NACA-RM-A50J26

Abstract

INTRODUCTION <br>In an effort to surmount the problems which arise with flight at transonic or supersonic speeds, many unconventional wing plan forms have been proposed. One of these, the delta or triangular wing, has shown considerable promise and therefore has been the subject of extensive theoretical and experimental investigations. One of these theoretical investigations (reference 1) has shown that, over certain Mach number ranges and for certain center-of-gravity positions, dynamic instability in the form of negatively damped oscillations of the short-period pitching motion is to be expected. A later paper (reference 2) presented a similar theoretical result. <br>Since the theory is based on linearized equations for the flow of an inviscid fluid, it is possible that second-order thickness and viscous effects my significantly alter the results. Further, the theoretical treatments are for quasi-stationary flow (reference 2), that is, for relatively slow oscillations. <br>In view of these limitations of the theory, an investigation has been undertaken in the Ames 6- by 6-foot supersonic wind tunnel for the purpose of determining the accuracy of the theory in predicting the dynamic behavior of wings and wing-body combinations in flight. The present report is devoted to an experimental investigation of the damping of single-degree-of-freedom pitching oscillations of triangular wings and wing-body combinations about a lateral axis lying within the wings. The report includes the results of a similar limited investigation made at subsonic speeds in the Ames 12-foot pressure tunnel employing one of the models used in the investigation at supersonic speeds.