Speed in the air is of less importance than predictability on the ground on a carrier deck. This is why the first test of an autonomous taxi flight by the U.S. Navy of an operationally configured MQ-25A Stingray landing was a small milestone with a big footprint. With one command, the plane was set in motion, followed assigned lines of taxiway, performed controlled turns, and stop-and-hold maneuvers that resembled the way aircraft are lined up and ordered in launch and recovery operations. Contrary to the previous unmanned showcasing, the jet in question was designed to standard levels of operation, and it is clear that the Navy is experimenting with an element of the fleet in the future and not a technological one-time experiment.
The technical success concerns less the element of “self-driving” novelty than the realization of autonomy in the most restricted spaces of the naval aviation. The people, aircraft, support vehicles, jet blast and constant tempo are pressed together by carrier decks into an environment where deviations will not be tolerated. Boeing engineers described an autonomy stack which combined the input of the navigation, control logic with safety constraints in order to generate consistent behaviour in a dynamic environment. In the case of naval aviation, that uniformity is a condition of the larger sequencing problem: once a system has been made to be trusted to taxi and roll to a halt where it should, the service can start developing repeatable human-machine choreography processes throughout the deck.
MQ-25 program is there in response to the dilemma of range of carrier air wings that could not be addressed through just tactics. By mid 2010s, naval analysis determined that combat range of carrier-based fighters had worn out due to the increase in the range and complexity of threats. The service moved towards enabling solution of organic aerial refueling instead of waiting to have a new manned aircraft to close the gap. In 2018, Boeing won the contract in Engineering and Manufacturing Development and the core mission of the aircraft is to offload the burden of the strike fighter to “buddy tanking” in order to restore the strike fighters to its flight hours and life airframe to strike, escort, and air defense missions.
Operationally, the Navy has pegged the Stingray on a carrier-specific performance feature of 15,000 pounds of fuel offload at 500 nautical miles, which is also reflected in the public oversight documents that outline the objectives of the program. The delivery of fuel is accomplished using the same fundamental mid-air refueling method that carrier aviation is already familiar with and the aircraft itself is designed with an endurance in mind which revolves around the Rolls-Royce AE 3007N turbofan. The practicality of the operational payoff is that there will be fewer Super Hornets in the air to act as tankers, more fighters to be able to fly fighter missions and more distance persistence of aircrafts that will be able to protect the strike group.
The long game of the Stingray was also influenced by the program oversight. MQ-25 in the context of congressional testimony and budget reports is positioned as a BRLC-25 “pathfinder” of the “air wing of the future”, in which unmanned aircraft play an increasingly significant role as the procedures, training and command-and-control evolve. The design of that change is not only the airplane. Its first Unmanned Carrier Aviation Mission Control System (UMCS) has already been installed on a carrier by the Navy, which will provide a control base with the potential to grow to include multiple types of drones.
Risk does concentrate though in carrier integration. Reviews of oversight have raised issues of schedule and test sequencing such as the stress formed by the introduction of production decisions before test programs have reached maturity. The Navy has termed an evolutionary strategy, develop, fly, deploy, and evolve since the operational utility of a carrier-based tanker is instant, despite a lack of normalization in an unmanned ecosystem around it.
At the head of that normalization is the autonomous taxi test. It does not consider deck handling a peripheral characteristic, but rather the gatekeeper capability that distinguishes between unmanned aircraft being members of a carrier air wing or not. Should a Stingray be given the ability to move, hold, and stop precisely on command, the Navy can start to transform unmanned carrier aviation into being an exception, and daily routine.
