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By pushing the atmospheric envelope at the edge of Earth’s stratosphere, the Airbus Perlan 2 glider’s next tests should pave the way for both future aviation on
The Perlan 2 sailplane/glider, which had its first test flight last September in Oregon, will attempt to reach its optimal cruising altitude of 90,000 feet as early as this coming June in Argentina , says McArtor. When it does, it will be the highest that any winged vehicle, powered or otherwise, has gone in sustained, level flight.*
As part of the Perlan Project --- a nonprofit supported by title sponsor Airbus Group and others; the glider’s two-man crew will scientifically sample the stratosphere at altitudes exceeding those of even the U-2 and the SR-71 spy planes.
McArtor stresses that Perlan 2 will offer
“Perlan 2’s wingspan [of some 84 feet] will just barely fit between first and second base,” said McArtor. But he says it should allow the Perlan Project to learn whether that’s a wingspan that would allow for optimum maneuverability in Mars’ two percent atmosphere. And Perlan should also give the team real time data on how the craft would handle banking and potential stalls in such a Martian atmosphere.
An artist’s conception of the Airbus Perlan Mission II glider at its target altitude of 90,000 feet,... [+]
With Mars’s thin atmosphere, McArtor says flight using a propeller or a standard turbine jet engine would be very difficult. Instead, he says that a Mars aircraft would need to be a hybrid that used some means of thrust and soar dynamics to move above the red planet’s surface.
Airbus says that any insight gained into flight at increasingly higher altitudes also has implications for the future of both sub-sonic and supersonic or hypersonic aviation, where given the right technology, higher operating altitudes could provide a range of potential advantages.
“Airbus recently filed a patent for hypersonic passenger craft that will go to suborbital space and back down again,” said McArtor. “It’s in that region of suborbital space that Perlan 2 will be flying.”
The Perlan Project owes its current fortunes to the ground-breaking work of Perlan’s founder, NASA test pilot Einar Enevoldson, who during back in the 1990s first collected evidence that stratospheric mountain waves actually exist. ‘Perlan,’ Icelandic for ‘pearl,’ refers to a type of lenticular cloud that only form at high altitude inside these stratospheric mountain waves.
The waves themselves are kicked up by winds that blow over high mountain regions such as the andes and propagate upward as high as 130,000 feet at speeds of more than 260 knots [300 mph].
“All the climate models assume there’s no mixing between the stratosphere and below but there really is,” said McArtor. “We’re going to prove that these mountain waves are exactly what enable the aircraft to soar to 90,000 feet.”
The Perlan 2 glider. Credit: Airbus Perlan Mission II
The current Perlan 2’s wings are designed to handle six Gs of gravity with daylight flight times of up to nine hours.
The glider reaches a position of several thousand feet altitude using a tow plane and cable, just like any other glider, then is cut loose to position itself to ride the Andes mountain waves.
McArtor says the tech that allowed for Perlan 2 was in part sparked by miniaturization; the ability to provide advanced avionics in very small packages. On the materials side, he says, the Perlan 2’s strong carbon fiber structure --- made by BRS Aerospace --- will enable the craft to be strong enough to handle such high-altitude conditions.
In 2006, the late Steve Fosset and Einar Enevoldson reached 50,000 feet in Perlan 1, the glider’s first incarnation. But unlike Perlan 1, in which the two pilots actually wore borrowed NASA spacesuits which greatly inhibited their ability to operate the vehicle, the Perlan 2 crew will operate in a pressurized cabin and use an oxygen re-breather system not unlike that used in scuba diving.
Perlan 2 will still travel light, with an empty weight of only 1100 pounds, but is equipped with high altitude radar; instrumentation and lighting for night flying; a few scientific instruments and cameras to record data and basic ground-communications equipment. In the event of an emergency, the glider has two parachutes to help it make a safe rapid descent.
Although McArtor stresses that Perlan 2 is not a prototype for any sort of marketable aircraft, the mere fact that it will fly where no one has flown before in sustained, level flight opens the door to a new wave of follow-on technology that the aerospace community will be implementing for years to come.
* Correction: A previous version of this story omitted the caveat that this is the first time a winged aircraft of any stripe will have operated at such an altitude in sustained, level flight. Previous turbojet aircraft have operated in zoom climb to temporarily exceed such altitudes, but not in what is considered controlled, or sustained flight.
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