ORIGINAL: CGRetired
You want to try to pull around a 40 size plane with a 25 engine? Ok.. let us know how that works out.. and if it even gets off the ground.
You will need something with enough pull to get airspeed up, and enough power to hold it there. You may get the thing up, but I imagine that you will be at full throttle no matter what prop you select. So, select something with a good diameter and a good pitch.. perhals 9-6 may work? Then again, the engine may not get enough RPM up to place it in the power band.
CGr.
Probably 95 per cent of the planes you see at a typical RC field are overpowered or way overpowered. It would be refreshing to see a plane flown on the wing with adequate power for good flight. The OP didnt say what plane he has, but most 40s would fly with a 25.
