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Old Feb 17, 2005, 10:22 AM
EABiker is offline
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Why does a nose heavy plane climb during a dive test?

This seems counter-intuitive; I would expect a tail heavy plane to want to nose-up when the stick is released. I posed this question to two of my flying friends, (what would a tail heavy plane do in a dive test), and both quickly answered the question wrong! Can anyone enlighten us on this?
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Old Feb 17, 2005, 10:51 AM
Andy W is offline
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Because if it's nose heavy, you have 'up' trimmed into the elevator to compensate. When you put it in a dive, this trim causes the model to 'recover'..

You can also perform this test inverted (if you have the skill!) to ensure it's accurate..
Old Feb 17, 2005, 11:38 AM
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Thanks! That was the only reason I could think of, at least I haven't totally lost my mind yet!
Old Feb 17, 2005, 02:07 PM
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If it helps remember that weight distribution (nose or tail heavy) is constant but the trim needed to compensate is sensitive to speed. So the nose heavy model pitches up when it goes faster.
Old Aug 06, 2005, 06:54 AM
jay flay tway is offline
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I like the way Andy put it. Most of us would understand it best that way, I think.
Also, I think it's mostly due to the relationship between cg and cl and how cg has less effect in a dive because of the change of angle (gravity is acting, in a 90-degree dive, totally differently than in "normal" flight).
Still, with respect to inertia, not gravity, the dive angle would make no difference. Wow, this stuff is compllicated.

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