Re: 42,000 feet

Date:         18 Mar 97 03:14:50 
From:         kls@ohare.Chicago.COM (Karl Swartz)
Organization: Chicago Software Works, Menlo Park, California
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>My guess is that at least one reason for the tiny windows [on
>Concorde] is to limit the rate of pressure loss if one fails, such
>that if an emergency descent is immediately started from FL 600 the
>cabin altitude will never get above FL 400 or so.

I suspect the size has more to do with stress on both the fuselage
and the window, including heat stress on the latter.  At the sort of
pressures involved, even a relatively small aperture will vent a lot
of air very quickly.  I'm not sure how quickly Concorde can dive in
an emergency, but 10,000 fpm seems pretty fast and even at that, it
would take two minutes to get down to FL 400, never mind down to
breathable levels.

For comparison, when a National Airlines DC-10's engine failure
punctured a cabin window at FL 390 in 1973, it took just a few tens
of seconds for the DC-10's much larger cabin volume to be vented to
the stratosphere.

--
Karl Swartz	|Home	kls@chicago.com
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