Wind Tunnel Experiments on the Effect of Combustion in the Wake Region of Supersonic Projectiles-Test Series III

Abstract

Abstract : This report summarizes the third set of wind tunnel tests to evaluate the effect of combustion of pyrotechnics on the base drag of supersonic projectiles. In this test series, a larger diameter model was used to expand the range of injection parameters for R20C. It was found that the base pressure rise vs I, the injection parameter, for R20C could be correlated by an expression requiring two parameters. The maximum base drag reduction achieved with pyrotechnics at M sub infinity = 2.0 was 68%. The maximum specific impulse at M sub infinity = 2.0 was nearly 8kN-s/kg. The maximum specific impulse was observed at an I value of 0.002. Direct measurement of the specific impulse by means of a force balance agreed with the specific impulses computed from integrating base pressure-time histories.