NACA-TN-1245

Abstract

INTRODUCTION <br>The lateral-control research that had been conducted by the NACA prior to 1957, and that was summarized in reference 1, was concerned primarily with the design of lateral-control devices having sufficient effectiveness to enable the pilot of an airplane to keep the wings level at all normal flight speeds. In order to meet that condition large rolling-moment coefficients are required only at speed approaching the stall; consequently, the provision of adequate rolling performance is principally a problem of the size of the device, the aerodynamic balance being of only secondary importance even for moderately large airplanes. <br>Between 1937 and 1941 a study was made of the lateral-control characteristics of a large number of combat and noncombat airplanes, The results of that study, reported in reference 2, Indicated that the provision of lateral control that is sufficient only to keep the wings level is inadequate, and that a certain minimum standard of rolling performance is desirable for any type of airplane, even at high speeds. Subsequent experience has indicated that combat airplanes may be required to perform rapid rolling maneuvers near maximum speed the problem of providing aerodynamic balance for light control forces at high speed therefore has become at least as important as the problem of providing adequate effectiveness of the lateral-control device. <br>In order to meet the requirements for light control forces the designer has the choice of relying entirely either on aerodynamic balance or on some form of booster mechanism, or of combining a booster mechanism of low capacity wit a small amount of aerodynamic balance. In any case, the control forces of fighter airplanes of average size may have to be reduced by amounts corresponding to as much as 95 percent of the unbalanced aileron hinge moments (reference 3). Some of the considerations relating to the provision of light control forces, as well as to other lateral-control problems, are discussed in reference 4. <br>The purpose of the present paper is to summarize rather completely the available information on lateral control, to point out the limitations of the available information and to indicate some of the problems that remain to be solved. No new investigations were attempted in preparing the present paper, although some of the data and analyses have not previously been published. <br>The symbols used in presenting the results are defined in the appendix. Figures that give data for use in design are listed in table I