I. Introduction

Propulsion systems have historically been the pacing technology for aerospace systems. From the counter-rotating propellers of the Wright brothers to the high-bypass turbofan engines of today, advances in propulsion system performance have extended the envelope of flight vehicles.1 Currently, there is an international push to extend the flight envelope beyond present limitations by increasing the flight velocity into the hypersonic regime. In the United States, NASA,2 the U.S. Air Force,3 and other agencies are all developing hypersonic aeropropulsion systems. Internationally, the Japanese,4 Australians,5 and European community6 are all actively involved in hypersonic aeropropulsion system research and design studies.

The development of a hypersonic propulsion system requires extensive testing in facilities that duplicate the environmental factors affecting aeropropulsion system behavior during its operational life. These environmental factors include such parameters as operational time, scale, and atmospheric conditions. Historically, gas turbine engine development has progressed to its current level of maturity by relying on ground test facilities such as those in the Engine Test Facility (ETF) at Arnold Engineering Development Center (AEDC). The state-of-the-art for turbine engine ground test is the Aeropropulsion System Test Facility (ASTF), pictured in Fig. 1. The ASTF is capable of testing at up to Mach 3.8 at temperatures and pressures representative of the air-breathing propulsion system's...