Remember that "UFO" spotted in June? Well, here it is in daylight

Not so much little green men as no men at all: the craft that triggered 911 calls and Twitter furore after being mistaken for a UFO back in June has been put on show by the US Navy, a human-made drone rather than ET's escape pod. The X-47B is a new, experimental unmanned aircraft the Navy has admitted, with a spokesperson telling Fox 5 that while the stealth aircraft wasn't meant to be a secret, the team "all got a laugh" after it was confused for something extraterrestrial while being transported on a truck two months ago.

"There was nothing real secretive about it," US Navy Test Engineer Matt Funk said of the drone, "but we didn't go out of our way to publicize it."

The drone itself, an X-47B Unmanned Combat Air System (UCAS) made by Northrop Grumman, is entirely remote instructed and the first of a new breed of air surveillance and attack systems expected to be increasingly commonplace in the coming years. Commanded remotely from a computer system – that will eventually be on an aircraft carrier, the Navy says – the UCAS can also return to base autonomously should it lose connection with its controller.

Unlike existing drones, the X-47B doesn't require continuous controlling from a human operator, but is instead given a flight target and relied on to get itself there and back. There are "space, weight and power provisions for weapons and intelligence, surveillance and reconnaissance sensors," Northrop says, but the current prototypes are not equipped with weaponry.

Its otherworldly looks make it a good candidate for something from outer-space. At 62.1ft wide and 38.2ft long, with distinctive kinked and truncated wings (that fold up to reduce width), the X-47B is more science-fiction at first glance than warfare-fact. Northrop Grumman says it will have a range of over 2,100nm and a maximum altitude of over 40,000ft, with "high subsonic" speed potential. It will also support in-flight refueling for continuous missions.

A 36 minute test flight at the end of July saw the X-47B fly at a maximum altitude of 7,500 feet and a maximum air speed of 180 knots. It's worth roughly $800m, and will begin aircraft carrier testing in 2013.