6 ms·

It's hard to tell from the video but arent they supposed to fail gracefully in a controlled descent and not drop like rocks?

cirrus3 5y ago
These don't look super graceful, but also not like rocks.
bjtitus 5y ago
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.
AdamHominem 5y ago
Yeah, kinda points to battery failure, but "our rivals haxxored us!!!" is certainly a nice cover story for the company and the local government.
- deleted 5y ago
  [deleted]
- LurkingPenguin 5y ago
  In China, both are equally probable.
  - curiousgal 5y ago
    Okay I don't care if my account gets banned but why in the FUCK does everything about China has to do with the government? Everyone here and on Reddit are bitching about Chinese propaganda bots but the only thing I see is people with new accounts attacking China and an immediate accusation of shilling to anyone who doesn't criticize China or even draws a parallel between whatever is being criticized and the U.S.. Seriously, y'all need help if you keep thinking China is the most evil bogeyman in the world. First it was Iraq, then Iran, now it's China. I am not saying China is great or even good but this whole immediate "fuck China" whenever anything happening in China is reported, is just pathetic and a symptom of brainwashing.
    - sbierwagen 5y ago
      >why in the FUCK does everything about China has to do with the government? Because it's... a single-party Communist state? Stories about North Korea also tend to talk about its government a lot.
    - detaro 5y ago
      I genuinely don't understand how the parent comment triggered this response for ... just saying they think both battery failure being "covered up" or sabotage are likely?
    - erhk 5y ago
rasz 5y ago
This is controlled descent. Wonder if anyone checked GPS/GLONASS/Beidou at the time and tweeted about it.

cirrus3 5y ago

These don't look super graceful, but also not like rocks.

bjtitus 5y ago

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.

AdamHominem 5y ago

Yeah, kinda points to battery failure, but "our rivals haxxored us!!!" is certainly a nice cover story for the company and the local government.

deleted 5y ago
[deleted]
LurkingPenguin 5y ago
In China, both are equally probable.
- curiousgal 5y ago
  Okay I don't care if my account gets banned but why in the FUCK does everything about China has to do with the government? Everyone here and on Reddit are bitching about Chinese propaganda bots but the only thing I see is people with new accounts attacking China and an immediate accusation of shilling to anyone who doesn't criticize China or even draws a parallel between whatever is being criticized and the U.S.. Seriously, y'all need help if you keep thinking China is the most evil bogeyman in the world. First it was Iraq, then Iran, now it's China. I am not saying China is great or even good but this whole immediate "fuck China" whenever anything happening in China is reported, is just pathetic and a symptom of brainwashing.
  - sbierwagen 5y ago
    >why in the FUCK does everything about China has to do with the government? Because it's... a single-party Communist state? Stories about North Korea also tend to talk about its government a lot.
  - detaro 5y ago
    I genuinely don't understand how the parent comment triggered this response for ... just saying they think both battery failure being "covered up" or sabotage are likely?
  - erhk 5y ago

rasz 5y ago

This is controlled descent. Wonder if anyone checked GPS/GLONASS/Beidou at the time and tweeted about it.