DRAG MEASUREMENTS IN A HYPERVELOCITY EXPANSION TUBE

A technique is described for the measurement of aerodynamic drag in a hypervelocity expansion tube in which the test flow period may be as s hort as 50 mu s. The technique is an application of the stress wave fo rce balance first proposed by Sanderson and Simmons (1991). The experi ments were conducted in a test flow of partially dissociated Carbon Di oxide 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 w ere then tested with the experimental drag forces being compared with a Modified-Newtonian prediction. In both cases agreement to within 11% was obtained.