Higher-Order Spectral Analysis of Limit Cycle Oscillations of Fighter Aircraft

Higher-order spectral analysis is implemented to identify quadratic and cubic nonlinear aeroelastic phenomena associated with limit cycle oscillations encountered in a specific F-16 flight-test maneuver that consists of a straight and level flight followed by a windup turn at a Mach number near 0.95 and an altitude of 10,000 ft. The results show that nonlinear manifestations of the limit cycle oscillations are most prominent at the forward locations on the wing-tip and underwing launchers. Physical explanations of identified nonlinearities and relations to vibration modes of the different components are presented.