RE: GP Super Stearman
The big aerobatic planes are much more substantial airframes designed for the bigger engines. This little Stearman is just not enough plane in my opinion for a 39cc engine. I think you'll find it is overkill for this airframe unless you're looking to do 3D with the plane or something crazy like that. Hold one of the 20x10 or 21x8 props up to the Stearman's cowl, dummy radial, and spinner and you'll see it was just not designed for power of this type. I'll post some pictures tonight of the comparison if I get the chance. Haven't checked on mine, but I'm guessing ground clearance may also be an issue, but mostly I would be concerned about overpowering the airframe with the 2.4. You'll never have to go over 1/2 throttle even for takeoff with that little powerhouse up front! I've used the Brison 2.4 on my DP Edge and also had one in a Yellow Aircraft P-47 once upon a time, and that was a 24 lb. plane that had plenty of power to do the big loops and such. If you're going to try it out, keep us posted as I am very interested in your results!