China has invested heavily in undersea warfare over the last decade. It is well known, for example, that during this period Beijing has been building at least four classes of submarines while simultaneously importing advanced diesel submarines and lethal undersea weapons from Russia. Less well understood in the West is China's broad effort to develop sophisticated unmanned underwater vehicles (UUVs) to complement its submarine force.
Many aspects of Chinese UUV development remain cloaked in mystery, since these systems do not yield their secrets to watchful satellites, as warships and aircraft sometimes do. This article marks the first public attempt to gauge the scope, progress, and ultimate ambitions of Chinese UUV development.
Steady Improvement
Before turning to the details of Chinese UUV development, it is worth reviewing some trends evident in their submarine force development. Close encounters between U.S. warships and Chinese submarines in both 2006 and 2009 suggest wider patrolling patterns and increased confidence on the part of the People's Liberation Army (PLA) Navy leadership. The 2006 event in which a Song-class diesel submarine appears to have entered close proximity with the carrier USS Kitty Hawk (CV-63) was troubling in many respects. Analysts now believe that the most advanced Chinese diesel submarine, the Yuan-class, may be equipped with air-independent propulsion, allowing it to stay submerged for extended periods. Also, the dramatic appearance in 2007 of China's new nuclear-attack submarines, the new-generation (SSNs), and nuclear-powered ballistic-missile submarines (SSBNs), coupled with the extensive work on the new nuclear submarine base on Hainan Island, have caused further anxiety among the established sea powers of East Asia.
Seen in a larger context, however, Chinese submarine development appears to be more incremental than radical. In the diesel force, there was the loss in 2003 of an entire Ming-class crew due to asphyxiation. The Song-class required a major redesign after the initial prototype, and there seems to have been dissatisfaction with Song-class performance more generally. With respect to the smaller nuclear-powered fleet, the successful prosecution of a Han-class by Japanese antisubmarine warfare forces in 2004 was a powerful reminder that the potential such forces arrayed against China's navy are experienced and retain formidable capabilities.
What is especially interesting is that China has not moved aggressively to build much beyond the two initial platforms of either the Type-093 SSN or the new Type-094 SSBN. The obvious explanation is that these vessels' growing pains are significant. This speculation is corroborated to some extent by a publicly released U.S. Office of Naval Intelligence assessment dated August 2009. Whereas the latest Chinese diesel submarines rate as relatively quiet, the acoustic signatures of the new Chinese nuclear submarines were estimated to be well behind the most advanced American and Russian vessels and thus are quite vulnerable to detection. China's naval strategists are not na
ve and do not believe its submarine fleet will close the gap in the near- or even the mid-term. While Beijing invests heavily in the submarine force, it is also making a major effort on unmanned undersea systems, aware that certain breakthroughs could transform undersea warfare.The Key to China's Future Sea Power
The perception among Chinese strategists that there is a gap in undersea warfare capabilities seems to be motivating China's extensive array of UUV programs. One Chinese engineer from Harbin Engineering University of Science and Technology (HEU) in Heilongjiang Province observes,
At the moment, our undersea military strength is not yet formidable, and yet our neighbors increasingly wield mighty navies that encircle us, so it seems our deterrent force is not sufficient. Therefore, unmanned combat systems with their relatively high efficiency and low cost will become a crucial component of our country's sea power.1
According to a researcher from the Beijing Academy of Naval Armaments, Chinese naval strategists are emphasizing the development of unmanned systems because they place "the mission at the core, rather than the human element," they have relatively simple construction, are highly flexible, and "are impervious to the most arduous combat conditions." The issue of cost also figures prominently in this prioritization.2
UUVs are expected to play a role in executing many future Chinese naval missions, some of which are relatively conventional, but others that appear to be particular to China's distinct naval culture and interests. As in the West, the mine countermeasures mission has been a significant priority. Likewise, oceanographic research and especially intelligence, surveillance, and reconnaissance missions are expected to be a major function for Chinese UUVs. For example, they apparently were deployed for surveillance during the 2008 Olympic Games to ensure subsurface maritime domain awareness. But Chinese strategists also anticipate a major role for them, both in support of submarines and antisubmarine warfare3 Using UUVs to deploy sea mines and support amphibious assaults may also be part of China's naval strategy.4
an area of lingering weakness for China. They could fulfill special missions, such as destroying enemy undersea cables and related communications infrastructure.China's plans for the UUV have required it to develop an appropriate research infrastructure, apparent in the voluminous scientific literature emerging from such centers as Tianjin University, Beijing University of Aeronautics and Astronautics, the Xi'an Northwestern Polytechnical University, and HEU. According to a recent interview with a senior scientist affiliated with HEU, Professor Xu Yuru, the university has been designated by the central government as a UUV technology defense science key point laboratory, boasts the most advanced testing facilities, and is staffed with about 100 researchers, in addition to a large team of graduate students.5 Chinese strategists and engineers keep a close and systematic watch on world developments in UUV technology, with regular surveys of U.S. Navy achievements in the field and follow discussions of the latest developments from Japan to Western Europe. Indeed, China has purchased numerous European UUVs outright. In this case commercial variants are likely to yield insights for military development.
Known Chinese Prototypes
Chinese engineers have been conducting UUV research for almost three decades, so it should not surprise that this effort is both vigorous and reaching maturity. According to HEU senior scientist Professor Xu, the earliest indigenous prototypes were built in the mid-1980s, when the Shenyang Institute of Automation Robotics Laboratory, directed by Professor Jiang Xinsong, built the Hairen 1 remote-controlled undersea robot prototype. In 1993 Chinese researchers rolled out the Tansuozhe, China's next evolution of UUV prototypes. The 1990s also saw the co-development, along with Russian scientists, of the CR-01, a UUV whose design borrowed heavily from the Russian MT-88. The CR-01 has apparently successfully served as an exclusive economic zone observation platform. The Zhishui 3 is another Chinese UUV prototype and features dual tail propellers and at least two cross-tunnel thrusters. It may also have a unique detachable external battery system. Funded by the PLA Navy, this system has progressed through several iterations.
More recently, Chinese scientists and engineers have developed an indigenous, glider-type UUV. Glider UUVs are dedicated to increasing endurance and maximizing energy efficiency. They employ two primary propulsion techniques. The more developed technology involves changing the buoyancy of the vehicle to provide flow over the wings, thereby propelling it as it rises toward the surface and falls back toward the ocean floor. According to UUV experts, the technique Chinese scientists are pursuing is actually more advanced. A team of researchers at Tianjin University has designed a prototype that uses temperature-difference propulsion in a UUV glider.6 The Beijing SPC-3 displays yet another design and relies on bionic-robotic concepts such as tailfin propulsion. SPC-3 recently completed a 22.8 km test.7
Chinese scientists also are developing an advanced prototype for mine countermeasures, which appears to be undergoing trials with PLA Navy units. This model seems to be a tethered system, and pictures suggest it has a cutting device and a camera and can likely deploy explosive charges. The new system demonstrates an important qualitative leap for the Chinese Navy, out of the lab and into the fleet.
These seven prototypes represent a significant current research effort. However, it is essential to note that China's military-industrial complex is highly opaque, and therefore it is quite possible that this represents but a fraction of the UUV research actually being conducted in China.
Challenges Remain
Arguably the most daunting engineering task in designing a UUV is determining the energy source. The Chinese writings surveyed for this study emphasize this problem in particular. Thus, HEU Professor Xu points out the advantages and drawbacks of several types of batteries: "Lead acid batteries have relatively low power and quality. Silver zinc batteries have a high power level and quality, but the price is expensive. These two types of batteries are already being replaced by lithium ion batteries." In the end, he concludes, "New types of energy sources are being developed, including undersea stored heat type thermo-electric direct exchange batteries, undersea proton exchange membrane fuel cells, and aluminum oxide fuel cells."
Another challenge is underwater communication, which UUV designers consider essential. Their articles suggest a concept of operations that entails the use of multiple, cooperating UUVs working as a "swarm." Nearly every Chinese article the authors reviewed on this topic showed that they usually preferred underwater acoustic communication methods over other alternatives. Yet Chinese experts acknowledge that underwater acoustic communication methods are still constrained by range and fidelity issues. The Chinese are also considering fiber-optic and laser communication methods. Interestingly, their literature also mentions a novel application for UUVs: "Using them as nodes in a larger information network will certainly be the key to . . . underwater weapon systems."8
Engineers at HEU envision UUVs that operate "in the ocean for several months, traveling distances ranging to thousands of kilometers." Such operational concepts put an intense burden on navigation. The preferred method of self-navigation is to calculate location relative to starting point and destination using data from gyro-sensors. Many Chinese research articles discuss the use of GPS to correct for navigational drift in UUV operations. The UUV is required to surface when taking a GPS reading, however, putting it at greater risk of being discovered.
Chinese experts realize that conventional propellers are not the only means of propulsion. The Beijing SPC-3 prototype, for example, relies on an unconventional method
a tailfin. Another group of Chinese researchers explains the advantage of the bio-robotic concept: "Propeller propulsion is fraught with low efficiencies, positioning difficulties, inflexibility in turning, and other disadvantages, such as the inability to hover." They conclude,In the next generation of underwater warfare platforms, the bionic UUV model, with its high efficiency, high mobility, low noise, decent ability to hide in aquatic settings, and advantages over conventional naval arms in terms of penetration, concealment, and deception, make it particularly suitable for military applications.
The Chinese bio-robotic design research is the some of the most advanced in the world.9
While UUVs are a true dual-use technology, most of the available Chinese literature discusses them in a military context and focuses on using the vehicles for intelligence, surveillance, and reconnaissance missions, for deception operations, perhaps as acoustic decoys. There is no available evidence of a weaponized Chinese UUV; however, some writings from reputable sources do discuss this possibility. For example, Chinese researchers are investigating the engineering challenges related to launching torpedoes from UUVs. Others discuss not only mine-hunting but mine-laying UUVs. Offensive mission sets add new engineering challenges for UUV scientists, of course, but if mastered over the coming decades, they will dramatically compound the challenges for China's prospective naval opponents.
The Future of Undersea Warfare
UUV technology remains immature compared to that of unmanned aerial vehicles, which have received an enormous developmental boost from the conflicts in Iraq and Afghanistan, in which they have proven indispensable. Such a role is still waiting to be written for UUVs. Moreover, the physical limitations imposed by the UUV's operating environment are arguably much more strenuous.
Nevertheless, China's broad front effort in undersea warfare is already paying off. For one thing, its deployment of an operational UUV for the mine countermeasures mission cannot be far away. This, combined with the building of several new minesweepers in the past few years, suggests that the PLA Navy intends to focus more on the challenges of mine countermeasures. This makes sense, given China's current dependence on maritime trade routes. Also, it is feasible that in the next few years China will make major gains in intelligence, surveillance, and reconnaissance, at least within the so-called first-island chain, by stealthy deployment of UUVs. Moreover, hints that China may use UUVs to complicate adversary undersea targeting with acoustic decoys may suggest a new level of complexity for undersea warfare in the already challenging environment of the western Pacific. Perhaps the most threatening capability to U.S. forces in the near-term, seems already to be in the Chinese Navy's arsenal: submarine-launched mobile mines, which function autonomously to the extent that they may also be considered UUVs. Mobile mines allow China's current submarine force to strike port targets without penetrating inner antisubmarine warfare barriers.
China intends to develop much more extensive UUV combat capabilities. As one HEU engineer involved in UUV research explains:
The aircraft-carrier battle group has a mighty deterrence power, [but] its underwater defense capability represents an area of relative weakness. At this weakness, one can direct an undersea attack system. If a conventional submarine were able to deploy a batch of attack-type UUVs, to strike the weak points, this might achieve twice the results for half the effort.
Chinese strategists also contend that "today's underwater king'10 And Beijing is systematically laying the groundwork for China to be a formidable player in the next generation of undersea warfare technologies.
the submarine will also be confronted by the challenge of UUVs."Weak Tradition, Powerful Ambition
Though Chinese undersea warfare still has certain obvious limitations, there is little doubt of China's grand ambitions in this arena. Mao Zedong once famously vowed that China would build nuclear submarines, "even if it takes 10,000 years." Over the last two decades, China's submarine force has made respectable gains, despite building on a weak tradition. But the U.S. Navy and its allies would be foolish to discount China's capabilities and ambitions.
Examining Chinese research on UUV technology yields several conclusions. First, as the PLA transitions to a high-technology, capital-intensive force, UUVs are attractive both as a cost-saving measure and a new war-fighting frontier. Second, Chinese researchers are testing at least seven confirmed UUV prototypes and likely many more of which we are unaware. One of these appears to be in the initial testing phase with the PLA Navy. No one should be surprised to find Chinese UUVs prowling the contested waters of the East Asian littoral during the next decade. Third, there are strong commercial incentives to develop UUVs in China, but the Chinese military is also actively involved in promoting UUV technology development. Fourth, a vigorous research infrastructure has been established in China to support indigenous UUV development. Finally, while Chinese researchers do not claim to be world leaders in UUV technology, this cannot be ruled out in the future.
For the moment, the United States maintains a healthy advantage in the crucial domain of undersea warfare. A commitment to increase production to two new SSNs per year starting in fiscal year 2011 would symbolize Washington's determination both to exploit and nurture that advantage. Continued prioritization of advanced UUV technologies in particular and antisubmarine warfare technologies in general is critical to preparing for an uncertain future.
1. 李彭超 [Li Pengchao], "无人潜航器" ["Unmanned Underwater Vehicles"] 舰船知识 [Naval and Merchant Ships] (April 2009), p. 55.
2. 尚燕丽 [Shang Yanli] "海军发展无人作战平台的需求, 现状与展望" ["Navy Requirements for Unmanned Combat Vehicles: Current Situation and Future Prospects"] 国防技术基础 [Foundations of Defense Science Technology] (January 2009), pp. 40-41.
3. 郭风水, 袁思鸣, 刘强 [Guo Fengshui, Yuan Siming, Liu Qiang] "
" ["Development of Military Unmanned Underwater Vehicles Their Missions and Capabilities"][China Ship Research] (October 2007), p. 77.
4. 秦立新 [Qin Lixin] "潜艇如何对抗无人潜航器" ["How Can Submarines Counter UUVs
"] 当代海军 [Modern Navy] August 2008, p. 56.5. "水下机器人海洋中的智者: 访哈尔滨工程大学徐玉如院士" ["Undersea Robots
Wise Men of the Deep: An Interview with Harbin Engineering University Academic Xu Yuru"] 舰船知识 [Naval and Merchant Ships] April 2009, p. 18.6.
[Wang Yanhui, Zhang Hongwei, and Wu Jianguo] "新型温差能驱动水下滑翔系统设计" ["Design of a New Type Underwater Glider Propelled by Temperature Difference Energy"] [Ship Engineering], Vol. 31, No. 3, March 2009, pp. 51-54.7. 文力, 梁建宏, 王田苗, 宋永生 [Wen Li, Liang Jianhong, Wang Tianmiao, Song Yongsheng] "
" ["Design and Experiment of an Underwater Vehicle Based on Capacity of Voyage"] 北京航空航天大学学报 [Journal of Beijing University of Aeronautics and Astronautics] Vol. 34, No. 3, pp. 340-343.8. 王蓬 [Wang Peng] "
" ["Current Development Status and Future Application of Navy UUVs"] 鱼雷技术 [Torpedo Technology] Vol. 17, No. 1, February 2009, pp. 5-9.9. 任铮, 金通, 魏榛, 杨基明 [Ren Zheng, Jin Tong, Wei Zhen, Yang Jiming] "双尾鳍组合仿生UUV的研制及特性研究" ["Design and Study on the Multiple-Bionic UUV With Double Tail Fins"] 舰船科学技术 [Ship Science and Technology], Vol. 31, No. 1, (July 2009), pp. 37-42.
10. Qin Lixin, Ibid.
Dr. Lyle Goldstein is associate professor and director of the China Maritime Studies Institute at the U.S. Naval War College in Newport, Rhode Island. He is the author of numerous academic papers on Chinese undersea warfare.
Shannon Knight is a former policy analyst with the U.S.
China Economic and Security Review Commission and former intelligence analyst with the Marine Corps Reserve. He is a computer scientist at the Naval Undersea Warfare Center.