Northrop Grumman, US Navy test UCAS refuelling

Northrop Grumman and the US Navy successfully completed a series of flight tests to demonstrate technology that could help extend the operating range and flight duration of future carrier-based unmanned systems. The testing was carried out on the X-47B UAV on 21 January 2012 in St Augustine, US.

The testing proved the functionality of the hardware and software that will enable the X-47B unmanned aircraft to demonstrate autonomous aerial refuelling (AAR) in 2014. The AAR activity is part of the Navy's Unmanned Combat Air System Carrier Demonstration (UCAS-D) program. Northrop Grumman is the Navy's UCAS-D prime contractor.

The AAR tests were conducted by a Northrop Grumman/Navy team using Calspan’s Variable Stability Learjet as the X-47B surrogate aircraft, and a K707 tanker provided by Omega Air Refuelling. The tests included simulated flight demonstrations of both boom/receptacle and probe-and-drogue aerial refuelling techniques. No fuel was exchanged between the aircraft during the test events.

According to Northrop Grumman, the Learjet surrogate was equipped with real or functional equivalents of the navigation systems, flight control processor and vision system that the X-47B will use to conduct refuelling operations. The aircraft contained no refuelling receptacle or refuelling probe. The K707, which is nearly identical in size and shape to an Air Force KC-135, was equipped with a Navy style refuelling drogue only.

For each simulated refuelling event, the Learjet/X-47B surrogate was piloted to a rendezvous position approximately one nautical mile from the tanker. Then the pilot transferred control of the aircraft to the X-47B's autonomous flight control processor, which controlled the Learjet during the test event.

The Northrop Grumman/Navy test team plans to conduct additional AAR surrogate testing using the same aircraft when flight-qualified versions of the relevant X-47B hardware and software become available.

The UCAS-D program plans to demonstrate in 2013 the ability of the tailless, autonomous, low-observable relevant X-47B demonstrator to safely operate from a Navy aircraft carrier, including launch, recovery, bolter and wave-off performance, followed by the autonomous aerial refuelling in 2014. The programme also plans to mature technologies required for potential future Navy unmanned air system programmes.