The Ju-287 Junkers and its derivatives I. Design of Junkers 287 |
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The Ju-287 Junkers marked the result of a study of project carried out by Junkers in the intention to produce a heavy bomber with the performances higher than those of all the allied hunters present or future. The sweptback wing was becoming à.la.mode in Germany, following theoretical studies and of wind tunnel tests carried out by institutes of search. The idea first Junkers was a back sweptback wing, formula intended to become traditional. The development of Ju-287 is then started with the autumn 1942 by engineer Wocke. Because of aerodynamic considerations, Wocke decides to conceive Ju-287 with wings with opposite arrow. Various reasons justify this choice. The back sweptback wing has poor characteristics at low speed, which explains current flowering on the aerofoils of this type of a whole range of aerodynamic easy ways. Without these artifices, the aileron efficiency worsens towards low speeds because the airflows tend to run out transversely along the wing, the combination of the side flow and marginal unhooking having for practical effect to deny with this section of the wing any value like airfoil and of control surface. The engineers of Junkers thought of being able to surmount this obstacle by reversing the direction of the arrow. The end of wing was then the last section to be taken down and side control remained effective until the end. However, under the effort of a gust, a traditional sweptback wing tends to an inflection in which the trailing edge in the vicinity of the end of wing is curved to the top more that the leading edge. On this type of wing, the tendency to torsion remains within acceptable limits because the relative wind is opposed to it and tended to lower the trailing edge. On a reversed sweptback wing, it is the opposite. The leading edge tends to be raised more that the trailing edge, and the effect of the relative wind is to accentuate the tendency by making pressure under the under-surface, which increases torsion. When this phenomenon occurs, the wing undergoes an effort growing of torsion, to to be literally torn off fuselage. Of course, there are means of protection. One of most effective consists in suspending under certain key points of the wing of the masses which are opposed to torsion. The nacelles of the turbojets offer appreciable masses. Therefore Ju-287 it was conceived with nacelles largely spaced on the scale. Their inertia was opposed to the torsional stresses aerodynamic and protected -- it at least was hoped for -- the cell from the catastrophe. Several models were tested out of blower to obtain data on the wings with opposite arrow and the best position to be adopted for the reaction engines: |
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The final stage towards Ju-287 was the model of blower EF-122 which has the same aerodynamic configuration as Ju-287 V1. The last model of EF known for the development of Ju-287 is the EF-125. It seems that he was a model of blower for Ju-287 of series, but only equipped with two Jumo 012 or BMW 018. Its opposite wing has a scale of 19.40 meters. The EF-125 is very similar to the posterior EF-140. |
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Sources: I Soviet X-Plane of Y. Gordon & B Gunston. II Secret Lufwaffe Projects of D. Herwig & H. Rode. III Luft' 46. |
The Ju-287 Junkers and its derivatives |