ORIGINAL: vmsguy
The best way to get the desired results would be to try different combinations and go from there.
But I also have to wonder.. does it really make a difference? Say the instructions require 1/2'' up and 3/8'' down.. it's a bleepin' 1/8'' difference. If I get 3/32'' or 5/32''.. is it going to be a big deal? What if I'm further off, and manager 5/8'' up and 3/8'' down.. Then what? Am I really going to see difference as it flies?
And what would that difference be? I'm guessing rolls wouldn't be as axial, they'd be more cork-screwy.
With most older plans, that
"bleepin' 1/8 difference" suggested by the designer is the amount of difference he found to work for him.
As for the rolls not being axial, the reason a plane needs differential is exactly that, the rolls weren't axial with equal deflection. The sucker exihibited what's called adverse yaw when the ailerons deflected equally up and down.
With cambered airfoils, the aileron moving down creates a uniformly increasing lift with associated drag increase. However, the upward moving aileron actually reduces drag as it starts to move and doesn't decrease lift uniformly at all. Differential helps reduce or erase the problems equal deflection produces with certain airfoils.