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Re: UBC97-- Redundancy Factor (DC-3)

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The old DC-3 was a twin engine airliner, and has stood the test of time in
peace and war in WWII etc.  There are still many of them around.

It was originally designed to fly with one engine inoperable at the worst
possible moment, over the rocky moutains, and fly on to safety or its
destination.  It was probably overbuilt mechanically and structurally, but
is a lasting tribute to its designers in the 1930's if I remember  correctly
(PBS Nova program).

Gary M. Wheeler, AIA, Architect
American Architecture Service.  Try our Portal at

-----Original Message-----
From: Christopher Wright <chrisw(--nospam--at)>
To: SEAOC Newsletter <seaint(--nospam--at)>
Date: Saturday, February 27, 1999 8:49 AM
Subject: Re: UBC97-- Redundancy Factor

>> people flying twins are really not prepared to
>>fly it on one engine
>Good example of Gilligan's comment about the presence of redundancy being
>negated by faulty details. But I think I'll stick to my guns on the
>issue. When 100% of your engines fail down you go; if you're over water
>or a big city or mountains you're in trouble. But if only 50% of your
>engines fail, you've at least got a shot at putting it down
>The redundancy thing may be getting mixed up with ductility. The
>difference is that ductility without redundancy can delay ultimate
>collapse although maybe not prevent it. Redundancy without ductility
>means no plastic reserve; sudden failures and dynamic load transfer.
>Probably comes from a background in pressure vessels, but I've found
>redundancy without ductility to be far scarier than ductility without
>Christopher Wright P.E.    |"They couldn't hit an elephant from
>chrisw(--nospam--at)        | this distance"   (last words of Gen.
>___________________________| John Sedgwick, Spotsylvania 1864)