Autonomous aerial refuelling inches closer

Northrop Grumman has announced that it has recently completed a series of flight demonstrations with DARPA and NASA Dryden Flight Research Center, marking an important milestone in DARPA’s Autonomous High-Altitude Refueling (AHR) programme.

The flight demonstrations, using two NASA Global Hawk UAVs – one configured as a tanker and the other as a receiver - were carried out at Edwards Air Force Base, California, between 11 January and 30 May.

The tests saw the lead receiver aircraft extend and retract its aerial refuelling hose several times, completing all planned tests to validate the associated programme hardware and software. The trail tanker aircraft also successfully demonstrated precision control in formation with manual and automated ‘breakaway’ manoeuvres – important safety features and criteria of the test programme.

The tests also saw two Global Hawk UAVs flown in close formation successfully for the first time in close formation – at times as close as 30 feet. During the close-formation flight, the aircraft rendezvoused and flew for more than 2.5 hours under autonomous formation control, with the majority of the time within 100 ft (or one wingspan) of each other.

The $33 million DARPA AHR programme aims to demonstrate autonomous fuel transfer between two Global Hawks, enabling flights of up to one week endurance. AHR is a follow-on to a 2006 DARPA Autonomous Aerial Refueling Demonstration (AARD), a joint effort with NASA Dryden that used an F/A-18 Hornet as a surrogate unmanned aircraft to autonomously refuel via a probe and drogue from a 707 tanker.

Fred Ricker, vice president and deputy general manager for Northrop Grumman Aerospace Systems' Advanced Programs & Technology, said: ‘The technical developments that enabled these two high-altitude, long-endurance unmanned Global Hawks in close formation is an outstanding accomplishment for the AHR programme. Coupled with the advanced design and technical implementation of aerial refuelling systems on board both aircraft, the demonstration has truly brought a concept to life, which has the potential to change the operations for unmanned aircraft utility and enable mission flexibility never before realised.’