EDWARDS AIR FORCE BASE, Calif -- A National Aeronautics Space Administration (NASA) Dryden Flight Research Center flight crew conducted the first-ever autonomous probe-and-drogue airborne refueling operation. The Autonomous Airborne Refueling Demonstration was a joint NASA/ Defense Advanced Research Projects Agency was carried out with a Dryden F/A-18 configured to operate as an unmanned test bed. The system used global positioning system based relative navigation and an optical tracker to position the probe into the center of a 32-inch basket streaming behind the tanker.
The first phase of the Autonomous Airborne Refueling Demonstration project was completed on August 30, 2006. The goal of this 15-month effort was to develop and flight-test a system to demonstrate an autonomous refueling engagement using the Navy style hose-and-drogue air-to-air refueling method. The prime contractor for this Defense Advanced Research Projects Agency sponsored program was Sierra Nevada Corporation, Sparks, Nevada. The responsible flight-test organization was the National Aeronautics and Space Administration Dryden Flight Research Center Edwards, California, which also provided the F/A-18 receiver airplane. The B-707-300 tanker airplane was contracted through Omega Aerial Refueling Services, Inc., Alexandria, Virginia, and the optical tracking system was contracted through Bracknell, Berkshire, United Kingdom. Nine research flights were flown, testing the functionality and performance of the system in a stepwise manner, culminating in the plug attempts on the final flight. Relative position keeping was found to be very stable and accurate. The receiver aircraft was capable of following the tanker aircraft through turns while maintaining its relative position. During the last flight, six capture attempts were made, two of which were successful. The four misses demonstrated excellent characteristics, the receiver retreating from the drogue in a controlled, safe, and predictable manner that precluded contact between the drogue and the receiver aircraft. The position of the receiver aircraft when engaged and in position for refueling was found to be 5.5 to 8.5 feet low.