Tank's Steering Movements Controlled by ONE Stick
 

In case of out-of-the-box RTR "bigger" tanks this is obtained using control boards. Standard is right stick for movement and left for turret opeartions. With aftermarket boards like Elmod you could setup this diferently. For smaller 1/35 tanks you could use this board :(link) P3

RC tanks typically use a different control board from RC cars that allows it to control two motors independently for steering. The tank ends up controlling very similarly to how one would behave in a videogame using a controller.
There are different, less common setups though. Some aftermarket boards allow you to set them up so that each stick controls it's own track. So you would have to push both sticks forward equally to go straight forward.
Tamiya's old 1/35 kits used a single motor, and a clutch on each drive axle to control which track got power.
I'm slowly brainstorming a 1/6 T-34 build and kinda thinking of mimicking the real tank's drive system. Use a single motor for power with a clutch and brake on each drive axle to control steering. Just quickly Googled around to see what was available and found some clutches for nitro RC cars. Seems like that might work. Get a basic brake system on each drive shaft past the clutch (perhaps bicycle brakes?) and whammo, you basically have a replica T-34 drivetrain.
Use a trigger on the transmitter as a throttle for the motor, perhaps a switch to change forward and reverse.
each stick controls each track. Full forward, track gets full power. As you pull back, the clutch starts disengaging, reducing power to the track, causing it to slow down. Pull back further and the brake starts engaging to allow a sharper turn. Pull back on both stick just enough to disengage the clutches and the tank can just cruise in "neutral" downhill under it's own weight (or if something breaks and you gotta make like a donkey and pull.). Pull all the way back to engage both brakes and it stops right there.

That's the idea anyway. Now just need to find a radio that has both sticks and triggers. And then a separate radio system to operate the turret. 2 man crew. :cool:

I've had the opportunity to ride in a real T-34/85. The amount of work the driver does is amazing since they have to really manhandle the sticks. In real life, the T34 is not a smooth driving tank. It is VERY jerky. There was a person working on a 1/16th tank with "brake steering", but I haven't seen any posts from him lately. In small scales it really is a tricky proposition as brake steering requires a large clamping force to stop the rotation of a track.

There is no need for a complicated control board to do one stick steering on a tank. All you need is two ESCs (one for each motor/track) and a radio that can V-tail mix the two channels you connect to your ESCs. Personally I don't like to setup V-tail mixing in my radio, but I do prefer to use a V-tail hardware type mixing circuit that sits in between your two ESCs and your receiver. I have controlled my large 1/6th scale tracked vehicles with this method. A third method is to buy a dual channel ESC with a channel mixer built in. That just plugs directly into your receiver and the mixing options are set on the ESC via some kind of programming or via a jumper setting. I have also used this method with great success.

Your biggest problem is going to be space. Even with just a battery and two esc's you're going to be pressed for space, your best bet is to look around and see if you can find a geko. Made by RC tanks Australia it was designed especially for smaller scale tanks and it's a very simple motor control board, about the size of two postage stamps next to each other. You might also want to check out another company, I think it's called 35RC? Anyway, they specialize in kits for motorizing smaller-scale tanks and I'm sure someone else here can probably provide a link to their site. Again, your biggest problem is going to be space, a 1:35th scale tank is Tiny compared to a 1:16th and there is very, very little room in there for electronics. I happen to have a gecko if you want to see photos to get an idea of size. I'm pretty sure they're out of stock at RC tanks Australia, but if you really needed one I might consider selling you mine.

Since you drove one, you might be able to answer a question for me? If I understand correctly the T34 basically has 3 clutches. 1 between the engine and transmission, like a typical clutch. And 2 on each drive axle to steer. Are the steering clutches "gradual" for lack of a better term? Can you apply more or less power depending how much you pull the steering lever? Or is it just a simple on/off, engaged/disengaged kinda thing?

Funny it was mentioned above about driving tanks and how you have to manhandle them. I drove a 432 APC and ok it was an old dog, but you really had to drive it hard and give it real welly to get it to turn at low speed. jam the brake in, give it a boot full of throttle. It was a real work out.
As for making it work in a model, i looked into brake setup and it is possible, but with bands etc they are going to need servicing alot. I would be looking at an alternative brake setup. Some tracked vehicles only clutched and brake out a track so you could get away with using high torque geared motors and setup limit switches to knock out the drive motor and use that. Or you could fit pots with servos to control mechanically, but the issue is space for all the extra mechanical parts.
If i were setting up a brake setup otherwise i would be looking into a electro magnetic setup possibly to lockup the inside wheel and use it with a heavy duty open differential using one large motor

It had two levers, one for each hand. Then you have a gas pedal. Pressing on the gas you go forward with both tracks. When you pull back on the right lever, it would stop the right track making you turn right. Same way with the left. As soon as you stop pulling back on the lever the track starts moving again. I didn't drive it, but I did get to ride in it. The issue is it takes A LOT of rearward pulling to stop a track so the driver was grabbing one lever with both hands and throwing his body backward to get it to turn.