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ground-recorded sonic boom signatures of f-18 aircraft in formation flightTwo F-18 aircraft were flown, one above the other, in two formations, in order for the shock systems of the two aircraft to merge and propagate to the ground. The first formation had the canopy of the lower F-18 in the tail shock of the upper F-18 (called tail-canopy). The second formation had the canopy of the lower F- 18 in the inlet shock of the upper F-18 (called inlet-canopy). The flight conditions were Mach 1.22 and an altitude of 23,500 ft . An array of five sonic boom recorders was used on the ground to record the sonic boom signatures. This paper describes the flight test technique and the ground level sonic boom signatures. The tail-canopy formation resulted in two, separated, N-wave signatures. Such signatures probably resulted from aircraft positioning error. The inlet-canopy formation yielded a single modified signature; two recorders measured an approximate flattop signature. Loudness calculations indicated that the single inlet-canopy signatures were quieter than the two, separated tail-canopy signatures. Significant loudness occurs after a sonic boom signature. Such loudness probably comes from the aircraft engines.
Document ID
19960055060
Document Type
Conference Paper
Authors
Bahm, Catherine M.
(NASA Dryden Flight Research Center Edwards, CA United States)
Haering, Edward A., Jr.
(NASA Dryden Flight Research Center Edwards, CA United States)
Date Acquired
August 17, 2013
Publication Date
July 1, 1996
Publication Information
Publication: The 1995 NASA High-Speed Research Program Sonic Boom Workshop
Volume: 1
Subject Category
Acoustics
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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IDRelationTitle19960055049Analytic PrimaryThe 1995 NASA High-Speed Research Program Sonic Boom Workshop
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