U.S. Department of Energy

    Swiss Solar-Powered Plane Makes First Night Flight

    July 14, 2010

    Photo of a sleek aircraft soaring in the sky

    The Solar Impulse soars during its day-and-night flight over Switzerland.
    Credit: Solar Impulse

    A solar-powered aircraft that flew over Switzerland for more than 26 continuous hours on July 7 and July 8 achieved the latest milestone in a project that aims to launch a zero-emission flight around the world in 2012. The Solar Impulse HB-SIA, a lightweight prototype with the 208-foot wingspan of a Boeing 747-400, completed what organizers said was the first-ever full nighttime flight by a solar-powered aircraft. Solar Impulse Chief Executive Officer Andre Borschberg was in the cockpit. The aircraft's nearly 12,000 silicon mono-crystalline solar cells—mounted on its wings and on its horizontal stabilizer—absorbed the sun' rays on the ascent and supplied the craft's four electric engines and lithium-polymer batteries, enabling Impulse to average about 26 miles per hour for the flight. Organizers said the flight set records for both the longest and highest solar-powered flight by a piloted aircraft, with the craft reaching just over 28,000 feet above sea level.

    Solar Impulse, seven years in the making, took its maiden flight on April 7 in Switzerland, staying aloft for more than an hour as a test pilot put it through its paces. During the night flight, Borschberg told his ground control crew that the cold caused his water supply to freeze and his iPod battery to fail. A second Solar Impulse aircraft, the HB-SIB, has been developed to attempt several consecutive 24-hour flight cycles and will be built this summer, according to the Solar Impulse team. Success in its day-and-night trials would enable the aircraft to attempt its first trans-Atlantic crossing, possibly by 2012. Finally, meeting that benchmark would clear the Solar Impulse team for its ultimate goal, an around-the-world solar journey. See the Solar Impulse press release and Web site.