[hwillis]

Electric motors can autorotate just fine: https://youtu.be/QADYnVeHQOQ

You can't descend quite as slow as a normal engine because the motor has somewhat more friction at low RPM, even though it's similar to free-spinning at higher RPM. That makes for a rougher final approach but just as much glide distance and control.

Small rotors will make it more of a hassle but should still be quite safe. Even if you do end up touching down hard, there's way less angular momentum stored up and you wouldn't have the chaos of giant blades exploding. Of course there's still the batteries, since li-ion cells have only slightly less energy than kerosene when burned.

A parachute is... not the kind of safety feature that should be relied on. Parachutes take >100 feet to open properly. 20 foot falls can easily be lethal.

[ramesh31]

>Even if you do end up touching down hard, there's way less angular momentum stored up and you wouldn't have the chaos of giant blades exploding.

That angular momentum is what allows autorotation to be possible. Theres zero chance a quadcopter blade could maintain enough energy to autorotate while carrying the weight of a person. The blades are also fixed pitch, which would make a landing flare impossible.

[nradov]

That is dangerously incorrect. Successful autorotation requires high inertia rotor systems with controllable blade pitch. Small rotors like on this Jetson don't have anywhere near enough inertia, and it looks like they're running fixed pitch props. The type of motor is irrelevant as long as the motors can be de-clutched from the rotors.

[Toutouxc]

> Electric motors can autorotate just fine

Your video shows an electric helicopter with a full size helicopter main rotor, which is not what the Jetson vehicle uses.

[Justin_K]

You should look up auto rotate and variable pitch propellers