There are only 2 things that really determine the size of a servo, in oz. in. , for ANY SIZED plane

The maximum speed in a vertical dive that you have screwed up in and have let it go to almost the maximum. The total area of the surface you want to deflect to the maximum deflection at the bottom of the dive.


This is assuming you are NOT using a surface with some of the area on BOTH sides of the hinge line.

I have a 2 page chart that someone did by moving the surfaces at various speeds from a car with different sized surfaces and angles of deflection.
-----I can scan them to someone to post if you are interested or just E Mail to you.----

The results are suprising. And far better than , " Harry said use this. "