What technology might Singapore's 218SGs incorporate: fuel cell or Stirling AIP, Vertical Multi-Purpose Lock (VMPL) or Lithium-ion batteries? (Diagram courtesy of Globalsecurity)

The following is another excellent article* by Michael Raska, Research Fellow, Institute of Defence and Strategic Studies, S. Rajaratnam School of International Studies (RSIS), Nanyang Technological University, Singapore. The article details competition involving ever larger, more numerous and more capable submarines in Northeast and Southeast Asia. 

I maintain that Australia will need to respond to this strategic submarine competition be acquiring a new class of larger SSKs or more prudently SSNs. This is in recognition that only SSNs can perform all the roles required of a modern submarine force. 

Michael Raska's article was published by RSIS on July 7, 2014 in html at http://www.rsis.edu.sg/rsis-publication/idss/toward-stealth-and-sea-denial-submarine-modernization-in-east-asia/#.U-gpBPmSySo and also in pdf at

http://www.rsis.edu.sg/wp-content/uploads/2014/07/RSIS1302014.pdf :

Toward Stealth and Sea Denial: Submarine Modernization in East Asia

 Michael Raska

IDSS / RSIS / Commentaries / East Asia and Asia Pacific / International Politics and Security / Maritime Security

07 JULY, 2014

DOWNLOAD

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RSIS Commentary No. 130/2014

"Synopsis

An important aspect of the regional “arms competition” in East Asia is the gradual introduction of new classes of conventionally-powered diesel-electric submarines (SSKs), which are increasingly becoming “platforms of choice” – as force-multipliers in diverse missions as well as against superior forces.

Commentary

Notwithstanding East Asia’s economic growth rates and deepening integration into the global economy, the region’s strategic realities reflect contending trajectories. As China expands its national interests in the broader context of “new historic missions”, it seeks to regain a great power status and reassert its geopolitical role in the region. As a result of China’s accelerating military modernization, regional powers are responding by revamping their force modernization priorities, alliances, and overall strategic choices.

The economic, political, and military rise of China, embedded in three decades of relentless Chinese economic growth, has propelled progressive modernization of the Chinese military with major improvements in virtually every capability domain.

China’s Naval Modernization and Submarine Expansion

Notwithstanding weaknesses and limitations in capabilities integration, China’s PLA Navy (PLAN) is gradually transforming toward a regional [blue water] defensive and offensive type navy with extended so-called anti-access/area-denial (A2/AD) capabilities, limited expeditionary capabilities, and corresponding defensive and offensive air power. China calls its comprehensive A2/AD strategy a “counter-intervention”, which is interpreted as denying the U.S. and its allies the freedom of action in China’s ‘near seas’ by restricting their deployments into theatre (anti access) and denying them freedom of movement there (area denial).

An important aspect of China’s multilayered strategy is the gradual introduction of new classes of submarines – both nuclear and conventional. China is currently operating as many as 45 submarines structured in six different classes: two classes of indigenously designed diesel submarines, including the Song class (Type 039) and the Yuan-class (Type 041), and four nuclear classes that include the Shang-class (Type 093), Jin-class (Type 094) nuclear powered ballistic missile submarines (SSBN) and the follow-on Type 095 nuclear-powered attack submarine (SSN) and Tang-class (Type 096) SSBN.

Since 2004, China is believed to have launched 12 Type 041 Yuan-class conventional submarines, which have been progressively modified to carry more advanced high-frequency sonar, upgraded weapons systems, noise reduction and air independent propulsion (AIP) technologies. The PLA Navy may procure up to 20 additional Yuan-class submarines based on technologies imported from Russian boats. Since the mid-1990s, China has procured as many as 12 Kilo-class submarines from Russia, and is reportedly negotiating the purchase of at least four fourth-generation Amur (Lada)-class or possibly a fifth-generation Kalina-class, both featuring advanced AIP systems.

Regional Responses

In Northeast Asia, Japan and South Korea are prioritizing the procurement of new types of submarines. In September 2013, South Korea launched a fourth 1,800 ton Son Won-ill class (German Type 214) submarine, featuring AIP and combat management systems. South Korea now operates 13 submarines: nine Type 209 Chang Bogo and four Son Won-ill class submarines. Meanwhile, in October 2013, the Japan Marine Self Defense Force (MSDF) launched its newest submarine the Kokuryu – the sixth of planned ten Soryu class boats first commissioned in 2009. With its range, endurance, sensors, weapons load and other systems, including the Stirling AIP propulsion system and Harpoon anti-ship missiles, the Soryu class is regarded as the most advanced in Japan’s conventional submarine fleet of 16 submarines.

In Southeast Asia, the relatively high acquisition costs and maintenance requirements have traditionally precluded a quantitative diffusion of submarines. However, the recent introduction of more capable coastal diesel-powered submarines provides unprecedented capabilities. Most recently, Vietnam received two of six Kilo-class (Project 636) diesel-electric submarines from Russia in 2013- 2014, designed for diverse reconnaissance and patrol, anti-submarine and anti-ship missions.

Indonesia, Malaysia, and Singapore are also planning to expand or upgrade their submarine fleets. From 2007-09, Malaysia took formal delivery of two French-built Scorpene-class submarines, equipped with underwater-launched Exocet anti-ship missiles. Both submarines are based at the Kota Kinabalu Naval Base in Sabah, East Malaysia, indicating their primary mission to protect Malaysia’s sovereignty in part of South China Sea. Meanwhile, Indonesia has ambitious plans to expand its submarine fleet to at least six, and ideally to 12 by 2024, a key element in the “Minimum Essential Force” (MEF) and declared goal of developing a ‘green-water’ navy. In 2012, the Indonesian Navy (TNI-AL) announced a US$1.1 billion contract for three Type-209/1400 diesel-electric submarines, constructed by South Korea’s Daewoo Shipbuilding and Marine Engineering.

In November 2013, Singapore announced a contract with German shipbuilder ThyssenKrupp to acquire two advanced Type-218SG submarines that will augment existing Archer-class boats and replace ageing ex-Swedish Challenger-class by 2020. Type-218SG, designed for littoral, shallow sea operations, is a customized design that will integrate features from Type 214 and possibly Type-216 ‘concept submarine’ fitted with fuel-cell AIP system. [Pete's Comment - the atypical 218 designation might also suggest that the 218s might be fitted with Stirling engine AIP in line with the Stirlings already incorporated into Singapore's two Archer class subs.]

Strategic Ramifications

Over the past decade, the operational utility of submarines in East Asia has widened: from anti-submarine warfare to force protection such as close submarine escort missions, intelligence surveillance, and reconnaissance (ISR), support of Special Forces, and other complementary deterrence and defensive tasks supporting territorial defense. At the same time, the introduction of submarine-launched anti-ship and land-attack cruise missiles, anti-submarine sensors and weapons, as well as air independent propulsion systems have increased their stealth capacity to remain undetected shortened their target-identification-and-attack cycle, and ultimately, improved their flexibility, mobility, endurance, reach, and lethality.

For smaller, defensively-oriented navies in East and Southeast Asia, these attributes enable “sea-denial” capabilities aimed at preventing an opponent from using the sea, rather than providing a degree of sea control to use the sea for own power projection. Submarines will therefore become an increasingly valuable strategic asset in the region, particularly with installed AIP systems. The key difference, however, will be in the experience, training, and skill set of its operators."

* Michael Raska's earlier submarine article appeared on this blog on July 31, 2014 as Air Independent Propulsion - A Game Changer .

Air Independent Propulsion - A Game Changer?

Hydrogen-oxygen fuel cell system. (Diagram courtesy of  http://webberswarships.ca/styled-9/index.html )

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MESMA closed-cycle steam turbine

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Stirling-cycle heat engine with external combustion

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Closed-cycle diesel engine? (Diagram courtesy of http://webberswarships.ca/styled-9/index.html )

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Diesel-electric engine for submarine, which can use any of the AIP technologies above.

Descriptions of the strengths and weaknesses of each AIP technology is on this website at Air independent propulsion (AIP) Technologies and Selection

August 5, 2014 http://gentleseas.blogspot.com.au/2014/08/air-independent-propulsion-aip.html

If-when Australia chooses an air independent propulsion (AIP) system for the long awaited Future Submarine Australia will have several technologies (above) to decide on. Perhaps Australia might choose no AIP if Lithium-ion battery technology is considered adequate.

The following is an excellent article, dated January 29, 2013, by Michael Raska, a Research Fellow at the Institute of Defence and Strategic Studies, S. Rajaratnam School of International Studies (RSIS), Nanyang Technological University in Singapore. It has been republished by Eurasia Review, http://www.eurasiareview.com/29012013-submarine-trends-in-asia-pacific-air-independent-propulsion-a-game-changer-analysis/ :

SUBMARINE TRENDS IN ASIA PACIFIC: AIR-INDEPENDENT PROPULSION A GAME CHANGER? – ANALYSIS

JANUARY 29, 2013

By RSIS

The contending strategic realities of the Asia-Pacific region compel states to adopt innovations of their rivals. This is the case for new classes of conventional submarine designs, which incorporate an array of innovative technologies in order to maximise their survivability and lethality in diverse maritime operations.

By Michael Raska

WHILE EUROPE and North America remain key submarine markets, China’s ongoing military modernisation coupled with contending international relations in the Asia-Pacific will increasingly drive submarine procurement in the region over the next decade. In 2011, the total submarine market in Asia-Pacific is estimated at US$4.4 billion, and for the next decade, submarine expenditures are projected to US$46 billion. 

With changing strategic realities, Asian navies aim to become increasingly flexible, and capable of varying mission profiles: from countering traditional coastal defence missions to protecting sea lanes and communication lines. Simultaneously, submarines are increasingly valuable strategic resource for both electronic and signal intelligence. To enhance the varying operational capabilities, increase submerged endurance and stealth, installing viable Air-independent propulsion systems is thus becoming a strategic necessity.

Advantages of AIP systems

Designed to enhance the performance of modern conventional (diesel-electric) submarines AIP is a key emerging technology that essentially provides a “closed cycle” operation through a low-power electrical source supplementing the battery, which may extend the submarine’s underwater endurance up to two weeks or more.

AIP systems close the endurance gap between nuclear and conventional submarines, and mitigate increasing risks of detection caused by advanced anti-submarine warfare technologies – from modern electro-optical systems and surface radars to magnetic sensors, active and passive sonars, and airborne surveillance radars. Advanced AIP technologies thus promise significant operational advantages and tactical flexibility.

In theory, there are four primary AIP designs currently available: (1) closed-cycle diesel engines; (2) closed-cycle steam turbines; (3) Stirling-cycle heat engines with external combustion, and (4) hydrogen-oxygen fuel cells. Each provides a different solution with particular advantages as well as limitations in relation to performance, safety, and cost factors.

Since the early years of the Cold War, while major naval powers shifted to nuclear propulsion, smaller navies – particularly in Europe (Germany, Sweden, Spain, Italy and France) continued to develop and rely on conventional diesel-electric submarine fleets, given their lower cost and operational relevance for coastal defence. Traditionally, however, these submarines were highly vulnerable to various types of sensors – acoustic, visual, thermal and air – particularly when running on engines.

AIP systems in Asian navies

On the other hand, when running on batteries, these submarines became very quiet and difficult to detect, yet their battery capacity, discharge rate, and indiscretion rate (the ratio of diesel running time to total running time) substantially limited their underwater endurance. To overcome these baseline limitations, naval innovation in propulsion technologies over the past two decades has shifted toward AIP systems.

There is a variance, however, in the procurement of AIP systems in select Asian navies. For example, the only AIP steam-turbine system currently available is the French “MESMA” (Module d’Energie Sous-Marine Autonome) module, operational on Pakistan Navy’s two Agosta 90-B class submarines.

Swedish-Kockum designed Stirling AIP technology is installed on Singapore Navy’s two Archer–class submarines, and Japan’s new Soryu-class submarines. The Chinese PLA Navy’s Type 041 Yuan and Type 043 Qing class submarines are also reportedly using Stirling technology. Meanwhile, the Republic of Korea Navy has ordered nine Type 214 submarines with German HDW AIP fuel cell technologies. Three first batch models of the new Son Won-Il class had entered service since 2007, and six second batch models will enter service from 2012.

Limitations and constraints

Notwithstanding the diverse AIP technologies, the overall effectiveness of each system will depend on how well it is integrated with other critical systems that ensure optimal submarine functions: power systems, sensors systems, safety systems, navigation systems, command, control, and communication systems, weapons systems, and climate control systems. In this context, any critical failure of an AIP during a combat mission or contested areas will mitigate survivability factors as well as tactical options.

Indeed, each AIP system design comes with an array of technological limitations, vulnerabilities, and risks, particularly in submerged operations – from the specific acoustic signatures produced by select AIP systems in specific operating regimes, to technical vulnerabilities in storing oxidizer/fuel, as well as their maintenance regime. At the same time, new anti-submarine warfare sensor technologies may provide viable AIP countermeasures.

Ultimately, AIP-related technological innovation and breakthroughs may not guarantee operational success – strategy, operational concepts, tactical development, leadership, training, and morale will continue to play as important role as emerging technologies and their operational capabilities.

Michael Raska is a Research Fellow at the Institute of Defence and Strategic Studies, a constituent unit of the S. Rajaratnam School of International Studies (RSIS), Nanyang Technological University in Singapore.