The U.S. Navy has not yet selected the design of its new carrier based UAV (the MQ-25A) but it is already testing new software developed so carrier capable UAVs can 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 UAVs 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.
While the navy has not selected the design of the new carrier UAV it did decide, in July 2016 that its first carrier-based unmanned combat aircraft would be called the MQ-25A Stingray and it would enter service in the early 2020s. This UCAS (unmanned combat air system) decision comes after a decade of design, development and test flights.
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 weighs a little less than the 24 ton F-18A 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 has 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 on May 14th 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.
Meanwhile 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 the F-35 (which is now replacing F-18s) in the 2030s. But if the UCAS progress continues to be swift and the costs low (compared to manned aircraft), the F-35 could find its production run reduced to make room for a cheaper and more capable UCAS.
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 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 mean 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 will be turned into museum exhibits upon completion of all flight testing in late 2015. Meanwhile at least four firms (Boeing, X-47B builder Northrop Grumman, Lockheed Martin and General Atomics) are expected to submit MQ-25A design proposals by the end of 2016 and there will be competitive flight testing for two or more proposals and a decision of a winner by the end of the decade.
The U.S. Navy has done the math and realized that they need UCASs on their carriers as soon as possible. The current plan is to get these aircraft into service by the 2020s. What drives this urgency is the realization that American carriers had to get within 800 kilometers of their target before launching bomber aircraft. Potential enemies increasingly have aircraft and missiles with a range greater than 800 kilometers. The MQ-25A UCAS has a range of at least 2,500 kilometers and is seen as the solution. But the MQ-25A can also refuel manned aircraft in the air and many carrier admirals see that as the solution to the range problem with manned warplanes.
There is one serious competitor to an X-47B design and that is the jet powered Avenger UAV. This aircraft was developed by the same firm that created the Predator and Reaper. In 2012 the second prototype Sea Avenger made its first flight. This UAV is 14.2 meters (44 feet) long with a payload of 1.6 tons and 16 hours endurance. The U.S. Air Force is still planning to use Avenger for reconnaissance and strike missions. The navy was impressed and particularly interested in using Avenger to replace the soon-to-be-retired EA-6Bs in their most dangerous attack missions. The air force likes the ability to arm Avenger with a smart bomb, including the 900 kg (2,000 pound) GBU-34 penetrator version. Avenger also has two hard points on each wing, each one able to carry up over 200 kg (440 pounds). The U.S. Navy has been interested in Avenger since the beginning of development. Thus the Avenger wings were originally designed so they can be built to fold for use on carriers and have a tail hook needed for carrier landings. The Avenger, unlike the larger Global Hawk, can operate from carriers. The Avenger uses landing gear from the F-5, an aircraft of the same weight class. The naval version is now called the Sea Avenger. The navy, and several air forces, are also looking at the Avenger as an ELINT (electronic intelligence) aircraft. The ability to carry a ton of sensors and stay in the air for twenty hours per sortie has a lot of appeal for an aircraft that is already stealthy and doesn't carry a pilot. Moreover, the Avenger can perform ELINT missions entirely autonomously, making it more difficult to detect.
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 will slow things down but the fear that China will get a carrier UAV into service first has proved to be a powerful motivator.