SONIC BOOM PREDICTION: A NEW EMPIRICAL FORMULATION AND ANIMATED GRAPHICAL MODEL

Sonic booms are a barrier to wider application of supersonic flight due to their harmful effect on humans, animals, and structures. This research presents an empirical formulation for rapid prediction of the magnitude of a sonic boom overpressure using linear regression of independent parameter groups operating on the Lee and Downing 1991 database of measurements of sonic booms created by military aircraft at Edwards Air Force Base. This formulation, originally developed as a student project, employs an empirical F function that characterizes the nearfield effects of shape, lift, and Mach number on the sonic boom. The prediction accuracy, as assessed by the scatter within the original database, is well within the resolution capability of the human ear, and produces correlations very much superior to alternative analytical prediction models. Further development led to an expression for the distribution of sonic boom overpressure lateral to the plane of the flight path. The entire method was incorporated into a user-friendly Matlab® Graphical User Interface that predicts the magnitude of the sonic boom overpressure and creates an animated graphical portrayal of the shock wave and sonic boom footprint. This paper presents additional work on the method by employing data from the 1960's on several aircraft that are different from those in the formulation database. Good agreement was found with two new conventional configurations, but significant adjustments to the recognition of wing area in the shape and lift factors are necessary to produce satisfactory results for the XB-70 because of its unique use of folding wingtips and compression lift. Because this method is presented as a simple linear algebraic formula for the overpressure, it can be used easily to screen new low-boom supersonic transport designs, to determine the environmental impact of a supersonic flight, and to educate the public about sonic booms.