Thursday, May 28, 2015

Why China's submarine force still lags behind

Franz-Stefan Gady/The Diplomat
28 May 2015
China is fielding an impressive fleet of conventional and nuclear submarines. According to the Pentagon’s Office of Naval Intellligence, the People’s Liberation Army Navy’s (PLAN) underwater force consists of five nuclear attack submarines (SSN), four nuclear ballistic missile submarines (SSBN), and 53 diesel attack submarines (SS/SSP).
The Pentagon in its annual reportto the U.S. Congress on Chinese military developments estimated that by 2020 this force will likely grow to between 69 and 78 submarines.
The bulk of China’s conventional sub armada consists of 13 Song-class (Type 039) diesel-attack subs and 13 Yuan-class (Type 039A) air independent-powered (AIP) attack submarines with an additional 20 Yuan-class vessels planned for production.
The submarine force’s main mission remains anti-surface warfare (ASUW) along major sea lines of communication (SLOC). Weaknesses in anti-submarine warfare and land-attack capabilities persist in the PLAN’s submarine fleet, according to a recently published report by the RAND Corporation.
One of the major structural weaknesses of the force is Chinese propulsion engineering, or the lack thereof, since the majority of engines used in Chinese subs are imported foreign technology, often license-built in the country.
A recent U.S. conference on the Chinese Navy’s capabilities at the U.S. Naval War College elaborated on this issue, as Defense News reported this week.
According to the conference host and Naval War College professor Andrew Erickson, propulsion engineering remains a work in progress in the PLAN’s underwater force:
 Here’s where things become more demanding for them (…) They’re going to want to be able to build a significant number of [attack submarines] whose reactors are efficient, long-lasting, reliable, and quiet enough. There’s no way to compensate for quietness if you don’t have it.
 Diesel-electric subs are usually significantly stealthier than their nuclear counterparts, mostly due to diesel engines that are specifically designed to minimize vibration and noise in order to evade sonar detection. For example, both the Song- and Yuan-class attack submarines are equipped with German-made state-of-the-art diesel engines — the 396 SE84 series — designed by MTU Friedrichshafen GmbH of Friedrichshafen, Germany.
“They are the world’s leading submarine diesel engines,” according to an experienced submarine engineer. Each Song- and Yuan-class vessel is equipped with three such engines, which have been built under license by Chinese defense contractors since 1986. The Yuan-class is also said to have incorporated quieting technology from Russian-designed subs and to be equipped with Stirling air-independent propulsion technology.
“They want the ability to be quiet and not to have to surface to charge the batteries. They have achieved that with a Stirling capability in the Yuan class. But technology is always moving ahead. And in AIP, even if you’ve mastered it, is a highly complex system,” Erickson explained.
China has also been experimenting with lithium-ion (Li-Ion) batteries, power sources that offer much higher energy density and longer dive times. “Chinese researchers clearly see Li-Ion batteries as the wave of the future for conventional submarine propulsion. They’re not there yet, but they are determined to get there,” Erickson noted. Erickson said China was discussing putting Li-Ion batteries “on a new generation of conventional subs sometime between now and 2020, but there is no indicator as yet of the type of submarine that might be.”
Chinese submarine technology is still generally considered to be a generation behind the West. For example, the much talked about new Type 095 nuclear-attack submarine SSN will, in all likelihood, be more on par with 1980s NATO nuclear-powered fast-attack submarines (i.e. roughly three decades behind current Western sub technology), rather than with the new U.S. Virginia-class vessels. Overall, Erickson emphasized that the PLAN’s modernization efforts will not immediately translate into increased capabilities:
 A lot of activity is occurring, there’s a lot of effort, they’re making achievements, but in this complex and difficult field it takes a lot of achievement to be accrued before that translates to a major increase in actual capability. They are far from hopeless, they are moving ahead, but it is a long and rocky road.

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