We've previously mentioned that the solar powered aircraft Solar Impulse was able to remain in the air for a full day. The similarly powered Zephyr, designed by the company QinetiQ, has now stayed in the air for more than a full week. Its engineers plan to continue its flight for at least another week in order to test its abilities. From QinetiQ's press release:
Launched by hand, the aircraft flies by day on solar power delivered by amorphous silicon solar arrays no thicker than sheets of paper that cover the aircraft's wings. These are also used to recharge the lithium-sulphur batteries, supplied by Sion Power Inc, which are used to power the aircraft by night. Together they provide an extremely high power to weight ratio on a continuous day/night cycle, thereby delivering persistent on-station capabilities.
Link via CrunchGear | Photo: QinetiQ