(Tail Wag) Torque Tube bearing install.

[daument]

All,
I've just finished my 600N and it has some tail wag issues. The Gyro rate is turned down and the heli runs smooth at 1700. When the head speed is 2000 or better the tail starts to wag and some vibration is apparent (tail fin starts buzzing). I've read that an additional bearing in the boom often helps. How are most people installing the second bearing? Do you drive the pin out of the coupler and slide the bearing on? Is the pin the reinstalled with any adhesive? thanks! Dave

[G MAN]

Sounds more like an engine tuning problem,too lean. The extra bearing is not needed and wont make it any smoother.

[daument]

FWIW YS 50 .. needle out 1 3/4 turns running rich as it only has two tanks through it. I've been tuning Nitro engines in helis since '82...... so, that's not it.

[vteknical]

You are officially "Chasing a Ghost". Unfortunately there is not magic bullet to this wagging. You will read many resolutions: ranging from torque tube bearing, tail blades, kasama tail unit, too rich, too lean, gyro settings, locking up main bearings, what time of the day, full moon, balanced clutch, twisted frame, bad bearings, vibration, gyro gain, gyro mounting, pad, servo voltage, balanced blades, head speed,

I know I'm missing some, the point is: guys that have been buiding for many years are still posting this anomaly. Sure they could missed something during the build, mechnical and electronic setup, but so many?

I still have a very ever so slight side to side pulse on my pro. Tube bearings, tail blades, tail hub, carb smart, gyro repositioning and it's still there. I've just learned to live with it until the Ghost is found.
Maybe it's normal, don't know this is my first 50 size nitro heli.

Victor

[fogger]

Yup, just gonna have to go through the process of trying everything you can think of / find in similar posts... Good luck figuring it out.

As for the bearing add, I have read that you can press that pin out, put on the second bearing, and then press the pin and back in, but definitely use some kind of adhesive when you put it back in, or physically deform the ends to keep it from coming out in flight.

-Fog

[aussiemick]

How are most people installing the second bearing? Dave

Dave

I installed the second bearing by grinding the pin down to flush so that the bearings could slide over it. This is a Mecuriel suggestion so I used it. After installation I applied thin CA to both sides of the pin. I think I will go back in to the TT assembly and apply about an inch of heat shrink over where the pin is, being careful of course not to make it too long and let it foul the tail drive gear. I have been waiting (not so patiently) for my main blades to turn up which happened this morning so I will get to maiden on the weekend.

Mick

[creightoncarr]

All,
How are most people installing the second bearing? Do you drive the pin out of the coupler and slide the bearing on? Is the pin the reinstalled with any adhesive? thanks! Dave

This is exactly how I do it. The pin is very easy to knock out and I just use a drop of medium CA when reinserting it.

[LONEWOLF2440]

I had a bad vibration on my 600 pro and yes the 2nd bearing did infact take care of it Some need it most dont but from now on ill always use 2 bearings in the torque tube

[lovespicyfood]

This is exactly how I do it. The pin is very easy to knock out and I just use a drop of medium CA when reinserting it.

I'm building my first nitro, the 600N PRO and I've read a little bit about this method of installing another torque tube bearing. Some say you don't need it, but I figure, it can't hurt, right?

Can someone post the bearing size? I'm assuming I can get the bearing pack from Align at my lhs.

Is the second bearing held in the tail boom with any adhesive? I'm assuming it should just be placed in the middle?

Sorry if some of this might not be making sense. I just installed my engine and haven't even opened the torque tube yet.

Thanks!
Pete

[fogger]

I always CA my bearing onto the tt. In the case of using 2 bearings you would want to divide up the tt into 3 roughly equal parts, but offset the bearings by a few cm so that no 2 of the 3 sections are exactly the same length; thus the resonant frequency of each section is different.

-Fog

[lovespicyfood]

I always CA my bearing onto the tt. In the case of using 2 bearings you would want to divide up the tt into 3 roughly equal parts, but offset the bearings by a few cm so that no 2 of the 3 sections are exactly the same length; thus the resonant frequency of each section is different.

-Fog

That makes total sense, THANKS!

Pete

[G MAN]

I had a slight wag with mine,but it went away when i got the engine tuned in. It was too rich and the gain was a couple of percent too high. I only have 1 bearing on the TT,even my 90's only have 1 bearing on the TT.

[daument]

well...its most definitely rich right now. I'll lean it after another tank or two. I used a high point on the main and tail blades, balanced the Align metal fan, checked the main and tail shaft for run out...whew. I ordered some bearings and spacers, I'll install them this weekend and see what happens. I had a chance to fly my buddies 600 sport and it wags too.....go figure. Dave

[aussiemick]

Have you tried Expo in the rudder channel?? Or maybe take a valium before flying, it could be that you rudder thumb shakes like a whatsit. :)

Mick

[OHIOBOWHUNTER]

I had a vibration that progressed to a wag then to almost nothing ...all i did was tuned down the gain ( 401 ) and progressively leaned the engine during break in ..it's fine now. try the obvious first ! :wink:

[creightoncarr]

Can someone post the bearing size? I'm assuming I can get the bearing pack from Align at my lhs.


I don't have the size offhand, but it is the same bearing used in the main blade grips.

[aussiemick]

Can someone post the bearing size? I'm assuming I can get the bearing pack from Align at my lhs.

The bearings are

Bearing MR148ZZ x 4(Φ8xΦ14x4mm)

and they come in this pack

http://wattsuprc.com.au/product_detail.asp?pid=H60124

Mick

[daument]

I installed the second bearing on the TT and leaned the motor a few clicks and no more wag! Dave

[storm57]

We've solve that issues on our 600 Nitro Pro tail fin oscillation and I hope this would really help you guys out.

- Move your Gyro upfront. The gyro picks up the vibration from the Torque Tube drive Gears / rod wobble.
- Disassemble your Tail Rotor assy from the Boom and check your Torque Tube for some wobble.
I noticed mine had a big amount of wobble from the tail end and installed a second TT rod bearings.
The pin can be slightly tapped off using a a pin punch and need not be grinded. It can be removed easily.
- Do engine tuning correctly corresponding to the right headspeed. Improperly tuned motor causes high vibe problems specially when using a governor.
- Replace your plastic bearing blocks and engine fan with metal. Then balance the engine fan and perform a runout check.
- To top it all, I replaced my Original Align Main Rotor / Tail Blades with RADIX . Rebalance the entire head without the swashplate using a True Dynamic balancer.

Align came out with a new front servo mounting plate. I fabricated mine using aluminum plate.
They also had a torque tube bearing available which comes 2/pack. Does this tell us something about adding one more bearing?

She now flies like a silk !

[lovespicyfood]

- Replace your plastic bearing blocks and engine fan with metal. Then balance the engine fan and perform a runout check.

Align came out with a new front servo mounting plate. I fabricated mine using aluminum plate.
They also had a torque tube bearing available which comes 2/pack. Does this tell us something about adding one more bearing?


I've already got my second bearing waiting to be installed in my 600N Pro build! :D

I had a couple questions on your recommendations.

I thought you really can't check runout with any sort of reliability because of the one way bearing in the start shaft. Is there something I'm missing?

I have not heard an issue with the front servo mounting plate. I assume you're talking about the tail servo? Can you elaborate? I have the adaptor plate for the smaller engine servo (HS81mg)...

Thanks!
Pete

[bembill]

Can you I put the 401 Gyro in front or should this gyro this gyro be back.

[daument]

Storm57 sez"] We've solve that issues on our 600 Nitro Pro tail fin oscillation and I hope this would really help you guys out."

Thanks for the post...here's my results.
- Move your Gyro upfront.
- Mine's aft and works fine (old skool CSM 400 won't fit up front!). It's on the list to replace someday.


- I noticed mine had a big amount of wobble from the tail end and installed a second TT rod bearings.
- As did my machine... same fix


- The pin can be slightly tapped off using a a pin punch and need not be grinded. It can be removed easily.
- I was more comfortable grinding the pin flush and not disturbing the pin/coupler fit. I did however CA the area and shrink wrap it after the bearing install.


- Do engine tuning correctly corresponding to the right headspeed. Improperly tuned motor causes high vibe problems specially when using a governor.
-Agree, two to three clicks on my YS made a big difference. I'm running a CSM carbsmart and it works flawlessly.


- Replace your plastic bearing blocks and engine fan with metal. Then balance the engine fan and perform a runout check.
-Agree.... I'm waiting for the G-Force thrust bearing assembly.



Dave.... yelling "I don't have it since '82" :D

[matrix1171]

any body thought about checking the TT to make sure that it runs true in the boom.

food for thought :thumbup::YeaBaby: