Solar Impulse: solar-powered plane goes on cross-country flight

Solar Impulse, the first fully solar-powered plane that can fly day and night, took off from Moffett Federal Airfield in California Friday on a transcontinental flight.

The plane has room for only one person, and at an average speed of 43 miles per hour, it is expected to arrive in Washington D.C. June 10.

Swiss developers used an ultra-light carbon-fiber frame, and the plane has the wingspan of a 747 but weighs only 3,500 pounds, about the same as a mid-size car. 12,000 photovoltaic cells form the top of its wings, and the solar power is stored in batteries near the plane's four electric engines, which put out about 10 horsepower.

Solar Impulse can fly up to 28,000 feet, about a mile below commercial airplanes. The cockpit is unheated, unpressurized, and about the size of a “bad economy seat,” according to chief executive and co-founder Andre Borschberg, 60, an engineer and former fighter pilot.

Borschberg practices meditation and advanced breathing techniques to stay energized when he pilots a long flight. His co-founder and the plane’s other pilot, Bertrand Piccard, a psychiatrist, does self-hypnosis.

Bob van der Linden, chairman of the aeronautics department at the Smithsonian National Air and Space Museum told The Washington Post that the Solar Impulse's innovations could lead to better energy efficiency for high- and long-flying unmanned craft.

Though commercial uses lie in the future, developers say the Solar Impulse will lead to more clean-energy flight.