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

"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

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

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

"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

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

"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

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.

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.

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.