Solar UAV Flies For 24 Hours
Earth Day was celebrated in silence on California's high desert as an electric car company marked an aviation milestone. AC Propulsion's SoLong unmanned aerial vehicle (it looks like a big model glider) landed at 12:45 a.m. on April 22, having spent a little longer than 24 hours aloft flying on battery and solar power alone, the longest such flight of its type to date. "During the flight the SoLong had made no noise, consumed no fossil fuels, emitted no pollution and contributed nothing to global warming," according to a report in EV World. The aircraft, which has a 15.6-foot wingspan and weighs 25.3 pounds, was launched just after midnight with a full lithium ion battery to run its high-efficiency electric motor until dawn. As the sun rose, the solar panels on its wings gradually increased output until the battery was being charged again. The aircraft also took advantage of the solar energy that produced thermals, enabling the motor to be shut down as it rode the air currents. By mid-afternoon, the battery was fully charged and ready to power the UAV through half the night. In fact, it landed with a half-full battery. Multi-day flights are now being planned.