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Aviation History
1946
1946 - 2270 - 0296.PDF
FLIGHT DECEMBER IQTH, 1946 Tailless Experimental ^Aailplane with Two Rolls - Royce Nenes: Many Advanced Features HE last weeks of 1946 will see the completion of the most advanced aircraft to be constructed in this country. Built to Specification E.9/44 and directly following the A.W.52 experimental glider (described in Flight of May 9th) this mailplane, apart from its very modern swept-back design and pure jet propulsion, em- bodies most of the latest features which have hitherto pro gressed little further than the drawing-board stage. It has, for example, boundary layer control by suction, thermal de- icing, a pressurized crew compartment, and steerable nose wheel. In layout and proportions the A.W.52 is very similar to the 52 glider from which a great deal of information on control and stability has been obtained. The fact that 1 Left) An inset wheel inthe main control column will operate the steer-able nosewheel through a servo motor. (Right)The adjustable rudder pedals also carry toe-operated brakes the experimental glider has remained virtually unchanged, and that the mailplane is practically a scaled-up version, is a credit to Mr. J. Lloyd and his design staff for the accuracy of their original conception. The unusual control system employing correctors, controllers and tabs, together with vertical wing-tip rudders, is also retained. Details o! the principle of these controls and of their pressure-sealed balancing were included in our description of the A.W.52 glider, and further new diagrams appear on later pages. Removal by suction of the boundary layer on the outer wing surface, just ahead of the controls, was another feature tried out on the glider. Two small fans on the undercarriage legs drove vacuum pumps for the purpose. On the mailplane this system is now largely under auto matic control due to interconnection with the throttle controls of the Rolls-Royce Nene turbo-jets from which the suction is derived. Wing1 Factors Removal of the boundary layer does .not alter the stalling speed of the aircraft appreciably, but it does delay con- siderably the loss of control due to the stalling of the wing tips carrying the control surfaces. This tendency to early wing tip stall is, of course, a weakness of the swept-back wing and is one reason for investigations of forward-swept wing characteristics. Forward sweep provides some of the good high-speed features of swept-back wings without the defect of early wing-tip stalling. No attempt has been made with the 52 to provide a thin wing for high Mach numbers and the t/c ratio is 18 per cent. Fundamentally the wing construction is designedto provide a smooth surface giving laminar flow to 0.55 l N.P.L. aerofoil section 655-3-218 is used at the wing and at the knuckle and tip, N.P.L. 655-3-118 and 645-3-015 respectively. As on the glider, the sweep back on the lead- ing edge is 35 deg., although projects under consideration will no doubt have greater sweep back and approximate 'more nearly to Delta shape. Provision of reasonable fore-and-aft stability, always a major problem with tailless designs, entails the fitting of devices to prevent early stalling. Slots are not to be recommended with a true laminar-flow wing, so for this reason boundary-layer suction was employed. Ultimately, for turbine-powered aircraft, one foresees the design with no engine air intake as such, but with compressors draw- ing all their air from the wing surfaces. The loss of power to be expected due to lack of ram effect would not, in fact, be important if the performance of the aircraft as a whole
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