RE: Balsa USA 1/4 Sopwith Pup build
Ewan, I'm using one 60 oz servo for the elevator with no problems. I've done many loops and a few snap rolls, etc with no hint of any trouble. You don't need fancy digital servos or high torque servos for this WWI machine. Of course, if you do a lot of 3D flying, that's a different matter!
-Les-