Hi all,

Seeking any advice. I don't normally give thought to these things for my "normal" size models; in this case it might be justified.

I'm planning, as a future project, to scratch-build a really large glider, and don't want to risk using undersize (w/respect to torque) servos, yet at the same time don't want to play it overly safe by using r/c sailboat winches

How can I realistically estimate pressure forces acting on control surfaces, e.g. flaps, in order to ensure that the servos can handle it?

As a starting point, figured I could take the product of dynamic pressure and projected control surface area, multiply by sin of deflection angle to get the perpendicular component, then multiply by distance from mid-chord of control surface to hinge axis to get a torque value.

Thought that would be conservative, since center of pressure should be somewhere on hinge side of mid-chord.

Would like to get an idea of pressure loads during level flight (speed est'd from CL and weight) and terminal velocity (from CD and weight).

Better method or data sources anyone?

Should servos be selected based on expected worst-case torque, or some multiple of normal operating torque??