A UK-built solar-powered plane has set the unofficial world record for longest flight time by an unmanned aircraft. The ultra-lightweight Zephyr-6 stayed aloft(空中に、飛んで)for 82 hours and 37 minutes in a demonstration for the US military. Built from carbon fiber and powered by paper-thin solar panels, the craft weighs a mere 66 lb (30 kg) and flies at an altitude of more than 60,000 ft (18,000 m).
A plane that can remain aloft indefinitely(無期限に)using solar power and can fly over the same area all day would be invaluable in military applications.