one question........ when u have balanced moving surfaces, ailerons, elevators and ruder, that are staticly and aerodinamically balanced, do you need high end servos, or can you go aroud with 70onz/inch servos?????? if you have flyng elevator for example, where the stabilizer and the elevator are the same thing, and move as one, if u split and hinge the elevator, say 45% foward and 55% back of the hinge, u are really moving only 5% o that structure...... true????? like the diabolic from spirit models........
thanks

Unclear.
Are you taking an all-flying horizontal and making a fixed horizontal and movable elevator, with the hinge line of the elevator at 45% of the total chord?
And is that elevator going to be statically and dynamically balanced?
Your hinge line position is VERY important!
Any further back than 25% of the chord of the -elevator-, and it will be unstable, trying to go to one extreme or the other in flight.

what i'm talking about is an elevator that has no stabilizer part, the entire thing moves.......and yes what i'm trying to find out is if the servos need to be as strong when you design your moving bodies like this balanced statically and aerodinamically....

check out this picture, but i'm talking on a 100" w.s. plane with a 70cc engine, for 3d

Please sort out your reguirements.
Plane and engine size... are you trying to build a larger Diabolatin?
Servo size IS the important thing for that extreme amount of surface travel.
Without knowing how the Diabolatin accomplishes that, and the servo requirement, there's no way to discuss this.

What you can say is that if you have the THEORETICAL case with the surface having no fuse, prop, sideslip effects and balanced about the 1/4 chord point where theoretically the moments from deflection are zero then it would take a very small servo to move the surface a few degrees about the zero deflection setting.

Move to the real world with wind downwash, fuse effects, sideslips effects, etc. then you have to account for a lot of variable airloads on the surface which would require a larger servo.

The torque required in most model applications is really unknown, we just throw a large servo at it and see if it works:-) I doubt anyone has sat down and calculated the exact servo torque requirements on any airplane. We try someting, it works and so we make that the requirements in the kit. Certainly you could progressively try smaller servos until you found the limit of control effectiveness but that is a lot of work.

What you can say is that if you have the THEORETICAL case with the surface having no fuse, prop, sideslip effects and balanced about the 1/4 chord point where theoretically the moments from deflection are zero then it would take a very small servo to move the surface a few degrees about the zero deflection setting.

Move to the real world with wind downwash, fuse effects, sideslips effects, etc. then you have to account for a lot of variable airloads on the surface which would require a larger servo.

The torque required in most model applications is really unknown, we just throw a large servo at it and see if it works:-) I doubt anyone has sat down and calculated the exact servo torque requirements on any airplane. We try someting, it works and so we make that the requirements in the kit. Certainly you could progressively try smaller servos until you found the limit of control effectiveness but that is a lot of work.