Is there a formula, or other method, to determine the servo torque needed for control surfaces? There are so many servos- and the cost escalates accordingly-that it's difficult to know what is needed. For example, I'm scratch building a twin engine jet (Su-27) with all moving stabs (elevons). One suggestion was to use two- JR 8611 at 220oz. each, on each stab. That seems extraordinary. Since I scratch build mostly, very few plans indicate what servos are required. Any thoughts? Bill S.