A clean-aviation milestone
Zero-emission flight leapt forward in July, when Swiss pilot André Borschberg flew the solar- and battery-powered Solar Impulse HB-SIA for 26 hours, 9 minutes and 10 seconds, reaching a height of 28,500 feet before gliding back down and marking the first time any aircraft had flown overnight on energy collected during the day.
Made largely of carbon fiber, the HB-SIA weighs 3,500 pounds, roughly the same as a midsize sedan. The plane's 208-foot wingspan and its horizontal tail stabilizer are covered with 11,628 solar cells that supply electricity to its onboard electronics, four 10-horsepower electric motors and lithium-polymer battery packs. The battery packs take over from the solar panels approximately two hours before dusk, when the sun's rays become too weak to be useful.
Bertrand Piccard, the endurance balloonist who co-founded Solar Impulse with Borschberg in 2003, says he wants the HB-SIA's successor, the HB-SIB, to achieve the first solar-powered flight around the world as early as 2013.
