Airbreathing Hypersonic Flight Vehicle Modeling and Control, Review, Challenges, and a CFD-Based Example

On November 16, 2004, NASA conducted the third flight test – the second successful flight – of a hypersonic research vehicle, X-43/A at Mach 10 or ten times the speed of sound, approximately 7000 miles per hour. The last successful flight prior to this was conducted on March 27, 2004, at an altitude of approximately 94,000 feet at Mach 7. This flight followed a failed experiment one year before. The unfortunate event however exposed the underlying uncertainty and risk still involved in this emerging technology. The incident highlighted the need for simulation models that can reliably analyze all possible scenarios over vehicle’s flight envelope and accurately predict aircraft behavior prior to the actual test flight. While unclassified models of many high-performance aircraft with various degrees of fidelity are available for use by the aeronautical community at large, little is reported in the open literature on the class of airbreathing hypersonic flight vehicle (AHFV). An effort is underway at the Multidisciplinary Flight Dynamics and Control Laboratory at California State University, Los Angeles in collaboration with University of Southern California and University of Kansas to develop a high fidelity simulation model for a full-scale generic airbreathing hypersonic vehicle, one resembling an actual test vehicle such as NASA’s X-43 and DARPA’s FALCON. This paper describes specific challenges involved in modeling and control of this class of vehicles, the current state of research, and future directions. It also presents efforts to date to design in-house a 2-D vehicle and develop a high-fidelity longitudinal model for control which accounts for the complexities and dynamic coupling specific to airbreathing hypersonic vehicles.