Solar plane's test-flight in 2008

A prototype of the “Solar Impulse” round-the-world solar plane should make its first piloted flight in autumn 2008, the Swiss project leaders said on Monday.

The reduced-size model of the aircraft — which will have a wingspan of 61 metres, the equivalent of an Airbus
A340 airliner — is currently being built in northern Switzerland to test the cutting-edge technology involved in its construction.

If successful, the dainty 1.5-tonne plane could make a pioneering 36-hour flight through the night in 2009, piloted by round-the-world ballooning pioneer Bertrand Piccard.

Piccard said the first flight just metres above the runway at Duebendorf would mark the “moment of truth” after nearly two years of computer simulations.

One of the big challenges for solar flight is how to store enough energy from its array of solar panels to keep the ultra lightweight aircraft flying in darkness. While pilotless drones have already accomplished the feat, it is far more difficult with the added size and weight of a pilot on board.

The $94 million project aims to emulate the achievements of aviation pioneer Charles Lindbergh — who in 1927 made the world’s first solo, non-stop transatlantic flight — but with a solar-powered twist.

The project’s goals include a transatlantic crossing in 2011 before what would be a historic, fuel-less circumnavigation of the globe.

About 150 specialists from six countries are involved in designing Solar Impulse, which is expected to break new ground with its aerodynamics, control systems, energy efficiency, materials and structure. One of the challenges will involve stretching carbon sheet just a few tenths of millimetres thick over lengths of up to 20 metres.