NASA CONTINUES INVESTIGATION OF DOWNED HELIOS.

Byline: Jim Skeen Staff Writer

EDWARDS AIR FORCE BASE - A NASA investigation team wrapped up its field work into the June 26 crash of the unmanned, solar-powered aircraft Helios off the coast of Hawaii and will return to the mainland for tests to try to determine the cause of the crash.

About three-fourths of the Helios prototype wreckage was recovered from the ocean off the Hawaiian island of Kauai and will be shipped to the Monrovia facility of AeroVironment, the aircraft's builder, for examination.

Over the next few weeks, the five-member investigation board will review available data and seek independent analyses and tests, the National Aeronautics and Space Administration announced.

The board will reconvene in early August to review the analyses and determine possible causes, NASA said.

The Helios prototype, a flying wing, began to break apart and crashed into the ocean about 30 minutes into a check-out flight over a U.S. Navy test range off Kauai. The aircraft began to break apart while flying at about 3,000 feet altitude.

The Helios was in Kauai for tests of a fuel cell to power the aircraft at night. The 743-pound fuel cell, which was not in use at the time of the crash, sank into the ocean and was not recoverable.

The flight testing was being conducted under NASA's Environmental Research Aircraft and Sensor Technology program, which is overseen by NASA Dryden Flight Research Center at Edwards Air Force Base. ERAST is aimed at developing technologies that allow companies to build unmanned aircraft that can carry out the dull, dirty or dangerous missions that would be impossible or impractical for manned aircraft.

The Helios prototype aircraft was testing technologies to create aircraft capable of staying aloft for weeks or even months. Such craft could operate essentially as low-flying satellites, by relaying the communications signals or studying the environment.

``Although saddened by the loss of Helios, the AeroVironment team will respond to the loss as a challenge to learn from the incident and incorporate Helios technologies into a new and better extreme-endurance UAV (unmanned air vehicle),'' said Bob Curtain, vice president in charge of AeroVironment's UAV design development center.

In 2001, Helios set a world altitude record for winged aircraft of 96,863 feet.

NASA plans to continue to push the kinds of technologies Helios was to have tested.

``The Helios prototype project has made great strides in advancing the technology of solar-powered aircraft, as evidenced by the record altitude flight in 2001,'' said John Del Frate, Helios project manager at NASA Dryden Flight Research Center. ``We will use results of the accident investigation to improve the next generation of Helios.''

Helios was only 12 feet long, but it had a 247-foot wingspan. The airplane cruised at speeds ranging from 19 to 25 mph.

The airplane was made of lightweight composite materials, such as carbon fiber and graphite epoxy, which are used in the B-2 stealth bomber, and Kevlar, which is used to make bulletproof vests.

Jim Skeen, [phone]

james.skeen(at)dailynews.com