AVIATION

Scientists hope glider Perlan II will unlock the secrets of stratosphere

Scientists, aviation buffs and entrepreneurs building a craft that aims to go 27,000 metres, set altitude record and study edge of space

PUBLISHED : Tuesday, 22 October, 2013, 10:30pm
UPDATED : Wednesday, 23 October, 2013, 4:58am
NYT

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It might be the weirdest part of the atmosphere, 24 kilometres above the polar regions, where vast stratospheric clouds of nitric acid and water vapor shimmer in iridescent pink while human-made chemicals play havoc with the ozone layer.

Scientists long to study the stratosphere at close range. But this is almost the edge of space, far too high for a conventional aeroplane in level flight.

How to get there?

In a glider.

Without the weight of engines or fuel, a glider can be lifted by natural atmospheric phenomena, engineers say. So a team of scientists, aviation buffs and entrepreneurs is building a two-seat sailplane designed to withstand the peculiar hazards of stratospheric flight. The journey is scheduled for August 2015.

The glider will be shipped by freighter to El Calafate, Argentina, where winds from the Pacific Ocean are deflected by the Andes Mountains to create a standing wave, like the waves of water that form over rocks in a mountain stream, with updrafts of nine metres per second.

"These mountain waves get so steep and energetic, they turn into white water," said Edward Warnock, an aerospace engineer who is chief executive of the Perlan Project, the non-profit organisation that is building the glider, Perlan II.

A single-engine plane, probably a crop duster, will tow the glider to meet these waves, at about 3,000 metres. Where the waves weaken, at about 18,000 metres, the glider is supposed to intercept another phenomenon, the polar vortex - circulating winds that act like a giant cyclone during the austral winter, delivering a strong uplift. If it can catch that current, the glider will soar still higher, into the Perlan Clouds, and higher, into the ozone hole, where the chemical reactions that disrupt the ozone layer take place.

The aim is to go to 27,000 metres, and set a new altitude record for a glider. The plane's predecessor, Perlan I, set the record of 15,461 metres on August 30, 2006.

Perlan II will cost an estimated US$7.5 million, of which US$3.5 million has already been spent; the project is still trying to raise the balance. The organisers include Dennis Tito, the pension fund manager who paid US$20 million to visit the International Space Station, and, until he was killed in the 2007 crash of his single-engine plane, Steve Fossett, the aeronaut and sailor who flew Perlan I.

The new sailplane will have a wingspan of 25.5 metres and weigh just 770kg, counting crew - 45kg lighter than Perlan I, even though the older plane had a 22-metre wingspan. The builders say Perlan II is 80 per cent complete. Huge carbon-fibre pieces that look like a woven fabric, a tight-knit plaid in two shades of gray, fill most of a hangar, waiting to be glued together.

In the end, all will be painted a reflective white to stop the sun from heating the parts enough to weaken the epoxy.

Squeezed into a fuselage about 90 centremetres in diameter, the two pilots will be almost recumbent. They will bring sandwiches and wear diapers. Because there is no way to warm the interior of the plane - another consequence of lacking an engine - the pilots will also wear socks with heaters in their soles.

The altitude is not completely virgin territory; the space shuttle, which was in effect a glider on its way back to earth, used to traverse it at several times the speed of sound.

Spy planes have reached that altitude, but only for brief periods in their parabolic flight, according to Warnock. Perlan's plan is to cruise for hours at a time, in peaceful silence.

"The idea of extended observations from a platform in the 70,000- to 90,000-foot range has huge potential scientific advantages," said James Anderson, a climate scientist at Harvard who is not affiliated with the project.