The Boeing Phantom Eye high altitude long endurance (HALE) unmanned airborne system completed 12 days of ground vibration and structural mode interaction tests this month at NASA's Dryden Flight Research Center at Edwards Air Force Base, California.

Phantom Eye is being prepared for its first flight, scheduled for later this summer.

Phantom Eye's two hydrogen fuel tanks also were successfully filled with nitrogen to test fueling procedures and the aircraft's full-fuel weight configuration.

Phantom Eye has a 150-foot wingspan and is powered by two 2.3-liter, four-cylinder hydrogen engines that each provide 150 horsepower.

Phantom Eye is designed to fly at 65,000 feet for up to four days; perform intelligence, surveillance and reconnaissance missions; and serve as a communications relay.