A Boeing-led team has been selected to continue development of a system enabling unmanned aerial vehicles (UAVs) to autonomously rendezvous with a tanker and refuel.

Phase 2 of the U.S. Air Force Research Laboratory's Automated Aerial Refueling (AAR) program will involve actual fuel delivery to a surrogate UAV.

In Phase 1, a Boeing-led government-industry team demonstrated a UAV could autonomously maneuver between seven standard refueling positions behind a tanker. Acting as a surrogate UAV, a Calspan-operated Learjet remained in position behind the KC-135 as the tanker flew a standard refueling orbit.

But the Learjet is not equipped for aerial fueling, so Phase 2 flight-tests will use the Air Force Test Pilot School's Calspan-operated VISTA F-16 in-flight simulator. The modified fighter is equipped for boom-and-receptacle refueling and can host the AAR-specific navigation and control systems.

Phase 2 of the AAR program is aimed at developing and demonstrating the capability for a long-range strike vehicle, including a future unmanned variant of the Air Force's planned Next-generation Bomber, to autonomously refuel from existing tankers.

During Spiral 1 of the program, the Boeing-led team will develop a multichannel precision-Global Positioning System relative navigation system, a redundant automated flight control system for the UAV, and a command and control system that allows the tanker's boom operator to handle refueling of unmanned aircraft in the same way as manned aircraft.

The relative navigation system will exchange precise GPS/INS positioning information between UAV and tanker using a dual-redundant high-speed datalink, and the automated flight control system will guide the aircraft into contact with the tanker.

Under Spiral 2, the team will evaluate non-GPS navigation sensors to augment the Spiral 1 system and potentially support autonomous probe-and-drogue refueling. The U.S. Navy needs this capability to extend the range and endurance of its planned carrier-based unmanned combat air system, N-UCAS.

The Boeing-led AAR Integrator Team includes Lockheed Martin, Northrop Grumman, GE Aviation, Rockwell Collins and Sierra Nevada.