Developing a High Altitude Simulating, Dynamic, Ground Test Capability at the Holloman AFB High Speed Test Track

Advances in the capabilities of jet engines over the last ten years combined with a new Presidential mandate to replace the space shuttle require the United States Air Force (USAF) and National Aeronautics and Space Administration (NASA) to cost effectively develop and demonstrate new and emerging jet engine technologies such as scramjets and pulse detonating engines. Wind tunnels, light-gas guns and other static test facilities are capable of testing these systems to some extent, but there remains a large performance region that cannot be tested without the engine operating in its design continuum. For over 50 years, the Holloman AFB, High Speed Test Track (HSTT) has served as an evaluation bridge between laboratory tests and full-scale flight tests. Historically, the HSTT has been able to test equipment in performance regimes for which other ground test techniques cannot fulfill the essential flight conditions, similarity parameters and environmental constraints. Characteristic examples include supersonic flight through rain and dust, fullscale interceptor impacts and high Mach number flight at low altitudes. Syncroness, Inc. has developed and will be demonstrating a concept for a high altitude simulation chamber that will enclose the HSTT as part of a recent Phase I and Phase II Small Business Innovative Research (SBIR) effort. This Very Large Volume, Variable Pressure Chamber (VLPC) will enable the HSTT to carry full-scale jet engines on rocket sleds at speeds up to Mach 7. The chamber is designed to allow the test to simulate a climbing, sustaining and descending pressure profile from 4,300 feet above sea level up to 160,000 feet above sea level. This technical paper will describe the SBIR progress to date, the relevance of the VLPC with regard to future USAF and NASA programs and other activities which must be undertaken to make the HSTT facility ready to test the next generation of jet engines.