Determination of Non-Linear Dynamic Aerodynamic Coefficients for Aircraft
Final rept. Jun-Dec 96
KURTZ LABS YELLOW SPRINGS OH
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In order to accurately predict the flight dynamics of fighter aircraft, a relatively complete data base for static and dynamic aerodynamics properties for a complete range of flight conditions is required. Since it is impossible to acquire a complete data base for all possible combinations of aircraft attitude and motion parameters, the available data base must be interpolated between test data points for conditions that were not specifically tested. This requires an aerodynamic math model representation - the means for interpolating and combining test data to provide the appropriate aerodynamics data. This Phase I study focused on finding new testing techniques to improve the ability to represent dynamic terms sufficiently to account for important nonlinearities with rotation rate and to recognize and accommodate significant effects of motion time history dependency. Water tunnel dynamic force and moment tests were conducted with single and multiple degrees of freedom of rotational motion on an FA-l8 model, and recent high-amplitude high-rate roll-oscillation wind tunnel experiments on a 65 deg delta wing model were reviewed with the objective of developing a new testing methodology for the future. A key element in this new approach is determining critical states in the flow field, often related to vortex breakdown phenomena, prior to performing dynamic tests.
- Test Facilities, Equipment and Methods