Controlled focused sonic booms from maneuvering aircraft

Abstract

In April 1994, the USAF Armstrong Laboratory, in cooperation with USAF Test Pilot School, conducted an experimental study of controlled focus boom generated by supersonic maneuvers. The objective of this study was to collect focus and postfocus 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 500–2000 ft apart with the denser spacing at the expected focal region. This spacing was chosen to evaluate the thickness of both the focal and postfocal regions. The target location varied from 2000–5000 from the uptrack end of the array. Of the 49 flights, a focus boom was placed within the array 37 times and within ±3000 feet of the target point 27 times, demonstrating the ability to place controlled focus booms.

Variability of focused sonic booms from accelerating supersonic aircraft in consideration of meteorological effects

“…Marchiano, Thomas, and Coulouvrat ͑2003͒ showed good agreement between numerical solution of the nonlinear Tricomi equation, and weak shock experiments in a water tank scaled to sonic boom. After extensive flight tests, Downing et al ͑1998͒ found a reasonable agreement between measured data and superboom simulations.…”

Reflection of caustics and focused sonic booms

“…A new algorithm has been recently designed [1,2] that is numerically solving the nonlinear Tricomi [3,4] equation modelling locally the nonlinear sound field around a fold caustic (the simplest caustic in the hierarchy of catastrophe theory [5][6][7][8]). Laboratory-scale experimental simulations [9] provide quantitative validation of the model, in agreement with outdoor recordings during test flights [10,11].…”

SCAMP: Application of Nonlinear Progressive-wave Equation to Sonic Boom Transition Focus

“…Boom profiles were, in general, described qualitatively; in only one more recent experiment were peak pressures compared with quantitative models. 4 The recent development of computational models capable of describing sonic boom evolution during focusing, as well as the advent of shaped sonic booms, motivated the SCAMP project. [5][6] One of the models being investigated is the Nonlinear Progressive-wave Equation (NPE), developed by McDonald and Kuperman.…”