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HomeTurbineAircraftHelicopterTurbine Helicopters › Make sure your chopper doesn't overheat.
10-13-2005 09:09 PM  12 years agoPost 1
Bell Bloke

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UK

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The other day I purchased from Maplin electronics some domestic temperature sensors, at £7or $10 why not after all, I'm sure to find a use for them.
As indeed I have!!
Now we can all sometimes get a bit too anal about our turbine gearbox temperatures, can't we? I know I have. We can all spend far too much time pouring over our fadec data can't we? I know I have.
But spare a thought for us pilots, how well are we performing, when we are on the job?
Is there is no real way to predict a catastrophic failure in the pilot which could result in the rapid descent of his chopper? Such problems can be disconcerting when on ones own, but downright humiliating when in company!
Well fear not help is at hand.
Today, I Bell Bloke, for the sake of pilots well being everywhere, have sacrificed myself yet again...
Earlier today, I attached, in the name of science, some of these sensors to a number of my bodily particles.
I then went out into the wild outdoors with my equipment in hand, and began recording the data, and this is what I found..
The results, I must say were very telling, although I was a little lack luster in some areas....on the whole...things were quite impressive. You know it's amazing what 2 minutes of data can tell you about yourself.
Yes these little probes can certainly expose your weak areas and enable you to STAY COOL.. when under pressure, and thus maximizing your all round performance.

PS. Little temp probe gadgets from Maplins (BAR CODE- 4 891727 003155)
buy them now while stocks last!

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10-13-2005 10:10 PM  12 years agoPost 2
bladebender

rrNovice

England, Central

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Cheers

I have just ordered a temp probe from Maplin!!!!

I am concerned now though why there seems to be wren gearbox failures!!!!!!!!!!!!!!!!

I have just run my wren/predator for the first time today but am now a bit scared to fly. Does anyone know why the gearboxes are failing and in what sense do thet fail??????????????

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10-13-2005 10:56 PM  12 years agoPost 3
Jetblast

rrNovice

East Sussex England

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probe thingy's
Sorry Bell bloke

Having trouble locating said temp prob thingy's on the old Maplin web site..........Any chance you could be a little bit more specific on thier location


thanks

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10-13-2005 11:15 PM  12 years agoPost 4
Bell Bloke

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UK

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I'm not worried about my gearbox, I was mearly trying to develop some kind of service schedule that might help other Wren users.
If there are some problems I suspect that maybe people are not putting oil in the gearbox when they should, or they are putting too much in. 15ml is recommended.
The probe thing maybe useful as a monitor but I'm not going to get hung up on it, and if my probe fails, I shall switch to manual, and use my finger. It, never fails.

Seriously though, Wren know what they are doing, there are lots of these engines all over the place and all are running quite happily with no problems.
Forums are really great for comparing notes but I'm now worried that by trying to help people, and by giving a blow by blow account of turbine ownership, I'm inadvertently creating issues where there are none. There is also a danger that when people have a problem this is where they come, and so all you see are problems. Not me though I'm having fun!!

Finally when I first bought a Li-po battery they were so new you couldn't get them in England. The benefits were enormous but people are so skeptical, mythology prevailed and ignorance reigned supreme. This was not helped by manufactures of the cells overcompensating with pages of warnings in their literature. Horror stories of death and destruction were rife.
BUT the benefits were imposible to resist, from 5mins/nicad to 30mins Li-Po, I just had to go for it. Now if I had heeded all of those warnings, I would never had continued with helicopters, Li-Po powered helicopters are fantastic, just like turbine powered ones. 2 stroke IC powered machines are the instruments of Satan and should be exorcised, but not in my back yard.
Now we all except Li-Pos, and all of these horror stories are usually as a result of peoples mistakes. I have never had a Li-Po fire, never even seen one. I have 16 high powered cells, including my vintage original, still going strong. It has well over 100 cycles on it, when will it give up? Who knows but I sure have got my moneys worth.

If you take a peek at the internals of the Wren box, you'll notice that you have 2 bloody great cogs soaked in oil, they are made of steel. These in turn drive, via the clutch, a big plastic cog; well call me old fashioned but my money is on the metal gears. I bet that they could contain enough power to hurl that plastic cog and several others like it into next doors cabbage patch.
So go on, spark the little lad up and give it some stick!! I know I am.......

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10-14-2005 07:44 AM  12 years agoPost 5
bladebender

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England, Central

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Well i have bought the temp probe because i just want to compare with fan to without fan.

am interested to see how effective it is!!!

Cheers for the good idea!!!

Will keep you posted!!!

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10-14-2005 09:39 AM  12 years agoPost 6
PETER ROB

rrElite Veteran

Devon UK

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concerned about gearbox failure
bladebender 2 causes of failure oil/grease and lack of gear meshing, the oil problem appears to be 2 fold, too much or too little, too little, overheating seizure, too much, pressure build up forcing lubicant past seals, result as too little, JetCat have done away with lub in the box and gone for a controlled feed of oil fuel, the result is a constant temperature of 85 degrees and no need to take your gearbox apart to check contents, after 6 hours of running time there has been no change in running temperature, the gearbox cooling is assisted by a fan that holds the govenor magnets, it appears to work so much so that one of the gearbox makers is using a modified JetCat system on his own Wren with HobbyParts gearbox before you ask how I check the temperature I have a Maplins infrared thermometer just follow the dot and capture the temp

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10-14-2005 10:17 AM  12 years agoPost 7
coolice

rrKey Veteran

Northamptonshire, England

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BladeBender,

To my knowledge there has only ever been one gearbox failure which happened over the Charmouth weekend and is currently being taken care of by WREN.
Quite what happened I do not know yet but will do soon. In this case something sinister was developing as the anodizing was coming off the gearbox case.

All other Turbine Predators out there are flying happily with no problems other than operator induced one's, ECU plugs coming adrift is a good one I suffered with to.

I did have an oil seal failure back in April, but then again it turned out for the previous 6 months or more before hand I had been running it without any oil.
My gearbox was getting harder to turn as the rubber seal hardened, then when I did put some oil in a few flights later it gave out.
No big deal as the seal was replaced, gearbox itself was in perfect order and we learnt to check oil levels periodically to be safe.
.

Ian Contessa
Team Robbe SchluterUK
Midland Helicopters

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10-14-2005 10:42 AM  12 years agoPost 8
Jetblast

rrNovice

East Sussex England

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Gear Box temp.
I run a Bailey's gearbox.......Just wondered what the running temperature should be. Just curious.......has been running fine for over a year now.....

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10-14-2005 11:43 AM  12 years agoPost 9
wolfdad

rrKey Veteran

Southern Maryland

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Jetblast,
Just got my new Bailey's installed and a couple of flights on it. I would also like to order one of the probes if one of you gents would be kind enough to post the URL for the web site.

I am not aware of any Wren failures either....other than the one Coolice mentions. I've had my own problem, however that was not with a Wren or Bailey's and was caused by a manufacturing defect that has since been corrected.

Bloke, I don't think you are "stirring the pot" at all. I think you are putting out some useful information and perhaps getting all of us to scratch our heads and ask questions and, that is a good thing. Having recently had a gearbox problem, that is an area that, right now, I am particularly interested in and anything that is done with regard to preventing future problems due to servicing or a potential over-temp is, in my opinion, positive, regardless of the brand of gearbox one flies.

wolfdad sends....

P.S. Roy, that decorative gas bottle is a nice touch.

"There are those who have...and, those who will" IRCHA #2117, AMA #70068, Turbine Waiver #105

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10-14-2005 12:52 PM  12 years agoPost 10
1275mini

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Wirral North West U.K.

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10-14-2005 03:32 PM  12 years agoPost 11
rspblake

rrApprentice

London uk. coulsdon

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Report on why it failed?
Hi all,

Ian, Wonder if you can let me know the reason the gearbox failed at Charmouth the other day.

Not nice when it’s not your fault and they go in!

After talking to the guy seems that it was a on going problem, and the discoloring of the box within a few flight, think I would of asked for a exchange, although I understand that it was checked a week before.

My one was checked for temp on the day and for the record was running at 43degs

Funny everyone was licking there finger before touching the gearbox and was all surprised how cool it was.

Would just be good to know if its something to keep a eye on

Just want to say hello to all that i met on the sunday while writing

Cheers Rob

(gunnell_s) still owes me money! ... web evorc.com

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10-14-2005 03:42 PM  12 years agoPost 12
Jetblast

rrNovice

East Sussex England

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II concur with Wolfdad......Its all about fixing things before they go wrong.

That’s done through monitoring.......and spotting trends. (Has been part of my day job for the last 30 years. See my gallery.)

As has been said else ware the gearbox part of the equation is quit new relative to the engines themselves. So we are at the bleeding edge of things as it were…….and as the number of Wren/JetCat two stage/gearbox users increases the more feedback becomes available this all goes towards improving the breed…….

So again, as Wolfdad has said. Keep it up, let us all know your experiences.

I personally think monitoring the gearbox temp is a good idea, hence my request for more information on the temp probe used…….


Jetblast

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10-14-2005 03:47 PM  12 years agoPost 13
Bell Bloke

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UK

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Just off to Maplins to get the probe details you need Gentlmen.
Will you be requiring just the one, or six for pilot monitoring aswell?
Back soon.

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10-14-2005 03:49 PM  12 years agoPost 14
richie1967_uk

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London UK

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does Mr Cheese have one?

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10-14-2005 04:40 PM  12 years agoPost 15
coolice

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Northamptonshire, England

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Hey Rob,

Will do mate. As soon as I know I will report back here, WREN may even do so themselves yet to satisfy any concerns.

As you have mentioned and I heard to, the box was diss-colouring badly to start with so I am sure something was amiss early on. Just like you say and it's the same with me, if a machine goes in through my fingers then it's bad enough, but failures are the worst.

It's an isolated incident I'm sure of that, my own model is being flown hard with no problems, but it will be interesting to know what happened.
.

Ian Contessa
Team Robbe SchluterUK
Midland Helicopters

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10-14-2005 06:03 PM  12 years agoPost 16
Bell Bloke

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UK

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Mr. Cheese is unavailable for comment, apparently he's still hung over after going out on the town with Gromit and his bitches following the world premiere of THE CURSE OF THE WERE-RABBIT.
But I can now tell you that the Probe Code is: GW57M Thermo/Clock
-50 - +70C.

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10-15-2005 09:46 PM  12 years agoPost 17
Skeeter Pilot

rrApprentice

England

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I bought Mr. Cheese a temp. probe today. After a blast around the helipad chasing a few bunnies the anodising on his name tag changed colour. He seems to be near melting point, I think he must need an oil change!
..........................

If there is soil going over the canopy, you're too low!

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10-17-2005 05:59 PM  12 years agoPost 18
coolice

rrKey Veteran

Northamptonshire, England

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Hey,

I have just had a long conversation with WREN regarding the reports of a second stage gear box failure at Charmouth Fly-In two weeks ago.

This is clarification of the conversation that took place :

"Following our discussion I am writing to confirm what I told you.

At the recent Charmouth event Fred Coulson model's helicopter auto rotated down after the transmission seized .The helicopter has now been examined at Wren's factory.

The gearbox was quite free and had not overheated, the oil was still a light honey colour and did not have a strong odour. The power turbine however had rubbed on the interstage and that had stopped the power shaft from rotating. This was caused by a misalignment of the engine, interstage and gearbox within the side frames.

The unit has now been repaired by Wren and will hopefully be in the air again very soon. Despite the speculation no gearboxes have overheated for any other reason than being overfilled.

Bye

John"

The equipment is more than up to the job, it's just us mortals that get it wrong
.

Ian Contessa
Team Robbe SchluterUK
Midland Helicopters

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10-17-2005 09:45 PM  12 years agoPost 19
rspblake

rrApprentice

London uk. coulsdon

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Hi Ian thanks for the reply.

"Gearbox was quite free"

Was locked solid when on the table at charmouth,
Had to of been a bit more than rubbing the way it felt, and to lock the head so the drive gear ripped the teeth to free it self takes some doing.

"Power turbine however had rubbed on the interstage and that had stopped the power shaft from rotating"

Could that not of happen as part of the crash? Plus surely if it was rubbing would it not of been heard on start up/ running before hand?

Just talking to the guy from Fred Coulson model's at the show said it had been back before hand because gearbox getting really hot.

Can the misalignment cause the extra heat, and if so should it not of been pick up when stripped and checked.

Just want to get it clear in my own mind!

Rob

(gunnell_s) still owes me money! ... web evorc.com

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10-17-2005 10:41 PM  12 years agoPost 20
coolice

rrKey Veteran

Northamptonshire, England

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Hey Rob,

Basically that is the response from WREN themselves, not pointing the finger of blame onto anyone person.

I chatted with John about the returned assembly and asked him to send me his report he verbally told me over the phone in writing.
That way I could copy and paste it here making sure the true findings of the examination are told and not my interpretation of the incident, which could have allowed inaccuracys to creep in.

It was noted that the gearbox had run hotter than normal, whether this is through to much oil being used in the past however we cannot say for certain. But rest assured it was not a part problem.
I'd run mine without oil for sometime, with the gearbox getting tighter & tighter to turn and the anodizing never changed colour on it.

The build up of heat I'm sure was as a result of the rotating parts coming into contact with one another. We all know any kind of contact between to moving surfaces will generate heat if not lubricated correctly.

As to if the problem would have been detected at startup I do not know. Bear in mind a govenor was being used and the full 160,000 rpm dialled in on the turbine RPM limit, to give full control to the govenor.
If the turbine wheel was being held back by the contact points slowing the compressor wheel, then I am sure the govenor would compensate for it with more power.
Then more power would mean more RPM and a greater heat build up through the contact points.

There was errors noted in the assembly, but these were not due to a design or part failure on WREN's part. Again we will not point fingers in any direction and do not wish to.

The turbine has been repaired, as has the gearbox with a new housing fitted so they are back to green again.
.

Ian Contessa
Team Robbe SchluterUK
Midland Helicopters

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