You won’t feel safe in any aircraft losing its engine power. It would be crazy as well to take off without an engine.
What happens in a helicopter? Imagine, you’re stuck in a fuselage with highly rotating blades just over your head, diving to the ground. Nobody wants to jump out, it would be like putting yourself directly in a mixer.
Now, you understand that a parachute wouldn’t be so useful. What you don’t know is that helicopters use their rotors as braking devices, still more efficiently than a real parachute.
The dynamic energy of the rotor is used to increase the pressure below the blades and to slow down the vertical movement of the helicopter.
As soon as you notice that you have to shut down your engine(s), you must dive dramatically and gain as much vertical speed as you can, in order to reach the necessary forward speed (check your pilot handbook).
When you’re close enough to the ground, you pull up the collective stick, increasing the angle of attack of the blades. Simultaneously, you pull the cyclic backwards to bring the nose up and decrease the horizontal speed.
With this maneuver, you transfer the energy of the spinning rotor to the airflow through the blades. The speed of the airflow is decreased, the pressure is increased and the atmosphere will carry the aircraft again, for a short time, just as long as you need to land safely.
An obvious remark: the more energy the rotor has, the more speed you will be able to lose. The lightest helicopters need to add weight at the tips of the blades, simply to get more energy in case of an autorotation.
You will like this video: a great display with an RC helicopter, even landing upside-down!
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