In the submarine world, it’s all about being quiet. In fact, the quieter the better.
The sound my laptop makes as I type this sentence can even be heard beneath the waves, if not for anechoic rubberized tiles that render enemy sonar ineffective.
Though China has launched newer nuclear-powered subs, the workhorse of their fleet is not outmoded — and experts say it may be as stealthy as Los Angeles class US submarines, according to a report by Caleb Larson at The National Interest.
The Type 093 or Shang-class ballistic missile submarine has a standard six-tube torpedo armament, though sources differ on the size (either 533 or 650 millimeter tubes). Thanks to an on-board nuclear reactor, the Shang-class has unlimited range and endurance, allowing them to make a respectable 30 knots submerged, the report said.
In addition to torpedoes, the Shang-class is able to launch both YJ-82 anti-ship and land-attack missiles. In contrast to the preceding Type 091 class, the Shang can fire missiles from vertical launch tubes behind the submarine’s sail.
Armaments aside, what is more impressive about the Shang-class is its “stealthy” design.
China’s first nuclear-powered submarine, the Type 091, or Han-class was an ambitious project that gave China cred in the nuclear submarine game.
Though the Han-class is nuclear powered, it suffered from an apparently high noise level. The Type 093 was built to address this very issue, the report said.
Submarines are only a good as their noise level — the quieter a submarine, the stealthier it is. One of the main factors that contribute to noise levels are propeller blades, which can cause an underwater phenomenon called “cavitation,” where bubbles form along the blade edges and cause noise, the report said.
The job of submarine engineers is to modify the shape of the propeller to reduce turbulence and reduce the overall noise of the blades as they slice through the water.
Another noisy factor is the submarine’s propulsion system. For diesel-electric submarines, diesel generator machinery can cause a great deal of noise. Nuclear-powered submarines also generate some noise, chiefly the coolant pumps that service the reactor core.
The Shang-class is much quieter — sources say it may have gotten some Russian design help.
The US Office of Naval Intelligence estimates the Shang is noisier than the Russian Victor III class submarines, 25 of which were produced between 1977 and 1991. Only four remain in service today, replaced by quieter, more modern designs.
Russia’s seven-bladed Akula (Shark) class submarines, which were first designed and built in the mid 1980s, are now reputed to be quieter than the majority of their American counterparts, thanks to intelligence from US spies John Walker and Jerry Whitworth.
According to the naval expert H. I. Sutton, Chinese submarine designs and manufacturing were initially far behind that of the US, the report said.
In an article for Forbes Magazine, he explained that, “the aim is to make the submarine as quiet as the ambient sea noise around it, typically around 90 decibels. Western submarines got close around 20-30 years ago. China has been seen as lagging.”
Sutton described how the Shang-class may be getting as quiet as some of the US Navy’s quieter subs, “according to unclassified US Navy estimates, the early Type-093 attack submarines are about 110 decibels. That is about the same as the US Navy’s improved Los Angeles Class boats,” which were built in 1982, the report said.
Improvements in reactor coolant pump design and improved anechoic tiles — rubberized tiles glued to the outside of the hull that absorb enemy sonar — may also have helped the Shang-class to pipe down.
According to Forbes, China is reputed to be working on a new generation of submarines.
Very few details are available about the Type-095 “Tang” Class, which is expected to be rolled out soon.
As a completely new design, it will be twenty years newer than the US Navy’s latest Virginia Class. That doesn’t automatically make it better, the Virginias are still being developed, but it has a newer foundation.