This is really all very simple, and is THE key to performing 3D.

1)Hold the plane by the left wheel after you remove the fuel tank.
2)Hold the plane high above your head with your right hand and reach for the tail with your left.
3)The coriolis effect will cause the plane to spin counter clockwise and whistle. If the plane does not spin it is unbalanced.
4)Add lead to the servo arms until you reach the right spinning speed, which is inversly proportional to your lattitude.

This all depends on the plane being a tail dragger, a tri-gear setup is much more complicated. And heaven help if it's covered in red....