I'm at the point of balancing my Sig Extra 300xs 1/4 scale (upside down) and have a question. The instructions specify the CG by telling me to measure 4.34" back from the leading edge of the wing and balance at that point. My thought is that I should cut a piece of string 4.34" long, attach it exactly "tangent" to the leading edge and then contour the string back over the top of the airfoil and mark the end-point and then balance there. I'm not sure if I explained myself clear enough but that would be a more accurate way then to just use a straight edge to measure since it wouldn't take into account the contour of the top of the wing. Please let me know if my measurement method is correct.
Thanks