Measurement of Controlled Focused Sonic Booms from Maneuvering Aircraft.

In April 1994, the USAF Armstrong Laboratory in cooperation with USAF Test Pilot School conducted a measurement study of controlled focus boom generated by supersonic maneuvers. The objective of this study was to collect focus and post focus booms and to assess the ability of aircrews to control the placement of the focal region during basic maneuvers. Forty-nine supersonic passes were flown and included level linear acceleration, level turn, accelerating dives and climbout pushover maneuvers. These flights were flown under calm and turbulent atmospheric conditions. Turbulent conditions had a defocusing effect which caused distortions in the focus region and resulted in smaller maximum overpressures. Sonic booms were collected by up to 25 Boom Event Analyzer Recorders BEARs placed in a 13,000 ft. linear array. The BEAR units were spaced 500 to 2,000 feet apart with the denser spacing at the expected focal region. This spacing was chosen to evaluate the thickness of both the focal and post-focal regions. Of the 49 flights, a docus boom was placed within the array 37 times and within approximately 3,000 feet of the target point 27 times demonstrating the ability to place controlled focus booms.