Drag measurements in a hypervelocity expansion tube

Abstract

A technique is described for the measurement of aerodynamic drag in a hypervelocity expansion tube in which the test flow period may be as short as 50 μs. The technique is an application of the stress wave force balance first proposed by Sanderson and Simmons (1991). The experiments were conducted in a test flow of partially dissociated Carbon Dioxide where the flow speed was in excess of 7 kms−1. The validity of the technique is first demonstrated by comparing the forces measured on a range of sharp cones with those expected theoretically. Agreement to within 10% is achieved. Two re-entry type heat shield geometries were then tested with the experimental drag forces being compared with a Modified-Newtonian prediction. In both cases agreement to within 11% was obtained.