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Aviation History
1942
1942 - 1483.PDF
JULY TOTH, 1942 FLIGHT S3 THE B.V. 141 determination of the late Gen. Udet that he at once appreciated the pos sibilities in the new development suggested. As no one could assume that it would be possible to build such a peculiar type quickly, that is without considerable modifications, the usual requirements concerning urgency were waived. It is one of the prettiest and, in aircraft construction, one of the most rare triumphs of technical thought that we were able to begin test flights one year after receiving instructions to build the machine; a few weeks later we could hand it over to the authorities for testing. All our guesses proved right, and special troubles with reference to the asymmetry were not encoun tered. From the performance point of view all who had to compare the machine with conventional develop ment were surprised. Tne flying characteristics of the tyr^e were so satisfactory that "general Udet was able straight away to make rolls, loops and other evolutions. Perhaps it might be interesting, in this connection, to make com parison with the contemporary English type in 'which also excellent view was aimed at: the Lysander. This machine had approximately the same engine power but was of smaller dimensions, and only a two-seater but without the greenhouse of our BV 141 Structural details of the BV 141. In the upper photograph the shell of the inner wing portion is shown without the single tubular spar. This, however, is in place in the lower picture of the outer wing portion in its assembly jig. Lysander and BV 141 Compared Lysander BV141 A. Airframe Power plant .. Crew Fuel Use Jul load .. kg- • 1.055 .. 785 200 33o 310 lb. 2,320 i.73o 440 726 684 kg. 1,640 1,030* 300 400 460 lb. 3,600 2,268 660 880 1,012 2,680 5,900 3,830 8,420 Loaded weight Speed at 3,500 m.— **/ (11,500ft.) 368 km./h. (22Sm.p.h.)388km./h. (241 m.p.h.) Initial rate of climb— 8.4 m./sec. (1,650 ft./min.) 9,5 m./sec. (1,860 ft./min.) * This figure includes self-sealing tanks; the Lysander did not have these. The Lysander has a wing area of 24 sq. m. (258 sq. ft.); the BV 141 43 sq. m. (463 sq. ft.). Lysander wing loading 22.9 lb./sq. ft.; BV 141 wing loading 18.2 Ib./sq. ft. These figuies show the superiority of the asymmetrical aircraft. During further tests certain new* information came to light from the point of view of armament and operational considerations. The view and field of fire from the tail end of the nacelle were exceptional. The interruption by the lop-sided fuselage was more than made up for by the free field of fire through the most dangerous defence sectors. In this connection it should not be forgotten that turning of the aircraft around the longitudinal axis, that is rolling, is one of the most easily executed tactical manoeuvres, since neither direction nor height has to be changed. (In order to bring the attacker into the field of fire.—ED.) I An attack from the side blanketed by the fuselage can ' therefore be defended much more easily than an attack from the blind spot caused by the tail in conventional tail defence. However, in the course of our tests we went a step farther and cut away the right tailplane, which pro jected into the field of fire from the tail of the nacelle, and thus obtained a further improvement. It was a very pleasant experience to find a combination of effects which not only improved the field of fire but the stability. We found it possible to retain trie same stability without increasing the tailplane on the left to compensate for that cut off on the right. It is even possible to use this experience in normal single-engined aircraft by using an unsymmetrical tail so as to get it partly out of the slipstream. More Power When the experiments had been concluded we received an order to develop a new aircraft type, the BV 141B, to take the more power ful engine, the BMW 801, needed to fulfil the requirements that had grown more severe in the mean time. With this new type a con siderably increased performance was attained, a fact which increased the possibility of using the machine operationally on special duties As regards the design, the follow ing may be mentioned. Since the general problems had already resulted in a radically new solution, it will be appreciated that in the narrower problem of view, etc., everything was done, in the way of shapes and com ponents, transparent coverings, equipment and armament, to facilitate the work of the observer in accordance with all the latest ideas. The observer sits on the right, by the side of the pilot, and has ample room to movp; his seat is adjustable fore and aft, and his equipment is placed within easy reach around him. The fuselage is built as a stressed-skin shell right back to the tail. As there are no uncovered cut-outs, it has proved very stiff in spite of its low weight. The wing shows the single tubular spar familiar from all B. and V. aircraft. With the numerous wing cut-outs in this machine (two fuselage cut-outs and two for the undercarriage) the tubular spar has proved a reliable structure member In the construction of the wing an interesting innovation has been introduced. The whole wing profile, with the excep tion of a strip on the underside for the insertion of the tubular spar, is manufactured as a finished unit. This facilitates assembly in quantity production as well as replacement in case of damage. Control Surfaces Ailerons are fitted on the outer wing portions only ; they have inset aerodynamic balances, and are also carefully mass-balanced. On the inner wing portions are mounted simple split landing flaps, which are hydraulically operated. The asymmetrical tail is carried on a "neck" growing from the fuselage. On the projecting side the tail is braced by a single strut. The centrally placed fin and rudder are continued downwards as far as possible so as to bring a large area into the airscrew slipstream. An undercarriage of very wide track is used in order to give good control on the ground (the offset thrust being balanced by a strong braking moment in opposite direc tion). In any case this swing only arises on rare occasions, (Continued at foot of next page.)
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