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CarbonXtreme . Midland Helicopters . HeliProz

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Robbe Cuatro - Millennium - Nova - Dyna-X > Head Dampening O' Rings?
 
 
kima
Senior Heliman
Location: Wellington, New Zealand

I have just been out to test fly my Cuatro after a crash i had some weeks ago. I am running a head speed of 1250rpm - Zenoha 231 - 850 MAh blades.

I have noticed that there is a small head shake, i have searched here on RR and it seams that the head could be to tight. At the moment i am using two shims. I have also not replaced the O'Rings for awhile not and they are a little hard.

Are they anything special and can i get some replacements from a seal company?

Any other suggestions to the head shake would be great.

K R Attwell
www.PhotoHigher.co.nz
05-06-2008 07:09 AM
HOMEPAGE  
 
 
ccheseldine
Heliman
Location: Ortonville MI

head shake

not a problem with the o rings, sounds if the head is out of balance, could be bent feathering spindle, could be blade balance, if you have checked all this then something else is the cause, all the o rings do is to allow the head to flex, make shure that all of the head parts are straight, and that nothing is binding, main shaft is another area that can cause this kind of problem, flybar not centered and balanced can cause this also

just because they are new shafts does not garantee they are straight. check them on a glass table or with a dial indicator

charles
05-06-2008 01:40 PM
 
 
tim tompkins
Senior Heliman
Location: Boston, Georgia sw Ga. Thomas County

Yes the head will shake even if everything is straight. The usual problem is not enough lube on the o-rings. The head axle should be able to slide in the rubbers. TimT
05-07-2008 01:07 AM
 
 
kima
Senior Heliman
Location: Wellington, New Zealand

Thanks i will re-check all the shafts etc to see what is causing it as well as lub the o rings and let you know what the issue was

K R Attwell
www.PhotoHigher.co.nz
05-07-2008 10:38 AM
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erichevy
Senior Heliman
Location: Zevenhoven The Netherlands

Kima,
I had a mishap with my Futura SE gasser lately while the engine hezitated doing a low flip, and bent the flybar, mainshaft, and the blade axle.
Together with both tailrotor gears, tail outputshaft AND the tailhub.
Did you change your blade axle too? bending this axle is very easy.

Cracked my torque tube, baseframe,mainblades,tailboom,tailfins,skidlegs,skids............

Eric.

Don't wan't to show my geoduck in public.
05-13-2008 05:27 PM
 
 
RCMarket
Key Veteran
Location: Belgium , Europe

orings

Kima

shouldnt the cuatro have 3 orings on each side?
also, warmly recommended to use central ball, and viton orings, especially with 850 blades.

the shake is not from the orings.. i would check the other stuff

Alex (Formerly Known as Futurac )
05-13-2008 06:09 PM
 
 
Jarno
Veteran
Location: Finland

Hello Kimberley.

I would not make the head any harder. Instead I would really try to lube the o-rings well and re-check blade and paddle tracking and see if that helps.

If it still shakes after these then try altering head speed and check if the shake still appears or not. If shake goes off on higher head speed then your head dampening is too hard. Central ball will sure deliver load better on dampeners than without on lower head speed, but it is not a solution for getting off the shake.

For low head speed like you use softer dampening is better.

Regards

Jarno
FAI F3C is my cup of coffee
05-13-2008 07:38 PM
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kima
Senior Heliman
Location: Wellington, New Zealand

Thanks guys,
I managed to get another fly in yesterday and the shake has gone; when i stripped the head i found that the feathering spindle was very tight in the center swivel bearing as it was a new shaft. i lightely sanded it lubed o'rings and reinstalled everything and it is now running smoothly.

Thanks for all the in put.

K R Attwell
www.PhotoHigher.co.nz
05-13-2008 07:59 PM
HOMEPAGE  
 
 
tim tompkins
Senior Heliman
Location: Boston, Georgia sw Ga. Thomas County

Thank you for the reply. Some of us have some real life experiences with Robbe machines and love to help. TimT
05-13-2008 08:41 PM
 
 
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Robbe Cuatro - Millennium - Nova - Dyna-X > Head Dampening O' Rings?
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