ORIGINAL: ravill
I have sat down and "done" the physics and have concluded that by balancing a low wing airplane rightside up, one has to add more weight to balance the plane because the (ok here's some physics jargon) moment arm on the center of balance is larger from the balance point on the bottom part of the wing. Contrast this to balancing upside down, the moment arm on the center of gravity is actually shorter because now it(the moment arm) does not pass through the thickness of the wing, meaning that less weight would be needed to move the center of gravity over to the balance point on the top part of the wing(were one would balance the airplane upside down).
Yes, balance a low wing plane upside down. You do not care about the length of the moment arm from the CG to the bottom or top part of the wing. This is irrelevant. You care more about the length of the moment arm from the CG to the place where you will be placing weights if the plane requires any.
Now, let me ask you folks a question, if I may. Does not the "lift" on the wing actually come from the bottom of the wing, where one would balance right side up?!!! And wouldn't one want to balance where the lift is "doing its thing?"
"Lift" on the wing does not necessarily come from the bottom of the wing. Lift results from air flowing pass the top and bottom of the wing while obeying continuity and the Bernoulli equations. Since most wing are semi-symmetrical with an angle of attack, air has to travel a greater distance over the top of the wing than under the bottom of the wing. Since airflow must meet at the wing trailing edge at the same velocity, according to the continuity equation, this means that air velocity on top of the wing is greater than on the bottom. This results in lower pressure on top of the wing, which "sucks" the wing up.
For more indepth reading, check out this: [link]http://www.1903to2003.gov/essay/Theories_of_Flight/Ideal_Fluid_Flow/TH7.htm[/link]
I suppose you don't plan on doing any inverted flying.