Top Gun without Ray-Bans – the X-47B
The X-47B on the test runway at NAS Patuxent River
Aircraft carriers are a key element in force projection. If you want to carry out military operations a long way from your own bases there are only two ways to provide air cover for your forces. One is to find bases in a nearby friendly country. The other is to have a powerful carrier air wing offshore that can do the job for you. Since the Second World War carriers have been the centrepiece of large navies and over time they have carried some of the most sophisticated aircraft available.
The newest carrier aircraft in development is the controversial F-35, which has two naval versions; the F-35B is a short takeoff and vertical landing (STOVL) close support aircraft for the US Marine Corps and Royal Navy, while the F-35C is a conventional carrier aircraft for the US Navy and USMC. Advanced as it is, though, the F-35 is a manned aircraft and militaries are increasingly looking to unmanned systems to carry out many missions.
Unmanned Air Vehicles or UAVs, often called drones, have several advantages. Because they don’t have a pilot and all his life support systems they can be smaller and lighter without losing fuel and payload capacity. Future Unmanned Combat Air Vehicles (UCAVs) will be able to carry out extremely violent manoeuvres that would leave a pilot unconscious or injured. Some UAVs can fly extremely long missions, sometimes spending several days in the air. In the worst case, if a UAV is destroyed there is no risk of a pilot being killed or captured. These are all attractive features and naval aviators want access to the technology. However landing on a carrier deck is one of the hardest tricks a flyer can do, and a key milestone for UAVs is to demonstrate that they can do it without a human on board. That has now been achieved.
The Northrop Grumman X-47B is a prototype UCAV developed for the US Navy. It’s part of the Unmanned Carrier Launched Airborne Surveillance and Strike System, which is hoped to enter service in 2019, and the plan is for the X-47B to be developed into a naval strike aircraft capable of operating semi-autonomously, with human control only required for key parts of the mission.
The X-47B is a “flying wing” design with some resemblance to Northrop Grumman’s B-2 Spirit stealth bomber, but it has folding outer wing sections to save space on a carrier’s deck. At 11.63 metres long and with an 18.92 metre wingspan (9.41m with wings folded) it’s a full sized aircraft, capable of flying just below the speed of sound and with a range of 2,100 nautical miles on internal fuel. It has also now been fitted with a refuelling probe, so in practice the only limit to its endurance is reliability; it can fly until something breaks and forces it to return to the ship. The single Pratt & Whitney F100-220U turbofan is buried deep inside the fuselage to hide it from radar and infra-red scanners, and the airframe’s shape should make for a highly stealthy machine. It also has two internal bays for up to 2,000kg of weaponry.
Flight testing began in February 2011 and on 26 November 2012 one of the two prototypes was taken on board the carrier USS Harry S. Truman. No flights were attempted, but the X-47B was tested for compatibility with the ship’s elevators, hangar space and communications systems.
An aircraft carrier is too expensive to risk landing an untried system on it, but Naval Air Station Patuxent River has a simulated carrier deck for pilot training. On 4 May 2013 an X-47B took off from a nearby runway, circled and came in for a landing on the simulated deck. Actually hitting the deck was no problem; the key test was picking up one of the arrestor wires that bring carrier aircraft safely to a stop before they run off the edge of the deck and get run down by the 100,000 ton ship. The F-35C is still having problems with that after dozens of tests. The X-47B managed it first time.
It will probably be a long time before fully autonomous UCAVs are capable of fighting enemy aircraft, and until then there will be a role for naval pilots. UAVs are perfect for long-term tasks like airborne early warning, though, and there is potential for developing a UAV tanker that can support both manned and unmanned systems. The UCLASS project aims to deliver reconnaissance and strike capabilities, and a stealthy UCAV that can sneak into the heaviest defences and launch pinpoint attacks, all without risking a single pilot, will be a useful addition to the USN’s carrier air wings. It’s almost inevitable that the programme will hit delays at some point, but with the PatuxentRiver test a success and at-sea trials planned in the next year the basic concept seems to be sound.