The Defense Advanced Research Projects Agency (DARPA), in a joint effort with NASA Dryden Flight Research Center, performed the first-ever autonomous probe-and-drogue airborne refueling operation August 30, at Edwards Air Force Base, Calif. USA.

Utilizing the demonstrated techniques, future unmanned systems will be able to automatically locate the tanker, form up, accept clearances, refuel, and disengage without any human intervention.

The demonstration was conducted with a NASA F/A-18 configured to operate as an unmanned test bed. The Autonomous Airborne Refueling Demonstration (AARD) system used GPS-based relative navigation, coupled with an optical tracker, to provide the precise positioning required, putting a refueling probe into the center of a 32-inch basket dangling in the air stream behind an airborne tanker. The tanker was equipped with a small relative navigation pallet, but production refueling equipment was not modified in any way. Pilots were on board the F/A-18 for safety purposes. Autonomous in-flight refueling is a critical enabler for affordable, persistent, unmanned strike systems. The AARD system was developed by Sierra Nevada Corp., with team member OCTEC Ltd. providing the optical tracking system.

During the tests, the aircraft made several attempts to hook up with the tanker. successfully engaged the basket in two out of six attempts. As important as the successful engagements, the system safely recovered from each missed attempt.

“This flight is a significant milestone – it demonstrates that autonomous systems can employ the benefits of air-refueling that have proven so valuable to military aviation,” said Lt. Col. Jim McCormick, DARPA program manager. “We chose to demonstrate the probe and drogue refueling method because it is the most challenging for autonomous systems. The precise station-keeping capability we’ve demonstrated applies equally to the boom and receptacle method used by most Air Force aircraft,” noted McCormick. The same technology also promises to enhance reliability, safety and the range of operating conditions for air refueling manned aircraft.

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