Solar Plane Climbs Into Record Books

An elongated flying wing, covered with solar panels and powered by 14 propeller motors not much stronger than hair dryers, climbed to 96,500 feet Monday, shattering a flight record that for more than a quarter century seemed unbreakable.

The remote-controlled Helios aircraft took more than seven hours, lumbering at a maximum speed of 23 mph, to reach the height, an aviation feat no jet or propeller airplane has ever accomplished.

The historic flight, rather than aiming only for an entry in a record book, demonstrated technology that could enable solar-powered planes to stay aloft for months. Fleets of such aircraft could carry global communications at lower cost than today’s satellites.

Helios’ accomplishment also underscores Southern California’s continuing leadership in aircraft design, being only the latest craft built here to achieve a major aviation record.

At an altitude of about 100,000 feet, the sky is black, the curvature of Earth is clearly discernible and the air so thin--only one-hundredth its density at sea level--it is incapable of sustaining the flight of any conventional airplane.

The highest reported altitude by an airplane before Monday was achieved by the jet-powered SR-71 spy plane, the world’s fastest jet. The plane, built in Burbank in the 1960s, flew to 85,068 feet in July 1976. Only short-duration rockets have flown higher.

Designed and developed by Monrovia-based AeroVironment Inc. with funding from NASA, the airplane surpassed the previous altitude record at 5:21 p.m. PDT as it flew over the Pacific Ocean west of the Hawaiian islands. It continued to ascend and had reached 96,500 by 7:09 p.m. It then began its gradual descent, and was expected to touch down by morning.

In addition to making aviation history, the aircraft is expected to provide NASA with tantalizing clues about flying in an atmosphere similar to that of Mars. NASA eventually hopes to use flying machines to explore the surface of the planet.

Plane Has Scientific, Commercial Interest

NASA also is interested in seeing how much higher it can take sophisticated science equipment aboard airplanes to study Earth’s atmosphere for climate change and ozone depletion. Telecommunications companies are interested in the planes’ ability to hover over an area for months at a time, high above the clouds and commercial aircraft traffic, enabling them to relay ultra-fast Internet, television and telephone signals directly to homes.

The aircraft was able to reach the record height thanks to its massive wing, spanning 247 feet--30 feet longer than the wings of the Boeing 747-400, the world’s largest commercial airplane--while weighing only 1,577 pounds. The aircraft is mainly constructed of Kevlar, Styrofoam and plastic film to cover the wing. The top of the wing is laden with 62,000 solar panels, which provide power to the electric propeller motors. Five pods under the wing hold the fuel cells and the landing gears.

Monday’s flight came as the U.S. Air Force officially squashed decades-long speculation that the SR-71 had reached an altitude of 100,000 feet or more, giving Helios the undisputed record.

Although aviation buffs have maintained for years that anSR-71 secretly has been flown higher than publicly disclosed, an Air Force official said last week that the airplane could not sustain a flight beyond the record set in 1976. Indeed, a flight manual for the SR-71, portions of which recently were declassified, warn pilots not to exceed the maximum altitude of 85,000 feet.

The plane took off from the U.S. Navy’s Pacific Missile Range Facility on the Hawaiian island of Kauai at 8:48 a.m. local time, or 11:48 a.m. PDT, after a 38-minute delay as operators waited for clouds to clear. The cloud cover kept the solar cells from developing enough electricity to power the propellers for a takeoff.

Flights Postponed, Then Finally Liftoff

The flight already had been postponed twice--first Saturday when heavy clouds and some technical problems forced NASA to scrub the mission and then Sunday as high-level cirrus clouds lingered over the island. Operators feared that the cirrus clouds, made mostly of ice crystals, would hamper the flight because they would have added weight to the plane and reduced its lift.

Monday morning, the chance for the record flight came as the low-hanging clouds cleared momentarily, providing enough solar power to launch the aircraft. But it was a tense 37 minutes before the airplane broke through the broad cloud layer and into the clear sky, prompting NASA officials to sigh with relief.

“We managed to climb above the cloud coverage,” a dispatch from the operator said as the plane climbed to 5,000 feet. “We are so relieved!”

From then on, the Helios climbed steadily, though some turbulence jolted wary NASA operators who had been up all night preparing for the historic flight.

Then at 2:21 p.m. local time, or 5:21 p.m. PDT, Helios climbed past the 25-year-old milestone.

“They’ve reached the record,” said Alan Brown, a NASA spokesman from Kauai, as he relayed the events via telephone.