My 766 sounds odd...

[Mark_NC]

Hi everyone!

Can you please watch/listen to this short video clip?

https://www.youtube.com/watch?v=f2DR2-mVja4

I think my 766 sounds odd. Its hard to describe but it sounds like a lower-frequency "noise/chop" different from the normal main rotor "hum". It definitely sounds different from other 766 videos. In real-life it is more noticeable and I don't hear similar sounds with my 500 heli.

Any ideas? My first thought was something in the tail may be off? But I have checked everything carefully. My motor-pinion to main-gear may be a little tight - I could back it off a fraction maybe, but everything else seems correct.

Any advice would be appreciated! Thanks! 

[curmudgeon]

I think the most prominent sound from the video is a mid to high pitch chirping.  One usually experiences that with high governor gains.  However, in your case it also happens after you engage Throttle Hold.  So it seems more consistent with some gear meshing issue.  Verify the mesh for both the motor pinion to main gear and the tail transmission spur gear to antirotation gear.

[Mark_NC]

Thanks for the advice - I have adjusted both meshes and will try it later today - we have 8-inches of snow that fell yesterday but I should be able to at least spool-up and see/listen to it... will let you know how it sounds.

[Mark_NC]

Fixed! It was my main-gear/pinion mesh that was too tight. Moved the motor-mount out a fraction to give me a tiny amount of play... now it sounds like all the other 766's! When I initially attached the motor/mount I followed direction for "0.1mm play" but I think when I tightened the bolts I must have moved it slightly and the mesh was too tight.

Thanks for the help

[curmudgeon]

I am very glad you solved the issue and also posted to educate the community.  As much as I love Synergy helis, my ideal heli design would use efficient TT gears for the tail (just like Synergy), but would use a belt system between the motor and the main gear mainly because it does away with the possibility of screwing up the mesh.

[quantummodz]

I still use the belt set was very light setup easy to tension both on e7 with mikado kevlar belt and currently e6 stock there is a big difference in tail assembly weight

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