The Accuracy of Meteorological Data Required to Support the Testing of a Lifting, Re-entry Vehicle

Abstract

The true aerodynamic velocity of a re-entry vehicle is expressed in terms of a relative velocity vector and a wind vector. An error analysis is performed to determine the effect wind errors have on aerodynamic velocity. A series of trade curves are plotted and, from these, the degree of accuracy required for meso-spheric wind measurements is determined. The results of this exercise are then incorporated in an error analysis of ambient density values used to determine force coefficients and aerodynamic heating. It is concluded that density must be determined with an accuracy of five per cent or less if uncertainties in the reduction of flight test data are to be kept within acceptable limits.