Tartare,
Helicopter = Bicycle
Back Wheel = Rotors
Pedals & Rider = Engine
Turn pedals with feet, back wheel turns, bicycle moves.
Stop pedalling, bicycle stops.
Going down hill, don't pedal, bicycle keeps going = autorotation.
About as simple as I can make it
In the case of the 135, the shape of the tail fin, essentially a wing mounted vertically, achieves most of the anti torque force required but only when above 70kts ish. As Sven has already alluded, if you lose tail rotor drive, the only way to have a successful landing after autorotation is to shut the engines down to lose the torque.
Last edited by Fortyodd2; 2nd Dec 2013 at 12:21.