Raptor Resonance

[andybenn]

Hi

I recently bought a second hand Raptor 30 which flies ok, except for a Resonance which affects it normally
when the engine and blades are under load.

I have changed the main shaft and feathering spindle which has reduced vibration to virtually zero, but I can
still ocasionally hear this power absorbing resonance. In the hover there is no sign of vibration with the UC, tail and
body of the heli perfectly steady.
On the ground the heli suffers from ground resonance and shakes when spinnng down.
I have checked the balance of the head and flybar and they are ok.

My next idea is to strip the engine/clutch assembly down, but I thought I would ask you guys first. Any ideas.

Thanks in advance

Andy

[Raydee]

Could be the bearing in the clutch bell, they get dirty fast. It could also be the muffler making the noise. As far as the shaking while spooling up goes, almost every Raptor 30 i have seen does it. When I switched to a R50 it stopped. I think it is very common.

[andybenn]

Hi

The resonance got worse. I changed the flybar control arms and the sloppy swashplate for the QuickUK
unit and that seems to have cured it. More power, better control and no resonance.


Andy

[aa7ol]

I am electrical engineer, and thinking of making vibration sensor for RC helicopter. I heard in real helicopter they often use vibration sensor to adjust tracking rather than strobe/blade height. can you give me a input, if such device may be useful ?
Niko

[tomi]

Shakes from spinning down when u are on the ground is normal. You need to adjust your pitch settings. Maybe give it a bit more negative pitch to keep the heli down. I had that when I first flew my raptor. Same for 2 other raptors that are new too which were my buddy's. Check the first and 2nd pitch curve settings. Mine did this before and I never landed it on the pavement. I only landed on grass. but now I land on pavement becuase it's gone, and pavement is my only option..

-Tomi

[barracudahockey]

http://www.raptortechnique.com

Sounds like ground resonance, land on grass or try some skid stops but they all do it.