Solar powered plane starts trans-American flight

The world's first solar-powered plane today took off from a San Francisco Bay airstrip for a trans-American flight that will take it to Washington by mid-June. The plane, powered only by the sun, is capable of flying day and night.

`Solar Impulse', carrying a one-man crew, lifted off from the World War II-era airstrip shortly after 6 am (Pacific time). The plane, developed by Swiss technology firms, has an average cruising speed of 43 miles (around 69.202 km).

The Swiss developers say `Solar Impulse' will take 19 hours to reach its first stopover in Phoenix, but the technology is worth the wait.

There are four stopovers, at Phoenix, Dallas, St Louis and Washington, where it is slated to land at Dulles International Airport in Northern Virginia, before taking off for the final destination New York.

The plane will spend a couple of weeks in each metropolitan area it visits.

The US tour is a prelude to a planned around-the-world flight in 2015 in an improved craft.

The plane developed using ultra-light carbon-fiber frame has a wingspan of the size of a 747 aircraft and a slender fuselage and weighs around 3,500 pounds (about 1,587.57 kg).

The craft is fuelled by power generated by an array of 12,000 photovoltaic cells that form the top of its wings. Power is collected in a series of batteries arrayed behind the plane's four electric engines. The plane's engines give about 10 horsepower of power.

The plane can reach an altitude of up to 28,000 feet, which is less than 1.5 km that big commercial airliners attain above 800 km per hour. On-board instruments alert the pilot if the plane strays away even by a degree.

Solar Impulse cannot take off or land in windy conditions or fly through clouds and its current stage of development, the plane is not anywhere near a commercial aircraft.

The pilot must endure extreme heat and cold and wear an oxygen mask at higher altitudes and on long flights the pilot Borschberg practices meditation and advanced breathing techniques to stay energised. His co-founder and the plane's other pilot, Bertrand Piccard, a psychiatrist, does self-hypnosis.

For routine bodily functions the pilot relies on spent water bottles and eschews fibrous foods in the days before a flight to avoid the use of diapers. Future versions are expected to address these shortcomings.