As a reply to the previous post--I'm using an APC 17x6W, but I've also flown this engine with an APC 18x6W. Both perform GREAT. The 17x6W allows higher revs with better throttle response. On a CG Sukhoi, the 18x6 turned a bit slower but really helped with the vertical. On this plane, I'm going to start with the 17x6W since I won't be performing any 3D-type maneuvers!!!