If you know how to perform an RC autorotation, you will save yourself a lot of money
Autorotation is that technique by which the helicopter is brought down safely even when it engines stops working properly.
This is very important in the times of engine failure. To practice it, the RC heli flyer stops the engine and enters the helicopter in an autorotation mode.
Autorotation is possible due to the presence of free wheeling unit in the rotor of the radio controlled helicopters. The free wheeling unit is somewhat like clutch of an automobile.
It is the link between the engine and the rotor and is the element which
transfer motion from engine to the rotor just like clutch in an automobile
is used to act as a link between the engine and the driving wheels.
When the engine of a radio controlled helicopter fails or is shut down
on purpose, the helicopter enters in an autorotation mode in which the
link with the engine is automatically removed and the rotor rotates directly
without being connected to the engine.
When the helicopter is running the blades and hence the rotor acquires much inertial force due to continuous rotation. When the engine fails, then the power from the engine is stopped but the rotor which was revolving at a real high speed still have stored much inertial power due to rotation.
So the free wheeling unit comes in play and the inertial force stored in the rotor is used to land the helicopter safely in the ground.
To practice the autorotation method, the power to the engine is cut on purpose. And the free wheeling unit starts to works due to the fact that power or motion from the engine suddenly stops. The radio controlled helicopter is then brought back to the ground safely by using the inertial power stored in the helicopter rotor.
On a real helicopter, the technique of autorotation saves lives but autoroation on a RC helicopter can save you a lot of money, by not slamming the RC helicopter to ground.
One piece of advice that I can give you is to try to practice auto rotation as much as you can, because it will come in handy on those unexpected engine fails. Trust me it will happen.