Some experimental and theoretical studies in aircraft stability at high angles of attack

A review of techniques for stability and response investigations is presented and the averaging technique of Beecham- Titchener-Simpson is applied to the lateral equations of. motion for two combat aircraft. The analytic technique predicts oscillation amplitudes and frequencies accurately, for non-linear aerodynamic characteristics with respect to sideslip or roll rate. However, limitations of the method are apparent when non-linearities in roll rate and sideslip are treated simultaneously. Rates of growth to limit cycle oscillations are predicted by the averaging method and two formulations for a local damping factor are compared with simulation results. Results from extensive wind tunnel tests on a High Incidence Research Model (HIRM) are presented along with estimates of dynamic stability derivatives and polynomial fits to the wind tunnel data. The lateral stability and response of the HIRM at high angles of attack, is investigated using the analytic techniques described earlier, as well as simulations. Six degree of freedom eigenvalue results for the HIRM are shown. An investigation into the effects of cross-coupling derivatives and different forms of roll rate data, using non-linear and linearised simulations, concludes the thesis.