Northrop Grumman’s X-47B unmanned combat air system (UCAS-D) demonstrator successfully completed its long-delayed first flight

By Guy Norris guy_norris@aviationweek.com
Los Angeles

Northrop Grumman’s X-47B unmanned combat air system (UCAS-D) demonstrator successfully completed its long-delayed first flight at Edwards AFB, Calif., on Feb. 4.

The stealthy, single-engine UCAS took off early in the afternoon Pacific time and landed some 29 min. later, having achieved an altitude of 5,000 ft. Aimed at gathering air vehicle management system data, the first flight also marks the start of a roughly 50-flight, year-long Block 1 envelope expansion test campaign at Edwards. Initial flight rate is expected to be once per week, rising to twice a week later in 2011.

Northrop and U.S. Navy officials passed the tailless, flying wing demonstrator for taxi tests at a flight readiness review in early November 2010.

The first air vehicle, AV-1, was rolled out in December 2008 but the start of flight tests has been delayed by engine-related acoustic and starting problems as well as issues related to software complexity. The Navy’s first dedicated stealth aircraft since the canceled General Dynamics/McDonnell Douglas A-12, the X-47B was originally due to fly in November 2009.

Following corrective actions and a rebalancing of the program towards carrier landings in 2013 rather than late 2011 as originally planned, the final timing of first flight came down to securing a suitable launch window at Edwards.

Longer term, a key priority remains landing on an aircraft carrier and proving that the unmanned system can operate in the carrier environment. Northrop says this will be a key confidence-building step to gaining widespread Navy support to eventually acquire UCAS-type systems that can ultimately perform the stealthy strike mission intended for the A-12, but with the increased range and endurance of an unmanned aircraft.

The Feb. 4 flight was carried out with the landing gear down, and the vehicle flying a racetrack pattern over the dry lakebed with standard-rate turns. The landing was made back on the same runway used for take-off.

Later this year AV-1 will be transferred to the Navy’s test center at NAS Patuxent River, Md., and eventually hoisted onboard a carrier. The UCAS will then be maneuvered around the vessel as part of the program’s Block 2 carrier deck operations and handling trials test plan.

The second X-47B, AV-2, has been transferred to a loads test rig for up to eight weeks of structural proof tests that will simulate carrier landing and critical flight loads, as well as check the structure for catapult and arrestment loads, fuel system integrity and control surface freedom under load. AV-2 incorporates design improvements to the nozzle structure to accommodate changes to deal with the acoustic issues from the X-47B’s single Pratt & Whitney F100-220U engine that contributed to delays to AV-1.

AV-2 is due to be transferred to Edwards in March for initial taxi tests and engine runs, but is not expected to make its first flight until the end of the year.