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Autorotation generally works just fine. Most helicopter crashes involve things unrelated to possibility of autorotation or not, and sometimes autorotation won't

by p_l 4y ago

Autorotation generally works just fine. Most helicopter crashes involve things unrelated to possibility of autorotation or not, and sometimes autorotation won't help when you hit something too hard at the end, with all of it happening because client pushed too hard and overworked the crew (I might be quoting a specific crash here...)

bombcar 4y ago
Also I suspect the majority of autorotation failures are from using the helicopter for things only a helicopter can do like hovering. This is why you rarely see them do that, instead they circle - which any small plane could do but the helicopter can hover if needed. It’s just the most dangerous part.
- fsckboy 4y ago
  if a helicopter hovers high in the air it's not dangerous because they have time to turn that height/energy into forward motion. see "dead man's curve" https://en.wikipedia.org/wiki/Helicopter_height%E2%80%93velocity_diagram https://en.wikipedia.org/wiki/Helicopter_height%E2%80%93velo...
- p_l 4y ago
  Hovering is the signature helicopter move for laymen, but it's also considerably hard, and "high hover takeoff/landing" is, IIRC, one of the hardest maneuvers (it's been years since I've read the pilot's textbook, though) There's also a lot of other things that can impact the event - for example, the crash I mentioned involved bad weather, tired crew, and losing both engines at once due to icing. They autorotated and nobody died... but they fell into a forest, landed hard enough to destroy undercarriage, and the first officer survived by accident due to helping get passengers into position when a tree smashed his station. EDIT: corrected captain to first officer, as visible in this photo: https://static.polityka.pl/_resource/res/path/bc/08/bc086fae-d035-4dd3-b5ec-354eded29f08_f1400x900 https://static.polityka.pl/_resource/res/path/bc/08/bc086fae... (it's Mi-8, so captain sits on the left, not on the right as is normal in western helicopters)
- cjg 4y ago
  Yes - at height, they tend to move forwards rather than hovering in one spot to avoid getting stuck in a column of downwards moving air: https://en.wikipedia.org/wiki/Vortex_ring_state https://en.wikipedia.org/wiki/Vortex_ring_state

by p_l 4y ago

bombcar 4y ago

Also I suspect the majority of autorotation failures are from using the helicopter for things only a helicopter can do like hovering. This is why you rarely see them do that, instead they circle - which any small plane could do but the helicopter can hover if needed. It’s just the most dangerous part.

fsckboy 4y ago
if a helicopter hovers high in the air it's not dangerous because they have time to turn that height/energy into forward motion. see "dead man's curve" https://en.wikipedia.org/wiki/Helicopter_height%E2%80%93velocity_diagram https://en.wikipedia.org/wiki/Helicopter_height%E2%80%93velo...
p_l 4y ago
Hovering is the signature helicopter move for laymen, but it's also considerably hard, and "high hover takeoff/landing" is, IIRC, one of the hardest maneuvers (it's been years since I've read the pilot's textbook, though) There's also a lot of other things that can impact the event - for example, the crash I mentioned involved bad weather, tired crew, and losing both engines at once due to icing. They autorotated and nobody died... but they fell into a forest, landed hard enough to destroy undercarriage, and the first officer survived by accident due to helping get passengers into position when a tree smashed his station. EDIT: corrected captain to first officer, as visible in this photo: https://static.polityka.pl/_resource/res/path/bc/08/bc086fae-d035-4dd3-b5ec-354eded29f08_f1400x900 https://static.polityka.pl/_resource/res/path/bc/08/bc086fae... (it's Mi-8, so captain sits on the left, not on the right as is normal in western helicopters)
cjg 4y ago
Yes - at height, they tend to move forwards rather than hovering in one spot to avoid getting stuck in a column of downwards moving air: https://en.wikipedia.org/wiki/Vortex_ring_state https://en.wikipedia.org/wiki/Vortex_ring_state