X-47B Completes First-Ever Carrier-Based Arrested Landing USS George H.W. Bush (CVN 77)– photo US Navy
Sept. 5, 2013 defense-aerospace.com
(Source: People's Daily Online; published Sept. 5, 2013)
What R&D Breakthroughs Are Required to Give China A Carrier-Borne UCAV?
Military experts are currently speculating on whether China's aircraft carrier may be equipped with unmanned combat air vehicles (UCAV). This has not only increased public interest in these new "robot fighters", but also led China's military devotees to wonder whether China's forthcoming self-developed aircraft carrier will similarly be equipped with shipborne UCAVs.
The technical threshold of the unmanned air vehicle is relatively low. A company that can manufacture sophisticated model aircraft has the technology to develop a UAV. However, the threshold of a UCAV is more than 10 times higher than that of a UAV. The combat capability of UCAV requires particular abilities in target identification and autonomous attack. Thus the requirements of the observing and targeting system (eyes), the control system (brain), and the communication system (mouth and ears) of a UCAV are very high. On the one hand, the UCAV should be able to detect the target that is to be attacked, while transmitting images to remote controllers; on the other hand, the UCAV should be able to receive remote directions based on human judgment, and then launch attacks or engage in combat under remote control.
Shipborne UAVs were not manufactured specifically for aircraft carriers. It is already the case that some advanced modern destroyers and surface vessels have been equipped with shipborne UAVs.
But the greater platform size of an aircraft carrier creates the opportunity for large-scale UAVs with combat and attack capabilities. However, this presents a technical difficulty - carrier-borne UCAVs need all the functions of ordinary UCAVs, but also require an independent capacity to take off from and land on aircraft carriers. The requirements of carrier-borne UCAVs include not only attack and combat capability, but also the delicate maneuvers of 'intelligent' aircraft.
Therefore the development of a carrier-borne UCAV involves extremely high research costs and a complex development process. If China intends to commission UCAVs similar to the US carrier-borne X-47B, five technical breakthroughs must be made.
The first is advanced aerodynamic design. It can be seen from the shape of the X-47B that these designs improve stealth, increase flight range, and respond to the demands of air attack and combat. The X-47B, the UK "Taranis", and France's "Neuron" all feature a recessed rear inlet and flying-V wings.
The second step is advanced flight control technology. This is the real technical challenge for the UCAV. The carrier-borne UCAV requires a full range of capabilities covering takeoff, cruise, combat, withdrawal, and landing. The demands on the electronic take-off and landing systems for the moving deck of an aircraft carrier are significantly higher than the requirements for a land-based airport.
A UCAV's flight control equipment adjusts the craft in flight. This requires the flight control computer to implement planning and design according to a series of algorithms as quickly as possible after feedback, and update in response to environment changes detected by sensors.
Combat imposes high demands on the UCAV's flight control system. Whether in aerial combat or an attack on an enemy target, both the UCAV itself and the target can be moving at high speeds. The flight control system must be able to control the aerial maneuvers of the UCAV in response to a dynamic battlefield environment.
Returning to and landing on the aircraft carrier are the steps with the highest accident rate for both manned and unmanned combat aircraft. Therefore, China’s shipborne UCAV will require not only advanced satellite navigation, but also a higher specification of flight control system to achieve a safe landing.
The third element is intelligent attack-defense integrated firing control. The U.S. military classifies UAVs in levels ranging from ACL-1 to ACL-10 (totally autonomous). A relatively complete firing control system begins at level ACL-4. The more advanced generation of shipborne UCAVs such as the X-47B are classified at level ACL-6, that is a UAV with the capacity to deal with sudden threats and targets in the form of multiple drones. At this level, the shipborne UCAV is required to have an autonomous attack-defense integrated firing control system with a significant degree of “intelligence”.
The fourth feature is a high thrust-weight ratio turbofan, achieved at low cost. The turbojet/turbofan engines used on American UCAVs are always derived from civil engines or manned military planes. For example, the X-47B uses the F100-220U turbofan engine derived from the F-100, originally developed for the F-16. The characteristics and combat environment for a UCAV require that its engine should have a low fuel consumption rate, a high thrust-weight ratio, low R&D and purchase costs, convenience for maintenance, and fitness for long-term storage.
The fifth element is information security. Communications between the UCAV and the remote controller are very likely to be targeted for disruption by the adversary. Thus the UCAV must use the most sophisticated network security technology, and error-free self-destruct programs.
Although the UCAV is an excellent weapon, the technical difficulties cannot be ignored. UCAV development experts throughout the world have racked their brains in search of solutions to the problems posed by intelligent flight and firing control systems, and the need to guarantee information transmission security.
In the development of a carrier-borne UCAV, we need to exercise patience. If China intends to research and develop such an aircraft, then high-tech combat attributes should perhaps be considered as a second phase. Functions such as early warning, investigation, and relay-guidance of UAV can be executed as a first priority.