Solar-powered plane's first international flight

Pioneering Swiss solar-powered aircraft Solar Impulse has landed in Brussels after its first international flight, 13 hours after it took off from Switzerland.

"This is wonderful," said Bertrand Piccard, joint founder and president of the Solar Impulse project.

The single-seater, piloted by Andre Borschberg, had lifted off gently in clear blue skies from Payerne airbase at 8.40am (1640 AEST) after being delayed by early morning mist.

It covered the roughly 480km from western Switzerland to Brussels airport, flying over France and Luxembourg at 3600 metres.

"With this flight, we would like to encourage politicians to opt for more ambitious energy policies," Piccard told AFP before the aircraft landed.

He also called for "a change in mentalities to encourage people to use new [green] technologies" and stop wasting fossil energies.

"It is crazy that mankind wastes a billion tonnes of oil an hour," he said.

"The flight is going really well. I have just flown over Liege; it's a real pleasure to enter Belgian airspace," Borschberg said as the dragonfly-like experimental and emissions-free aircraft cruised at 50km/h.

"The view I have here is extraordinary," the Swiss pilot said in a live internet feed.

"I'm above the clouds, for now I'm taking advantage of the blue sky."

Solar Impulse HB-SIA, which has the wingspan of a large airliner (63.4 metres) but weighs no more than a saloon car (1600kg), made history in July last year as the first manned plane to fly around the clock and through the night on the sun's energy.

It holds the endurance and altitude records for a manned solar-powered aeroplane after staying aloft for 26 hours, 10 minutes and 19 seconds above Switzerland, flying at 9235 metres.

The high-tech plane has since flown several times, notably between Geneva and Zurich airports, but the journey to a busy airport in Brussels through crowded airspace was regarded as a new test.

"Flying an aircraft like Solar Impulse through European airspace to land at an international airport is an incredible challenge for all of us, and success depends on the support we receive from all the authorities concerned," said Borschberg, who also piloted July's flight.

HB-SIA relies on 11,628 solar cells on its 64-metre wings to charge the batteries that provide the energy for the four 10-horsepower electric motors driving the propellers. The aeroplane's average flying speed is 70km/h, with a take-off speed of 35km/h and the maximum altitude it can reach is 8500 metres.

Its record-breaking flight last year demonstrated its capacity to store up enough energy to fly through a summer night.

The showcase for green technology will be on display at Brussels airport until 29 May before flying to the international air show at Le Bourget in Paris from 20 to 26 June.

"This time, we have a real aeroplane — flying — proof that new technologies can reduce our dependence on fossil energy," said Piccard.

The Solar Impulse team is planning to fly even further, including possible transamerican, transatlantic and round-the-world flights — in stages — in 2013 and 2014 using a slightly larger aircraft.

Asked about upping the speed, Borschberg said: "That's not the aim of this plane for now."

Piccard, himself the first man along with Briton Brian Jones to fly non-stop around the world in a balloon, comes from a dynasty of pioneers.

His grandfather, Auguste Piccard, twice beat the record for reaching the highest altitude in a balloon, in 1931-32.

His late father, Jacques Piccard, was a deep sea explorer, who holds the record for travelling to the deepest point underwater, 10,916 metres below sea level in the Marianas Trench in the Pacific.