Junkers Ju 287 V1

Junkers Ju 287


The Junkers Ju 287 project originated as part of studies conducted to create a heavy bomber that would outperform not only current but also future fighters of potential adversaries. The use of the arrow wing was a bit of a fashion in Germany anyway, and by this time was being worked out in fairly solid theoretical works.


The idea of the forward arrow became typical for this company. The development of the Ju 287 began in the autumn of 1942 under the direction of Ing. Wocke. Ing. Wocke promised a number of advantages from the forward arrow - improved flight characteristics at low speeds, better airflow on the wings, which in the "classical" arrow was solved by massive aerodynamic fins, improved efficiency of the ailerons … At the same time, he expected that the flow behind the wing so shaped should not so significantly affect the efficiency of the tail surfaces. The aircraft was also to receive jet engines, which promised higher speeds than conventional propulsion.


The design work was accompanied by both careful theoretical calculations and a series of experiments with blowing models and individual parts in an attempt to achieve the best possible results.


The development was very complicated, with different wing shapes and angles, combinations of different numbers of engines and their placement. Models for the wind tunnel played a key role. The models were designated EF (Entwicklungsflugzeug, i.e. experimental aircraft) and about 12 were built -


The EF-55 : an unpowered monoplane, designed for research on the characteristics of the forward wing
arrow
EF-56 : unpowered monoplane with a conventional arrow wing
EF-57 : unpowered monoplane with a forward arrow wing, V-lift
EF-58 : monoplane with forward arrow, oval wings, engines under wings
EF-59 : 2 engines under fuselage, 2 under wings behind trailing edge
EF-66 :forward arrow, 2 engines under wing - followed by EF 122
EF-67 : 2 engines in fuselage
EF-68 : designed specifically for research on different engine locations
EF-116: another model for research on the arrow wing
EF-122 : final form of the development series, best results, expected model for
construction of the actual Ju-287 V1 prototype.
EF-125 : last known model version, similar in concept to the V3 prototype and the EF-140 type


Probably there was also a production model for blowing, i.e. the Ju 287in actual size, intended for aerodynamic tests, carrying 2 Jumo 012 or BMW 018 engines. Wingspan 19, 40 m.


The EF-125 was very similar to the later EF-140. Careful work with the models allowed a relatively rapid progress of prototype construction. The Ju-287-V1 was designed to verify the wing configuration of the EF-122.


At the beginning of 1943, a group around Prof. Hertel started work. It is a well-known story that in order to build the first Ju-287 prototype (RS+RA) as quickly as possible, a number of already finished parts from other machines were used - the fuselage from a Heinkel He177A-3, the tail section from a Junkers Ju-188 G-2, the landing gear even from a downed American B-24 from Convair's licensed production.


RLM ordered a total of 6 prototypes:
Ju-287-V1 = 1st prototype
Ju-287-V2 = identical to V1.
Ju-287-V3 = the most famous. Fuselage from the Ju-288, 2 nacelles under the wings with a trio of BMW 003 A1 engines, one under each wing. Very similar to the EF-131 developed in Russia with six RD-10 engines.
Ju-287-V4 = Identical to the V3.
Ju-287-V5 = Identical to the V3, tested with a machine gun turret on the aft fuselage.
Ju-287-V6 = Matched to V5.


The wing had a negative angle of 19.9° of the spars, the trailing edge angle was -23.5°, and the span was 20.10 m with a 58.30 m2 wing area. This wing carried 2 Jumo 004B-1 engines, but the huge experimental machine needed additional power units. Therefore, 2 more engines were hung on the fuselage sides at the nose. As even this power was not enough for take-off, the prototype was given Walter HWK 501 rocket launchers with 500 kgp thrust, suspended under the underwing nacelles of the jet engines. These rocket motors were discarded after launch.


The prototype was tested at Leipzig-Brandis Airport, as the runways at Dessau were too short. On 16 August 1944, just shortly after the world's first Ar-234 jet bomber, pilot Siegfried Holzbaur made the first flight of the Ju-287 V1. The flight tests were successful and confirmed the concept's practical applicability. The machine behaved very well both in standard flight modes and in slow flight, including landing. After 17 flights were conducted from Brandis, the prototype was moved to Rechlin test base.


However, the designers were dissatisfied with the speed achieved; the top speed of Mach 0.7 did not match the calculated Mach = 0.85. The Rechlin researchers assumed that by using more powerful power units, the machine would reach Mach = 0.92. This required - among other things - the installation of braking parachutes to reduce the landing speed.
During the construction of the second prototype, RLM initially decided to stop the program, but later - in March 1945 - the decision was reconsidered and RLM ordered a stocus series. The manufacturer was to be Allgemeine Transportanlagen GmbH in Leipzig. The serial machines were to be equipped with Jumo 012 engines.


In January 1945, a Ju-287 V1 was photographed at Rechlin by an RAF reconnaissance Mosquito. An air raid followed, during which the Ju-287 V1 was severely damaged. By the end of the war, research work continued with both the repaired V1 and the completed V2, and especially with the V3, which was already a newly built prototype from the ground up, intended as a prototype for series production flight trials. The V4 prototype was to be used for ground static tests.


At the end of the war, many of the machines and their creators fell into the hands of the Red Army and development moved to the USSR. See https://www.valka.cz/topic/view/9421/


Sources:
www.arms.ru
http://xplanes.free.fr/

Junkers Ju 287 V1 detail

A few images from the http://prototypes.free.fr ..

Jen tak pro zajímavost. Na Aubiho fotografii jsou dobře vidět malé proužky látky (někdy kousky popruhů či silnějšího papíru) používané pro výzkum aerodynamického proudění na letounech. Obvykle byly snímány filmovou kamerou či fotoaparátem.