Nonlinear characteristics of F-35 flyover waveforms

Metrics indicating the presence of acoustic shocks are calculated from noise measurements of F-35 aircraft during flyover operations. The sound pressure level, average steepening factor, and skewness of the first time derivative of the pressure waveform are calculated for the A and B variants of the aircraft. Other metrics more specific to flyover measurements are also shown. Comparisons of nonlinear indicators are made between engine thrust conditions, aircraft type, microphone height, microphone size, and sampling rate. Nonlinear indicators are also compared against other full-scale military aircraft. Comparisons are made with similar conditions during ground run-up operations.