Automated aerial refueling (AAR) refers to methods for autonomous refueling of manned and unmanned aircraft.

History

Air Force Research Laboratory The Air Force Research Laboratory (AFRL) is a scientific research organization operated by the United States Air Force Materiel Command dedicated to leading the discovery, development, and integration of aerospace warfighting technologies, pl ...

program was started in 2004 at the AFRL Air Vehicles Directorate. The initial program was the evaluation of technologies that could be used for AAR. The key new concept is the use of precision

GPS The Global Positioning System (GPS), originally Navstar GPS, is a satellite-based radionavigation system owned by the United States government and operated by the United States Space Force. It is one of the global navigation satellite sy ...

. The AAR program has since held several flight tests. The important factors were the software and communication systems that kept the aircraft at the proper altitude and speed. In 2007, the Defense Advanced Research Projects Agency (DARPA), with the help of

NASA The National Aeronautics and Space Administration (NASA ) is an independent agencies of the United States government, independent agency of the US federal government responsible for the civil List of government space agencies, space program ...

, demonstrated automatic refuelling from a conventional tanker by a high-performance aircraft. A pilot was on board to supervise, so the demonstration was not entirely automated. It served as the basis for DARPA's Autonomous High-Altitude Refueling program which, in 2012, demonstrated the potential for fully autonomous aerial refueling of unmanned air vehicles. The final test involved modified

RQ-4 The Northrop Grumman RQ-4 Global Hawk is a high-altitude, remotely-piloted surveillance aircraft of the 1990s–2020s. It was initially designed by Ryan Aeronautical (now part of Northrop Grumman), and known as Tier II+ during development. The ...

drones flying in close formation less than 100 ft from a tanker, close enough for refueling to take place.

Automated flight control

Appropriate flight control systems (FCS) include sensors to detect the position of the tanker and its refueling drogue along with rules to control the client aircraft. Several different techniques have been proposed for controlling the refueling process. One proposal involves the use of LED beacons on the drogue and an optical sensor on the tanker to determine the drogue's position and attitude. A second involves treating the drogue's position as fixed, ignoring turbulence with the help of a

low-pass filter A low-pass filter is a filter that passes signals with a frequency lower than a selected cutoff frequency and attenuates signals with frequencies higher than the cutoff frequency. The exact frequency response of the filter depends on the filt ...

in the control system.

References

{{Reflist United States Air Force