Application of bifurcation theory to the high-angle-of-attack dynamics of the F-14

Bifurcation theory has been used to study Ihe nonlinear dynamics of the F-14. An 8 degree-of-freedom model does not include the control system present in operational F-14's has been analyzed. The aerodynamic , supplied by NASA, includes nonlinearlties as functions of the angles of attack and sideslip, the rotation about the velocity vector, and the elevator deflection. A continuation method has been used to calculate steady states of the F -14 as continuous functions of the elevator deflection. Bifurcations of these steady states been used to predict the onset of wing rock, spiral divergence, and jump phenomena that cause the aircraft enter a spin. A simple feedback control system was designed to eliminate the wing rock and spiral divergence . The predictions were verified with numerical simulations.