Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!tut.cis.ohio-state.edu!att!cbnews!military From: mjt@super.org (Michael J. Tighe) Newsgroups: sci.military Subject: Sonic Booms Message-ID: <7634@cbnews.ATT.COM> Date: 21 Jun 89 02:46:16 GMT Sender: military@cbnews.ATT.COM Lines: 21 Approved: military@att.att.com From: Michael J. Tighe From: henry@zoo.toronto.edu (Henry Spencer) >>... the author claimed that the sonic boom of an SR-71 (at cruising alti- >> tude can not be heard at the ground - is this true? ... > Audibility of sonic booms on the ground seems to be a very complicated > function of altitude, aircraft configuration, atmospheric conditions, But not too complicated that it cannot be expressed as a simple equation. The distance y at which the farthest ray of sound from an atmospheric source hits the surface of the Earth is a function of: T = surface temperature (in degrees Kelvin). h = elevation (in km) of the source. d = vertical temperature gradient (in degrees Kelvin per km). The formula for y is: y = 2(Th/d)^(1/2) Calculating y for various altitudes is left as an exercise for the reader.