Robert C. Blanchard*NASA Langl_ Research Center, Hampton, Virginia 23681andKevin T. Larman * and Christina D. Moats _;Lockheed Engineering and Sciences Company, Hampton, Virginia 23666A model of the Shuttle Orbiter rarefied-flow aerodynamic force coefficients has been derived from the ratioof flight acceleration measurements. The in-situ, low-frequency (<1 lq[z), low-level (,-_1 × 10-6 g) accelerationmeasurements are made during atmospheric re-entry. The experiment equipment designed and used for this taskis the High Resolution Accelerometer Package (HiRAP), one of the sensor packages in the Orbiter ExperimentsProgram. To date, 12 HiRAP re-entry mission 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 hypersoniccontinuum coefficient equations as functions of angle of attack, body-flap deflection, and devon deflection. Normaland axial free molecule flow coefficient equations as a function of angle of attack are also presented, along withflight-derived rarefied-flow transition bridging formulae. Comparisons are made between the aerodynamics model,data from the latest Orbiter Operational Aerodynamic Design Data Book, applicable computer simulations, andwind-tunnel data.aCgKnMMmicro-gSVX,Y,Z6olPSubscriptsA