8-4 apc is gonn'a load that engine badly. Mine has a 7-4 apc and pulls a lightened Yak-9 trainer with stationary flaps pretty good. MM
That sounds disturbingly weak for stunt, I would have expected it to be pretty strong. f it won't even spin 8-4, then it is far too weak, the 15FP has no problem at all with a 9-4 and pulls airplanes like the Yak around with reasonable authority. I think Paul Walker test-ran his 15s in a Mike Deitrich Cobra. That was one of the engines we did not try in the small engine experiments, for more-or-less the same reason from the other thread - I could never find one that didn't require some mechanical fixes or required extensive break-in. Brett
Mm is that the sterling/Brodak Yak 9. 323 sq in ? Are you happy with the power on that plane ?Mike