Solar craft goes for altitude record

Helios reached an altitude of 22,800 metres on its first test flight

A giant solar-powered flying wing has begun an attempt to reach a higher altitude than any non-rocket-powered aircraft.

The American space agency Nasa launched the Helios aircraft from Barking Sands on the Hawaiian island of Kauai, after two previous attempts had been delayed by bad weather.

The aim of the flight is to get the 74 metre-wide-wing to 100,000 feet (30,000 metres) - three times higher than any commercial jet.

Depending on weather conditions and how fast it climbs, the record could be broken within eight to nine hours of its departure at 0848 local time (1848GMT), said a Nasa spokesman.

Helios, an unmanned craft powered by 62,000 solar cells, reached an altitude of 22,800 metres (75,000 feet) in its first test flight earlier this year.

The present altitude record stands at 24,000 m (79,000 ft).

Eye in the sky

Helios weighs about 700 kg (1,557 pounds), less than many cars. The wing is flexible, so that it can bend to cope with air turbulence. The entire craft is packed with solar cells, which power 14 engines.

Nasa developed the Helios with AeroVironment Inc., of Monrovia, California in a bid to build a remotely piloted aircraft that could replace space satellites for some uses.

A pilot-less plane that stays aloft for days using rechargeable fuel cells at night could be used for weather forecasting and as a communications platform that would be much cheaper than satellites.