RAREFIED-FLOW SHUTTLE AERODYNAMICS FLIGHT MODEL

A model of the Shuttle Orbiter rarefield-flow aerodynamic force coeffi cients has been derived from the ratio of flight acceleration measurem ents. The in-situ, low-frequency (<1 Hz), low-level (approximately 1 x 10(-6)g) acceleration measurements are made during atmospheric re-ent ry. The experiment equipment designed and used for this task is the Hi gh Resolution Accelerometer Package (HiRAP), one of the sensor package s in the Orbiter Experiments Program. To date, 12 HiRAP re-entry missi on data sets spanning a period of about 10 years have been processed. The HiRAP-derived aerodynamics model is described in detail. The model includes normal and axial hypersonic continuum coefficient equations as functions of angle of attack, body-flap deflection, and elevon defl ection. Normal and axial free molecule flow coefficient equations as a function of angle of attack are also presented, along with flight-der ived rarefield-flow transition bridging formulae. Comparisons are made between the aerodynamics model, data from the latest Orbiter Operatio nal Aerodynamic Design Data Book, applicable computer simulations, and wind-tunnel data.