This is an excerpt from EERE Network News, a weekly electronic newsletter.

September 08, 2004

NASA Releases Report on Crash of Helios Solar Plane

Two photos show first the Helios with its wing bent into a u-shape and then crumbling as it falls toward the ocean.

The wing tips of the Helios bent up sharply (left) shortly before the craft failed (right).
Credit: NASA

The National Aeronautics and Space Administration (NASA) released on September 3rd its final report on the crash of Helios, a solar-powered "flying wing" that suffered structural failure and fell into the Pacific Ocean during a long-duration test flight last summer. A review of the flight data concluded that atmospheric turbulence caused the plane's wing tips to bend upward abnormally and then caused the entire wing to oscillate. The growing oscillations caused the Helios to gain speed until it suffered a structural failure. The accident investigation board determined that the mishap resulted from the inability to predict, using available analysis methods, the aircraft's increased sensitivity to turbulence following modifications to allow long-duration flights. Specifically, the addition of a hydrogen-air fuel cell pod and two hydrogen storage tanks placed significant loads along the length of the flying wing, reducing the safety margins for the aircraft. See the press release from the NASA Dryden Flight Research Center or go directly to the full report (PDF 2.6 MB). Download Acrobat Reader.