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#1
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High altitude Helicopter work
I am curious about use of a chopper in the higher altitudes of
Afghanistan. The Canadians are in Kabul and the word is our Griffin, a Bell 412 helicopter, can't work in the mountains. Anyone now why..... lack of power at altitude, lack of oxygen ? Allen |
#2
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"Allen" wrote in message
.. . I am curious about use of a chopper in the higher altitudes of Afghanistan. The Canadians are in Kabul and the word is our Griffin, a Bell 412 helicopter, can't work in the mountains. Anyone now why..... lack of power at altitude, lack of oxygen ? Rather than lack of oxygen, I imagine it would be that the lower air pressure simply means the rotor is unable to achieve lift without an unacceptable increase in rotor speed, which would likely overstress the engines and gearbox. Have a look at: http://www.bellhelicopter.textron.co...pec_detail.htm and you'll see the service ceilings. Not much room there to take mountains into account, less so with a full load. Si |
#4
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Highest heli-rescue was in Nepal...Mount Everest, 7000 meters i think.
That's pretty high! Anyone know what it was? Gazelle i think? B2431 wrote: From: "Simon Robbins" Date: 11/17/2003 12:46 PM Central Standard Time Message-id: "Allen" wrote in message ... I am curious about use of a chopper in the higher altitudes of Afghanistan. The Canadians are in Kabul and the word is our Griffin, a Bell 412 helicopter, can't work in the mountains. Anyone now why..... lack of power at altitude, lack of oxygen ? Rather than lack of oxygen, I imagine it would be that the lower air pressure simply means the rotor is unable to achieve lift without an unacceptable increase in rotor speed, which would likely overstress the engines and gearbox. Have a look at: http://www.bellhelicopter.textron.co...z412EP_spec_de tail.htm and you'll see the service ceilings. Not much room there to take mountains into account, less so with a full load. Si There was an example of that which made the rounds last year. There was a high altitude rescue involving an H-60. The helicopter simply dropped out of the sky, hit the mountain and rolled down the slope. If anyone has a clip of that please post a link. Dan, U.S. Air Force, retired |
#5
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"Simon Robbins" writes:
Rather than lack of oxygen, I imagine it would be that the lower air pressure simply means the rotor is unable to achieve lift without an unacceptable increase in rotor speed, which would likely overstress the engines and gearbox. I've wondered what keeps you from building a high-altitude version. I envison big fat blades and an engine design for thin air. Or is there some other issue I'm not seeing? -- A host is a host from coast to & no one will talk to a host that's close........[v].(301) 56-LINUX Unless the host (that isn't close).........................pob 1433 is busy, hung or dead....................................20915-1433 |
#6
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#7
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"B2431" wrote in message ... From: Archibald Highest heli-rescue was in Nepal...Mount Everest, 7000 meters i think. That's pretty high! Anyone know what it was? Gazelle i think? I don't believe that one went to the top. I seem to recall a Soviet attempt to land helicopters on the summit of Everest in the 1970s. Dan, U. S. Air Force, retired Thanks for the info guys. I checked out a web site with articles by the crews of the CH-47Ds that worked the mountain ranges in Afghanistan. They frequently did landings at 17000 - 20000 ft. All very interesting and informative. Allen, RCAF/Canadian Air Force, retired |
#8
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There was an example of that which made the rounds last year. There was a high altitude rescue involving an H-60. The helicopter simply dropped out of the sky, hit the mountain and rolled down the slope. If anyone has a clip of that please post a link. Actually, that was a windy situation on a very steep slope that ended with a rotor strike (if I remember correctly). The footage clearly showed the machine hovering, attempting to get in close, then things got bad. It was on Mt Hood or Mt Rainier. But many helios have fairly limited ceilings and simply can't go very high. |
#9
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The footage clearly
showed the machine hovering, attempting to get in close, then things got bad. It was on Mt Hood or Mt Rainier. Right down the street at Mount Rainier. -- (¯`·._.· £ãrrÿ ·._.·´¯) "steve gallacci" wrote in message ... There was an example of that which made the rounds last year. There was a high altitude rescue involving an H-60. The helicopter simply dropped out of the sky, hit the mountain and rolled down the slope. If anyone has a clip of that please post a link. Actually, that was a windy situation on a very steep slope that ended with a rotor strike (if I remember correctly). The footage clearly showed the machine hovering, attempting to get in close, then things got bad. It was on Mt Hood or Mt Rainier. But many helios have fairly limited ceilings and simply can't go very high. |
#10
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On Mon, 17 Nov 2003 20:19:57 -0500, "Allen"
wrote: Thanks for the info guys. I checked out a web site with articles by the crews of the CH-47Ds that worked the mountain ranges in Afghanistan. They frequently did landings at 17000 - 20000 ft. All very interesting and informative. Allen, RCAF/Canadian Air Force, retired Mind posting the link. As an ex-hook driver from during the Vietnam era I'd be very interested. Our A-models had a service ceiling of 12,500 due to hydraulic cavation. Hooks, at least the A, B, & C models (all of which I flew), are hydraulic dependent (an understatement to say the least). Can't even spool up the engines without pressurizing the systems with the APU. A lot of changes were made on the D model however. Thanks, Snyder, US Army, retired. |
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