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View Poll Results: Preference between Torque Tube vs Belt Driven tail
Torque Tube 20 47.62%
Belt Drive 15 35.71%
TT and Belt Drive equally 7 16.67%
Other 0 0%
Voters: 42. You may not vote on this poll

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Old 05-14-2013, 03:59 PM   #1
curmudgeon
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Default Torque Tube vs Belt drives

All of my bigger helicopters (550 to 700 size) are TT driven. I have no issues with them. My only experience with belt driven tail helicopters is with the economically priced Blade 450 3D and Blade 450X. Although the belt never gave me any obvious trouble, I disliked "guessing" the appropriate belt tension during rebuilds.

I cannot make a fair comparison between TT vs belt driven tails mainly because I have never tried or converted one type to the other on the same helicopter.

When I searched this subject of "TT vs belt drives", it seems that people stopped discussing this subject back in 2011, a time before the Goblin and other nice quality helicopters made a debut. These were the main points discussed:

1) TT more expensive to fix after crash, so belt wins.
2) TT strip easier if tail blades contact tall grass, so belt wins.
3) TT more precise for hard core 3D, so TT wins.
4) TT has less drag and is more efficient, so TT wins.
5) Belt releases static, so TT wins.

It almost seemed from those discussions that the TT was going to be used mostly for hard core 3D pilots, and the belt was going to be reserved for beginner pilots or the more economical helicopter kits.

However, the very popular and upscale Goblin's and Logo's are belt driven with no sign of switching to TT. Also, there are various threads of pilots trying to convert their TT helicopters into belt driven.

Now in 2013, what is the current thinking of TT vs belt drives?
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Old 05-14-2013, 05:17 PM   #2
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Default Re: Torque Tube vs Belt drives

Quote:
Originally Posted by johnahamelv View Post

3) TT more precise for hard core 3D, so TT wins.
This is a common misconception. Saying this is like saying that your belt skips teeth, which would only happen if your heli is poorly built, and anyway would not fly well at all.
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Old 05-14-2013, 06:01 PM   #3
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Stop the insanity, you can have a preference, but in the end both effectively make tail blades spin.
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Old 05-14-2013, 08:04 PM   #4
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Bottom line, a well designed/manufactured belt is better than a poorly designed/manufatured TT and vice versa.

Concentrate on the merits of individual designs, as there are both crappy TT and Belt designs.
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Old 05-15-2013, 01:59 AM   #5
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There are several manufacturers that have switched from belt drives to TT's. Is there a manufacturer that has switched from TT to belt drive?
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Old 05-15-2013, 02:02 AM   #6
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Quote:
Originally Posted by fastflyer20 View Post
Stop the insanity, you can have a preference, but in the end both effectively make tail blades spin.
How does a manufacturer figure out whether to design a new helicopter with TT or belt drive? Is it just the result of a coin toss?
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Old 05-18-2013, 03:56 AM   #7
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I find a TT more straightforward on a scale helicopter where it can be difficult to access the bolts to adjust the belt tension. Also, whereas a TT can fail with tail ground strike that is not likely to result in the loss of the helicopter because it is already down. But if a belt fails mid flight it will most likely be a bad crash. For people who crash a lot for other reasons this is not not likely to be a big factor, but when a scale body is involved we can get more paranoic about minimising as many in flight hazards as possible.
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Old 05-20-2013, 03:09 PM   #8
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I mostly fly TT, but my trex250 SE had a belt. It worked just fine, but at some point I hadn't crashed for such a long time (300+ flights? maybe more) and then my tail rotor grabbed some grass. Immediate countertorque, I had to switch off the heli. The belt was COMPLETELY worn out, didn't have teeth on it anymore for a big part. I was lucky it didn't break earlier... Yeah I do check for slop and loose screws every now and then, and I lube the stuff, but never checked the belt (thats a PITA anyway).

So yeah you need to check your belt every now and then. For the rest I'm a TT guy, but performance wise I don't think I'll feel the difference.
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Old 06-08-2013, 12:05 PM   #9
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Default Re: Torque Tube vs Belt drives

Im intrigued by the idea that a TT has less drag. On the bench, this is clearly the case ie hand spinning my blades I can get 2-3 times the revs on my Trex 450 Pri (TT) v my Mini p (same sized blades and belt driven) but I have heard that at high speed the Tt creates more drag and thus equates equally to a belt. How is this so?

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Old 06-08-2013, 12:53 PM   #10
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I believe the TDR manual mentions something related to how TT design is more efficient than belts. However, my understanding is that it is only a 2-3% improvement.
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Old 06-08-2013, 07:17 PM   #11
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Quote:
Originally Posted by desertstalker View Post
Bottom line, a well designed/manufactured belt is better than a poorly designed/manufatured TT and vice versa.

Concentrate on the merits of individual designs, as there are both crappy TT and Belt designs.
This. So much.

As you noted John, even the TDR guys note that the potential improvement of a well designed TT system is only 2% or so when dealing with 90* torque changes, extra bearings, mass, and gear friction.

Honestly, I think the most important things we should look at for why so many people go for TT lately is:

1; Lets face it, a TT is much easier to just "forget about" once you have it flying well, and that's not so hard with one that isn't built like crap and has straight tubes and good gears. People like to forget about stuff. I personally don't mind checking in on a belt now and then if the system is well designed though if it'll save me money on crashes and vibe rage

2: On the surface, just bench testing, one can make the incorrect assumption that a TT heli must have far less drag than a belted heli "because it's easier to turn and my head spins longer" and other such observations. A lot of folks in this hobby (as extra and desertstalker, etc, have nuked) will make what seems like an intuitive assumption about something...however this is rotary flight and the explanations are usually backwards and completely weird The other thing to keep in mind is it is FAR easier to set up a belt wrong by wrenching it as hard as you can, than with a TT heli.

3; Fads. No one in this hobby, or any hobby like it, can deny that there are always people chasing after various bling, "things", designs, etc like a Justin Beiber fan crowd . Ask the old guard and they'll tell you at one point shaft drive helis using cable were all the rage when helis with flat belts sucked. Then helis using cogged belts came out and those were awesome. Now TTs aren't terrible and folks are looking at those again. Folks want to dump money on TT helis, the money is there, so the mfgs follow suit.

I really think a lot of it has to due with many people owning Aligns or similar at one point, and with a belt. Align's belt system (and others like it) isn't so great. You now have a pile of folks who are pissed at belts, try Align's TT drive (which isn't nearly as bad) and have better luck. They then extrapolate that belts must suck and plaster that all over the forums.
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Old 06-08-2013, 08:35 PM   #12
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How about tail pitch range? It is my understanding that with the Synergy E7, pilots need to leave a wider gap at the extremes of tail slider travel when using the belted tail. Apparently, the newer TT system allows full range of the tail slider travel.
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Old 06-08-2013, 08:37 PM   #13
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"Ask the old guard and they'll tell you at one point shaft drive helis using cable were all the rage when helis with flat belts sucked. Then helis using cogged belts came out and those were awesome. "

I resemble that remark!

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Old 07-03-2013, 01:26 AM   #14
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Default Torque Tube vs Belt drives

I agree about the design being most important. I like a well designed belt aesthetically, because has less gear noise. As far as drag, it's not a huge difference unless you need to tighten your belt a lot because you fly such radical smack. My beam 450 has a belt with low enough drag to do really nice autos. - John
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Old 07-03-2013, 08:25 AM   #15
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My main concern with belt drives is my lack of understanding of high tight or loose the belt should be. It is already difficult enough trying to determine how tight the main blades and tail blades need to be. I really don't want to add belt tension to the mix.
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Old 07-03-2013, 09:31 AM   #16
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Default Torque Tube vs Belt drives

Fair point on the belt tension being an added variable. On a big heli like my Logo 600SE, you may also have to adjust tension due to temperature changes shrinking and expanding the boom. Of course there are fixes for that. I put a carbon boom on my Logo, which solved the problem. The Goblins have an automatic tensioner.

Belt tension is very forgiving. If it is too loose, you will hear it slip a few teeth when you load up the tail, but that's it, you won't crash or even damage anything. You may also hear a loose belt start slapping the inside of the boom when you land and spool down. The only penalty for a belt being too tight is a little power loss, and added bearing wear. Again, this won't lead to catastrophic failure. Belts are really tough, you can tap your tail blades one the ground and fly away, with a TT, you are done.
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Old 07-03-2013, 09:49 AM   #17
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Default Torque Tube vs Belt drives

Quote:
Originally Posted by johnahamelv View Post

I cannot make a fair comparison between TT vs belt driven tails mainly because I have never tried or converted one type to the other on the same helicopter.
One more thing then I'll be quiet. You make a point in the above quote I think is the key to the history of the debate. Belt helis that can be converted to TT have the tail gear under the main gear, and a lay shaft to the toothed pulley. This design has many of the weaknesses of the TT ( fragile gears, gear noise, complexity) and all the belt problems. I used to fly a belt drive Trex 600. Converting to TT was a huge improvement for that heli.

Now days if you talk about belt helis like Logo, Beam, Goblin, Compass, and Protos, they have much better belt drive designs that can't be converted to TT. With these you really get the benefits of a belt - John
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Old 07-03-2013, 09:51 AM   #18
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Quote:
Originally Posted by johnahamelv View Post
How about tail pitch range? It is my understanding that with the Synergy E7, pilots need to leave a wider gap at the extremes of tail slider travel when using the belted tail. Apparently, the newer TT system allows full range of the tail slider travel.
This has nothing to do with TT vs belt. It's simply the result of the E7 TT tail box being wider than the belt tail box and both using the same tail shaft. The total slider travel and therefore pitch range should be the same.
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Old 07-03-2013, 10:02 AM   #19
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Why did Matt decide to release a TT conversion kit for the E6/7 and only released the E5 as a TT version? Is it mainly marketing to capture the pilots who prefer TT drives or did Matt see an advantage to switching to TT drive?

Just trying to learn.
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Old 07-03-2013, 07:04 PM   #20
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Quote:
Originally Posted by johnahamelv View Post
Why did Matt decide to release a TT conversion kit for the E6/7 and only released the E5 as a TT version? Is it mainly marketing to capture the pilots who prefer TT drives or did Matt see an advantage to switching to TT drive?

Just trying to learn.
IIRC the E7 had an issue with the belt slapping the boom bouncing back and locking with itself, thus snapping the belt. The only occurred if flown very hard (AFAIK the Tail boom was a touch too narrow diameter). Hence the TT conversion, I suspect he figured people would demand a TT conversion on the E5 as well if it was released as belt and so released it only as TT to save developing another belt drive.

There is no detectable performance difference one way or the other when comparing a well designed TT (the E5/7 or TDR for example) with a well designed belt (Goblin, Logos Diabolo) drive. AFAIK the belt got a bad name from align's implementation more than anything (the pulleys on that are too small, requiring excessive belt tension and increasing wear) contrast that with the good belt designs (large pulleys, or idler pulleys to ensure more of the belt wraps the pulley).

When deciding on a heli, look at the individual design strengths/weaknesses rather than simply the kind of tail drive.
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