Northrop Grumman and the U.S. Navy successfully demonstrated fully autonomous aerial refuelling (AAR) with the X-47B Unmanned Combat Air System Demonstration (UCAS-D) aircraft on April 22, marking the first time in history that an unmanned aircraft has refuelled in-flight.
This is another historic aviation milestone for the X-47B, which in 2013 became the first unmanned aircraft to autonomously launch from and recover aboard an aircraft carrier, Northrop Grumman said. “In combination, these landmark demonstrations constitute a major step forward in autonomy that has application in both manned and unmanned aircraft. Autonomous launch, recovery and refuelling have the potential for reducing operational costs in the future.”
“AAR testing with the X-47B helps solidify the concept that future unmanned aircraft can perform standard missions like aerial refuelling and operate seamlessly with manned aircraft as part of the Carrier Air Wing,” said Capt. Beau Duarte, the Navy’s Unmanned Carrier Aviation programme manager.
During the probe and drogue (or “Navy-style”) AAR demonstration, the X-47B performed a close formation flight rendezvous with an Omega K-707 tanker. Upon clearance from the tanker crew, the X-47B manoeuvred into position behind the K-707 and successfully engaged the drogue. On completion of the refuelling, the X-47B autonomously disengaged the drogue and manoeuvred away from the tanker before returning to base.
“We are very pleased with the outcome of this first round of probe and drogue flights with the X-47B,” said Pablo Gonzalez, UCAS-D programme manager, Northrop Grumman Aerospace Systems. “The AAR system and X-47B both performed as expected. While we would certainly benefit from additional probe and drogue flight testing, we have reached a tipping point at which AAR is now feasible.”
Northrop Grumman began developing AAR technology for both Navy and Air Force application nearly a decade ago, pioneering a “hybrid” approach that integrates both GPS and infrared imaging to enhance navigational precision and hedge against GPS disruption. Initial UCAS-D flight testing began in 2012 using a manned Learjet as a surrogate for the X-47B. These successful proof-of-concept flights demonstrated the overall feasibility of the X-47B AAR system and helped refine its navigation, command and control, and infrared sensor processing components.
Northrop Grumman is the Navy’s UCAS-D prime contractor. The UCAS-D industry team includes Lockheed Martin, Pratt & Whitney, GKN Aerospace, Eaton, General Electric, UTC Aerospace Systems, Dell, Honeywell, Moog, Wind River, Parker Aerospace, Sargent Aerospace & Defense, and Rockwell Collins.
The air-to-air refuelling trials are planned to be the last tests for the two X-47Bs, which will then have completed all planned testing. By the end of this Fiscal Year on October 1, both will be transferred to museums or placed in storage at Davis-Monthan AFB.