Historic trip: Solar Impulse flies from San Francisco Bay, California to Phoenix, Arizona. Photo: Reuters
A plane powered only by the sun has completed the first leg of a journey that aims to cross the US.
The plane, the first able to fly day and night, began a transcontinental journey that will reach Washington by mid-June.
Solar Impulse lifted off from a World War II-era airfield in San Francisco on Friday and has room for only one person and an average cruising speed of about 69km/h. It landed in Phoenix, Arizona, some 18 hours later.
Success: Borschberg greets Piccard in Phoenix. Photo: AP
Pilot Bertrand Piccard landed having used only three-quarters of the plane’s battery power.
”It’s a little bit like being in a dream,” Piccard said as he stepped on the tarmac.
The plane has an ultra-light, carbon-fibre frame and weighs 1585 kilos – about the same as a mid-size car. It has the wingspan of a 747 and a slender fuselage, giving it the look of a giant, high-tech dragonfly.
The plane’s power is drawn from the sun by 12,000 photovoltaic cells that form the top of its wings. It is collected in a series of batteries arrayed behind the craft’s four electric engines.
It routinely reaches altitudes of up to 8500 metres, well below the thin air traversed by big commercial aircraft zipping around at close to 800km/h. On-board instruments alert the pilot if the plane banks even a degree too far.
For all of its innovations, at this stage of development, Solar Impulse is no more practical for commercial flight than was the single-engine Spirit of St Louis that Charles Lindbergh piloted across the Atlantic Ocean in 1927.
The plane’s engines put out about 10 horsepower – roughly the same amount as the Wright brothers’ first planes. Solar Impulse cannot take off or land in windy conditions, nor can it fly through clouds. The lone pilot wears a parachute and is confined to an area the size of a ”bad economy seat,” noted the project’s chief executive and co-founder Andre Borschberg, 60, an engineer and former fighter pilot.
The tiny cockpit is unheated and unpressurised, meaning the pilot must endure extreme heat and cold and wear an oxygen mask. On long flights, Borschberg practises meditation and advanced breathing techniques to stay energised. His co-founder Piccard, a psychiatrist, does self-hypnosis.
And as for bodily functions – the pilot relies on spent water bottles and eschews fibrous foods in the days before a flight to make sure that nappies do not have to be used.
But comfort is not the goal. ”The point of this is to underscore how far we’ve come and how far we need to go to develop alternative sources of power, particularly solar energy,” said Bob van der Linden, chairman of the aeronautics department at the Smithsonian National Air and Space Museum. ”This will help push the technology along.”