Soryu Class diesel-electric submarines are being built by Mitsubishi Heavy Industries and Kawasaki Shipbuilding Corporation for the Japan Maritime Self-Defense Force (JMSDF). Soryu Class is an improved version of the Oyashio Class submarine.
Keel for the first submarine in the class, Soryu (SS-501), was laid down in March 2005. It was launched in December 2007 and commissioned in March 2009. The second submarine Unryu (SS-502) was laid down in March 2006, launched in October 2008 and commissioned in March 2010.
The third submarine Hakuryu (SS-503) was laid down in February 2007 and launched in October 2009 for commissioning in March 2011. The fourth and fifth submarines, Kenryu (SS-504) and Zuiryu (SS-505), were commissioned in March 2012 and March 2013 respectively.
The sixth and seventh submarines in the class Kokuryu (SS-506) and Jinryu (SS-507), were commissioned in March 2015 and March 2016 respectively. The keel for the eighth submarine, Sekiryu (SS-508), was laid in March 2013 and its commissioning took place in March 2017.
The ninth ship Seiryu (SS-509) was commissioned into the JMSDF in March 2018. The tenth and eleventh submarines in the class, Shoryu (SS-510) and Oryu (SS-511) were launched in November 2017 and October 2018 respectively. The next two submarines, SS-512 and SS-513, are currently under construction.
The class is also referred to as the SS 2,900t and the 16SS project. Soryu and Unryu have been named after the World War II aircraft carriers. Soryu was one of the carriers that participated in the Pearl Harbour attack. Both submarines are home-ported at Kure and operated by Subron 5, S-flotilla-1 of the JMSDF.
Soryu Class design and features
Soryu Class carries a hydrodynamic design based on the Oyashio class submarine. It has a larger displacement than any other submarine class in JMSDF’s service. The hull form is made of high tensile steel and is covered with an anechoic coating to reduce the reflection of acoustic waves. Interiors of the submarine boast acoustic isolation of loud components. The submarine features computer-aided X control planes. The design incorporates highly automated systems.
The submarine is equipped with Stirling engines for increased propulsion performance and underwater endurance. The engine supports superior submerged operations. The high-performance sonar on-board improves surveillance capabilities. The submarine also features stealth capabilities and enhanced safety measures such as snorkel equipment.
The vessel has an overall length of 84m, a beam of 9.1m and depth of 10.3m. The normal draft of the sub is 8.4m. It has a surfaced displacement of 2,950t and a submerged displacement of 4,200t. Soryu Class complements a crew of 65, including nine officers and 56 enlisted members. The submarine can sail at a surfaced speed of 13kt and a submerged speed of 20kt. It has a maximum range of 6,100nm at 6.5kt speed.
Soryu Class is fitted with six HU-606 533mm torpedo tubes for Type 89 torpedoes and UGM-84 Harpoon anti-ship missiles. The Harpoon has a range of over 124km and speed of 864km/h.
Type 89 is a wire-guided torpedo with active and passive homing modes. It has a maximum speed of 130km/h and can engage targets within the range of 50km. The torpedo can carry a warhead of 267kg.
Sensors / radars
The submarine is equipped with a ZPS-6F navigation or surface search radar. The sonar suite integrates four low-frequency flank arrays, a bow-array, and towed array sonar.
Soryu features ZLR-3-6 electronic support measures (ESM) systems. There are two 3in underwater countermeasure launcher tubes installed for launching acoustic device countermeasures (ADCs).
Soryu is powered by a diesel-electric propulsion system. Two Kawasaki 12V 25/25 SB-type diesel engines and four Kawasaki Kockums V4-275R Stirling engines provide a total power output of 2,900kW surfaced and 6,000kW submerged.
Soryu is the first submarine of the JMSDF to be equipped with Stirling engines manufactured by Sweden-based Kockums.
Stirling is a silent and vibration-free external combustion engine. The Kockums Stirling air-independent propulsion system on-board reduces the need for frequent battery charging and increases the submerged endurance of the submarine
The electric propulsion motor drives a propeller through a single shaft. The submarine is also fitted with an X rudder to provide high manoeuvrability to the submarine when operating very close to the seabed. This X rudder configuration was initially developed by Kockums for the Swedish Gotland class. The propulsion system provides a maximum speed of 20kt.
Australia’s decision that DCNS of France would be the preferred partner for the delivery of 12 Shortfin Barracuda submarines (the first delivery is estimated in 2030); China’s reported construction of Type-039C submarines, with at least one believed built and undergoing trials; India’s six licence-built Scorpene submarines (with the first commissioning expected in late 2016); Indonesia’s contract with South Korea for three Type-209s, with the first launched in spring 2016; Japan’s 12 Soryu-class submarines, with the seventh having been commissioned in 2016; Pakistan’s contract with China for eight submarines, which was confirmed in 2016; Singapore’s procurement of the German-manufactured Type-218SG, with first delivery expected in 2020; and Vietnam’s procurement of six Russian Kilo-class submarines, with the fifth of class delivered in 2016. To this list can be added Thailand’s announcement regarding the procurement of three conventionally powered Chinese submarines, with funding reportedly earmarked in the 2017 defence budget. Taiwan’s newly elected government also announced the life- extension upgrade of its two Hai Lung submarines and announced its intention to move forward with the Indigenous Defense Submarine programme to build six to eight submarines domestically. Related to this, Taiwan’s China Shipbuilding Corporation opened a new submarine-development centre in the southern port city of Kaohsiung in 2016. Japan also earmarked for its FY2017 budget the development of a new generation of locally produced submarines, designed by Mitsubishi Heavy Industries and Kawasaki Heavy Industries.
Japan’s recent attempts to internationalise its defence-industrial cooperation have had limited success. Kawasaki failed to sell the P-1 maritime- patrol aircraft to the United Kingdom in 2015, which instead chose Boeing’s P-8A Poseidon. More strikingly, in 2016 MHI and Kawasaki Shipbuilding Corporation failed in their bid to export Soryu-class attack submarines to Australia. The Abe administration had hoped the bid would help kick-start Japan’s export of military technology and cement the Australia-Japan strategic partnership. A number of factors contributed to Japan’s failure to win the contract, including questions over the suitability of the Soryu technology for Australia’s defence needs and, crucially, Japanese defence contractors’ lack of experience in competing in international markets. However, Tokyo appears undeterred and, with negotiations over pricing and technology transfer apparently resolved in late 2016, is still looking to sell the ShinMaywa US-2 search- and-rescue aircraft to India. In an attempt to improve the coordination of these weapons-export efforts, the defence ministry established an Acquisition, Technology and Logistics Agency in 2015. However, Tokyo still needs to do more to encourage Japanese defence manufacturers to venture into international markets, and also learn the skills concerned with lobbying and the provision of offsets as incentives.