danzet76, The instruction book for the Skyward trainer is a very vague, sometimes uninformative book that covers four different size planes (25, 40, 60, and 120). It gives only one set of specs for control surface throws, and I don't know how the same amount of throw on a 25 size plane will also be right for a 40, 60 and a 120 size plane. With that said, the aileron throw spec given is 7mm (9/32"), the elevator throw spec given is 13mm (1/2"), and the rudder throw spec given is 16mm (21/32"). It does give different C/G positions for the different size versions. The spec given for the 40 size Skyward is 106mm. They then state "this is the furthest back it can be and still fly properly". I urge you to not blindly set your C/G at the 106mm without doing an easy double check of what % range that puts you in. Basic rule of thumb for determining C/G is to set it at 25%-35% of the mean aerodynamic cord (MAC). Measure the wing cord (distance from the front of the leading edge to the rear of the trailing edge) and multiply this number by the C/G % you want. On a trainer like this start with (and stay close to) 25 % of MAC. If the wing cord is say 10", then multiplied by .25 (25%) gives you a C/G setting of 2.5" behind the leading edge. Please do the math on your plane (I don't know what the correct wing cord for your 40 size is). The 106mm (4.17") number given would require a 12" wing cord and then that is 35% of MAC which is NOT where you want it to be, so I do not trust the info given in the book. Do the math, or tell me what the cord measurement is and I will give you the right C/G spot to start at. Now, the control throws given in the instruction book actually sound about right for a 40 size trainer and you can start with those settings and adjust them as needed after test flying. Hope this helps. BTY, there is yet another size Skyward Trainer not covered in the book and that's the one I have (Skyward 80). The book didn't even mention it! No problem, I just did the math for the C/G % and guessed on the control throws. It is a great flyer. I modified mine, added flaps, converted it to a taildragger, added wing struts & wheel pants, and set the C/G and throws up a little more aggressively than you would for relaxed training style flight. I kept the engine (OS 65 LA) in an upright mounting position with a stock muffler to keep it simple.