Glider pilots aim for the stratosphere

November 20, 2015 by Gary Robbins, The San Diego Union-Tribune

Talk about serendipity. Einar Enevoldson was strolling past a scientist's office in 1991 when he noticed a freshly printed image tacked to the wall. He was thunderstruck; it showed faint particles in the sky that proved something he had long believed:

The winds that rise off mountains travel far, far higher into the atmosphere than most people imagined, representing something of an "elevator" to the heavens.

It was an "a-ha!" moment for Enevoldson, a renowned test pilot and engineer. He soon began sketching out plans for a manned glider that could ride those winds toward the edge of space. No engine required.

So began a 24-year quest that inched closer to reality earlier this month when Enevoldson's glider - Perlan 2 - underwent stress testing at ATA Engineering in San Diego. The company is helping to evaluate whether the sailplane, which is lighter than a Honda Fit, could climb to 90,000 feet.

That would obliterate the current altitude record for gliders, which was set in 2006 when Enevoldson and fellow pilot Steve Fossett rose to 50,727 feet during a lazy climb through the skies above Argentina.

They succeeded by taking advantage of the comparatively rare moments when mountain winds are given extralift by the polar vortex, an expanse of cold, swirling air found out the world's poles. Scientists call them stratospheric mountain waves.

Enevoldson oversees a team that will try to ride a glider to a new record next year. Once again, the attempt will again be made in Argentina, only this time Enevoldson won't be in the cockpit. He's 83 now, and coping with health issues.

But he knows how he'll feel if pilots Jim Payne and Morgan Sandercock guide the milky white glider to new heights.

"It'll prove that I'm right; you can really ride these mountain waves to great heights," Enevoldson said, standing next to aircraft. "It will show that I'm not some crack pot."

That's not quite how marketing people would word it.

Enevoldson is founder and chairman of the Airbus Perlan Mission 2 project. It's an effort to show that a manned glider can make the transition from the lowest layer of the atmosphere - the troposphere - to the stratosphere, where most commercial jets fly. The goal: slowly climb to 90,000 feet, or roughly 19 miles high.

It is literally a lofty goal that begins with some basic physics.

"The wind blows over the mountain, comes down the backside, then it rebounds, just like water does as it moves over a rock in a stream," said Jim Payne, who will fly Perlan 2 with Morgan Sandercock.

"It's an extremely amazing phenomenon."

Scientists used to think that the winds that rise from the leeward side of mountains didn't travel much higher than the troposphere, which varies in altitude, depending on location and season. The altitude generally ranges from 4 miles to 12 miles.

But researchers learned that these mountain waves can make their way well into the stratosphere, if conditions are right. Enevoldson says he came to understand this on a deep level in 1991 when he noticed a research photo that a scientist had placed on his wall at DLR, the German Aerospace Center in Munich. A laser sensor system picked out particles of high altitude clouds that arose, in part, due to wind.

"I happened upon this by accident. I wasn't looking for it," Enevoldson said. "I was just walking from one place to another."

He was one of a comparatively few people who could appreciate what he was seeing. Enevoldson had decades of experience flying, including long service with the Air Force as a fighter pilot and years with NASA as a test pilot. He also had a deep background in engineering.

He later partnered with billionaire adventurer-pilot Steve Fossett, and with scientists, to explore the idea of riding these waves to record heights in a glider. That led to his successful flight with Fossett. But Fossett died in a plane crash in 2007 and the project limped along until Airbus, the European airplane consortium, began providing financial support in 2014.

The project leaped ahead in September of this year when Payne and Sandercock guided Perlan 2 on a successful test flight in Oregon. That led to this month's stress testing at ATA Engineering.

Sanderock makes a point of saying, "The ultimate purpose is this aircraft is scientific research. We can go higher than any other aircraft, taking samples and measurements that no one else can do."

But Enevoldson stresses a more fundamental form of human curiosity.

"What this amounts to is a place on Earth that no one has been, and no one has explored," he said, as engineers jostled Perlan 2's wings.

"The Earth is such a magnificant and interesting thing. When there's something new about it, you have to go see it. It's there. I have no choice. I have to do this."

Explore further: Forecasters look higher for clues to winter weather

More information: www.perlanproject.org/

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abecedarian
5 / 5 (4) Nov 20, 2015
"It's an effort to show that a manned glider can make the transition from the lowest layer of the atmosphere - the troposphere - to the stratosphere, where most commercial jets fly. The goal: slowly climb to 90,000 feet, or roughly 19 miles high."

Most commercial jets rarely exceed 35,000 feet in altitude.
U-2 spy plane has published service ceiling of 70,000 feet.
SR-71 has a published service ceiling of 85,000 feet.
antialias_physorg
5 / 5 (5) Nov 20, 2015
Sounds a bit dangerous, because if the glider ever leaves the updraft current (for whatever reason, be it pilot error or shift in updraft current location) it'll plummet (and spin) like a stone without any way to right itself until it hits denser atmosphere.

I hope this guy knows what he's doing.
barakn
3.4 / 5 (5) Nov 20, 2015
If the updraft was significantly denser than the surrounding air, gravity would quickly slow it down and reverse it. Your fears of plummeting and spinning are unfounded.
Nik_2213
5 / 5 (1) Nov 20, 2015
Air-brakes ? Anti-spin drogue ??

He's been a test-pilot. He'll know the tech for such contingencies.

FWIW, he'll probably have a pop-out 'chute for the cabin lest a wing-root fail...
antialias_physorg
5 / 5 (5) Nov 20, 2015
Air-brakes ? Anti-spin drogue ??

These don't work if he leaves the dense air of the current for quite some time. He'll be as helpless as Baumgartner in his epic jump until there's enough air resistance.
https://www.youtu...N-cWe0A0
(Baumgartner jumped from 93k feet)

The danger is not that he'll crash without being able to slow (in denser air chutes will start to work), but that he'll black out due to uncontrollable spin and not wake up in time to recover the craft.
antialias_physorg
5 / 5 (3) Nov 21, 2015
You need AIR to spin a plane in....

Look at the video of Felix Baumgartners jump. Notice how he tumbles? Any angular momentum (and you always have some when you enter airless spaces) will not be counteracted by drag: so you spin (or better: keep on spinning)

the air density is so low that it will equate to flying at a normal speed, in a reasonable air density.

No. If that were true Baumgartner would have had no problem righting himself like a parachutist before his chute opened (according to your 'logic'). Look at the video. He's completely helpless for quite some time.
In this video you can see it even better:
https://www.youtu...FlhzNq8o
Zzzzzzzz
5 / 5 (2) Nov 21, 2015
I took several long distance (8 and 9 hours) commercial jet fights recently. The typical cruising altitude for these flights was 38000 ft. At times the outside temperature was as low as - 70's F. I wonder what conditions the pilots will need to endure at 90000 ft, in an unpowered craft. They will need self contained suits, similar to a space suit.
SuperThunder
5 / 5 (1) Nov 23, 2015
Here is their web page about the aircraft.
http://www.perlan...aircraft
I don't see mention of any kind of RCS system, but they have a lot of confidence in the wing design and emergency parachutes.

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