Most 30 size nitro helis do not have a driven tail. This is probably to insure they have as little energy as possible taken from the mainblades durring the auto.

As long as the rotor is turning faster then the maingear, the main rotor will be the only thing providing power for the auto, and there will be no torque to counter.

So if you set your throttle slow enough when in the auto mode, it will drive the maingear (which drives the tail rotor) slow enough to keep it disengaged from the mainshaft, but just fast enough to turn the tail rotor at a speed that would give you enough yaw control to counter crosswinds or anything else on your way down, and also to hold heading as you land.

Of course, this will not provide enough yaw control to do backwards autos or inverted autos or other aerobatic type of autos, but you will still be able to easily do a complete 360 degree turn on your way down.

There are many videos on youtube of such helis doing some very successful autos - even in scale bodies - without a driven tail!

Here is a couple of videos of two helis that are set up as described. If you just want to check out the auto, you can fast forward to the 3:45 mark on the firstwhere he is climbing for one:

http://www.youtube.com/watch?v=glVYWrZdiCI

and the of this one (autos from about the 1:50 mark):

http://www.youtube.com/watch?v=cJjiIARYMFo