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CarbonXtreme . Midland Helicopters . HeliProz

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Thunder Tiger Raptors 30-90 - Imperio > Exploding tail on your raptors.
 
 
w.pasman
Elite Veteran
Location: Netherlands

Quote 
The Gohbee Stinger tail has trust bearings also, and is almost identical to the Raptor tail


I looked in the gohbee manual (download from the web at http://www.gohbee.com/Merchant2/docs/instructions/GBS30 Instruction Manual.pdf) and I just see two radial bearings just as with the raptor
08-10-2006 Over year old.
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w.pasman
Elite Veteran
Location: Netherlands

I'm following Barney's way to do this mod (see page 7) and use the trust bearings from the raptor V1 head.


Is the shim necessary? I just tried by hand and there seems to be no binding of the radial bearing. By hand I probably can't put the required load on it but I don't expect much flexing of steel bearings...

Without a shim, the locknut should fit snugly as normal, while with the shim you would have to rely on red loctite which I don't like

BTW Why would putting the trustbearing on the outside NOT be OK?
08-10-2006 Over year old.
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arceye
Veteran
Location: UK

Quote 
Is the shim necessary?


Yes otherwise the thrust bearing will touch the outer ring on the radial bearing and so lock it up.

The reason the thrust bearing is on the inside is so it places force on the inner part of the radial bearing so it will not allow the radial bearings to split inner from outer, if the thrust bearing was on the outside of the radial then there is nothing to stop the radial bearing from splitting.


Andy


Kasama Head :(
The Blingiest DOWNGRADE a Raptor can have
08-10-2006 Over year old.
 
 
firefox
Senior Heliman
Location: Thailand

Have been following this thread (and Runryder) with interest, but this is my first post here.

I think that this problem is not only Raptors, and really shouldn't be blamed on poor design, since this same design with the same faults is used in plenty of other helis from other manufacturers. In the reviews of the Tiger from Audacity models, one person mention that his tail exploded 3 (three!) times due to failed bearings. And here
http://www.dream-models.com/eco/maint-tail.html
You see an electric heli, the Eco, experience the same thing.

Anyways, in my country, the main distributor of Thunder Tiger doesn't carry the SUS steel hub... but I've already asked a friend to get them for me. Most people who fly Raptors here have no idea of the problem. I did manage to get thrust bearings for cheap (with different inner diameters, same type as the main rotor), $2.50 each (compared to $10 each for the TT ones). I fitted it without a shim (couldn't find one that thin/small) on the inside, and it worked well. Tried it on the outside, and it also worked well. Couldn't see a difference, but I've only had a few flights with them on.

For the Raptor 50's, the thrust bearings are on the inside of the main blade grips, while the 90's have them on the outside. Doesn't seem detrimental to either size heli, so I guess either way works (maybe not in theory, but in practice)?
08-10-2006 Over year old.
 
 
w.pasman
Elite Veteran
Location: Netherlands

Andy Yes I understood that already.

What's preventing you from putting the trustbearing at the blade side instead? That way the trust bearing would be pushing the outside of the radial bearing instead of the inside as it is now. The big ring of the trust bearing already has larger internal diameter which might be enough to unload the inside ring of the radial bearing (are you still there )
08-10-2006 Over year old.
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Flying Tivo
Veteran
Location: Monterrey,NL,Mexico

Thrust bearing and radial bearing

As long as the washer on the outside sits properly and evenly across the radial bearing on the inside and outside the force will be transmited accordingly and evenly if its on he outside. If the radial bearing is on the inside then the radial should sit evenly across the thrust bearing, and the forces would be transmited evenly and no lock up should occure.

If the thrust bearing is on the inside and the radial on the outside and you only use a small washer that sites on the inner part of the radial bearing, then you are looking for trouble.

So if you have a washer, then the thrust and radial can be used on either side, but if you dont have a washer then the thrust bearing has to be used on the outside.

Felipe

If life throws at you lemons......Squirt some lemon juice in the eye of your enemy!!!!
08-10-2006 Over year old.
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G-Force Heli
Senior Heliman
Location: Ontario, Canada

I have never blow my tail rotor bearings. I find the oil that comes with the tail bearings are too thick of a viscosity for it at the speed it runs.

The lighter the oil the better for this application.

I use air tool oil which is rated beyond 10,000 rpm. Just keep it lubed often because the high speed tend to throw out all the oil as time goes by.
08-10-2006 Over year old.
 
 
Barney
Key Veteran
Location: Inverness Scotland

w.pasman


If you have a read back through my other posts (page 8 & on) you will see why they had to be fitted that way up to work..Also further on in the thread you will see that It didn't work out for me..

I suppose It is a possibly that it was low grade brgs I was supplied I'm not sure. Anyhow Iv'e reverted to the standard setup meantime
08-10-2006 Over year old.
 
 
Avetikus
Heliman
Location: Outer Sloboubia

I talked to the general manager at Boca Bearings via e-mail in regards to finding angled contact bearings of the appropriate size for the tail rotor.

The upshot is that these bearings are not yet made and it would take a considerable outlay to 'make the mold' so to speak. Even at triple the price to purchase them it wouldn't be feasible for a company to make these very specific-application bearings.

So.. thrust bearing replacements it is. At least for now.



Av

'heli' (n) 1. A contraption lifted and propelled by burning money.
08-10-2006 Over year old.
 
 
JakeDaSnake
Senior Heliman
Location: Mobile AL

I just read most the post, and the TTR Thrust bearings seems to fix the problem?

If you keep having problems, you could go to a Century Predator tail... the SE and Gasser's have 2 Radial and 1 thrust per tail grip... and I believe the tail shafts are the same size! so the entire Century hub would fit...

Just a thought...

Later,
Jake

Jake Wiggins: AMA 856496
08-10-2006 Over year old.
 
 
firefox
Senior Heliman
Location: Thailand

I recall on Rick's helis (at least I think it was Rick's) that they said they had success with changing the Raptor tail to the JR tail, using part #'s JRP960470,JRP960056 and JRP960057. Of course, changing the whole shebang is a bit steep, compared to buying just the steel hub (6 bucks) and 2 5x10x4 thrust bearings (5 bucks), and getting the same result.

I'll do some more flying with these non-shimmed and really cheap thrust bearings, and see if there are any problems. Done a lot of circuits and hovers with them with no problems. I'm still a beginner, so I can't do 3D tests yet.
08-11-2006 Over year old.
 
 
w.pasman
Elite Veteran
Location: Netherlands

Barney,

Quote 
As soon as I changed back to the hub with the thrust brgs installed I had gyro problems again..I've just stripped it all down for a look to see whats happened and found that the races in the thrusts are already heavily pitted.

When this lot was assembled last week I used new brgs and even now I can feel little sign of a problem...they have only had 4-5 flights.. So either the brgs I got are from a dubious source or the loads we are subjecting them to far exceeds there capabilities.


Ah thanks, I missed that. Interesting indeed. I can't believe the trust bearings are not strong enough as they were used on the raptor v1 to hold the MAIN blades. So thrust bearings in this way does NOT solve the problem either...

With this setup there is only 1 radial bearing remaining. Is it possible that sideways loads on the tail (eg, slight hit of tail against the ground) pushes the thrust bearing out of center, damaging it?
08-12-2006 Over year old.
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firefox
Senior Heliman
Location: Thailand

Strange, since I saw no difference between no thrust bearing, thrust bearing inside, and thrust bearing outside. At least not yeat... the gyro (401) is still holding fine. However, when I tried installing them initially, I used tri-flow (had no grease on hand), and later when I checked, they looked a bit worn, since the tri-flow was flung out by the spinning forces. Later I switched to synthetic grease, and have checked the bearing and seen no further wear.

Another thing I notice is that the Titan has 18.5mm set screws on the tail, as opposed to 18mm on previous models (including the 90SE). I guess Thunder Tiger changed that... but they really should have changed it to the SUS hub. Also, I saw that Thunder Tiger had sent a bag full of 18.5mm set screws to the local distributor with little notes attached to the individual baggies saying to replace the old set screws.
08-12-2006 Over year old.
 
 
BlakeMcBrayer
Elite Veteran
Location: Georgetown, Ky

Here we go guys and gals, A complete tail rotor assembly with THRUST BEARINGS built for the Raptors by Quick UK. I currently have 2 of the first versions with no thrust bearings and I have been very pleased with them. I got the 2 upgrade kits and 1 complete assembly today. With the trust bearings installed, they are super smooth. Considering the quality of QUK stuff, I think an affordable solution has been offered up!

http://www.runryder.com/helicopter/t281812p1/

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Don't come off the throttle untill you see your GOD!
09-01-2006 Over year old.
 
 
rerazor
Elite Veteran
Location: Mich.

Did you order that direct from Quick in the UK?
09-01-2006 Over year old.
 
 
BlakeMcBrayer
Elite Veteran
Location: Georgetown, Ky

Not this time, but from time to time I do order directly from them. Most of the time I order my QUK stuff from Al's Hobby Shop. They are a QUK dealer and sell slightly below recommended list. It's actually a little cheaper to order from them than from QUK directly. There web site isn't very good, so I do all of my orders over the phone. When you call ask for Cindy, if she isn't available, then wait till she is, cause she is the customer service BOMB! Tell her Blake sent ya.

Here is a link to Al's so you can get the number:

http://www.alshobbyshop.com/store/index.asp

Don't come off the throttle untill you see your GOD!
09-01-2006 Over year old.
 
 
rookie5
Veteran
Location: Harlow, Essex - United Kingdom

ive just bought and built my 90se how do i know if i have the same problem as you do ?
09-02-2006 Over year old.
 
 
Tday
Key Veteran
Location: Needham, MA

Rookie,

This exploding tail thread is bigger than I would have imagined. I've owned a bunch of 50's and have 2 90's that I've flown for a long time. At my field, many fliers are TT flyers. I've never seen an exploding tail BUT it sounds like it happens and not just on TT ships. I think a key variable is the head speed you fly at. If you're inching up to 1900 and above---a very aggressive flyer, then I think the new QuickUK with thrust bearings might be smart. There are other fixes available, but the quickUK is raptor specific. This is just my take, anyway.

Tom
PS: I have the quickUK tail on both helis and have the thrust bearings on the way.
09-02-2006 Over year old.
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rerazor
Elite Veteran
Location: Mich.

Will the Quick thrust bearing work with the stock TT grips/tail?
09-02-2006 Over year old.
 
 
Yug
rrProfessor
Location: UK. Herts

firefox - interesting what you say about the 18.5mm setscrews. I would still suggest that 18.5mm is too short and would prefer 20mm. Sadly, it seems TT are still not paying attention to basic maths and specifications of screws, bearings and forces

Vegetable rights and Peace
09-03-2006 Over year old.
 
 
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Thunder Tiger Raptors 30-90 - Imperio > Exploding tail on your raptors.
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