A simple method of computing CD from wake traverses at high-subsonic speeds

Abstract

This note gives a convenient method of obtaining CD from a pitot-static traverse in an aerofoil wake, using Jones' equation as modified by Lock, Hilton and Goldstein for compressible flow. Charts are provided from which the integrand CD' can easily be obtained for any point in the traverse, but it is shown that in nearly all cases an accuracy of 1 per cent in CD can be obtained by applying an integrating factor to the area under the total-head loss curve. Three Appendices give (a) a summary of the standard theory and equations, (b) details of the construction of the charts and (c) an empirical equation giving CD' in a simple analytical form.