WASHINGTON – The U.S. Navy conducted its first-ever aerial refueling between a manned aircraft and an unmanned tanker on June 4, with a Boeing-owned MQ-25 Stingray test vehicle performing its first midair tanking mission with a Navy F/A-18E-F Super Hornet.

The test mission out of MidAmerica Airport in Mascoutah, Illinois, proved the unmanned tanker could successfully use the Navy’s standard probe-and-drogue aerial refueling method.

Once fielded, the MQ-25 will operate from aircraft carriers, refueling the air wing operating at sea and relieving the Super Hornet fleet of the tanking mission, which the Navy has said can at times account for more than one-third of Super Hornet flight hours during carrier air wing operations.

“This flight lays the foundation for integration into the carrier environment, allowing for greater capability toward manned-unmanned teaming concepts,” Rear Adm. Brian Corey, the program executive officer for unmanned aviation and strike weapons, was quoted as saying in a Navy news release. “MQ-25 will greatly increase the range and endurance of the future carrier air wing – equipping our aircraft carriers with additional assets well into the future.”

During the test, a Navy Super Hornet approached the Boeing-owned MQ-25 T1 test vehicle, coming within 20 feet of the unmanned aircraft to take some measurements and observe several features of the unmanned tanker, Dave Bujold, Boeing’s MQ-25 program director, told reporters in a press call.

“They wanted to see how stable it was to be flying in close proximity to the aircraft,” he said. “They wanted to observe officially, using their trained eyes, the behavior of the air refueling store and the basket. Very important to see stability and [have] confidence that when they approach it, it’s not going to try to hurt them.”

The two F-18 aviators from Air Test and Evaluation Squadron 23 were in radio contact with the MQ-25 operator, who was controlling the unmanned aerial vehicle from a ground control station. Once the operator deployed the hose and drogue from the UAV, the Super Hornet came in for an even closer look, Bujold said, before backing up and connecting for the first time with the UAV.

The Super Hornet first did a “dry connect,” where all the aerial refueling gear between the two aircraft attached but no fuel was passed from the tanker to the fighter.

On the second connection, 300 pounds of fuel was passed from the MQ-25′s Aerial Refueling Store pod to the Super Hornet. Bujold said this happened while the aircraft were flying at operationally relevant speeds at about 10,000 feet altitude.

Another smaller refueling was made at 16,000 feet, passing 25 pounds of fuel to the Super Hornet. Several additional dry connects were made as well, ensuring that the procedures were good for connecting and disconnecting the gear during a flight.

In total, Bujold said, the mission lasted about four and a half hours, and the two aircraft were connected for dry or wet connects for more than 10 minutes total of that time. A total of 325 pounds of fuel was passed from the MQ-25 to the Super Hornet.

As the Navy and Boeing analyze data from the test, they’ll make any software updates that are needed as the MQ-25 testing schedule continues in the coming months.

“The importance to the program is early confidence in the design and the aerodynamics of this transfer. Having the T1 test asset available this early, prior to even having the Navy’s aircraft built, gives us all kinds of feedback and data on how the mission is performed, how the equipment operates, how the communications and comms between the receiver and the refueler take place, and how that all looks in the data,” Bujold said during the press call.

The Navy plans to conduct deck handling demonstrations later this year in Norfolk, Virginia, where it will take the T1 test UAV out to an aircraft carrier and make sure it can be safely moved around the hangar and the flight deck without impeding manned aircraft operations or posing a hazard to the dozens of sailors that work on the flight deck during air operations.

In the fall or winter of 2022, Boeing will deliver to the Navy the first of seven engineering and manufacturing development (EMD) UAVs that will conduct more thorough testing. Boeing’s T1 test vehicle has the same outer mold line and engine as the MQ-25 and therefore can conduct aerodynamic testing and begin to practice the procedures of aerial refueling, but it is not outfitted with carrier landing gear and has not been hardened for carrier landings or operations in a saltwater environment. The first seven MQ-25 vehicles will be able to pick up the testing program from T1 and conduct test flights from a carrier and over the ocean beginning in 2023.

Starting with T1 and then moving into the EMD vehicles, the Navy-Boeing team will have to ensure the MQ-25 can safely conduct aerial refuelings at a range of speeds, altitudes, turbulence levels, weather and lighting conditions and more. While this recent first flight was meant to be in an operationally relevant but relatively benign flight profile, the test events will grow more challenging over time.

“We want the first event to be representative … but we’re not trying to test any edge of the envelope. So we went for the heart of the air refueling speeds for both platforms and we went for a set of, you know, a nice altitude, air turbulence, the whole thing, right in the heart of the envelope,” Bujold told Defense News during the call. “What we will do as time goes on with this program, we will continue to expand our knowledge of refueling. When we’re heavyweight with the EMD aircraft, when we’re lightweight with the EMD aircraft. When we’re higher and slower speeds, higher and faster speeds, lower and slower speeds, and lower and faster speeds – and accommodating, really, what the operational fleet pilot needs for his mission as a receiver.”

“Really the big deal on Friday was building this trust and confidence and understanding of how it’s going to be. But the really next step … is to get to the point where we are a trusted partner in the combat mission,” Bujold continued, saying that meant being able to handle any flight profile the receiving aircraft needed to fly, and ensuring the MQ-25 could operate with other aircraft in the carrier air wing, too, including the E-2D Advanced Hawkeye.

The Boeing MQ-25 T1 test asset transfers fuel to a U.S. Navy F/A-18 Super Hornet on June 4, marking the first time in history that an unmanned aircraft has refueled another aircraft. The MQ-25 Stingray will assume the carrier-based tanking role currently performed by F/A-18s, allowing for better use of the combat strike fighters and helping extend the range of the carrier air wing. (Boeing)
The Boeing MQ-25 T1 test asset transfers fuel to a U.S. Navy F/A-18 Super Hornet on June 4, marking the first time in history that an unmanned aircraft has refueled another aircraft. The MQ-25 Stingray will assume the carrier-based tanking role currently performed by F/A-18s, allowing for better use of the combat strike fighters and helping extend the range of the carrier air wing. (Boeing)

Capt. Chad Reed, the Navy’s unmanned carrier aviation program manager, said during the call that, in parallel, work was ongoing to integrate MQ-25 with a Lockheed Martin-built ground control station, which is new since Boeing was selected to build the Stingray in 2018. The Navy had to change its plans for the control station, Reed said, to keep in line with evolving Navy plans to network manned and unmanned systems together in a secure, robust network now being called Joint All-Domain Command and Control (JADC2).

In combination, the aerial refueling tests, the carrier compatibility work and the ground station integration will get the Navy much closer to its vision for manned-unmanned teaming as a way to outpace an adversary in future operations.

“As the very first carrier-based unmanned aircraft, Stingray is fundamental to the Navy’s unmanned campaign framework … strategy for making unmanned systems a trusted and integral part of warfighting. Unmanned systems alongside our traditional combatant force provide additional capability and capacity to give our warfighters the advantage needed to fight, win and deter potential aggressors,” Reed said during the media call. “The MQ-25 is that first step toward a future where the carrier-based fleet is augmented by unmanned systems. By establishing the basics of safely integrating and operating Stingray on and around the carrier in close proximity to manned aircraft, Stingray is laying the foundational building blocks for introducing new and successively more complex unmanned capabilities into the carrier environment.”

“The Navy is also exploring the ability for manned aircraft to provide direction or task MQ-25 via local communication networks in lieu of an air vehicle operator providing that tasking from the carrier- or shore-based ground control station,” Reed continued. “Manned-unmanned teaming capabilities are an essential component of the Navy strategic vision: it improves operational flexibility, it increases lethality and it allows the Navy to extend the reach of the aircrew through seamless integration and interaction between manned and unmanned systems. Friday’s historic test gets one step closer to providing MQ-25′s critical capabilities to build that foundation for integrating manned and unmanned platforms to give our forces the competitive advantage to keep ahead of the evolving threats in the 21st century.”

The June 4 test comes after 25 test flights of the T1 test vehicle since 2019.

Current testing is being conducted with a Boeing-owned vehicle. The Navy awarded Boeing a contract in 2018 for four test aircraft – plus a contract modification in 2020 for three more – which are set for delivery by 2024. The MQ-25 Stingray program is expected to reach initial operational capability in 2025, the Navy said during the press call.