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HomeAircraftHelicopterGasser Model RC HelicoptersOther › Almost a Spectra disaster - light grey links vs. black links
04-23-2011 02:09 AM  7 years agoPost 1
flyinfriend

rrApprentice

North American continent

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Hi,

This afternoon I flew a tank and all was well. Fueled up again and was just beginning to hover about 6ft off the ground and the heli went into a fast spin. I had lost all tail control. I hit throttle hold and was able to land it upright while it was still spinning. I've been practicing piro hovering on the sim and IRL and it paid off.

There was a partial tip-over that caused a main to touch the ground and I righted it. My servos will need new gears. Other than that no damage to anything.

The cause was a worn light grey tail link, the one that goes from the bell-crank out to the tail rotor. It had popped right off. It was quite loose but it didn't seem 'pop-off' loose. There was a lot of play in it on the ball. In looking at all of the light grey links there is plastic dust on the balls and they are ALL fairly loose. The black links that are used throughout the entire head and some of the servo balls are all perfect and not warn at all. This heli only has weekends for the last 2 1/2 months on it. Why would the light grey plastic links wear so quickly and the black links are as tight as when I first built it?

When I had the Century muffler on it (now using the stock) I had problems where it would rev to really high rpms and I'm sure that created bad vibrations. I would try and land it immediately when that happened.

Why does min air use two differnt materials in their links. I know some are going to say high freq vibes and that may have been the case when it was reving, but there are no signs of vibes when it is in a hover. Are the light grey min air links just made of a poor quality material? Any insight into this would be greatly appreciated.

I'm off to look at servos or gear replacements kits.

Thanks,

Tom

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04-23-2011 02:38 AM  7 years agoPost 2
GREYEAGLE

rrElite Veteran

Flat Land's

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Better pull a Print
I have to pull my drawing's - not positive : but I believe there's actually two different sizes - internal bore wise for the link rod diameter's. A 2mm and a 2.5 mm. Grey's are the 2.5's

Theirs also two different lengths of shoulder's.

You might have got very blessed

Nothing of MA's is of low or substandard quality - all Top Shelf !

Maybe Tom or Ra can pull it right off the top of his head.\\

Guy's ???

greyeagle

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04-23-2011 03:04 AM  7 years agoPost 3
flyinfriend

rrApprentice

North American continent

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Hi Greyeagle,

You are correct they are different bore sizes. I'm wondering why all the grey ones wore so quickly and left a powdery residue on the ball and all the black ones are a solid fit still. The grey ones are the larger bore as you mentioned and used from the servos to the bellcranks.

Thanks,

Tom

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04-23-2011 03:18 AM  7 years agoPost 4
GREYEAGLE

rrElite Veteran

Flat Land's

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I got that one figured.
The heavy duties are either mineral filled or maybe a fiber filled resin for added strength " like talc" and the plain black ones are just a thermo plastic resin. Hence the the traces .

When I hear guy's using ball reamer's or sizing tool's on "the others" I just shudder !

greyeagle

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04-23-2011 03:53 AM  7 years agoPost 5
spiderco

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Henderson, Nevada

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Same problem
I've got the same problem with my Spectra, the gray link on the tail pushrod is very loose and has the same dust particles. I have to try to get it off and replace it but the brass sleeve is over it. I might have to heat it up for removal.

The link was new with two 15 minute flights on it.

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04-23-2011 03:56 AM  7 years agoPost 6
turboomni

rrProfessor

East of the Equator

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flyinfriend just curious what motor you using? Is it modified?

Setup is everything, All my heli's can fly far better than I can pilot them

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04-23-2011 04:43 AM  7 years agoPost 7
rbort

rrProfessor

Franklin, MA - USA

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Vibes
Sounds like you have more vibes than necessary. You have choices:

a) find the cause of vibes and cure it
b) you can use the black links if you drill them out
c) you can do the ball link trap thing that I did with mine to guarantee no links can pop off.

Option c) is a security insurance policy and is only necessary for the fat rods. The thin ones don't move enough to cause wear. That's probably why you're seeing the black ones hold up better.

Key is lower the vibes. When my friend was testing motors, some were powdering the links more than others. Not all are created equal.

-=>Raja.

MA 1005 Hanson 280, 4220 flts
Spectra 27 3DMax, 3310 flts
Whiplash V1-2 Hanson 300, 1618 flts
Whiplash V2 Hanson 300, 473 flts

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04-23-2011 01:53 PM  7 years agoPost 8
Against Gravity

rrVeteran

Pottstown PA

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Wrong Place
Wouldn't this question be better placed, "on the Min Air forum"

AG

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04-23-2011 03:37 PM  7 years agoPost 9
flyinfriend

rrApprentice

North American continent

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turboomni,

I am using a stock G231. I have the hub runout to just under .002. That was the best I could get. There aren't any visible vibes from the tail or the skids and there is no foaming in the tank.

I am going to try and use the black links as Raja mentioned. I have no desire to get the engine modified at this point.

Against Gravity,

My Spectra is a gasser so I didn't think this was the wrong forum. There is actually not a lot of talk of the Spectra on the Min Air forum as there is more nitro volume on that forum. So I thought it would get more visibility here. I think your reply might have been relevant had I posted in the Electrics forum. I found the help I was looking for and within a day of posting found another Spectra owner with the same issue. I think it was ok to post it here.

Thanks,

Tom

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04-23-2011 03:48 PM  7 years agoPost 10
turboomni

rrProfessor

East of the Equator

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I was asking only because some guys try to use an out of the box 26cc .
231 should be fine i hear. Let us know what you find out. I just got to buy my motor for my Spectra and then can maiden her too....gulp!

Setup is everything, All my heli's can fly far better than I can pilot them

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04-23-2011 03:53 PM  7 years agoPost 11
rbort

rrProfessor

Franklin, MA - USA

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Some 231 motors are better than others
I heard that they can by anywhere from 1/2 thousands up to 4 thousands off as they come to the factory. So it all depends on the luck of the draw and if you get one that is not as true as another you will probably see some effect due to that.

If your fan is 2 thousands off or close to it then its more than I like to see. My specs are usually within 1 thousands. That may not be your only problem, but it definately can contribute to vibes.

Did you:

Balance the fan?
How about, balance the engine rotor?
Check the gap between the fan and the clutch and make sure its even all around?

-=>Raja.

MA 1005 Hanson 280, 4220 flts
Spectra 27 3DMax, 3310 flts
Whiplash V1-2 Hanson 300, 1618 flts
Whiplash V2 Hanson 300, 473 flts

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04-24-2011 01:05 PM  7 years agoPost 12
flyinfriend

rrApprentice

North American continent

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Hi Raja,

I didn't balance the fan. I need to buy a high point I guess. I'm not sure how I would balance the rotor or even sure how to pull it off. The gap between the clutch I did check with feeler gauges for evenness around.

I might pull the engine and try to dial it again. But I tried all the spots (0,90,180, 270) around with the fan and the best I could get was just under .002". The crank was just under two by itself so I guess that is the best I'm going to get unless I send it in.

Thanks,

Tom

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04-24-2011 05:04 PM  7 years agoPost 13
rbort

rrProfessor

Franklin, MA - USA

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Yup
If your crank is 2 thousands out, then that's what you got. Mine are 1/2 thousands out, but they are straightened not stock.

You will need a high point balancer to balance the fan, drilling some dimples in it on the back side where its heavy.

If you send the motor to get the crank trued, your rotor can be balanced at the same time as it has to come off to get the crank out.

All these things will help.

-=>Raja.

MA 1005 Hanson 280, 4220 flts
Spectra 27 3DMax, 3310 flts
Whiplash V1-2 Hanson 300, 1618 flts
Whiplash V2 Hanson 300, 473 flts

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