In mid-2021 the new U.S. Navy MQ-25A carrier-based UAV carried out its first aerial refueling mission, successfully transferring fuel to an F-18E carrier-based fighter. Development of the MQ-25A has been swift. In 2018 the U.S. Navy selected a conventional UAV design, similar to the Reaper or larger Global Hawk, proposed by Boeing to be the MQ-25A. The Boeing design is 16 meters (51 feet) long with a 23-meter (75 feet) wingspan. The wing can be folded to be only 9.5 meters wide, for more efficient storage on the carrier. Powerplant is one jet engine, and weight not disclosed but apparently similar to that the of the earlier 20-ton X-47B carrier UAV. Boeing received a contract to build the first four MQ-25As for about $201 million each. Prototypes are basically hand-built aircraft, and more expensive than mass-production aircraft. In 2020 Boeing received an order for three more, at a cost of about $29 million each. The navy claimed that development cost for the MQ-25A would be about $5 billion and no one believed that was going to be the final development cost.
In 2019 the Boeing MQ-25A flew for the first time. The first MQ-25A is expected to enter service by 2025. Since the Boeing design has only been flying for two years, it surprises many that it should be ready for service so quickly. The reason for that is that the navy had a lot of carrier UAV software already developed and tested using the X-47B carrier capable UAV that was able to operate from carriers like manned aircraft. In 2017 that UAV software was upgraded so that it could be communicated with using the same software used for manned carrier aircraft. Called UMCS (Unmanned Carrier Aviation Mission Control System) this uses existing software modified to communicate with UAVs on the carrier deck as well as the air. The navy has already tested the X-47Bs equipped with software for landing and taking off from a carrier as well as refueling other naval aircraft in flight. There is a growing library of combat tested UAV software for just about every aspect of aircraft operation. But operating from a carrier has always been the most difficult environment to work in.
In mid-2016 the navy came up with the official designation of its new carrier-based UAV; MQ-25A Stingray. This new UCAS (unmanned combat air system) comes after a decade of design, development and test flights. The navy expects to spend $15 billion on developing and building 72 MQ-25As. That comes out to $208 million per UCAS. That seems a bit high, nearly three times what a F-18F costs. Details of the cost escalation are murky, which is not unusual. The first armed UAV, the Predator, was initially described as an inexpensive attack and surveillance aircraft and the cost of the UAV alone was. But as upgrades and new equipment was added the Predator was soon costing ten times as much. At least it remained cheaper to operate than manned jets.
The UAV that made the MQ-25A possible rolled out as the X-47B in 2008. This was the first carrier-based combat UAV, with a wingspan of 20 meters (62 feet, and the outer 25 percent folds up to save space on the carrier) and could stay in the air for up to twelve hours. The 20-ton X-47B weighed significantly less than the 30-ton F-18E and has two internal bays holding two tons of smart bombs and missiles. It is a stealthy aircraft. As built the X-47B could be used for a lot of bombing missions, sort of a super-Reaper. The navy had been impressed with the U.S. Air Force success with the Predator and Reaper. But the propeller driven Reaper weighs only 4.7 tons. The much larger X-47B uses a F100-PW-220 engine, which is currently used in the F-16 and F-15 and is built to operate more like a manned jet warplane.
Development moved ahead pretty quickly with the X-47B, which made its first catapult launch from an aircraft carrier in May 2013, and landed at a shore-based facility. That was followed by several touch and go landings on a carrier. The first carrier landing, as expected, followed soon after. This was not a surprise because in 2011 the navy successfully tested its UCAV landing software using a manned F-18 that landed on a carrier completely under software control. This version of the software has been further expanded into a system that makes it a lot easier (and safer) for manned aircraft to land on carriers.
By the end of 2013 more flight tests further stressed the capabilities of the X-47B automatic landing system, especially in high speed and complex (different directions) winds. The autolanding software passed all these tests. The X-47B was also the first UAV to land and be off the carrier deck in less than 90 seconds, just like manned aircraft. There were a lot of other tests to see how effectively and reliably the X-47B could operate on the carrier and hanger deck and do it alongside manned aircraft. An X-47B carried out the first fully autonomous aerial refueling, with a manned with a KC-707 tanker, in April 2015. All this was part of a long-term navy plan to introduce an UCAS replacement for manned fighters by the 2030s.
While software-controlled landing systems have been around for decades, landing on a moving air field (an aircraft carrier) is considerably more complex than landing on a stationary airfield. Dealing with carrier landings required more powerful hardware and software aboard the aircraft. The navy expected some glitches and bugs but managed to rapidly match the reliability of commercial landing software within months rather than decades. The U.S. Army pioneered the use of automated landing (and take off) software for its larger UAVs and eventually the air force adopted that approach as well, which has been used very successfully on UAVs.
Rather than begin development on the slightly larger X-47C, which was originally supposed to be the first naval UCAV to enter service, the navy decided to conduct a competition to find the most effective design for the MQ-25A UCLASS (unmanned carrier-launched airborne surveillance and strike) aircraft. As expected, the X-47B was successful enough to be the one of the competing prototypes for the MQ-25A. It was always believed that the X-47C would be closer to 30 tons and have a payload of over four tons. The X-47B was never meant to be the definitive carrier UCAV, but the navy hoped it would be good enough to show that unmanned aircraft could do the job. Normally, "X" class aircraft are just used as technology demonstrators. As successful as it was, in February 2015 the navy stated that the X-47B was too costly and insufficiently stealthy to become its carrier UCAV, and the two X-47Bs were turned into museum exhibits upon completion of all flight testing in late 2015. Meanwhile three firms (Boeing, X-47B builder Northrop Grumman, and General Atomics) submitted MQ-25A design proposals and the Boeing design won.
The navy leadership is still divided on how fast to proceed with carrier UAVs, as can be seen as several changes already made to the MQ-25A design requirements. That could slow things down but the fear that China will get a carrier UAV into service first has proved to be a powerful motivator. Although the existing X-47B and Avenger designs could carry and launch smart bombs and missiles, the navy needed an efficient aerial refueling aircraft to extend the range and endurance of existing F-18F and F-35 carrier aircraft. Additional missions will be added to the MQ-25A once it demonstrates its ability to effectively perform the aerial refueling role. Currently the only carrier-based aerial refueling capability comes from using one F-18F to refuel another. The MQ-25A is much more efficient at aerial refueling, able to carry 6.8 tons for refueling and refuel several manned aircraft per mission and extend the effective range of the F-18E or F-35 by more than fifty percent.