this post was submitted on 26 Mar 2025
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Safety first! (lemmynsfw.com)
submitted 2 months ago by [email protected] to c/[email protected]
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[–] [email protected] 17 points 2 months ago (3 children)

Helicopters are actually really neat. If they suffer a loss of power, they can spin up the rotor while falling, and then reverse the blade pitch and turn all that momentum into lift and make a soft landing. Or something like that. Smarter Every Day can explain better: https://youtu.be/BTqu9iMiPIU

[–] [email protected] 7 points 2 months ago (1 children)

Check out "gyrocopters". They look kinda like helicopters, but their rotors are not connected to the engine. Instead, they use a propeller to drive the aircraft forward, and airflow drives the rotor disk.

They operate on the same basic principle as autorotation, but for normal flight rather than arresting an emergency descent.

[–] [email protected] 1 points 2 months ago

Those are so weird! Brilliant.

[–] [email protected] 3 points 2 months ago (1 children)
[–] [email protected] 4 points 2 months ago

The longest helicopter autorotation in history was performed by Jean Boulet in 1972 when he reached a record altitude of 12,440 m (40,814 ft) in an Aérospatiale SA 315B Lama. Because of a −63 °C (−81.4 °F) temperature at that altitude, as soon as he reduced power, the engine flamed out and could not be restarted. By using autorotation he was able to land the aircraft safely.

What a mad lad, setting two records at once.

[–] [email protected] 2 points 2 months ago

Sort of correct. They can feather the blades to induce auto-rotation. Long explanation short, the rate the blades rotate is based on the total airflow though the rotor disk from any angle, so much like a glider, you can trade forward speed for vertical speed/rotor speed.