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The Honolulu Advertiser
Posted on: Friday, May 18, 2001

NASA solar wing may rise 100,000 feet over Kaua'i

By Jan TenBruggencate
Advertiser Science Writer

BARKING SANDS, Kaua'i — The designers of Helios, a massive solar wing fitted with propellers, hope it will fly to a record 100,000 feet this summer over the skies of Kaua'i.

AeroVironmentâs Dale Tietz holds one blade of a high- altitude propeller for the Helios solar plane, whose wing is seen in background at the Pacific Missile Range Facility on KauaÎi. With the solar panels on the wing for power, NASA hopes this craft will reach an elevation of 100,000 feet ÷higher than any non-rocket- powered craft has flown.

Jan TenBruggencate • The Honolulu Advertiser

That would be the highest any aircraft without rocket propulsion has ever flown — 19 miles up where the atmosphere is 1/100th as dense as it is at sea level.

Helios is the successor to Pathfinder, which holds the record at 80,200 feet, made in 1998 over Kaua'i.

Both aircraft are part of NASA's Environmental Research and Sensor Technology program, which aims to develop an aircraft that can act like a satellite but is cheaper to deploy and easy to upgrade.

If the new record altitude is reached, the next goal is to keep it aloft overnight, and then for weeks and months.

Builder/designer AeroVironment Inc. calls Helios an "eternal aircraft."

The first flight, a test flight to 80,000 feet, is scheduled for June 7. The company has scheduled up to five flights, but could reach 100,000 feet as early as the second flight if nothing goes wrong, AeroVironment's Dale Tietz said.

The version that was unveiled at the Navy's Pacific Missile Range Facility on West Kaua'i yesterday has solar panels but no energy storage capability, so it can stay under power only as long as the sun shines.

A separate research project is developing a lightweight regenerative fuel cell system. Sometime next year, AeroVironment and NASA hope the Helios and fuel cell programs will merge, producing an aircraft that will fly day and night.

The plan is for Helios in 2003 to stay aloft for a month, said Bob Curtin, AeroVironment vice president. NASA's ultimate purpose is to develop a cheap-to-launch vehicle that can function much like a satellite, staying up for months and acting as a communications vehicle, an airborne camera or for environmental monitoring, weather observation and other capacities.

The 100,000-foot level is for the record books, but the actual flying would mostly be done in the calm air between 60,000 and 80,000 feet.

A plane that could stay at 60,000 feet for months at a time would be the equivalent of an 11-mile-high communications tower, said John Del Frate, NASA project manager for solar-powered aircraft.

Helios is 247 feet long but weighs just 1,600 pounds. Tietz said the $10 million worth of solar photovoltaic panels on its wing will power 14 electric motors with wide propeller blades for the thin atmosphere at high elevation. For lower flights, fewer motors would be needed, he said.