babyhuey

An open Question to all,
Can someone explain to me how a shaft drive is supposed to be more efficent than a belt? The modern timing belt that we use on our helis is light, can't slip, minimizes gears and bearings and doesn't get hot so where does the "wasted energy" go?
Go ahead guys, Give me hell.

broggyr

The only thing I can think of (while not having a belt machine) would be maybe they are thinking of all the pulleys - but I would personally think that the shat would be less efficient, due to the changes of direction and gear lash...

The Hedgehog

The belt can slip under hardcore 3D manuvers and can stretch during these stunts, not giving your tail the require power to hold it rock solid. That is the main reason pro helicopter pilots use shaft driven tails when they are avaliable on the current model that they are using.

Cyclic Hardover

My Feedback: (3)

I would think shaft would be much better and more of a direct drive. Sure things can break but its a helicopter. If that won't break , something else will. Another way of looking at it is along with "Automan, the belt could get you the shaft!

LateApex31

Energy is lost due to the heating of the belt. As it is stretched and swapped around each pulley, the molecules that make up the belt move relative to one another, generating heat. It isn't much, but it is indeed present. I would prefer a lighter belt drive over a shaft drive (for an RC model anyways), however cases can be made for both. Obviously each is a valid way of powering a tail rotor, but what's best for you comes down to the specific application.

babyhuey

I know that this also comes down to whether or not you are talking about a 300 size electric or a 90 size nitro but I still wonder if there is really that much difference between shaft or belt as long they are of equal quality.

ClemenTang

Energy is continuously comsumed to bend the belt around the pulleys, plus their being tight and under load press directly on the bearings.

Clement

Druss

there are advantages and disadvantages of each but I prefer belts in general, they aren't as precise (my opinion) but easier for maintenance.

The Hedgehog

At my skill level belts are fine, shafts break in a crash, belts don't so I'll stick with belts unless I become as good as the pros.

babyhuey

That's how I look at it also. And if you look around Utube you will see some mighty impressive flying done with belt drive Helis.

stevennh

I don't think a drive shaft is not more efficient than a belt. That's why motorcycles have belts and chains rather than shaft drives (at least most of them). You lose more energy when you change the axis of travel (gears on both ends) than you do with a belt (no change in axis of rotation). A well adjusted belt will not slip doing 3d, but it will when the tail strikes somthing (better than breaking teeth).

Steve

Rafael23cc

My Feedback: (6)

Shaft drives have more inertia than a chain, and as you mentioned the inertia is on the wrong plane (90 degrees to the axis of travel). My Suzuki M109R (1800CC Cruiser) is a shaft drive. My friend's Hayabusa (Suzuki GXS1300R Crotch rocket) is a chain drive. He has accepted the fact that in a race, he has to stay on top of the gears and not fall behind. I will catch up to him and pass him if he's not in total concentration. I don't think a comparison between motorcycles and RC helicopters is fair.

For another discussion on the same subject go here:
[link]http://www.rcuniverse.com/forum/m_6948706/anchors_6948706/mpage_1/key_/anchor/tm.htm#6948706[/link]

Rafael

stevennh

Fair enough. I did some reading on the web and see quite a bit of conflicting data. I have had both shaft and belt drive tails (Falcon-3D, T-Rex 450SA) and like the belt drive better. I get great tail responce with no slip with the tail, and the belt is very forgiving (two fairly good crashes without damage). I have had both chain and shaft driven motorcycles with common power plants (750CC Honda V-4's, I had a Sabre (shaft) and now have a Magna(chain)). I'm not sure what the numbers say, but the magna seems to get more power to the rear wheel.

Steve

babyhuey

I agree that the belt is vastly better at holding up in a crash as it has just enough give to save parts. I think that just like a chain on a motorcycle the main advantage is in weight savings. The chain is the lightest drive system you can get on a bike that has the strength to transmit high horsepower. The belt drive is lighter and smoother but is not strong enough for really high power systems.
The shaft drives are clean, low maintenence, and long life.

babyhuey

Has anyone had experience with a wire drive tail?

Rafael23cc

My Feedback: (6)

Last wire drive tail that I've seen was in the late 80's and early 90's with my Concept 30DX and the MFA Sport 500. I can tell you that there is a reason wire tail drive does not exist anymore.

Rafael