3D Pro Head shake

[stikflyer]

My 3d pro has a bad vibration around the 1/4 throttle point during throttle up and throttle down. It vibrates so bad that the skids and tail support actually bounce clear of the floor. Above this throttle setting or below it the heli is very smooth. The blades are balanced and tracking good as well it has the belt drive conversion.
When I first got it I was afraid to go past the 1/4 throttle mark because it skook so bad but finally decided what the hell, lets see what happens and much to my surprise it settled down and hovered very stable.
Now I just have to determine the cause of the shake rattle and roll. There is absolutely zero play between the head and the blade grips. Should there be some sort of dampning in that area?

[Chris DeSain]

No the grips should not have play.

Is the pin in the head block installed thru the spindle?

The blades are probably balanced lateral but the chord wise balance is off. that would cause this and is really hard to change in a blade that is pre made. Chord wide balance went out the window after we stopped having to install our own lead like the old days. I had a set that did what you are having. I got a different set of blades and it went away.

[stikflyer]

Yup, a different set of blades cured the problem. I took the carbons off and replaced them with the stock woodies and everything smoothed right out.

[Chris DeSain]

:glasses2: