The waspish prototype of Solar Impulse, with the wingspan of a jumbo jet, was rolled out before some 800 guests at an airfield near Zurich after six years of development.

Ten years after Piccard and Briton Brian Jones achieved the first non-stop flight around the globe in the Orbiter balloon, the Solar Impulse team are aiming to demonstrate that clean technology is not a pipedream.

The Swiss adventurer — who is again joined by Jones — said the idea emnerged after that hot air balloon trip, when Orbiter was partly kept aloft by fuel canisters even if the wind ensured its progress.

"That historic success could have turned sour because of the lack of fuel," Piccard said at the Dubendorf airfield.

"That's why we took the decision to to attempt a trip around the world without relying on fossil fuels," he explained.

The seemingly flimsy carbon fibre concentrate of technology has a 63.4 metre wingspan but weighs little more than a medium-sized car.

Some 12 000 solar cells spread over its slender wings will fuel four tiny ten-horsepower electric motors, while 400 kilogrammes of batteries will keep it going overnight.

Wedged in the narrow cockpit, the pilot will also be helped to fly the aircraft by some novel control technology.

Although computer simulations have been tried out, the prototype HB-SIA will make its maiden test flight by the end of this year.

Its mission is to test the feasibility of a complete flight sequence through two days and one night, propelled only by solar energy, and pave the say for a second aircraft's bid to circumnavigate the globe in five stages in 2012.

AFP