PPRuNe Forums - View Single Post - Piper crop spraying type crash in Mexico.
Old 9th Sep 2023, 16:53
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hans brinker
 
Join Date: Nov 2010
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Originally Posted by Capn Bug Smasher
Newton's second law of motion applies

Force = mass x acceleration

Force exerted by elevator is the same throughout manoeuver

Mass reduces on drop

Therefore acceleration (i.e. g-load) must increase for same force

I never realised the implication for aerial application: I have learned from this poor chap's accident.
Originally Posted by Vessbot
The question is, which of these correlates to wing stress?
Originally Posted by Capn Bug Smasher
All of them
Even if the G load increases for the pilot, that does not mean the drop will cause an upward force on the wing.... The mass has changed, force (lift) hasn't, so aircraft goes up, and pilots experience an increase in G. Wing is still producing the same lift, so no change in load on wing attachments.
I don't know why the wing failed. I think it could be either the wing brace strut being pulled out of it's attachment by the reduction in upward force on the wing while the load was dropped, followed by the wing folding up during the pull up, or the wing strut brace buckling due to the increase in force during the sharp pullup after the drop. But the releasing the load does not lead to an instant increase in positive load on the wing attachment, if anything in a decrease in positive load.

Last edited by hans brinker; 9th Sep 2023 at 23:57.
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