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Sailplane to StratospherePerlan 2 ma 90 000 stóp.
By Tom LeCompte Smithsonian Magazine | Subscribe June 2016
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Optimized for altitude: Jim Payne, one of the most accomplished glider pilots in the world, is one of four who will fly the purpose-built glider on its record attempts. (Chad Slattery)(...) When it is ready, Perlan 2 will attempt what no glider—what no piloted aircraft—has ever achieved: sustained flight at 90,000 feet, far into the stratosphere and near the vacuum of space. To get there the sailplane will ride stratospheric mountain waves, prodigious currents of air created by winds that sweep over mountains. The highest known waves rise up over the Andes in southern Argentina and interact with the polar vortex, the giant cyclone of air that swirls around the poles. In the rarefied atmosphere 90,000 feet up, the air density is just two percent of what it is at sea level, and about the same air density as on the surface of Mars. At such heights, an aircraft can maintain lift and power only if it is very light or very fast. A handful of pilots have “zoomed” fighters or X-planes to above 100,000 feet by using ballistic trajectories like that of an artillery shell, but for level flight, the current record by a piloted aircraft is 85,068 feet, set in 1976 by an SR-71 Blackbird spyplane, the world’s fastest jet aircraft. (...)
Perlan 2 may break the altitude record set by Einar Enevoldson and Steve Fossett. (Tago de Pietro)(...) Nearly 10 years after setting the altitude record with Fossett, Enevoldson has a clear idea of how the next record-breaking flight will unfold. Reaching the site of the most powerful mountain waves will take about an hour. Perlan 2 will release from the towplane at 12,000 feet, and the climb to 35,000 feet will happen very quickly: as little as 20 minutes, suggests Enevoldson. Then the pilots will need to find a secondary wave to carry them into the stratosphere. They figure it will take around three and a half hours before they arrive at 90,000 feet. The aircraft will carry enough battery power for electric blankets and socks, but the pilots are more likely to overheat than freeze: Ordinary, unpressurized gliders let in cold air, so the pilots often wear heavy winter clothing, but because Perlan 2 has thick pressurization bulkheads, it retains the heat and moisture that would ordinarily leak out. (The team had to install anti-fog film on the windows to prevent condensation from clouding them.)
The team doesn’t expect much trouble in handling the aircraft above 60,000 feet, even though at extremely high altitudes, the difference between stall speed and never-exceed speed narrows into what pilots call the “coffin corner.” Perlan 2’s wing design allows a luxurious 17-knot (20-mph) difference (The U-2, routinely flying over 70,000 feet, has only a five-knot difference). And though computer simulations show a tendency to enter a tail-wagging oscillation known as Dutch Roll, a yaw damper on the tail should counteract the phenomenon. (...)
https://www.airspacemag.com/flight-today/sailplane-stratosphere-180959154/#LiVOfsRUl3Py2Uwt.99
Wątek: Perlan - wysokościowy szybowiec (Przeczytany 5712 razy)