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Old Dec 09, 2012, 07:27 PM
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Originally Posted by zenman View Post
I have been having tha same problem off and on (yawing, pitching, rolling, or droping and arm) and was having a hard time figuring out the source of the problem. So I built a little test rig that shows me the thrust of a prop. Checking at full throttle I can see that thrust values can vary greatly even on brand new props, sometimes even up to 30% or more.

You should also check to make sure each blade of a prop
tracks in the same path as the other blade. A lot of the props
I've bought are not true in their track. One blade will track
higher or lower that the other.
It's not very important to "track" a prop on a fixed pitch rotor system. That is critical in a CCP helo but not so much with a fixed pitch prop. If the prop lays pretty much flat on a table out of the box that should be fine. The little 5 " props on my micro quads are very easily bent and I just gently bend them back. Balance it as best you can. I prefer the scotch tape on the light blade method and keep the tape as far out the blade as possible.Less weight the further from center.

I once had the opportunity to "track" a Navy SH-3 using the flag and crayon method. We marked the blade tips with different color crayons and with the rotor turning 100% and the pilot holding slightly up collective I had to get the flag into position so each blade hit the flag as it passed by. I only did this once. That was enough for me.

Oh yea, we do it with optics now!

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