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Revving to high - Fly 200


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So I managed to tune my Fly 200 this weekend, since it was running rich and got it running much better. However I noticed that it seems to rev way to high. It’s revving to over 8.5K and the book says 7.8K max. I suspect the replacement prop I have is the wrong pitch. Is there any other reason why it would rev to high? That being the case, I’ll fit my nice new 3 blade since that should be the correct spec for it.



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Also, can someone explain how you measure prop pitch. Just checked the walkerjet site and it says a pitch of either 8 or 11. I've no idea how you tell. I do know my prop is to short as its running a 125 and should have a 130 but I guess the pitch is key.

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The pitch of the prop is the distance it would move through the air in one revolution assuming no 'slip'. This would be the same for a two or three bladed prop. Pitch is a direct function of the angle of the blades relative to the prop axis. This angle is steeper at the root than the tip, to allow for the tip moving faster than the root.

It is possible to measure, but to do so you'd need to define the plane of the blade section reasonably accurately, measure it's angle at a given radius, then calculate the distance given by that angle projected over the circumference of the circle described at the given radius. It might be difficult to define the section plane well enough to tell the fifference between 8" and 11" pitches.

Since you've recently purchased both props, I would expect some reference to their pitches in the spec or other paperwork.

Good luck :)


Bailey 175

Ozone Indy

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