NACA-RM-A7L02

Abstract

INTODUCTION <br>Considerable control-surface research has been conducted during the past decade and may attempts have been made to derive theoretical and empirical relations which will permit the aerodynamicist to predict control-surface characteristics with a reasonable degree of accuracy. The bulk of this effort and the major part of the available information, however, has been concerned with the low-speed, incompressible characteristics of control surfaces. (See references 1 through 8.) An urgent need exists for dependable information which can be used in the design of control surfaces for use at high speed. There have been repeated instances where control surfaces for use at high speed. There have been repeated instances where control surfaces satisfactory for low-speed use were unsuitable for high-speed use. <br>Because of the large number of factors involved, prediction of control-surface characteristics at high speed is often more difficult than the prediction of the characteristics of a wing. The lack of a suitable theory accounting for the effects of compressibility, separation, gap, surface discontinuities, and many other variables affecting control-surface characteristics has resulted in the widespread use of experimental data as the best guide. Unfortunately, most high-speed wind-tunnel investigations conducted during the past few years were directed toward the development or improvement of specific tactical airplanes and systematic high-speed control-surface research has been initiated only recently. The present report combines the extensive high-speed control-surface data obtained from many unrelated investigations with more recently obtained results and includes a discussion of the general high-speed control problems.