Its going to be a formula...remember that geometry/algebra you thought you would never need Essentially think of your controle surface as a Isosceles triangle where the length (chord) of the control surface is two sides of the triangle. and you want to know what the length of that other side (your deflection in one direction) is. Now, I have found a web site if your so inclined to figure it out it is here: http://www.ajdesigner.com/phptriangl...erimeter_s.php

However if this plane is an OMP profile 3D flyer. Max that sucker out, dial in a good bit of expo and go have fun with it.