Simulations of X-59 low-booms propagated through measured atmospheric profiles in Galveston, Texas

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Simulations of X-59 low-booms propagated through measured atmospheric profiles in Galveston, Texas

William Jeffrey Doebler

During NASA’s Quiet Supersonic Flights 2018 (QSF18) test, residents of Galveston, Texas and surrounding communities were exposed to low amplitude sonic booms for a community noise survey. Despite the flight test lasting only 11 days, substantial weather variability occurred including snow and record high temperatures. Similar atmospheric variability could occur in future community noise flight tests with the X-59 Quiet Supersonic Technology aircraft that is currently being constructed. X-59 is designed to have a Stevens Mark VII Perceived Level (PL) of 75 dB in a standard atmosphere. In this work, X-59’s low-boom performance in real atmospheres was tested by using NASA’s PCBoom code to simulate propagation of its nearfield pressure through the atmospheric profiles measured during QSF18. Results indicate undertrack booms would not exceed 75 PLdB in these atmospheres. A range of about 8.5 PLdB between the loudest and quietest undertrack boom was observed indicating adjustments to the X-59 flight condition may be needed to achieve target loudness levels during future sonic boom community noise surveys. Attenuation rate, ray tube area, path length and other quantities throughout propagation of the loudest and quietest booms are presented, which indicate humidity differences below 15kft were a primary driver of the PL differences.