Sonic Booms From Aircraft In Maneuvers

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.

Sonic booms generated by F-4C aircraft flying low-level terrain- following profiles during Joint Task Force II operations near Tonopah, Nevada, were recorded under and near the flight tracks, and responses of structures, animals, and people were observed. Recorded overpressures up to 144 psf were analyzed, correlated with available aircraft operations data, and compared with data from different aircraft flying similar profiles. Observations of structures, animals, and people were correlated with the measured overpressures. Results include acquisition of near-field recordings of overpressures generated by the F-4C, the finding that some window glass fragments were propelled a short distance rather than falling directly below the window, an instance in which the measured overpressure of a sonic boom 1 mile to the side of the track far exceeded the predicted value, the finding that livestock (undetermined prior exposure to acoustic stimuli in this situation) did not respond adversely to the sonic booms, confirmation that very intense sonic booms do not harm people directly and the reaffirmation that the selection of site locations for low- level supersonic training missions will continue to pose a problem.

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.