US Navy Doubles Down On Range Requirements For Its MQ-25 Tanker Drone

The service says it now wants the Stingray to fly more than twice as far with 50 percent more fuel.

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The U.S. Navy’s top aviation officer, Vice Admiral Mike Shoemaker, has offered new details about what the service expects from its future MQ-25 Stingray tanker drones. Based on his comments, the plan is for the final unmanned aircraft to nearly double the operational range of carrier-based F/A-18E/F Super Hornets, a significant increase over the initial requirements.

In an interview with the U.S. Naval Institute’s magazine Proceedings, Shoemaker, who holds the position of Commander, Naval Air Forces, said the goal was for each MQ-25 to be able to dispense more than approximately 2,200 gallons, or nearly 15,000 pounds, of fuel 500 miles from the carrier. At present, the Super Hornets have an effective combat radius of around 450 miles.

“The MQ-25 will give us the ability to extend the air wing out probably 300 or 400 miles beyond where we typically go,” Shoemaker explained. “That will extend the reach of the air wing, and when we combine that with additional weapons we are buying, we will get an impressive reach.”

The fuel load Shoemaker described is 50 percent greater than the minimum figure the Navy had provided in the materials it submitted as justification for the multi-mission MQ-25 designation in 2016. The service had asked for the new moniker after deciding to change the pilotless plane’s mission from long-range strike and reconnaissance to tanking following the end of tests of Northrop Grumman's X-47B as part of the Unmanned Combat Air System Demonstration (UCAS-D) program and the cancellation of the follow-on Unmanned Carrier-Launched Airborne Surveillance and Strike (UCLASS) project.

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One of the X-47B demonstrators lands aboard the aircraft carrier USS George H.W. Bush in 2013.

It also appears that the idea is for the drones to fly more than twice as far before refueling any aircraft. Based on the interview questions in Proceedings, an initial concept of operations saw the unmanned tankers providing fuel only 200 miles out from the carrier.  

And when Shoemaker mentioned new weapons, he was most likely referring to the Navy’s interest in advanced stand-off bombs and missiles, such as the AGM-154C Joint Stand-Off Weapon (JSOW) glide bomb and AGM-158C Long Range Anti-Ship Missile (LRASM). Combined with the extended range the Stingrays would provide, these could give F/A-18E/Fs, and eventually F-35C Joint Strike Fighters, the ability to engage targets at even greater distances.

These new details reinforce earlier reporting that suggested the Navy was focusing almost exclusively on the MQ-25 as a tanker, which could free up the carrier air wing's Super Hornets from having to fly that mission, at least in the near term. Initially, the service said the Stingray would be a mix of tanker and reconnaissance aircraft, reflected in its multi-mission designation. 

"Right now the focus is to make it [the MQ-25] a tanker to extend the reach of the  air wing and reduce some of the fatigue life expenditure on our Super  Hornets," Shoemaker said. "The only tankers we have in the air wing are the Rhinos [Super Hornets]."

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An F/A-18E Super Hornet deploys the probe-and-drogue from a Cobham air refueling pod.

On top of that, it seems that the service is looking to further downplay the recovery tanking portion of that mission in favor of mission tanking, as well. Mission tanking involves refueling aircraft well away from an aircraft carrier or land base in order reach targets at longer distances. 

For the Navy, recovery tanking has the aerial refuelers flying closer to the carrier in case returning planes are running low on gas. Landing on the deck of an aircraft carrier, a moving target that can be changing position dramatically in rough seas, can be a difficult proposition in general, with pilots needing to make multiple passes in some instances. A recovery tanker protects against a pilot running out of fuel and having to bail out, risking injury or death and losing a multi-million dollar aircraft, before they can safely touch down on the ship.

In 2016, the Navy suggested that recovery tanking versus mission tanking would be the primary job of the MQ-25. In July 2017, the service revealed to new emphasis on providing fuel during actual missions, declaring it to be one of just two key requirements for the Stingray.

According to Shoemaker, this shift in focus is due in no small part to the Navy’s development of new technology to simplify carrier landings, aptly nicknamed Magic Carpet. The new software handles more of the work, making it easier for pilots in Super Hornets and other manned aircraft to safely and accurately plot their course.

Studies showed that Super Hornet pilots made an average of 200 to 300 course corrections in the final 18 seconds of their landing approach, U.S. Navy Captain David Kindley, the service’s F/A-18 and EA-18G Program Manager, told USNI News in 2016. With Magic Carpet, even new pilots with no experience with the system had cut that down to around 20 corrections. As a result, Navy expects the overall need for recovery tanking to drop.

Still, we don’t know if the fuel and range figure Shoemaker gave Proceedings were minimum thresholds a prototype aircraft would have to meet or a less firm goal the Navy wants competitors to do their best to meet. Regardless, it does raise additional questions about whether or not the four companies vying for the final contract – Boeing, General Atomics, Lockheed Martin, and Northrop Grumman – will be able to offer the desired capabilities with their present designs.

All four firms had initially developed concepts based on the idea of a strike and intelligence gathering platform that could break through enemy air defenses at long range. As such, they were generally low-observable aircraft with space for relatively modest payloads.

If Shoemaker’s parameters represent the baseline requirements, each design will have to find space for more than 2,200 gallons of additional fuel – approximately 15,000 pounds – while still being able to fly more than 1,000 miles per sortie. Pictures recently emerged of Northrop Grumman testing its X-47B demonstrator with a Cobham air refueling pod under one wing and what looked to be either a standard 330- or 480-gallon drop tank under the other.

Lockheed Martin

Lockheed Martin's MQ-25 "concept art," prominently showing the Cobham refueling pod.

The Cobham pod, which the Navy says the MQ-25 has to use, can hold 300 gallons of fuel itself, along with the probe-and-drogue system to connect to another aircraft. At most the two under wing stores would hold less than 800 gallons of fuel in total.

The aircraft would need to carry another 1,400 gallons, plus what it needs to fly the mission itself. However, the X-47B only has 4,500 pounds of internal payload capacity – equal to less than 700 gallons of fuel – and it’s not clear if all of those spaces can accommodate tanks full of gas.

It was likely this combination of emerging requirements and existing constraints that led Rob Weiss, head of Lockheed's Skunk Works advanced projects office, to suggest in March 2017 that all the companies working on the Stingray program would have to fundamentally rework their submissions. In August 2017, General Atomics rebuked this notion, saying it had great confidence in its Sea Avenger design, derived from the existing Avenger drone, no doubt owing to the drone’s existing internal payload bays and provision for six under wing pylons, each of which could carry a drop tank.

General Atomics

General Atomics Avenger.

There’s still no definitive word on whether or not the MQ-25 will still have a secondary reconnaissance and surveillance mission, as the Navy had originally outlined in 2016. In his interview, Shoemaker effectively confirmed that the plan was to start with a tanker first and then explore other options in the future.

“The MQ-25 will start primarily as a tanker, but we will keep our options open in terms of additional capacity or capabilities,” he explained. However, as we at The War Zone have noted in the past, by focusing on the one mission almost exclusively, it is very possible that the Stingrays will not be readily adaptable to other mission sets.

According to USNI News, the U.S. Navy top officer, Chief of Naval Operations Admiral John Richardson, is interested in having the unmanned aircraft flying from carriers as early as some time in 2019.  The laser-like focus on the tanking mission could definitely help competitors meet this relatively truncated timeline, but might limit the drone's flexibility in the future.

Contact the author: jtrevithickpr@gmail.com