Japan Commissions First Li-Ion Battery-Equipped Sōryū-class Submarine, JS Ōryū

The Japan Maritime Self-Defense Force (JMSDF, Kaijō Jieitai) has commissioned its first Li-Ion battery-equipped Sōryū-class submarine, JS Ōryū (SS-511), during a ceremony at Mitsubishi Heavy Industries’ (MHI) Kobe shipyard on March 5.

JS Ōryū (“Phoenix Dragon”) is the 11th submarine in the Sōryū-class and is also the first Japanese submarine to be installed with lithium-ion (Li-ion) batteries. The Li-ion batteries have improved the submarine’s underwater endurance significantly and will be an advantage over the slow recharge capability of the air-independent propulsion (AIP) system installed on the first ten Sōryū-class boats.

Sōryū-class SSK

Sōryū-class submarines (16SS) are diesel-electric attack submarines (SSKs) operated by the JMSDF. The design is an evolution of the earlier Oyashio-class submarine, from which it can most easily be distinguished by its X-shaped stern combination diving planes and rudders.

The Sōryū-class submarines have a length of 84 m and a displacement of 4,100 tonnes when submerged. They have the largest displacement of any submarine used by post-war Japan and are its first air-independent propulsion (AIP) submarine.

The first ten boats of the class are powered by two Kawasaki 12V 25/25 diesel engines and four Kawasaki Kockums V4-275R Stirling Air Independent Propulsion (AIP) engines. This enables the boats to have a top speed of 20 knots when submerged and of 12 knots when surfaced. The submarines, from the 11th one (JS Ōryū), is equipped with lithium-ion (Li-ion) batteries. This has improved the underwater endurance significantly and will be an advantage over the slow recharge capability of the AIP system.

The Sōryū-class boats are equipped with six HU-606 533 mm bow tubes that can fire Type 89 heavyweight torpedo. The boats are also capable of deploying the UGM-84C Harpoon medium-range anti-ship missile (AShM) against surface targets. The submarines also have two 3-inch underwater countermeasure launcher tubes for the launching of Acoustic Device Countermeasures (ADCs).

Each of the Sōryū-class submarines has a crew complement of 65 (9 officers, 56 enlisted).

The first boat in the class, JS Sōryū (SS-501), entered service in 2009. The 12th Soryu-class submarine, JS Toryu (SS-512) “Fighting Dragon”, was launched by Kawasaki Heavy Industries (KHI) during a ceremony at its facility in Kobe on Nov. 6, 2019.

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