The second in a series of checkout flights leading up to a
planned long-endurance flight demonstration by the solar-electric
Helios Prototype flying wing is planned to lift off Thursday morning,
June 26, at the U.S. Navy’s Pacific Missile Range Facility (PMRF) on
the Hawaiian island of Kaua’i.

The flight could mark the first time that a large aircraft is
powered by electricity derived from an advanced experimental fuel
cell system.

Takeoff is nominally scheduled for about 8:30 a.m. on the
full-day shakedown flight, which could last up to 20 hours before
Helios returns to the Navy facility on the west shore of Kaua’i. The
final schedule and "go – no go" decision will be made at an all-hands
crew brief late Tuesday afternoon. Should weather or technical issues
force a postponement, Friday and Saturday June 27-28 are backup
flight days.

John Del Frate, Helios project manager at NASA’s Dryden
Flight Research Center, said the primary objective of the second
check flight is to verify the in-flight operation of the fuel cell
system, including stable operation of the system and its compressor
at 50,000 feet altitude and at a rated power of 18.5 kW. A rapid
shutdown of the fuel cell system and a restart at night on battery
power is also planned.

During the first check flight June 7, the Helios Prototype
was aloft for about 15 hours at altitudes up to 52,000 feet while
engineers checked out modifications and upgrades made to the aircraft
over the past two years. The fuel cell system was not brought on-line
due to some leakage in the coolant system and compressed air lines
that feed the fuel cell while the Helios is aloft.

The overall goal of the flight series is to demonstrate the
ability of the Helios Prototype to fly a long-endurance mission of
about 40 hours, including at least 14 hours above 50,000 feet
altitude. The Helios flies on electrical power derived from solar
arrays during the day and from the experimental fuel cell system that
combines oxygen from the atmosphere with hydrogen stored on the
aircraft at night.

A new photo from the Helios Prototype checkout flight on June
7 is now posted on the NASA Dryden web site photo gallery at:

http:// www.dfrc.nasa.gov/Gallery/Photo/Helios/HTML/ED03-0152-32.html

Video footage is also available for television news and
documentary broadcast. For photo prints or video dubs, please call
(661) 276-2665.