripod directly ahead of the plane’s tailfin.

After the seventeenth and last flight in late autumn of 1944, the V1 was transferred to the Luftwaffe’s primary Erprobungsstelle evaluation and test centre at Rechlin, for flow tests.

However, in March 1945, for unknown reasons, the Ju 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.

Variants

Ju 287 V1 (cover designation Ju 288 V201)

First prototype, technology demonstrator with fixed landing gear, fuselage taken from He 177A-5, tail empennage taken from Ju 188G-2, and 4 x Jumo 004B engines.

Ju 287 V2 (cover designation Ju 288 V202)

Second prototype; similar to Ju 287 V1 in overall layout, but with tail wheel removed, horizontal stabilizer lowered 12 inches (30 centimetres), and inward main undercarriage braces; originally intended to utilize 4 x BMW 003s in under wing pairs and 2 x Jumo 004Bs mounted on the sides of the fuselage, but engine configuration later changed to utilize two under wing triple pack configurations composed of 2 x Jumo 004Bs and 1 x BMW 003.

Virtually complete when Ju 287 program halted in late 1944, but not flown.

Ju 287 V3

Third prototype intended prototype for Ju 287A-1; fuselage based on that of the Ju 288, fully glazed, pressurized cockpit accommodating three crewmembers; retractable landing gear, no provision for armament, and 6 x BMW 003 engines mounted in two triple pack configurations under the wings.

Approximately 80% complete by war’s end.

Ju 287 V4

Fourth prototype intended prototype for Ju 287 A-2; layout similar to Ju 287 V3 except in having 6 x Jumo 004Cs (4 mounted in under wing pairs, 2 mounted on the sides of the fuselage); reportedly 60 percent complete on the eve of Allied takeover of Junkers factory at Dessau.

Ju 287 V5 & V6

Armed prototypes equipped with ejection seats and an FHL 131/Z turret with two MG 131 machine guns; V5 intended as prototype of the Ju 287 B-1.

Ju 287 A-1

Production version based on Ju 287 V3 with operational equipment and FHL 131/Z turret featuring two MG 131 machine guns: no ejection seat.

Ju 287 A-2

Production version based on Ju 287 V4 with operational equipment and FHL 131/Z turret featuring two MG 131 machine guns: no ejection seat.

Ju 287 B-1

Production version based on Ju 287 V5 with operational equipment, FHL 131/Z with two MG 131 machine guns, and larger nose wheels: no ejection seat.

Ju 287 B-2

Variant similar to baseline production Ju 287 but powered by either two Junkers Jumo 012 or BMW 018 turbojets mounted under the wings.

EF 131

Similar to production Ju 287 but with fuselage stretched by 8.2 feet (2.5 meters) and two under wing triple packs of RD-10s.

Specifications

Ju 287 V1

Crew

Two

Length

18.30 m (60 ft 0 in)

Wingspan

20.11 m (66 ft 0 in)

Height

4.70 m (15 ft 5 in)

Wing area

61 m2 (660 sq ft)

Airfoil

Root

Ju 0.9 23 10.7-0.825-40.

Tip

Ju 0.9 23 12.7-0.825-40

Empty weight

12,500 kg (27,558 lb)

Gross weight

20,000 kg (44,092 lb)

Powerplant

4 × Junkers Jumo 004B-1 turbojet engines,

8.825 kN (1,984 lbf) thrust each

Performance

Maximum speed

558 km/h (347 mph, 302 kn) at 6,000 m (19,685 ft)

Cruise speed

512 km/h (318 mph, 276 kn) at 7,000 m (22,966 ft)

Range

1,570 km (980 mi, 850 nmi)

Service ceiling

9,400 m (30,800 ft)

Rate of climb

9.67 m/s (1,904 ft/min).