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#11
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"David Lesher" wrote in message ... "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? Lack of demand most likely. Not a lot of places to land on mountains that tall. |
#12
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Don't know the helicopter type, but it belonged to the Nepalese army
and was piloted by a gent named Madan, who twice flew to above 21,000 feet to rescue two Everest climbers in the spring of 1996. See John Krakauer's Into Thin Air, a very fine book. all the best -- Dan Ford email: (put CUB in subject line) see the Warbird's Forum at www.warbirdforum.com and the Piper Cub Forum at www.pipercubforum.com |
#13
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"Dick Snyder" wrote in message ... 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. Here's a couple: http://www.globalsecurity.org/milita...aft/mh-47e.htm http://www.nationaldefensemagazine.o...cle.cfm?Id=850 Afraid I couldn't find the exact site I found last night. Shame on me for not providing references for my sited info. Allen |
#14
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On Tue, 18 Nov 2003 00:10:26 +0000 (UTC), David Lesher
wrote: "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? Density altitude is a crucial factor in high-altitude helicopter operations. In a helicopter, the higher you go the more power is needed. But due to density altitude, the rotor system and engine(s) are less efficient at higher elevations, and the engines develop less power. A helicopter may be able to fly at high altitude but may not be able to hover, and even in level flight might need to use full throttle, and if it lands it may not be able to take off. Also, most helicopters don't routinely carry oxygen systems. The current altitude record for a small helicopter is: FAI Class E1b - Altitude Without Payload - takeoff weight 500-1000 Kg International: 40,820 ft; 12,442 m. Jean Boulet (France) Alouette SA 315-001 Lama Artouste IIIB 735 KW engine Istres, France June 21, 1972 John Hairell ) |
#15
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It was either a AS350 Ecureuil or a AS355 TwinStar. Examining the photos, I couldn't tell. There was a great account in Aviation Week & Space Technology of the rescue. They pointed out that the pilot was operating above the helicopter's published service ceiling. |
#16
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In article ,
"Larry" wrote: 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. Nope, it was on Mt. Hood. Among many other links.... http://www.traditionalmountaineering..._HeliCrash.htm --Mike |
#17
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I just found this: http://www.au.af.mil/au/goe/eaglebio...s/khatri98.htm It was a AS350 B2 Ecureuil. I remember reading that he did the rescue after stripping the interior and he only had a partial fuel load. |
#18
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Hmmm...impressive, considering that Ecureuil has ceiling of 4400m.
David Lednicer wrote: I just found this: http://www.au.af.mil/au/goe/eaglebio...s/khatri98.htm It was a AS350 B2 Ecureuil. I remember reading that he did the rescue after stripping the interior and he only had a partial fuel load. |
#19
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Hmmm...impressive, considering that Ecureuil has ceiling of 4400m. It is indeed impressive. Note, h owever, that "service ceiling" is usually defined as the height at which an aircraft can no longer gain 100 feet per minute. The B-36 seems to have exceeded its service ceilding by 10,000 feet on occasion. all the best -- Dan Ford email: (put CUB in subject line) see the Warbird's Forum at www.warbirdforum.com and the Piper Cub Forum at www.pipercubforum.com |
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