4 ms·

It seems like most are doing that but some are dropping rapidly, although not in a freefall.

breckenedge 5y ago
Autorotation? Sorry I don’t know enough about drone aerodynamics, but it’s something seen in helicopters. https://en.wikipedia.org/wiki/Autorotation https://en.wikipedia.org/wiki/Autorotation
- NovemberWhiskey 5y ago
  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.
  - schiffern 5y ago
    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.
    - 05 5y ago
      > 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-Freewheeling-prop-in-wind-tunnel-results/page2 https://www.rcgroups.com/forums/showthread.php?3753127-Freew... [2] https://www.peter2000.co.uk/aviation/misc/prop.pdf https://www.peter2000.co.uk/aviation/misc/prop.pdf
- taneq 5y ago
  Drones almost always use fixed pitch props which aren't capable of autorotation (in this sense anyway).
- deleted 5y ago
  [deleted]
taneq 5y ago
Yeah they're doing a fast controlled descent. Whether it's a low battery failsafe or a response to loss of control signal isn't clear but they're doing their best to land. The first few look precipitous but you don't see them approach the ground, later in the video you see one that's coming down very fast and then makes a reasonable effort to brake when it gets near the ground. Edit: Most of them are doing a fast controlled descent, a few seem to have just powered off and become rocks.
Aeolun 5y ago
One of these drones in the second video is pretty much upside down as far as I can see.

Autorotation? Sorry I don’t know enough about drone aerodynamics, but it’s something seen in helicopters. https://en.wikipedia.org/wiki/Autorotation https://en.wikipedia.org/wiki/Autorotation

NovemberWhiskey 5y ago
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.
- schiffern 5y ago
  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.
  - 05 5y ago
    > 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-Freewheeling-prop-in-wind-tunnel-results/page2 https://www.rcgroups.com/forums/showthread.php?3753127-Freew... [2] https://www.peter2000.co.uk/aviation/misc/prop.pdf https://www.peter2000.co.uk/aviation/misc/prop.pdf
taneq 5y ago
Drones almost always use fixed pitch props which aren't capable of autorotation (in this sense anyway).
deleted 5y ago
[deleted]

taneq 5y ago

Yeah they're doing a fast controlled descent. Whether it's a low battery failsafe or a response to loss of control signal isn't clear but they're doing their best to land. The first few look precipitous but you don't see them approach the ground, later in the video you see one that's coming down very fast and then makes a reasonable effort to brake when it gets near the ground. Edit: Most of them are doing a fast controlled descent, a few seem to have just powered off and become rocks.

Aeolun 5y ago

One of these drones in the second video is pretty much upside down as far as I can see.