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HomeScaleAircraftHelicopterScale Model RC Helicopters › Need help with a Bell 230/Raptor 70
10-09-2013 12:21 AM  4 years agoPost 1
JoeTer

rrNovice

Green Bay

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I have a Raptor 70 installed in a Bell fuse. I have flown the mechanics as a boom and pod for years with no problems. Installed in the fuse I get a violent shake as it spools up. It almost seems like the gyro is searching. I do have retracts with wheels if that makes a difference. Any ideas from the experts out there?

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10-09-2013 12:48 AM  4 years agoPost 2
payne1967

rrElite Veteran

uk

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have you tried taking off with the wheels retracted?
if not try it and you will more than likely find the shake isn't there
the shaking will be due to ground resonance with the wheels down

try adjusting the head speed to help the issue

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10-09-2013 02:25 AM  4 years agoPost 3
Copter Doctor

rrProfessor

Enterprise/ft.rucker ,al- home of army aviation

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if it shakes as described, you may not have the mechs braced properly or at all. 1st, always make sure there is a lite plywood floor for the mechs to mount to. the plywood floor should be about a half inch or so larger than the base (footprint) of the mechs and should be epoxied in place. this makes the floor of the fuse rigid. if the shakes are still present, then some upper bracing of the mechs to the top of the fuse around whenre the top brng block is. I usually do this upper bracing if deemed necessary as in if there is the shakes. sometimes that bracing can cause shakes as well as prevent it. now if upper bracing isn't it, then attention must be paid to how tight you have the blades in the grips. snug but not tight is usually the key. 90% of resonance ive seen especially in the wheeled birds come from mechs being mounted to a floor that flexes from lack of a plywood floor.
headspeed sometimes cures this but isn't what I believe to be a true solution. you should be able to have any headspeed with no issues

drive a rotary, fly a rotorcraft

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10-12-2013 11:19 AM  4 years agoPost 4
JoeTer

rrNovice

Green Bay

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Just got back to town and read the replies. Thanks for taking the time I really want to get to the bottom of the problem. First off the ply and mounting is very stable and there is no flex. Very rigid mounting system for mechanics. I did try to take off with the wheels is the up position and the shake was slightly less but still what I would call violent. Every time I spool up I can see the tail rotor hunting more than ever before. The tail servo will hunt from max to max as far as I can see. Do you thing the shake is being caused by the tail hunting because of the less stable wheels instead of standard landing gear? I just cant understand how this mechanics flew so nice until put into the body. The mounting is very rigid so I'm at a loss. I do really appreciate the input from all you folks. Any ideas or suggestions will be investigated and tried. THANKS!

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10-12-2013 12:13 PM  4 years agoPost 5
Copter Doctor

rrProfessor

Enterprise/ft.rucker ,al- home of army aviation

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the fact that this is a model with wheels should have nothing to do with shakes, it just means something somewhere is not quite as it should be. since the model in pod n boom configuration is smooth, it may need additional bracing. a wagging gyro also should not be am issue either. another thing to ensure is to make sure the tailrotor gearbox is "hard mounted" to the fuselage back there in the tailrotor housing.

drive a rotary, fly a rotorcraft

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10-12-2013 12:36 PM  4 years agoPost 6
JoeTer

rrNovice

Green Bay

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You may have something with the tail box mounting. It is just supported with foam in the tube and not very rigid. I'll put some rigid mounting in there today and give it a try. thanks.

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10-12-2013 10:56 PM  4 years agoPost 7
Copter Doctor

rrProfessor

Enterprise/ft.rucker ,al- home of army aviation

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yeah I always use a really long bolt that passes thru the gearbox, a spacer, then into the wood plate that is the wall of the gearbox area.

drive a rotary, fly a rotorcraft

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10-13-2013 05:10 PM  4 years agoPost 8
love for scale

rrVeteran

Omaha, Nebraska U.S.A.

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Is the upper portion of the mechanics braced to the fuselage?

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