The U.S. Navy’s Northrop Grumman X-47B ended its run as a demonstrator on April 22 by completing the first autonomous aerial refueling of an unmanned aircraft. The tailless, fighter-sized drone received two tons of fuel from an Omega Aerial Refueling Services Boeing K-707 tanker, the Naval Air Systems Command (Navair) announced.

“What we accomplished today demonstrates a significant, groundbreaking step forward for the Navy,” said Capt. Beau Duarte, the service’s unmanned carrier aviation program manager. “The ability to autonomously transfer and receive fuel in flight will increase the range and flexibility of future unmanned aircraft platforms, ultimately extending carrier power projection.”

During the test off the coast of Maryland and Virginia, the X-47B “exchanged refueling messages” with a refueling interface system on the tanker, Navair said. The drone autonomously maneuvered its fixed refueling probe into the tanker’s trailing drogue, or basket. After receiving more than 4,000 pounds of fuel, it safely disconnected from the tanker.

The X-47B first engaged the refueling drogue of an Omega K-707 on April 15 while preparing for the fuel transfer test.

Aerial refueling was the final test objective of the unmanned combat air system demonstrator, or UCAS-D, program, a contract awarded to Northrop Grumman in August 2007. Pratt & Whitney supplied the aircraft’s F100-220U turbofan engine.

AV-1, the first of two air vehicles Northrop Grumman built, made its first flight at Edwards Air Force Base, Calif., on Feb. 4, 2011, with AV-2 following that November. The AV-1 aircraft performed the first carrier-based catapult launch from the USS George H.W. Bush on May 14, 2013, and first carrier-based arrested landing at sea on July 10 that year.

The Navy has said it will retire the two air vehicles by providing them to museums or storing them at the “boneyard” of Davis-Monthan Air Force Base in Arizona. The service’s next program is to build an unmanned carrier-launched surveillance and strike (Uclass) platform. Contractors Lockheed Martin, Northrop Grumman, Boeing and General Atomics are developing Uclass concepts in advance of an expected Navy request for proposals for the program’s air vehicle component in Fiscal Year 2016.