PPRuNe Forums - View Single Post - 787 First Flight - Signs of Trouble Ahead?
Old 19th Dec 2009, 15:00
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barit1
 
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Assuming that by "negative deflection", RumorMonger means upward aileron deflection:

1) Yes, the structural effect is to move the center of lift inboard, reducing the bending moment on the center section; perhaps not uncommon for first flights, as a means of introducing extra conservatism.

2) Another effect is on handling qualities: raised outboard ailerons would help insure the wing root stalls first, so the ailerons remain effective throughout the stall.

Further, on a swept wing, keeping outboard lift available aft of the CG aids a nose-down pitching moment to aid stall recovery.

I wouldn't expect this to be a permanent feature of the production airplane, but merely "belt and suspenders" insurance during early flight test.
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