Bad vibes still rank
as Helios affliction
BARKING SANDS, Kauai >> NASA issued a preliminary report yesterday on the June 26 crash of its $15 million Helios solar-powered flying wing, but the space agency offered no new information on the cause.
The five-member NASA team completed its field investigation and returned to the NASA Dryden Flight Research Center at Edwards, Calif., where it is scheduled to release a final report on Sept. 30.
Helios crashed about a half-hour after taking off from the Navy's Pacific Missile Range Facility, breaking apart at an altitude of about 3,000 feet and falling into the ocean. About 75 percent of the 247-foot-wide aircraft was recovered.
The report issued yesterday noted "undampened pitch oscillations," which NASA previously had said immediately after the crash. That means the forward edge of the aircraft was vibrating up and down, and pilots flying Helios from the ground were unable to control it.
"There's not one single factor here," said NASA spokesman Alan Brown. "There are some very, very complex interactions here."
Helios and most of its subsystems are cutting-edge technology, much of it still experimental.
Two years ago, a test flight of Helios from Kauai was aborted because an on-board computer was overheating before takeoff. An investigation showed the computer was being powered both by Helios' solar panels and the aircraft's batteries, and the conflict caused it to fail.
After that problem was corrected, Helios went on to set the world altitude record for winged aircraft at 96,500 feet.
Last month's crash was the first since NASA began testing solar-powered aircraft on Kauai in 1997.