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Old 11-05-2012, 02:43 PM
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Bozarth
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Default RE: help on balancing low wing planes

da Rock (I still don't know your real name),

I applaud your diligence. But it falls under the TLAR method if you apply science to part of the equation, and experience to the other. Specifically, how are you determining what the coefficient of lift is for your wing and tail? Or the wing's pitching moment coefficient? My guess is you are estimating. Which then leads to an estimated SM, which then leads to an estimated desired CG location. Which I would bet, falls somewhere between 25 to 35% of the MAC.

How do you learn of these coefficients for ARFs? I bet you estimate based on your experience. And I bet you know how it should feel when you fly it. And I bet you recognize there is a trade-off between maneuverability and stability, etc.
There is no "correct" cg provided it is within the static margin.

Measuring a cg location to the nearest 1/16" means nothing. How do you like how the plane flies?

Measuring the cg to the nearest nth degree is like measuring how much hair the barber cut off. What matters is do you like your haircut.

Kurt