RE: ModelTech Sonic 500, need cg and surface travel info
A 9" prop would be fine on that engine. 9x7 or 9x8, I've tried them all on that engine and plane and definately like the 10x7 best for overall consistant speed and handling. That motor develops its best power between 14k and 14.5k. We use to bend the gear forward on those planes so that the center of the wheel was at the LE, it made for an easier plane to land. Also, it should float better than what you are saying, my guess is that you can move the C.G. back a hair.