Abstract:

To fulfill its ongoing mission of evaluating the environmental noise effects of training operations, the U. S. Air Force Materiel Command has initiated research studies on the penetration of sonic boom noise into seas, bays, and lakes. All of the previous research on sonic boom noise penetration into water from supersonic aircraft have assumed steady flight. In realistic training, however, aircraft accelerate and decelerate and are involved in maneuvers such as climbing, diving, and turning. The present research will report the results of initial studies predicting the penetrating sonic boom noise created by maneuvering supersonic aircraft. The commercial package PCBOOM3 [Wyle Laboratories, Arlington, VA] is used to calculate the ray paths taken from the supersonic aircraft to the water surface. The sonic boom waveforms and respective incident angles on the surface are obtained from PCBOOM3 and are input to an algorithm for calculating the underwater sound field recently presented by Sparrow and Ferguson [AIAA Paper 97-0486 (1997)]. Given an arbitrary shaped incident waveform, the algorithm provides the resulting underwater sound field assuming the water surface is flat. [Work supported by Armstrong Laboratory, Air Force Materiel Command, USAF, under Grant No. F41624--96--1-0003.]