News for hackers. Stuff that matters.
Re:Drones Raining from the Sky in Zhengzhou by breckenedge on Monday October 04, 2021 @10:50PM (#28754975)
Autorotation? Sorry I don’t know enough about drone aerodynamics, but it’s something seen in helicopters.

https://en.wikipedia.org/wiki/Autorotation

Re:Drones Raining from the Sky in Zhengzhou by NovemberWhiskey on Monday October 04, 2021 @10:54PM (#28755005)
Not nearly enough energy in the rotor system of that kind of drone to manage an autorotation landing; and they lack a freewheeling system in any case.
Re:Drones Raining from the Sky in Zhengzhou by schiffern on Tuesday October 05, 2021 @12:22AM (#28755479)
Not sure about these drones, but on my toy drone I can absolutely cut the power and let the wind autorotate the rotors while it falls toward the ground. No need for a freewheel, since the unpowered electric motors spin freely (which isn't necessarily true for a helicopter's engine).

There's no collective so you can't "flare" for landing like a helicopter, but during autorotation the terminal velocity is still much lower than if the blades were fixed.

The drones in this video fall a lot slower though. This looks like controlled descent, not autorotation.

Re:Drones Raining from the Sky in Zhengzhou by 05 on Tuesday October 05, 2021 @01:46AM (#28755860)
> but during autorotation the terminal velocity is still much lower than if the blades were fixed

it's not that straightforward, whether or not braking or freewheeling causes more drag depends on the prop.

[1] https://www.rcgroups.com/forums/showthread.php?3753127-Freew...

[2] https://www.peter2000.co.uk/aviation/misc/prop.pdf

Re:Drones Raining from the Sky in Zhengzhou by taneq on Monday October 04, 2021 @11:04PM (#28755078)
Drones almost always use fixed pitch props which aren't capable of autorotation (in this sense anyway).