NACA-RM-A54H27

Abstract

INTRODUCTION <br>The target-pursuit maneuvers or programmed trajectory of guided missiles frequently require flight at large angles of attack (of the order of 30&#176;), particularly at high altitudes. Limited experimental information at supersonic speeds indicates that the aerodynamic characteristics of missile configurations at such angles can be significantly different from those at small angles and that existing theoretical methods (based on small angle-of-attack considerations) can be inadequate for the prediction of these characteristics. These methods have been shown in references 1 and 2 to predict satisfactorily the lift and pitching-moment characteristics of a wide variety of body-wing-tail combinations at small and moderate angles of attack (0&#176; to 20&#176;), despite the neglect of the following high angle-of-attack effects: <br>1. Reduction in lift-curve slope of the wing with increasing angle of attack (ref. 3 ) , an effect accounted for in the method of reference 2 by use of the experimental lift curve of the wing instead of linear theory as a basis for the calculations. <br>2. Effect of viscous crossflow on the wing and body loading (refs. 4 to 6). <br>3. Change in the wing spanwise load distribution (refs. 7 and 8) and in the character of the trailing vortex wake (ref. 9) with increasing angle of attack. <br>4. The destabilizing effect of roll on a cruciform wing-body combination at large angles of attack (ref. 10). <br>In order to obtain information on the importance of these high angle-of-attack effects, a wind-tunnel investigation was performed of the longitudinal characteristics of a representative supersonic missile configuration and various combinations of its components. The purpose of the investigation was to isolate the factors contributing to the lift, stability, and control characteristics of the complete configuration through a comparison of the experimental results with theoretical results for which as many as possible of the high angle-of-attack effects are taken into account. This investigation is part of a coordinated experimental and theoretical research program to study the aerodynamic characteristics of wings, bodies, and combinations at high angles of attack and to develop methods for predicting these characteristics. The completed portions of this research program are reported in references 4, 3, 6, 8, 9, 11, and 12.