Flight tests of retractable ailerons on a highly tapered wing

Wetmore, J W
naca-tn-714
June 1939


A flight investigation was conducted to determine the lateral-control characteristics of retractable ailerons installed on a highly tapered wing. The effectiveness of the ailerons in producing roll was measured at various air speeds with full-span plain flaps both neutral and deflected 45 degrees. The direction of the yawing moment created by the ailerons was also noted. The lateral control provided by the retractable ailerons used in this investigation was approximately the same as that obtained with the plain ailerons of equal span with which the airplane was previously equipped. The amount of control available was found to be somewhat inadequate, apparently because of the rather short span of the ailerons (0.327 of the wing span). It is likely that, with an aileron span of from 0.50 to 0.60 of the wing span, a satisfactory degree of control would be obtained. With the full-span flaps deflected 45 degrees, the rolling action of the ailerons was increased about 30 percent over that obtained with the flaps neutral at the same speed. The yawing moment produced by the ailerons was in the same sense as the rolling moment, i.e., right roll was accompanied by yaw. Lag in the response of the rolling action to control application was not large enough to be noticed by the pilots. No appreciable control force was apparent to the pilots, which was considered somewhat undesirable. Minor modifications in the design of the ailerons, however, would probably correct this fault.

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