Re: 747 wing stress test: This can't be true can it?

Date:         09 Apr 97 03:09:26 
From:         euclid1@juno.com (Ptolomy)
Organization: Netcom
References:   1
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"Hans Jakobsson" <hansj@algonet.se> wrote:

>I just received a question regarding stress tests on 747s.

>Quote:

>"Is it true that a 747's wings were pulled upwards until both
>wing tips touched. (In some sort of stress test)."

>End of quote.

>I know that they do all sorts of stress tests but this can hardly be true,
>can it? My reference archives don't mention this at all. Sure, the wings
>can withstand some stress but this is a bit too heavy, I think.

>Could any testing experts please comment on this?

I recently saw a series on the development of the B777, and they
mentioned the B747 wing loading stress tests.  They showed that the
747 wings were deflected up in excess of 25 feet before the spar gave
way in an explosive display.  In the particular video clip they aired,
the wingtips came no where near touching.......until after the spar
failed, that is : after that point, I imagine that you could have
folded the wings over the fusilage if you so desired!
Happy Easter and best regards,  JCD.