Eventually it will fly for four days straight, making only water as its waste product. But a journey of four days starts with a few minutes, so the chubby PhantomEye’s first autonomous flight was under half an hour.

The aircraft took off June 1 from NASA’s Dryden Flight Research Center, climbed to 4,080 feet and cruised at 62 knots in a flight that lasted 28 minutes, Boeing said Tuesday. When it landed, the gear dug into the lakebed and broke.

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But Boeing officials were glad to see their persistent intelligence demonstrator take off and fly on its own. It uses a liquid hydrogen propulsion system, which will allow it to fly at 65,000 feet for four days. It can carry a 450-pound payload, too, but its goal is continuous surveillance.

It’s hard to tell from the pictures, but its wingspan is enormous, spanning 150 feet. Here it is in a hangar before its props were attached.

PhantomEye’s next task is a higher-altitude flight, Boeing said.

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The Phantom Eye sits without its propellers in a hangar at Boeing Phantom Works. Its wingspan is too long to capture the whole thing from any vantage point inside the building.