My friend and I fly identical ancient Cermark Sukhoi's, with .91FX, pitts muffler, and 10% Cool Power. 15% makes 'em die in the air. With no other modification, 10% works for us.
Great engine, on 10%, with a 14X6. A 13X8 will make it a rocket, a 15X6 will give it great braking, really slow it down for landing. I prefer the 14X6 becuase it revs almost as fast as the 13X8, and I don't want it to slow down for landing as fast as the 15X6 causes it to do.
Good luck,
Dave Olson
ORIGINAL: W4RCF
I have a problem with burning out glow plugs on a O.S. .91 FX and am hoping someone can give me some advice. I have been using Fox's "miracle Plug" and am getting only one flight per plug! I run 15% 2 stroke fuel (Omega) and a 1.5 volt glow driver.
The engine wants a rich mixture and will overheat very quickly if too lean. Even holding the model vertical with no loss of RPM can result in a lean run if not careful. I can see the stream of exhaust in a clear blue sky, and I know it's ok then. Does anyone have a suggestion as to cause, a better type of glow plug for this engine, or other suggestions? I would appreciate any help.
Fred Lomax (W4RCF) [:@]