After being out of the hobby for yearsI bought a used H-9 Alpha from a guy the other day took it up for a flight, he said it was all set up ready to go. Well I was not very impressed with the plane after the the 6 or 7 flights. It was slow to get off theground and lazy.I took it home and played with it a little. First, it was nose heavy thec.g. was about 1/4 in. forward of limits and no ballast on the plane, the plane was as built from Horizon. I pressedthe 2.oz flywheel off the engine prop driveand change the prop to a 2 blade 11x6 APC that was enough to bring her in balance. I also took the baffle out of the mufflerandit gave me about 200 more rpm and not much more noise. All I can get is 11,900 rpm I think a 10.5x6 may be a better choice(I also question my tach a little). End result is a whole different airplane, it leaps off the ground much more nimble and still slows down great. I now much happier with the plane.

Also taking out the baffle was only of minimal help this is what I noticed. Not much more power, not much more noise, I might be crazy but I swear it had better throttle response an itdid not idle as smooth. (i am comparing smoothness befor and after baffle with flywheel already removed).

Hi

I have an Alpha 60 RTF I found that the evolution that comes with the Alpha 60 will fly it very nicely with a 12 X 6 prop.
I think the 11 X 6 will lack in low end grunt.

If you havent already pulled the stop out of the high speed needle valve you may want to do so, they make adjusting the needle valve a pita.
if you want to make it a little more responsive, play with your servo linkage to get a bit more throw.
enjoy!