Normally, the power listed for a specific 2C engine is at a specific RPM. Most flyers don't approach that RPM because it is way to high and sustained operation at that RPM may eventually cause problems. Also, the noise level at that RPM is sometimes not tolerated at certain clubs. Remember that noise does not necessarilly equate to power.

For instance: The OS 45 AX engine shows 1.65ps at 16000 RPM. Operating it at RPM would probably drive every one crazy and would use a small prop. Normally you may operate that engine at a peak RPM of about 12000. This would probably work out well using the props listed above.

I normally use a 15-10 prop on my OS 1.20 AX. That gets me a peak RPM of about 9800. I chipped that prop and the only one I had on hand that was balanced was a 15-6. It tached at about 11000 RPM and was very noisy. The prop tip speed was making tremendous noise and the prop was not that efficient. The original prop would have been much better.

I'm sure lots of people would shoot for the max RPM they can get, but that normally equates to short engine life. You are better off sticking to what is recommended and working around that number.

DS.