Methods for the Determination of Aerodynamic Parameters and Trajectory Reconstruction of the Orion Command Module from Scale Model Aeroballistic Flight Data
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Date
2008-12-05
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Abstract
Determination of aerodynamic coeffcients and stability derivatives is necessary in defning a model of the Orion CEV dynamics. This involves reducing experimental data, which can include acceleration, angular rate, or orientation data. This sort of extraction of dynamics from experimental data is often performed on data gathered from experiments conducted on uninstrumented models at indoor ballistics ranges. The US Army Research Laboratory (ARL) has developed a high-g survivable stand-alone instrumentation package that can transmit in-flight measurements of acceleration, angular rate, and local magnetic field. This telemetry module (TM) was installed in a scale model of the Orion CEV, which was fired from a 175mm cannon at the ARL range. The instrumentation package was upgraded to include pressure transducers to measure forebody pressures. A minimum variance with a priori method was formulated to solve for both the "local" flight parameters of Mach number, angle of attack, and sideslip angle at each timestamp and the "global" parameters of scale factor and bias for each pressure transducer. Results using both simulated and experimental data indicates that these parameters may be estimated and used to compute stability coeffcients. Low pressure differentials between symmetrically-opposed pressure transducers, however, increased uncertainty in the parameter estimates. Validation of this method of data generation and analysis supports a low-cost method of vehicle testing.
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pressure, experimental, NASA, aeroballistic, CEV, Orion, minimum variance
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Degree
MS
Discipline
Aerospace Engineering
