The Brits have broken a UAV endurance record for unmanned flight:
An international governing board for aeronautic records has confirmed that a solar-powered drone shattered a long-standing endurance record by flying continuously for 14 days last summer.
Built by British defense contractor QinetiQ, the drone remained airborne 336 hour, 22 minutes, crushing the previous endurance record for a robotic plane, which was held by Northrop Grumman Corp.’s Global Hawk drone. That unmanned flight, which took place in March 2001, lasted 30 hours, 24 minutes.
The QinetiQ drone, dubbed Zephyr, flew from July 9 to July 23 over the U.S. Army’s Yuma Proving Ground in Arizona.
The challenge to building such a device is to make it lightweight enough to require minimal power to maintain station, has sufficient battery power to climb to target altitude while carrying a useful payload: If you can get a UAV up to 70,000 feet or so, you mostly escape the effects of wind and weather.