Path: utzoo!attcan!uunet!cs.utexas.edu!tut.cis.ohio-state.edu!att!cbnews!military
From: henry@zoo.toronto.edu (Henry Spencer)
Newsgroups: sci.military
Subject: Re: Can the sonic boom of an SR-71 be heard at the ground?
Message-ID: <7603@cbnews.ATT.COM>
Date: 20 Jun 89 03:47:26 GMT
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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,
phase of the Moon :-), etc.  Studies of making the boom of a commercial
SST inaudible tend to end up requiring cruising altitudes of 100,000+ ft.,
which are unlikely even for the SR-71.  (Its highest unclassified cruise
is 70-something, and the difference between that and 100 is awfully large
to be just secret performance margin.)

                                     Henry Spencer at U of Toronto Zoology
                                 uunet!attcan!utzoo!henry henry@zoo.toronto.edu