Think in terms of static and dynamic loads. You balance your sailplane in a static mode using either your fingers, or some type of machine/gadget. When you fly your plane it sees the addition of dynamic loads. The static loads still apply, but now you have a dynamic load to deal with.
As the plane speeds up, the dynamic loads have more affect than the static load, i.e. the elevator trim setting has more authority than the static balance. Sooooooo, if you have more lead in the nose than needed, you need to carry some "up" elevator to make the airplane fly level at normal speeds. As the speed increases, the elevator over rides the balance and the plane pitches up. The opposite is also true and that's why the airplane will tuck if the CG is too far out of range.
I hope that helps. gv
invicta421 wrote:
I have been pondering this question for the last few weeks, but haven't satified myself with an explaination yet. Most aerodynamics seem to make intutive sense to me, but this doesn't.
The test I am speaking of is when you put the sailplane into a 45 degree dive and see if it pulls up, flys neutral or tucks under. A page on how to do this can be found here:
http://www.polecataero.com/articles/cg_art.shtml
But this page doesn't explain why... to me it seems that a nose heavy glider should tuck not rise when the CG is in front of the average lift on the wing. Any help understanding this?
Thanks
-Richard
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