Nosedive,
I have to know, what did your professional builder do to make your airplane weigh 21 lbs. There is absolutely no unused weight in mine and it weighs 15lbs plus fuel (64oz.) What does yours weigh TAM, including the smoke set-up? The only thing that was done for balance was to use a six cell car battery pack in the nose. The CG is about 1 in aft of the hatch line, using the formula to calculate the location (ask Eric or Ron at GPA Hobbies for that one). Eric flew mine at Fentress a few weeks ago, and it flew GREAT!! Unless you have a "Need for Speed", a Ram 500 is perfect for this airplane