Second X-47B robo-drone takes to the air (photos)

Northrop Grumman and the U.S. Navy are doubling down on their efforts to get the X-47B robotic drone in shape to use an aircraft carrier for take-offs and landings: a second test aircraft now has made its first flight. The 29-minute low-altitude excursion took place November 22 at Edwards Air Force Base in California, as part of the Navy's Unmanned Combat Air System Carrier Demonstration (UCAS-D) program. "With two aircraft now available, we can increase the amount of aircraft performance data we gather, which will allow us to meet our required aircraft capability demonstration goals in a timely manner," Carl Johnson, vice president and UCAS-D program manager for Northrop Grumman's Aerospace Systems sector, said in a statement this week.

The second X-47B demonstrator, known as Air Vehicle 2 (AV-2), reached an altitude of about 5,000 feet and flew several racetrack patterns, Northrop Grumman said. Before the end of the year, one of the two aircraft will be moved to Naval Air Station Patuxent River in Maryland for what the defense contractor calls "shore-based carrier suitability testing." The other will continue with "envelope expansion flight testing" at Edwards AFB.

In an earlier milestone for the UCAS-D program, the first X-47B drone in late September achieved cruise mode for the first time. With the aircraft's landing gear retracted, that flight gave a test run to the navigation hardware and software, as well as the overall aerodynamic performance of a tailless and nearly flat design that's heavy on triangles and sharp corners.

Back in the late winter, the AV-2 version of the X-47B was undergoing stress testing, with dozens of hydraulic jacks pushing and pulling on the airframe, at Northrop Grumman's Palmdale, Calif., facility. The company has said that the two X-47B aircraft are identical except that AV-2 will be equipped with aerial refueling gear.

This was the state of testing in July 2009, in the early stages of validating whether the X-47B could handle the stresses and strains of life at sea on an aircraft carrier. "Arrested landings, catapult launches, high winds, pitching deck, subsonic speeds, you name it--the operating environment of the carrier air wing is unforgiving," Scott Winship, a Northrop Grumman VP, said in a statement at the time. "The X-47B was built for these conditions, and as the results of the rigorous proof test show, the design of the aircraft is structurally sound for all aspects of carrier operations."

The first-ever flight of an X-47B happened in early February 2011 at Edwards AFB. Like the maiden flight of the AV-2, it too lasted 29 minutes. The upcoming test flights at the Patuxent River facility will begin in early 2012, Northrop Grumman says. There, the company and the Navy hope to get a better sense of how the aircraft handles the precision approaches and arrested landings, as well as catapult launches, that are necessary for aircraft carrier operations. The next phase of testing will also assess recently installed guidance, navigation, and control software.

The wingspan of the X-47B is 62 feet. The short test flights notwithstanding, the aircraft is said to have a range of more than 2,100 nautical miles, as well as a maximum payload of 4,500 pounds. Northrop Grumman says the jet-powered aircraft (the engine is a Pratt & Whitney F100-PW-220U) will be able to fly at "high subsonic" speeds; in test flights back in March, the X-47B flew as fast as 200 knots for about 40 minutes.

The birdlike profile of the X-47B in flight belies its high-tech guts. The unmanned aircraft can fly autonomously on a preprogrammed mission, and in contrast with other UAVs, Northrop Grumman says, it is not flown via remote control. Instead, a mission operator monitors its operation "using simple situational awareness displays," providing only occasional mouse clicks to initiate steps such as take-off and return to base.

Beyond next year's testing, Northrop Grumman and the Navy have laid out this timetable: in 2013, expect the first demonstration of launch and recovery involving an actual aircraft carrier, and in 2014, look for demonstrations of autonomous aerial refueling.

Just a week after its first flight in February, the X-47B strikes a pose at Naval Air Station North Island in San Diego, at the start of the yearlong Centennial of Naval Aviation celebrations.