Determination of Non-Linear Dynamic Aerodynamic Coefficients for Aircraft

This proposal is focused on determining the significance of dynamic aerodynamic coefficients in aerodynamic mathematical models used to evaluate the flight characteristics of modern fighter and transport aircraft. This assessment will be accomplished with a unique method of dynamic testing in the Eidetics' water tunnel using a sophisticated 3-axis computer-controlled model support and high-sensitivity force and moment balance. The approach is based on previously demonstrated successes in conducting dynamic experiments in the water tunnel where 5 components of forces and moments (no axial) were measured on a model undergoing computer-controlled motions in either pitch, yaw or roll. Because of the low free stream velocity of the water tunnel, the required model motion rates are quite low, and acquisition of force and moment responses to the commanded motions is relatively straightforward. Data can also be acquired in real time simultaneously with flow visualization. Results from these measurements will provide (1) an assessment of which dynamic coefficients are relevant for a typical fighter and transport aircraft and (2) guidance to determine the requirements for future dynamic wind tunnel test methods. In conjunction with this effort, present-day wind tunnel experimental methods to determine dynamic coefficients and aerodynamic modeling methods will be evaluated.