Torque tube - carbon vs metal

[itsmillertime0]

I don't like how much play the b gear has on my stock torque tube and it's too long for my stock boom so I'll be making my own. I'm curious of the pros/ cons of carbon vs. metal torque tubes. I think the carbon might be possibly lighter but not as torsionally strong as metal especially where the flats need to be ground. But replacing a small length of carbon will be cheaper than replacing c gears and won't bend like a metal one. Another thought I had is to use a 1.6 or 1.8 rod and turn down just the ends that will go through bearings/ gears to 1.5 essentially making the torque tube non-floating.

[poor_red_neck]

The issue I see with this, is thin carbon has alot more flex, less "springiness" and without a bearing in the middle, I think your carbon torque rod is going to turn into a guitar string vibrating like crazy.

It's always worth a shot to try! Keep us updated.

[Liduno]

I like the idea of a non floating TT.

I would think a CF TT that small would splinter, or at least get springy like when you crack an mcpx main shaft.

[so-fly]

Im using carbon rods for my TT. I stretched mine 1/2" and the TT spins vibration free compared to the metal one. You will need to CA B gear on or else it'll fling off/snap the tip of the carbon rod where the notch is. Other than that over 30 flights smooth tail with no vibration on spool up and crashes don't hurt the c d or a gears. Probably because the carbond rod twists under impact to allow a spring like cushion.

Overall very satisfied with my upgrade

[pixeltim]

I'd like to see how you make that? I would like to try it too.

[Liduno]

Originally Posted by Liduno

I like the idea of a non floating TT.

I would think a CF TT that small would splinter, or at least get springy like when you crack an mcpx main shaft.

Just looking at mine and realized the rear bearing isn't captive so the non floating TT would be tricky.

[itsmillertime0]

Originally Posted by so-fly

You will need to CA B gear on or else it'll fling off/snap the tip of the carbon rod where the notch is.

Splitting the frame to replace the shaft doesn't sound too appealing though.

[so-fly]

Originally Posted by itsmillertime0

Splitting the frame to replace the shaft doesn't sound too appealing though.

Lol. Just a dab on the tip or even loctite would work. For removal I just remove one servo and use heat to remove the gear.

A alternative is to just make the slot go through the gear and come out the other side

How often do you break a TT shaft on this sized heli

[itsmillertime0]

Originally Posted by Liduno

Just looking at mine and realized the rear bearing isn't captive so the non floating TT would be tricky.

How so? The front bearing is captive. If you stepped down your torque tube to 1.5mm to fit through the bearings after careful measurements I can't think of any issues. The b gear can only put pressure on the front bearing so no force should be applied to the rear bearing and will also make sure the torque tube stays exactly where you want it so no worries of the tube moving forward dis-engaging the c gear causing it to strip.

[RapTH44]

What diameter cf rod are you using for the TT?

[Liduno]

Originally Posted by itsmillertime0

How so? The front bearing is captive. If you stepped down your torque tube to 1.5mm to fit through the bearings after careful measurements I can't think of any issues. The b gear can only put pressure on the front bearing so no force should be applied to the rear bearing and will also make sure the torque tube stays exactly where you want it so no worries of the tube moving forward dis-engaging the c gear causing it to strip.

Ok I get what you're saying now.

Another option would be to have a C clip in front of the B gear along with your step down shaft behind the front bearing.

[rallyant]

The walkeras have a carbon TT. Unfortunately its about 15mm to short. But other than that it looks to be a fit. Ground flats on the ends one short one long and all!




I see no down side to running a carbon TT. I'll be doing it to mine as soon as I get some rod to file down. Might to a 1/2" stretch while I'm at it.
The only real problem and maybe even the reason its steel, is to get the CG right. Even with the stock pack its nose heavy. A carbon tt would make it real nose heavy. Stretch will fix that

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[itsmillertime0]

I have 3mm square carbon tube, 1.57mm metal wire, 1.5mm carbon rod, 2mm carbon rod and a 5,300kv motor for 3s operation on the way. I plan on running fairly heavy 320mah 3s packs so the stretch is probably going to be a must. I'm also going to extend my boom supports out a few inches an use to tail servo to balance it an make a custom tail servo push rod if need be.

[Sowa]

After putting my heli into the ground a few times the c gear popped out. I thought it was stripped but came home to find out it was fine.

While I had everything apart I decided to try a carbon torque tube.

I used a piece of 1.5 mm rod cut to length. Sanded down the ends so they fit nicely in the bearings and put a flat spot in each end.

stock metal torque tube = 2.5 grams.

Carbon torque tube = 0.7 grams.

I took my time and ended up with a perfect fit between the torque tube and gears, and also spent the time to achieve proper gear mesh.

After I was happy with the result I put a few drops thin ca on a paper towel and rolled the ends in the ca to prevent any fraying.

Take your time, it took me two tries to get it right.

But the result feels amazing. Unfortunately this shifts the cg pretty far forward after removing 1.8 grams from the tail.

[Sowa]

Has anyone been able to get a carbon torque tube to work with the 130 x. It seemed going from metal to carbon made, the spool up vibes worse. And I can't seem to get rid of tail vibes for the life of me.

[rallyant]

I am hoping to try . Will let you know. I'm going to stretch mine at the same time hang get the COG right.

I'm sure I have seen another post of one working well with cf tt?

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[so-fly]

Mine works fine and no vibes...check your tail blades?

[Sowa]

I suspect it may be my tailcase bearings

[itsmillertime0]

Originally Posted by itsmillertime0

I have 3mm square carbon tube, 1.57mm metal wire, 1.5mm carbon rod, 2mm carbon rod and a 5,300kv motor for 3s operation on the way. I plan on running fairly heavy 320mah 3s packs so the stretch is probably going to be a must. I'm also going to extend my boom supports out a few inches an use to tail servo to balance it an make a custom tail servo push rod if need be.

Got everything today. I received 4mm square tube instead of the 3mm I ordered but oh well. I still got to experiment with the other stuff. I hand filed the 1.57 rod (which took forever, will not ever do again without a dremel) down enough to fit through the bearings essentially making a non-floating torque tube. Then I filed the front flat so it was a nice, slop free fit into the b gear. Then I cut the rod too short to engage the c gear . Next up carbon tt, much easier to shape. I cut just enough to fully engage the c gear with my boom pushed all the way in with the b gear all the way back resting on the front tt bearing. Spun the main rotor and there was very, very little resistance and no slop. Holding the tail rotor stationary and twisting the main rotor did exhibit a few degrees of the carbon rod twisting which might lead to a waggy piro stop. Maybe 1.6 or 1.8 carbon rod will have less torsional flex? My 130x is still not running so no further testing can be done. Which leads to my next project - the Medusa 5,300kv 3s motor. Same diameter, slightly shorter in length, much stronger magnets as it cogs whereas the stock motor spins very freely, 14.9g with no connector/ pinion (stock is 15.4g) and the mounting diameter is the same. It uses a different pitch screw though which aren't supplied. I learned this after snapping a stock screw off in my new motor . I plan to power it with a home-made Hyperion 240mah pack and custom xp-7a esc. I also got some 4mm solid rod to make new mainshafts but it is a little undersized at 3.88 vs the stock 3.98. I was hoping to find some that is a true 4mm to take some play out of the main bearings/ swash/ rotor hub. Maybe the stuff from RCfoam is a little thicker. I'll call and ask them to mic a few rods.

[rallyant]

Looking forward to see how that goes for you!!!
Are any archery arrow shafts 4mm? They have very good straightness to! So should help stop any vibes

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