I need help on the engine spec. While I look at the OS engine manual, one of the spec says "2.9bhp/15000rpm." How do I have to use that information? Does it mean that I have to rev my engine at 15000rpm to get a best performance or it means something else? Also, one of my heli buddy keep telling me that you have to put your engine on a powerband. But if there exist a powerband for a engine, then how do I get that information? The OS engine manual never mentioned power band.

Kev

Kev,

The number given by O.S. is the peak horsepower, which happens at that RPM number. It's a calculated number, based upon testing by the factory. Depending upon the engine, though, you'll never run it anywhere near the horsepower peak. Use the propellers suggested in the instructions, and you'll be fine.

Since you didn't mention which engine you're asking about, we can't give you any recommendations for propeller and operating RPM.

Well, I'm running an OS91SX-H, and 8.4 gear ratio. I was trying to find an right RPM for my gear ratio. I want the main rotor head speed to be around 1700rpm. Thanks.

Kev