Need a book? Engineering books recommendations...

Return to index: [Subject] [Thread] [Date] [Author]

Re: UBC97-- Redundancy Factor

[Subject Prev][Subject Next][Thread Prev][Thread Next]
> As I understand it the greater the number of
>>members means that there is a greater likely hood that one of the members
>>will fail and that this failure would more likely lead to a failure of the
This is the craziest thing I ever heard of. Even if it weren't obvious, 
you can put together a real two column proof that redundant structures 
necessarily require that two or more elements must fail in sequence 
before collapse, thus staving off collapse while plastic hinges develop. 
Statically determinant structures always collapse when one member fails. 
The logic behind 'greater likelihood that one ... members will fail' 
truly escapes me. Sounds like someone's studied too much statistics or 
too little.

As far as the multi-engine airplane argument more multi-engine aircraft 
land safely with an engine out than single engine aircraft. This is 
particularly true when an engine fails on take-off. You can get into 
trouble when a twin engine aircraft can't maintain altitude or isn't 
stable with one engine out, but that's rarely the case. Could be that the 
twin engine configuration that Lindbergh rejected couldn't fly on one 
engine--if so he was right to opt out. Nex time you catch any film of the 
ETO air war on the Discovery Channel, compare the numbers of B-17's and 
B-24's flying with feathered props to the numbers of single engine 
fighters in the same circumstances. 

Christopher Wright P.E.    |"They couldn't hit an elephant from
chrisw(--nospam--at)        | this distance"   (last words of Gen.
___________________________| John Sedgwick, Spotsylvania 1864)