The X-47B . is the U.S. Navy stealth strike fighter by Northrop Grumman.The Northrop Grumman X-47B is a demonstration unmanned combat aerial vehicle (UCAV) designed for aircraft carrier-based operations. Developed by the American defense technology company Northrop Grumman, the X-47 project began as part of DARPA’s J-UCAS program and subsequently became part of the United States Navy’s Unmanned Combat Air System Demonstration (UCAS-D) program. The X-47B is a tailless jet-powered blended-wing-body aircraft capable of semi-autonomous operation and aerial refueling.The X-47B first flew in 2011, and as of 2015, its two active demonstrators have undergone extensive flight and operational integration testing, having successfully performed a series of land- and carrier-based demonstrations. In August 2014, the US Navy announced that it had integrated the X-47B into carrier operations alongside manned aircraft, and by May 2015 the primary test program was declared complete. The X-47B demonstrators themselves were intended to become museum exhibits after completing flight testing, but the Navy later decided to maintain them in flying condition pending further development.The US Navy did not commit to practical UCAS efforts until 2000 when it awarded contracts of US$2 million each to Boeing and Northrop Grumman for a 15-month concept-exploration program. Design considerations for a naval UCAV included dealing with the corrosive saltwater environment, deck handling for launch and recovery, command and control system integration, and operation in an aircraft carrier’s high-electromagnetic-interference environment. The Navy was interested in using UCAVs for reconnaissance, penetrating protected airspace, and identifying targets for follow-on attacks.Northrop Grumman’s proof-of-concept X-47A Pegasus, which provided the basis for the X-47B, first flew in 2003. The J-UCAS program was terminated in February 2006 following the Quadrennial Defense Review. The US Air Force and Navy proceeded with their own UAV programs. The Navy selected Northrop Grumman’s X-47B as its unmanned combat air system demonstrator (UCAS-D) program. To provide realistic testing, the demonstrator was built to be the same size and weight as the projected operational craft, with a full-sized weapons bay capable of carrying existing missiles.General characteristicsCrew: None aboard (semi-autonomous operation)Length: 38 ft 2 in (11.63 m)Wingspan: 62.1 ft (18.9 m) extended; 30.9 ft (9.4 m) foldedHeight: 10 ft 5 in (3.10 m)Wing area: 953.6 sq ft (88.59 m2)Empty weight: 14,000 lb (6,350 kg)Max takeoff weight: 44,567 lb (20,215 kg)Powerplant: 1 × Pratt & Whitney F100-220U turbofanPerformanceRange: 2,400 mi (3,900 km, 2,100 nmi)Service ceiling: 42,000 ft (12,800 m)Cruise speed: Mach 0.9+ (high subsonic)Armament2 weapon bays, providing for up to 4,500 lb (2,000 kg) of ordnanceAvionicsProvisions for EO/IR/SAR/ISAR/GMTI/MMTI/ESMThe X-47B prototype rolled out from Air Force Plant 42 in Palmdale, California, on 16 December 2008. Its first flight was planned for November 2009, but the project fell behind schedule. On 29 December 2009, Northrop Grumman oversaw towed taxi tests of the aircraft at the Palmdale facility, with it taxiing under its own power for the first time in January 2010.