Solar Impulse Prepares For U.S. Flight
The Solar Impulse's HB-SIA solar-powered aircraft has been delivered disassembled to Moffett field, California, and its team has started the process of reassembling it in preparation for a four-stop flight across America. The aircraft's wing spans more than 205 feet and is covered with nearly 12,000 photovoltaic cells that run four 10-horsepower electric motors. The cells also charge the aircraft's lithium-polymer battery packs. In flight, the 3,527-pound plane cruises at less than 50 mph. Test flights will be made prior to the transcontinental journey. Stops, other than Washington, D.C., and New York, have not been precisely identified. The program last summer suffered setbacks.
Engineered for efficiency more than strength, HB-SIA avoids turbulence through flight planning, by taking off early and cruising near 30,000 feet, and also by avoiding observable weather. A second, larger aircraft being built to undertake longer flights failed a safety check last July, when its main spar cracked during structural tests. The Solar Impulse team now hopes to begin work on a new aircraft, this fall. That aircraft they hope to fly around the world in 2015. To date, the longest flight for HB-SIA was recorded at just over 26 hours. The new aircraft will be 15 percent larger than the HB-SIA prototype.