PLAN’S Undersea Heft

China to procure new subs for constant patrolling of its coastal waters

Prasun K. Sengupta

As part of the celebrations marking the 73rd anniversary of the founding of the China’s People’s Liberation Army’s Navy (PLAN) on April 23 this year, several major revelations about future submarines have emerged from China’s major shipbuilders that are subsidiaries of the state-owned China Shipbuilding Industry Corp (CSIC).

The PLAN aims to procure eight double-hulled ballistic missile-carrying nuclear-powered submarines (SSBN) comprising six Type 09-IV-class second-generation SSBNs and two Type 09-VI-class third generation SSBN — all of which will be built by the Bohai Shipbuilding Heavy Industry Co Ltd (BSHIC) in Huludao, Liaoning Province. Beijing wants to maintain five SSBNs on patrol constantly in China’s coast, especially in the East China Sea and South China Sea where the waters are not deep enough (about 100 metres deep on an average). The construction of the first Type 09-VI SSBN began in early 2020. It will carry 12 JL-3 SSBNs that have a 9,000km range. The JL-3 was first test-fired in December 2018.

Such SSBNs usually cruise at very low speeds of around eight knots in their patrol areas to avoid cavitation, a form of noise generation involving the collapse of air bubbles created by a propeller. But even in patrol areas, such SSBNs, if required, can operate at speeds of around 16 knots, much higher than the cavitation threshold speed. The PLAN’s Rear Admiral Ma Weiming, an academic at the Chinese Academy of Engineering and Director of the Power Electronics Research Institute at the PLA Naval Engineering University, has claimed that China’s shaftless, rim-driven, pump-jet technology meant for the Type 09-VI SSBNs is more than 10 years ahead of that of the US.

The PLAN has called for procuring 15 BSHIC-built nuclear-powered attack submarines (SSN) and 20 double-hulled diesel-electric submarines (SSK) built by the Wuhan-based Wuchang Shipbuilding Industry Group Co Ltd subsidiary of the CSIC, with the latter being fitted with low-power/low-pressure auxiliary nuclear powerplants for electricity generation. Beijing wants to maintain 10 SSNs on patrol constantly in China’s waters, especially in the East China Sea and South China Sea. The construction of the double-hulled Type 09-III family of second-generation SSNs began in the late 1990s and the first-of-its-class, Boat 407, was launched in 2002. After sea-trials that lasted for four years, the SSN was finally commissioned by the PLAN in December 2006.

The second, Boat 408, was launched in late 2003 and commissioned around 2007. Production then stopped and the boat was replaced by follow-up variants. The Type 09-IIIA that was launched in 2012 and commissioned in 2015 is an improved variant with a redesigned sail with a tapered front and all windows removed. There is a hump located immediately behind the sail, which accommodates a winchable VLF communications buoy.

The basic variant, Type 09-III, features a water-drop shape hull with a pair of fin-mounted hydroplanes and four diving planes. Six (three on each side) flank-mounted sonar arrays are clearly visible on the hull. There are six 533mm bow torpedo tubes (four above, two below), capable of carrying various anti-submarine/surface torpedoes of wire, acoustic and wake-homing types, as well as the YJ-18 supersonic anti-ship cruise missile.

The PLAN’s third-generation Type-09-V boats will be single-hulled SSGNs, four of which are being built with the lead boat due for launch by the year’s end. Each of them will have 12 vertical launch cells aft of the coning tower for launching YJ-18 missiles and will also feature electronic noise-cancellation technology like a shaftless, rim-driven, pump-jet. But technological challenges remain in the arena of remote-controlled Non-Penetrating Periscope (with photonics/optronics mast), which does not penetrate a submarine’s hull, but records a 360-degee digital image for the command team to analyse at leisure.

The projected 20 fourth-generation double-hulled diesel-electric SSKs fitted with low-power/low-pressure auxiliary nuclear powerplants for electricity generation are similar to the Soviet-era VAU-6 auxiliary nuclear powerplant tested in the late 1980s on a Project 651 conventional cruise missile submarine (SSG). The latest variant of the Type 041 Yuan-class SSK will receive such powerplants. Such boats will replace the existing Type 039A/041/S-26T/S-30 SSKs that currently use Stirling Engine-based air independent propulsion (AIP) systems. The auxiliary nuclear powerplants could also be offered for export on board the CSIC-supplied 2,600-ton S-26T and S-30 SSKs that are on order for Pakistan and Thailand.

Also being developed by Harbin Engineering University and the Jiangsu Automation Research Institute is a compact nuclear reactor design—using mature technologies—will fit into an unmanned underwater vehicle (UUV) the size of a 533mm torpedo, making it deployable by existing naval assets. The reactor will be partially seawater-cooled and use low-enriched fuel so as to minimise radioactivity (when the reactor is in off-state) and eliminate the need for heavy and bulky radiation shielding.

Instead of using a steam turbine, which is obviously too large to fit, a thermo-electric generator has been chosen. The reactor will be less than three metres in length with a diameter smaller than 533mm. It will weigh less than 750kg with a power output of 100kW. The reactor is one-time use only, capable of operating at full power for 200 hours, enabling the underwater vehicle to dash for thousands of kilometres at high speed or alternately cruise for longer ranges when operating at partial power.

A battery is placed toward the rear of the vehicle, which is used to power the vehicle when it is initially deployed and before the reactor is started. This should put a safe distance between the vehicle and the crew because once the reactor starts, its radioactivity increases significantly. The battery also enables the vehicle to briefly reach higher speeds than relying on reactor power alone. Interestingly, the researchers propose that the reactor can be jettisoned, with the vehicle operating on battery power alone if necessary.

For the export markets the CSIC’s subsidiary, the China Shipbuilding and Offshore International Company (CSOC), is offering three new single-hulled SSK designs: MS-200, S-600 and S-1100. Except for the MS-200, the CSIC is also offering a range of Air Independent Propulsion (AIP) systems. Several countries have already shown interest in the submarine’s designs, including Algeria, Cuba, Egypt, Libya, Myanmar, Saudi Arabia, the United Arab Emirates and Venezuela. All three SSKs feature single-hull designs.

The sails of these three new submarines also seems to have benefited from the latest research in hydrodynamics and acoustics of the 701 Institute, the CSIC Group’s main research bureau. These sails are in line with the trapezoidal shape already observed on the new SSKs of the last batch of PLAN Type 041B SSKs. This further reduces underwater noise. The MS-200 adopts the form of the teardrop and single-hull structure. The sail has a three-dimension streamline shape, the steering plane adopts bow hydroplane and cross stern rudder.

Displacing 200 tons, the design has a length of about 30 metres, breadth of 3.6 metres and a height of 4.4 metres. Its maximum speed is about 8 knots, its submerged range is 120 nautical miles and mixed range about 1,500 nautical miles. Its maximum diving depth is 200 metres. Its endurance is 15 days at sea. The service life of the submarine is 25 years. The SSK can accommodate six sailors and eight special operations forces personnel. The MS-200 has two torpedo tubes. Displacing 600 tons, the S-600 has a length of about 50 metres, a beamwidth of 4.6 metres and a height of 5.6 metres.

In terms of performance, its maximum submerged speed is about 15 knots (9 knots surfaced), its range is 2,000 nautical miles (400 nautical miles while submerged and using an air-independent propulsion, or AIP, module). Its maximum diving depth is 200 metres. Its endurance is 20 days at sea. The submarine can accommodate a crew of 15 personnel and has four torpedo tubes. The S-1100 SSK adopts the form of the teardrop and single-hull structure. Displacing 1,100 tons, the SSK has a length of about 60 metres, beamwidth of 5.6 metres and a height of 6.8 metres. Its maximum submerged speed is about 15 knots, its range is 3,000 nautical miles (800 nautical miles while submerged and using an AIP module). Its maximum diving depth is 200 metres. Its endurance is 30 days at sea. The SSK can accommodate a crew of 18 personnel. The service life is 25 years. The S-1100 submarine has four torpedo tubes.


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