AeroVironment Helios Prototype

The AeroVironment Helios Prototype was an experimental, remotely piloted flying wing powered by solar cells, and the fourth and final aircraft in a series of solar- and fuel-cell-powered unmanned aircraft that AeroVironment built for NASA's ERAST program. It was made by taking the NASA Centurion and adding a sixth wing section and a fifth landing gear and systems pod, which gave it a wingspan of 247 feet, or 75 metres, longer than that of a Boeing 747. Built mostly of carbon fibre, Kevlar and thin plastic film, it made its maiden flight on 8 September 1999 and could be set up in two ways, one for altitude using batteries and solar cells and one for endurance that added a hydrogen-air fuel cell for night flying. On 13 August 2001 it reached 96,863 feet, or 29,524 metres, a world record for sustained horizontal flight by a winged aircraft. It broke up in turbulence over the Pacific west of Kauai on 26 June 2003 and was destroyed.