No observers from the Fédération Aéronautique Internationale (FAI) were on hand, so the flight may not officially break the previous record of 30 hours, 24 minutes, 1 second set by Northrop Grumman’s RQ-4A "Global Hawk" on March 21, 2001.
But the FAI is currently reviewing a second test flight of the Zephyr that lasted 33 hours, 43 minutes.
The Zephyr is an ultralight aircraft made of carbon fiber. Though it has a 60-foot (18-meter) wingspan, it weighs just 66 pounds (30 kilograms) and is launched by hand.
During the day, the plane draws on power supplied by paper-thin solar arrays mounted on its wings, while simultaneously charging batteries used for night operations.
With further improvements, it’s hoped that not everything that goes up has to come down. The solar-powered aircraft could stay in the sky indefinitely, acting as a permanent surveillance source or temporary communications relay during an emergency.
"Both flights were achieved in the face of thunderstorms and debilitating heat in the hostile environment of the New Mexico high desert in the summertime," Paul Davey, Zephyr business development director at QinetiQ, said in a press release.
"They have proved that an autonomous UAV can be operated on solar-electric power for the duration required to support persistent military operations."