Variation of Falcon 9 noise in the mid-field

The rapid launch cadence of SpaceX’s Falcon 9 rocket provides the opportunity to study the relative consistency of noise radiation. Acoustical measurements of several Falcon 9 launches have been made on and near Vandenberg Space Force Base within 1 km of the launch pad. This paper compares collocated mid-field measurements from different Falcon 9 missions to begin to understand data variability as a function of launch and environmental conditions. One location 395 m from the pad has been measured over 5 times. This comparative analysis includes time-varying levels, spectra, and waveform statistics such as the pressure derivative skewness. Time periods of particular interest are liftoff, peak noise, and late into the launch when the vehicle is significantly downrange. [Work supported by USACE.]