Vic7 wrote in
:


Wrote:
I have heard talk about that under stress testing of airplanes (eg. big
Boing machines), they bend the wings so much that they touch each
otherover the airplane?
Has anybody seen such photos, or is this just a lie?


Not a lie that they perform this test, although as previously pointed
out, the spar fails long before the wing-tips meet. I remember seeing
a PBS/History/Discover channel program about the initial production of
the B777. They had impressive footage of the destructive load testing
of the wings. IIRC they failed at a 40-something degree deflection.

I've have also seen footage on the web site of one of the German
sailplane manufacturers (A. Schleicher, Schempp-Hirth, or Glaser Dirks,
perhaps) of the destructive test of a new wing design with a carbon
fiber spar. That was very impressive and violent.

V7

I've seen these tests as well. Something to keep in mind though is
that these are static loads. That is, the loads are applied slowly
until the wing fails. Dynamic loads are another matter entirely.
If the wing fails a static load at 40 degrees, it'd probably still
break if it was deflected to a lesser degree quickly, like within
seconds.

Brian
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