Northrop Grumman will modify the second X-47B naval unmanned combat air system demonstrator (UCAS-D) to allow autonomous aerial refuelling (AAR) using both U.S. Navy probe-and-drogue and U.S. Air Force boom-and-receptacle methods.

The U.S. Navy has announced plans to award the company a sole-source contract to support the demonstration of AAR capability by 2013, saying the X-47B is the only carrier-suitable unmanned aircraft capable of the task.

AAR would extend the surveillance and strike reach of a 2020-timeframe naval UCAS (N-UCAS) well beyond that of manned aircraft and allow carriers to engage land targets while staying out of range of anti-ship ballistic missiles.

Both X-47Bs being built under the UCAS-D program are designed for aerial refueling. N-UCAS program manager Scott Winship says Northrop Grumman will activate the roll-over receptacle and mount the refueling probe on the second air vehicle.

The X-47Bs are being built to demonstrate carrier-based launch and recovery in the 2011 timeframe. Demonstration of autonomous aerial refueling is planned under the parallel technology-maturation phase of the UCAS-D program.

It is not clear if the Navy plans its own demonstration or whether it intends to join the Air Force Research Laboratory’s (AFRL) Automated Aerial Refueling program, which plans to demonstrate boom-and-receptacle refueling in 2011 using an F-16 as a surrogate unmanned aircraft.

Boeing is leading a team including X-47B partners Northrop Grumman and Lockheed Martin for the four-year second phase of the AFRL program. Spiral 1 of Phase 2 involves a precision-GPS relative navigation system to guide the unmanned receiver to the manned tanker.

Under a planned Spiral 2, the team will evaluate non-GPS sensors to support probe-and-drogue refueling. Winship says the X-47B could be used to provide a “graduation exercise” for the AAR effort.

Northrop Grumman