The advent of vehicles capable of broad-envelope hypersonic flight requires the development of advanced methods for the measurement of air data parameters for vehicle flight and propulsion control. The requirements for hypersonic air data measurement are reviewed, and techniques for the measurement of air data parameters for hypersonic vehicles are presented and assessed.
Today's hypersonic vehicles, primarily the space shuttle, have had restricted flight envelopes and required minimal air data measurement performance. Advanced hypersonic vehicles are now being designed that will greatly expand the envelope of hypersonic travel. Accurate measurement or derivation of vehicle altitude, rates, Mach number, angle of attack, and sideslip are required to ensure that operation of a hypersonic vehicle over a broader envelope is possible.
The hypersonic vehicle must operate in an environment characterized by low atmospheric and high dynamic pressures combined with high external-surface temperatures that reach extremes higher than 2000°C with flow velocities approaching Mach 25. The air data measurement system must be able to operate within the stressing operational environment expected at the vehicle surfaces or within the propulsion subsystem. Finally, the system must be able to provide rapid update rates and, in some cases, spatially resolved measurements.