Gerry, I have no idea! I built the Sterling kit as it was in the box, covered it with olive drab coverite, put the Fox 36x in it and flew it until some power lines sucked it in. This was when we flew on AM and my first radio cost $400.00! I built another from plans put an old K&B .61 in it with retracts and it flew just great. I lost this on to a midair at the field. I will build another someday, but may change the servos and ailerons around and add flaps. I still have the plans and cannot believe the size of the servos this was designed around. Just for fun I also built the Sterling Spit and still have the plans for it.