RE: Sterling Spitfire
Hi Dave,
According to the plan, the CG of the Sterling Spitfire is 4.65 inches aft of the wing leading edge, measured at the center of the wing.
My old Spitfire was very stable in pitch. I initially balanced it at the point shown on the plan, but later put an 8mm movie camera in the cockpit area (pointing out the windshield) to take in-flight pictures. The camera was light by 1970's standards, but still pretty heavy for the airplane. I don't recall how far this mod moved the CG aft, but it still flew fine.
Dick