ORIGINAL: dick Hanson
On my 1/3 and large scale - I use them on the ailerons ends-for adding counterweight ( Igo for 25% cg on the aileron- .
On the rudder they really do unload the servos better - -on some designs - they are too effective and unless a lot of rudder holding power is used - they will cause tail wag as they self servo. seen it , fixed it, etc.
What exactly do you mean you go for 25% cg on the aileron? You add enough mass in front of the hinge line that it balances 25% back from the hinge line?
When designing what is a rule of thumb that makes the counter balances enough without going to too much? What percentage of the total control surface area?