Re: Sonic Boom

From:         m.t.palmer@larc.nasa.gov (Michael T. Palmer)
Organization: NASA Langley Research Center
Date:         07 Oct 93 00:54:15 PDT
References:   1 2
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In article <airliners.1993.626@ohare.Chicago.COM> rdd@cactus.org (Robert Dorsett) writes:

>In article <mumble> somebody wrote:
>>P.S. Can somebody please elaborate on the original question:
>>does the sonic boom arise only on passing through the sound barrier,
>>or during the whole supersonic flight?

>The sonic boom is a byproduct of a shock wave created as the airplane 
>flies through the air.  It travels with the airplane, leaving a series
>of "booms" in its wake.

Right.  What causes the "boom" is that as the shock wave boundary passes
by, the rapid change in pressure up and then down can generate enough force
on certain structures (like large panes of glass) to cause damage.  It
really doesn't take much of a delta-p to exert some pretty big forces on
a 4-foot by 7-foot sliding glass door or picture window.

Although flying at FL600 (roughly 60,000 ft) definitely results in much
less of a delta-p than flying at, say, rooftop height, I seem to remember
that several "studies" done during the time that the Concorde was being
developed showed that repeated exposure to even non-damage-causing sonic
booms was bad for livestock, children, troop morale, and the foreign
exchange rate of the U.S. Dollar.  :-)

Hope this helps.

--Mike

Michael T. Palmer        | "Freedom suppressed and then regained bites with
m.t.palmer@larc.nasa.gov |    keener fangs than freedom never endangered."
RIPEM key on server      |                Cicero, 106-43 B.C.