Electric aircraft crashes into sea off Hawaii

A prototype electrically-powered aircraft has crashed into the Pacific Ocean off Hawaii during a test flight. The remotely controlled, solar-powered Helios craft broke up while flying at a height of around 2.4km, about 29 minutes into a test flight in preparation for a two-day mission planned for July.

The craft (seen above during a recent flight) was built by California-based AeroVironment and funded by NASA. It was intended to be the forerunner of a generation of remotely controlled aircraft that could cruise at high altitudes for months on end, for duties such as communications, atmospheric science and imaging. Two years ago, the Helios prototype set a world altitude record for winged aircraft when it flew to a height of 29.5km above the earth`s surface.

The cause of the crash is being investigated. The Helios had recently started to test a fuel cell power system which would allow it to fly at night when power was not available from the 62,000 solar cells built into its upper wing surface.

The Helios, whose unladen weight was just 600kg, had a 75m-wide wingspan - wider than that of a Boeing 747. It was propelled by 14 1.5kW brushless DC motors driving 2m-diameter lightweight propellers. Its cruising speed was 30-43 km/h.

NASA says it plans to continue with the Helios programme.