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