Tuesday, September 30, 2008
The 109th Airlift Wing pilots the world’s largest ski plane to the Greenland ice cap
|Overcast skies create challenging near-whiteout conditions|
Touching down on the 15,000-foot skiway is bumpy and noisy, but with propeller pitch set to reverse, it doesn’t take much distance to stop. “As a general rule of thumb,” Falvo tells me, “2,000 feet is enough distance to bring the aircraft from near takeoff speed down to taxi speed. As airspeed decreases, the friction between the skis and the snow increases, since any lift the wings were generating goes to zero, and the weight is transferred to the skis. It feels similar to flying a single-engine airplane on a soft field.”
|Rocket bottles are attached to the fuselage for additional takeoff power.|
The Summit research station, at 72 degrees north latitude and on an ice depth of more than 10,000 feet, supports 40 personnel from the NSF. The location attracts some of the foremost scientists in the world as well as first-time college students. Much of their work focuses on global climate change, using ice core samples to analyze weather system history. (Read “Ice Stories: Dispatches From Polar Scientists,” a blog maintained by these Arctic researchers, at icestories.exploratorium.edu.)
“The Greenland ice cap is the only big ice cap in the northern hemisphere, so it’s very important,” explains ice coring expert J.P. Steffensen from the University of Copenhagen’s geophysics department. “Greenland is a living mountain made of one mineral: frozen water. Over time, the overall ice cap shape stays the same, but new snow is deposited in the middle, and ice on the edges breaks off.” Researchers have drilled through layers dating 125,000 years old; and a new project aims to go as deep as 250,000 years. “Something big is going to happen,” predicts Steffensen. “We’re in an interglacial period now. An ice age is a concern, not just global warming. Scientists provide facts to politicians who make the moral decisions.”
Getting our ski bird off the snow isn’t an easy task, and our first two takeoff “slides” are aborted. “Much of what we do is a matter of technique, not always procedure,” says Maj. Falvo. “Sixty-five knots is in the ballpark of when it’s possible to lift the nose and have enough elevator authority to keep it off the snow, but much of this depends on snow conditions, center of gravity, flap setting and fuel quantity, so it isn’t really an exact airspeed every time.” Pilots will try different flap settings, rearrange cargo or leave equipment on the ice. On open snow, a takeoff slide can extend as far as 20 miles! When necessary, the crew will employ assisted take-off (ATO—not JATO, which implies the use of a jet engine). Eight rocket bottles attached to the fuselage will provide the same power as an additional engine for just 15 seconds, so timing is critical.
On our third takeoff attempt, the nose comes up and stays up. As we fly west from the center of the ice sheet toward its edge, the monotone terrain transforms into little ripples of snow and then sizable cracks, deep crevasses, ice upthrusts and, finally, gigantic glaciers with calving icebergs—we’re flying in fast-forward through geological history. Disko Bay greets us with a stunning sight of immense floating icebergs and pools of brilliant aqua and turquoise glacial water.
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