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Aviation History
1935
1935 - 0336.PDF
i66 FLIGHT. FEBRUARY 14. i935 THE MODERN TREND How They Originated Some Sixteen Years Ago Representative Types ^TO^M Reviewed : The Vogue Spreads to Biplanes ALTHOUGH the first practical aeroplane had no wheels (we refer, of course, to the Wright Brothers' L machine, which was launched along a rail by the pull of a cable over a pulley in a short towei, a dropping weight providing the extra motive force), it was not long before the early designers introduced wheeled under carriages, and wheels have remained with us ever since, a necessary evil which many have come to accept as inevitable. Until a comparatively few years ago, when speeds were of the order of 100 m.p.h. or under, the drag of an undercarriage was of relatively small importance. As speeds increased and experience brought to light the vicious circle of trying to get more speed merely by " piling on power," the reduction of drag passed from being a desideratum to becoming a necessity. The undercarriage obviously presented one very fruitful field for improvement, and gradually the retractile under carriage came into being. It has now become firmly established, and a number of systems have been tried out, differing in detail but mostly falling into two general classes: those in which the wheels are swung upward in a longitudinal plane and those in which the movement is in lateral direction. With the former it is usual to find that a portion of the wheel projects beyond the surface of the structural member used for housing it. When lateral operation is employed, it is rather easier to " bury " the wheel completely, and in several instances wooden or metal discs and strips are employed for closing com pletely any small opening left between the wheel and struts and the surrounding surface. It is a matter of some difficulty to decide who was the first to employ a retractile undercarriage. Mr. James V. Martin, an American who was well known at Hendon in the early days of flying, certainly invented a retractile system and used it just after the war. In the Gordon Bennett Race held at Etampes, France, in 1920, a small monoplane built by the Dayton-Wright company cf America was entered and made some flights, although a broken rudder cable prevented it from competing in the race. That machine not only retracted its wheels into the fuselage, but also had variable-camber wings, so that neither idea is quite new! Various Types Equipped Obviously the aircraft most suited for the installation is the low-wing monoplane, in which the size and move ments of the working parts of the undercarriage are small, and which allows the wheels to be folded into the wing or engine nacelles. But high-wing monoplanes and biplanes have also been equipped. The Dornier Do.F and Fokker F.XX are examples of the former type, and the latter machines, in which the wheels, when retracted, are usually housed in the fuselage, are to be seen almost exclusively in the U.S.A. Considering monoplanes, it is apparent that the wheels may fold in a lateral or longitudinal plane, or with a " twisting " motion, although this last type is not yet in general use. Let us first consider the most usual form of undercarriage—that which folds longitudinally. •ssfi The Airspeed " Retractor " undercarriage folds longitudina^y(| dercarriage on a production aircraft, and is now fitted to ^ (Left) On the D.H. " Comet " racing monoplane the wheels retract rearwards into the engine nacelles.
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