Abstract:

Item No. 05015 presents a semi-empirical prediction method for normal force and pitching moment of forebody-cylinder combinations of elliptic cross-section at supersonic speeds. Because the data available for bodies with elliptical sections are relatively limited both in number and scope, the method is based wholly on an adaptation of the ESDU prediction method for circular bodies given in Item Nos 89008, 89014 and their associated computer program in ESDUpac A9034, which itself is described in Item No. 90034. Those Items provide a prediction method applicable at angles of attack up to 90 degrees and Mach numbers up to 5. Although the method is derived from test data for bodies with either tangent-ogival or conical profile forebodies, the method can, with care, be applied to other forebody profiles. The method's accuracy for normal force prediction is within 15% and when used in combination with the estimation method for pitching moment gives estimates for centre of pressure position of within about 0.08 on body length. The applicability of the method is fully discussed, and its use is illustrated by meansof a worked example.