"Chris Clarke" (shiftsandgiggles)
07/17/2014 at 15:10 • Filed to: helicopter crash
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"Chris Clarke" (shiftsandgiggles)
07/17/2014 at 15:10 • Filed to: helicopter crash | 1
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Not much is know about the accident except that all 5 crew have died and 1 civilian has been injured. The aircraft was on its way home from search mission of the ferry disaster in April. Mechanical failure is suspected.
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Porschephile
> Chris Clarke
07/21/2014 at 08:58 |
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I remember having a discussion with someone on here about the difficulty in gliding a helicopter. Seems I may have been right.
Poor crew - that was quite the impact speed shown in the second video.
Turbineguy: Nom de Zoom
> Porschephile
07/25/2014 at 14:46 |
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They do glide but the rate of descent is pretty quick. If power is lost a pilot will peform an autorotation, where the rotor is disengaged from the transmission. It freewheels in the wind and just before touchdown the collective pitch is pulled up increasing the blades' angle of attack, and slowing the descent for landing. It's a rough touchdown, but done correctly everybody walks away from it. Needing a change of undergarments.
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Porschephile
> Turbineguy: Nom de Zoom
07/28/2014 at 05:34 |
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Thanks, nobody has explained autorotation to me properly before. I presumed they basically plummet. Is there a fail-safe high lift pitch for the blades to default to in such a situation I wonder?
There was a police Eurocopter crash up in Scotland last year - gearbox failure meaning locked rotor. Nasty.
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Turbineguy: Nom de Zoom
> Porschephile
07/28/2014 at 10:30 |
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I'm a fixed-wing instructor, so my understanding is somewhat limited. There is no fail-safe here because in an autorotation rotor rpm must be maintained (as in normal flight) and if it decays below a certain point you'll fall like a bank vault. Energy in the rotor system is maintained by its rpm (low pitch), so in the landing flare the pilot pulls up on the collective (increasing AoA to high pitch) and converting that energy to lift to cushion the touchdown. It's a rough landing, but you're down in one piece.