Tailless Aircraft - Reflex and other design issues

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Norman

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Nov 28, 2003
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3,108
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Grand Junction, Colorado
I thought that this was because the wings sag when on the ground, but level out when in flight due to the lift. If you made a wing stiff enough to not sag when on the ground then it would be too heavy.
Nope, it's not sag, it's anhedral to help counteract the dutch roll tendency of swept wings at high Cl. If what you said about adequate stiffness being too heavy were correct it would also be true of all other planes with a similar aspect ratio. A google image search on "c-5 galaxy" will turn up some pictures of it in flight that show the anhedral is still there.
 

Andy_RR

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Sep 29, 2009
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299
Location
Melbourne, Australia
Like more conventional airplanes, flying wings still keep their center-of-gravity forward of their center-of-lift, creating a nose-down pitching moment.
Not true. The centre of gravity and centre of lift must coincide longitudinally otherwise pitching will occur.

The centre of gravity must be ahead of the neutral point for positive static margin, the neutral point being where the pitching moment curve is flat - i.e. dCm/dalpha = 0
 
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