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HelicopterMain Discussion › I am doing something wrong with my Millenniums
06-06-2004 06:02 PM  13 years agoPost 1
Simon Brown

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Leicestershire

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Hi all.

Since I fitted the ridged pinion holder system from rcmarket, and since Robbe made the pinion top support to be double on the Millennium3, I have been having clutch shoes fail!.

I am at a loss as to what I can be doing wrong so I put this out for suggestions.

Basically I think that as we know, the Millennium frames do tend to flex more than some machines, when inputting strong aileron. Say metronoming or sharp multi piont rolls.

I reckon that now the clutch bells will not move at all, that the clutch shoe takes all the flex and fails with strong aileron 3d... Now I cannot figure out another reason as all my fans and hubs are as dialed up as they have been for the past years with my Milleniums.
I align the bell and engine with great care and ensure a smooth run. I find a good proof of a good alignment is a completly ripple free fuel tank, which I do have..

So how can I stop taking 4 stroke robbe clutch shoes out, to order .. one per flight.?/ I use 4 stroke clutches because I use 91 sized engine, running as slower rates. C spec in one at 15000 rpm and a webra 91 running at 13000 in the other...

I cannot believe this is just a problem for me, but if it is, there has to be some real clever reason that I cannot see the problem and cure..
any help would be damn cool..
chow
si

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06-06-2004 06:13 PM  13 years agoPost 2
S_Owen

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Wichita Falls, TX.

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3 questions

What's the head-speed?

Is it bogging?

What's the gap between the shoes and the liner?

[b]Murphy's Constant:[/b] Matter will be damaged in direct proportion to its value.

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06-06-2004 06:20 PM  13 years agoPost 3
ESchmidt

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Salem, NH

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Is it possible that the clutch shoes are breaking because they are 4-stroke shoes?? Have you tried using a standard one yet? I'm using the standard clutch shoe in my YS80 powered Nova running the engine at 14500, and have never had a problem.

How much clearance do you have between the liner and shoe??

These are all things I'm sure you already thought of and/or checked, but I've never even heard of anyone having clutch issues with a Robbe.

Eric

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06-06-2004 06:20 PM  13 years agoPost 4
Simon Brown

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Leicestershire

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Hi there

Both machines have a head speed of 1760rpm which I have always used..
Neither of them bog down because they are both powerful but I tend to fly the machines with care and also set the pitch limits to match.

idle up, I do not load the engine in a climb out because with added 3d cyclic inputs, is can indeed bog the engines..

In these regards nothing has changed from the time when I did not take out shoes.

Not sure on clutch liner clearance, but the Millennium 3 has flown next to non so the liner is going to be as per supplied, or very close to it.

I can check the clearances when I have to strip them both down yet again and fit new clutch shoes to both...

What thoughts would you be thinking re bogging, and head speeds?

Any thoughts would be great please .

Also it would be good for a pilot to tell me he has a mill 3 with the more ridged pinion and that he gives his mill 3 3d greif with no problems.. At least I can here from some one who has whaty I have..

si

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06-06-2004 06:30 PM  13 years agoPost 5
Simon Brown

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Leicestershire

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Hi Helifreek.

Well your mention of clearance is the same as the first reply and thanks for that one..

I thought that the "nova" was a different clutch design to the Millennium? I thought it was more like the Futura se, which was a superb solid clutch design which would last and last..

Robbe used to have one bearing at the top of a Millennium pinion.. I could always see a carbon line round the clutch bell where it had rubbed on the frames but there is a clearance when sitting on the bench.

that top bearing would tend to spin on the pinion and with time could ware the top pinion flange. one would use various adhesives to lock the inner bearing to the pinion but in time, these would fail..

Robbe have obviously seen this and made the double bearing support and longer flange on the pinion.

Clearly this does not flex any more, or a far clutch bell is locked ridged to the top frames and the engine is moving underneath, that the piont of joint is the clutch shoes which fail..

Again, I have not had clutch shoes fail for many years of flying my Millennium2 and now after the pinion mount change I can not get two flights without shoes cracking off.

But if someone has a Millennium3 pro and it does not take shoes out with strong 3d, I need to find out why or how.

nightmare..
si

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06-06-2004 07:27 PM  13 years agoPost 6
Chen Zarfati

rrApprentice

Israel

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Hi Simon my name is Chen Zarfati and I flies my both Mille2 and DynaX
with dual bb start block which I bought from rcmarket and it works great in metronome. I put a shim between the cluch bell and the pinion gear because me heli was bogging and it came from the engine and when I put it , the heli stop ped bogging.

Hope it's help you,

Chen Zarfati

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06-07-2004 12:35 AM  13 years agoPost 7
MJA

rrKey Veteran

UK

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Simon,
Can you be sure that the clutch bell itself or pinion you have
is a 100%
accurate piece of machining?For the rigid pinion to work well the fan hub and stack up would need to be near
perfect which we all tend to
check,especially on the Millenium as it's a bit of a bastard:-)
,but what's the clutch bell and pinion like for accuracy?

Does the MiIl 3 still have plastic standoffs
between the inner and outer
frame stacks,if you supsect it's due to frame twist you'll probably have
to replace them with alloy ones as an experiment.

i don't like the 4 stroke HD clutch,it
looks weaker at the hairpin eye than the originals.I think they're done like that so that the take up rpm is lower.I think i'd be tempted to try the original clutch's and if the take up rpm is a problem at all,maybe glue
some shim brass in the clutch liner first
then glue in another liner piece.
I used the original clutches in my Millenium and Futura SE with 91's
without modifying the clearence at all and have never had a problem with them

I wonder if it's possible that the engine is generating a vibration frequency
that can break the clutches but not show up as a milk shake in the tank or even a ripple?
i think probably unlikely , as it'd do it before the pinion support was fitted.
Just a thought

Fitting carbon lower angles and base plate might help to further stiffen the frame structure on the engine mount area lower plates.

Martin

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06-07-2004 12:48 AM  13 years agoPost 8
rappy112

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Guelph Ont.

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Simon have you upgrade the engine mount? could be the engine is flexng now if you havent upgraded it. This could cause the engine to flex instead of the pinion, when I upgraded the engine mount havent had any problems.

Proud member of Team Bob00

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06-07-2004 08:52 AM  13 years agoPost 9
Roger Hamilton

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Surrey, England

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Hi Simon,

You may find the 4 stroke clutch is your problem. I would recommend the 90 clutch, which is not as heavy as the 4 stroke version. I had one fitted to my Nova which failed recently, but the 90 version is lighter and seems to have a reasonable life.

Secondly, Skyline now supply an aluminium frame spacer set for the Millennium which considerably improves overall rigidity and which may help.

Lastly, you could have a look at the liner in your clutch bell, maybe its worth sticking it in a lathe and ensuring the liner surface is true.

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06-07-2004 12:42 PM  13 years agoPost 10
tim tompkins

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Boston, Georgia sw Ga. Thomas County

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Me Too

I just last week replaced my Milli III clutch.The shoe broke and the resulting damage to the liner had me replace the liner also.When I called HUI I asked about the part # being listed as the four stroke version.No mention about this being a problem though.Paul sold me a new unit and liner that I installed and now have flown about four or five flights.I have not yet done any hard 3-d with my Milli III.Before it broke the clutch rattled but seemed to function fine for the first couple of gallons.I have had some trouble with the YS-91 so I have had this new bird apart several times already.This new ship is playing a little hard o get.I already love to fly it so I will work out any issues.

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06-07-2004 08:05 PM  13 years agoPost 11
Simon Brown

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Leicestershire

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Wow so many constructive ideas.

I did wonder about the 4 stroke shoes, so I tried the standard one from Robbe and that failed in one flight also.

I shall look at the fan and hubs on the engine with a dail gauge again.. make sure it is perfect if I can.

i will look at the liners, although both are almost new with little use, so are stock robbe thickness with new shoes.

I have already tried the metal frame spacers and have fitted to both the latest engine mount back brace.. no change.

I really do not think I have engine resonance or vibes, as both are totally different engines, running at their respective ideal revs. Until I fitted the upgrade from Rcmarket to the Mill 2, All I got was the top pinion bearing coming off the pinion top and if not fixed regularly it would ware away the pinion. but never did I take out shoes.. Well... that is not true.. They would fail from time to time..

One of you mentioned a rattle.. Now, I have had this loads of times with my Millenniums.. I would find that the clutch shoe would slide over the keyway nice and tightly.. but if I did not put a tiny bit of epoxy on this, with a short amount of flying, the shoe would be slightly loose and rock on the keyway!.

I have been told that in a few cases, the pinions do not sit perfectly flat on the clutch bells.. In these cases, once this was identified and touch of filing was done, their problems of bogging down and vibes were gone.
I really don;t think I have this, but I am going to crawl all over these clutch / bell assemblies with a microscope now.

One thing I am not sure of if the mention of a 90 shoe in relation to 4 stroke? I thought there were two for the Millenium.. the standard and the 4 stroke which is black metal and used for 91 engines..???
Is there a third, and if so what is the robbe part number, cause i will go get one and fit that, rather than the softer 4 stroke ones I am using now...

simon.

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06-08-2004 12:51 AM  13 years agoPost 12
MJA

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UK

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Simon,when you say the std clutch failed in one flight,do you mean std std as used on the original 60's or a std 90 or HD clutch.I got a HD clutch with a Milli2
90 conversion set which has extra metal removed from it(which to me weakens the outside wall near the hairpin eye), i took it to be the same thing as the 4 stroke clutch,but it isn't black it's steel coloured.I just use the std clutch's ie not HD or 90 or 4stroke,whatever they're known as

What is the gear mesh like,is the alignment spot on.Left to R and Fore to Aft of engine line through the clutchbell and pinion
If the upper frame section flex's making the maingear teeth go out of alignment and force the pinion/clutchbell which is now fixed rigid at two points
,you'd expect to see wierd wear pattern on the maingear teeth.
What does that look like?

Did you use the same exhaust/pipes on both engines,i don't think it's impossible for aggresive pipe pulses to cause metal fatigue but i could be wrong.

Also the MPII or a zimmerman one piece is alot of weight hanging out the side of an engine that resonates ie head of engine resonates with the exhaust ,if the clutch bell is fixed
rigid it could be enough to break the clutch when the engine resonates & also tries to swing L to R side of heli slightly with the torque or normal running vibration

The torque i'm talking about is the twisting force that acts around the crankshaft axis but the engine beam end of the engine is fixed rigid or may flex in the frames whilst the other end isn't fixed but may have weight on it like a relatively heavy one piece exhaust ie with no silicon joiner


Martin

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06-08-2004 10:47 AM  13 years agoPost 13
Chen Zarfati

rrApprentice

Israel

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Another Suggestion

Hi Simon,
Somthing else that I forgot to tell you is to put a larger cluch lining in the cluch bell.

Try to find a larger lining and will help you.-I did it and it works fine.

bye,
Chen Zarfati

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06-08-2004 09:00 PM  13 years agoPost 14
Simon Brown

rrVeteran

Leicestershire

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hi Martin.

WOW, well techincal engineering stuff to take in there.. thanks for all those ideas..
I will endevour to make the alignment as perfect as possible and will go looking at gears etc..
I have to consider though, that shed loads of pilots out their use Muscle pipes and tuned pipes on their milleniums, and indeed I have for ages too.
problem came with I change the way of holding the clutch bells..Like Robbe's new twin support pinion and Rcmarkets double bearing support unit..

I have used the standard 60 sized clutch shoe after taking out many of the black heavy duty ones from Robbe.. the 60 standard one fails exactly the same.

I hear of three choices??
I know of the 60 one, I have the black one which I understand to be the right one for a 91 engine? But whats this third one??
has any one got some Robbe code numbers so I can track down if I am actually using the wrong one, or the best suited etc!..

Chen..
thanks for the liner mention. I have picked up on that one now from various pilots and thanks to them all for that.
I have had the rcmarket clutch bell assembly out last night and offered in a new clutch shoe
I have to say there is quite a bit of side movement .But the liner is much as a new one.. I have been told that Robbe have reduced the thickness of their liners some time back? Well I can not confirm that one, but for sure, I shall make the liner real close to the new clutch, the align it the best I can..

On the alingment, I am very careful and eye it up. I spin it round and around and ensure all is running so well.. Dial up the fan and hub too..
I ensure that the mesh is good but not tight.
Never had any problems before these more riged clutches and I feel pretty sure that the majority of pilots out there who do not have a problem, do not spend ages with dial guages and feeler gauges, lining and clocking it all up...

Well lots to work with..
A bit of a shame for me, as in the UK, there are some new flyins which need supporting.. Am sure I will find out whats going on in due coarse.... thanks to every ones help.

chow
simon.

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06-08-2004 10:30 PM  13 years agoPost 15
Shagga

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Wiltshire, UK

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Hi Simon

Forgive me for asking the obvious question -

But are you not a UK rep for Robbe?
What support and feedback are you getting from Robbe themselves?

I assume you have already spoken to them about this problem.
I understand that you may also want direct feedback from people who actually fly the models. That is why you have posted on RR.

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06-08-2004 10:54 PM  13 years agoPost 16
MJA

rrKey Veteran

UK

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<<
Never had any problems before these more riged clutches and I feel pretty sure that the majority of pilots out there who do not have a problem, do not spend ages with dial guages and feeler gauges, lining and clocking it all up...
>>

Simon,
Lots of people probably don't spend time dial gaugeing,lining up etc ,true, but lots of people probably aren't using dual ballrace supported clutch bells either and you have no way of knowing how hard they are being flown either.Maybe you are the unlucky one who has the dodgy pinion,clutchbell,fan hub

When you have a std one top bearing only on the clutch bell

(i know there's one larger inside the clutch bell lower down on a std setup but it can move with the engine via the top hat guide above the clutch)


When the bearing is fastened into the block,because they aren't a precision ballrace as a rule
, there is a few thou of "rocking type"
movement,which is sufficient to let the clutch bell follow the clutch if need be,unless it has excessive runout

.Now say if the engine flexes out of line due to torque,outer frame flex ,runout on the hub or whatever.Same with
the clutch bell if the block that the top bearing housing is in flexes at all ,
the clutch bell can be more self aligning due to some "rocking" type
play allowed in the single bearing inner to outer race.

So i think it becomes much more critical that everything now is absolutley spot on lined up and has no eccentric running anywhere
and also can't flex off line at all otherwise the clutch is trying to run in the bell off angle at times and the clutch bell now being fixed more or less solid at the top
can't take out the slight highs and lows anymore so the clutch breaks

I think i would slacken all the bolts on the clutch bell pinion support,take the plug out of the motor and turn the engine over carefully (by the fan if possible) and see if you can observe the pinion or clutch bell trying to move offline when the engine crank plus clutch is rotated through a full 360degrees.
Also if you drop the engine out and look throught the frame openings from underneath does the clutch bell run absolutely true at the lower edge where the liner is,in other words the inside face that the liner is glued to.

When you do that test with a single support bearing they never run quite true due to the rocking play you get in the upper bearing making it difficult to check for.With the dual support above and below the pinion that rocking won't be there anymore so the clutch bell must run true or the clutch and clutch bell will do an impression of a universal joint on a small scale that'll fatigue the shoes


I'm not trying to slag off the dual bearing pinion support,but feel it has cured one problem (the loosening/polishing up of pinions in the inner race of the top bearing
)but now makes alignment and accuracy of some of the machined parts more critical than before


Martin

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06-09-2004 12:48 AM  13 years agoPost 17
Reesy

rrKey Veteran

In the doghouse ... Nottingham UK

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Wow so many constructive ideas.
OK .. so you've had all the brainy input so here's the dopey "way out left field stuff"
Have you thought of measuring up your clutch stuff and sending it to Budd and his estimable modelling emporium?

I know nothing of the dimensions of the clutches you are using but if you could fettle up a (say) QuickUK Rap90 clutch say with a beefier liner to take up the slack then shag that in one flight ...

Well my misus would sure like to meet YOU .....

Paul

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06-09-2004 09:20 PM  13 years agoPost 18
Simon Brown

rrVeteran

Leicestershire

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Martin.

Your last comment is exactly where I am coming from.
In that, they cure one problem with the polishing of pinion etc and cause the problem in the clutch..

See, No matter how spot on I make that clutch unit, when I go out and give the machine some serious aileron 3d, the frames flex big time.

I can see this because on the bench there is clearance round the clutch bell side, but after aileron activity there is a carbon rub line around the clutch bell.
If I refain for any aileron inputs, no line appears on the outside.

So clearly as we all know, the triple stack millennium frames do tend to flex in flight some what.
When I ran my design of clutch with the 5mm ground shaft coming from the bottom hub, up to a hex cap, this made the whole assembly extremely ridged. And I could feel the change big time.. Flew so much better...sharper.. As per a Futura.. ridged!.
That was not the right way to make a machine ridged..(using the clutch to do it) and that is why it evenatually failed.. But, wow that was good while it lasted..

SO since the double bearing support which locks that clutch bell solid, then the engine flexes underneath and the bell does not go with it at all.
So as you described, it is a bit like a universal joint.

I would sware that this is what is going on, since if I refrain from a single aileron 3d manoeuvre, the clutch works fine..

I will align to the max.. I will dial every thing with a thou if poss. I will get a liner which is mega close to the shoe..
And see how that goes.
IF I get more grief, I shall revert back to the original pinion mount and see what happens then...

simon.

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06-09-2004 11:00 PM  13 years agoPost 19
MJA

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UK

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Simon,
On the Kalt Alpha60 V1's that had thinner stamped frames,with alot of mainshaft above the top bearing block compared to below it,plus very narrow mainshaft bearing spacing, they used to have two side outrigger type frame pieces that would brace the narrower upper section to the lower going right around the outside of the maingear
just behind it's centreline.

If you could arrange/make something like that on the Milleniums, going from top mainshaft bearing block right down to the lower frame angles on each side it should eliminate all the flex completely.
Only problem is the maingear on a Millenium is like a dinner plate as you know,so it wouldn't look too good.

If the Mill3 has plastic spacer blocks either side of the lower mainshaft bearing block still,i would ditch those.Then see where else it can be stiffened up by double plating or putting extra blocks in.

Or just go back to a single bearing support for the clutch bell

Martin

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06-10-2004 12:38 PM  13 years agoPost 20
MJA

rrKey Veteran

UK

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Simon,
From a design point of view this is what would work to remove the flexing of the inner frame stack relative to the outer.

Have engine mount frames with most of the frame opening above the tank blanked off,that no one seems to use
,it's too near the engine mounts to be a good location for the gyro
anyways.

Ditch the current centre mainshaft bearing support.

Use a longer mainshaft and have a lower 3rd bearing block just above the tank somewhere and that extends a little backwards due to the limited clearence forwards where the fan shrouds need to be.

This would add a bit more weight though unless a hollow mainshaft was used.

Also on that note, Robbe needs to redesign the rotorhub too so that more mainshaft is in the hub above the jesus bolt, so that there's no risk of snapping the mainshafts at the 3mm hole with hollow mainshafts.A redesign to a 12mm hollow mainshaft with 4mm
bolt holes would have been good,considering the powerplants that are going in these things nowadays.Too late for that now though


Martin

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