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  #61  
Old 06-19-2015, 07:56 PM
BillL BillL is offline
 
Join Date: Sep 2007
Location: Central IL
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Quote:
Originally Posted by glenn654 View Post
Is there a computer program available that may be used to test a hypothesis of the failure sequence and forces applies in the process?

Glenn Wilkinson
Good question - -

Looking at both accident pictures and reports the sequence of failure suggested for the VS/rudder seems consistent with the pictures and comments in the structural NTSB report. Not sure when the counterweight might have separated, though. They did state (hint?) that "much" could have happened between radar return points. Looking at the plot of time vs G loading, it was not a rapidly increasing G loading. Unless the AC was not relatively stable roll wise. It seems a lack of g loading early in the maneuver allowed the speed to build up anyway. I don't understand the "roll" graph they had, and it could totally change the picture. It seems like the roll (presumably inverted) and pull to breakup was 6 seconds.

Bent stick. Either forward or backward, the loading case prior to impact would be normal force at the handle and a torque at the base. That kind of load yields a maximum bending stress at the pivot. So, if pilot forces were to bend it, it would not be nicely bent in the middle. Honestly, it looked like impact damage to me. Maybe someone would know if the stick was always bent that way.
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RV-7
Lord Kelvin:
“I often say that when you can measure what you are speaking about,
and express it in numbers, you know something about it; but when you
cannot measure it, when you cannot express it in numbers, your knowledge
is of a meager and unsatisfactory kind.”

Last edited by BillL : 06-19-2015 at 07:59 PM.
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  #62  
Old 06-20-2015, 06:00 PM
KTOA KTOA is offline
 
Join Date: Aug 2010
Location: SoCal
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Quote:
Originally Posted by Toobuilder View Post
I have personally been well in excess of 270 knots (followed by a 6 G pull at gross weight) with no damage of any kind. Based on that experience as well as the number of Rockets flying with -8 tails, I think there is more to this than a "simple" overspeed.
I used to fly a T-34A and was caught up in the 2004 wing spar failure, AD, and subsequent AMOC.

One of the many things I learned was that the 'damage' of one 6 G event equaled many, many 3 G events. So if you experience some number of high G events you can have unseen damage to the infrastructure, especially if the loads were asymetrical (...yanking and banking...).

And I'm not a metallurgist nor an aero engineer.
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