I have a P-82 Mustang I believe came from VQ ARF. Wing span is 70.6 inch and fuselage is 47 inch. Manual on last page gives C.G. as 80mm or 3.15 inch behind leading edge, measured at where wing meets the fuselage. My twin mustang flies well at this setting. DO NOT go 5 inches back as this would give you a very tail heavy plane. Start at 3 3/16 inch and fly plane and check how she flies and adjust C.G. by 1/4 inch at a time to get plane to fly the way you want. Remember nose heavy planes fly, not to well, but tail heavy planes are uncontrollable and flight will end badly very quickly. I hope this helps you out and good luck with your twin engine plane. Ken C.