mjt@super.org (Michael J. Tighe) (06/21/89)
From: Michael J. Tighe <mjt@super.org> 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.
henry@zoo.toronto.edu (Henry Spencer) (06/23/89)
From: henry@zoo.toronto.edu (Henry Spencer) >> 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... Sigh, please read my posting again. I said "audibility", not "location". The issue is intensity, not arrival time and location (which are indeed pretty predictable). Henry Spencer at U of Toronto Zoology uunet!attcan!utzoo!henry henry@zoo.toronto.edu