Soryu and New Japanese Submarine Class Table

Anonymous kindly provided many details on September 23 to 29, 2020, regarding diesel generators (diesels) and Lithium-ion Batteries (LIBs) for Japan's newest submarines. I have noted these changes in the revised  SORYU TABLE below the details.

Anonymous's September 23 to 29, 2020 comments are:

"Japan’s Ministry of Defense (MoD) is building 3,000 ton submarines as successors to the Soryus, and the fourth ship (02SS) [1] will be equipped with new diesels [2].

[1] "SS" numbers and Financial Year names for Japanese submarines are based on the era of reigning Japanese Emperors. So that is the eras of former Emperor "Heisei" and present Emperor "Reiwa". Hence the names of the newest (post Soryu) Japanese submarines are 29SS, 30SS, 01SS and 02SS for Financial Years 2017 (Heisei 29), 2018 (Heisei 30), 2019 (Reiwa 01) and 2020 (Reiwa 02), respectively.

[2] The final two Soryus, which use LIBs, are 27SS and 28SS. LIBs makes them "Soryu Mk IIs". The early New Class 3,000 ton (surfaced) submarines (29SS, 30SS, 01SS) will be equipped with 12V32/25S diesels which are longer stroke versions of the 12V25/25SB used for LAB+AIP Soryu Mk Is. Performance of new diesel generators for 02SS seems to be improved significantly.

[Pete Comment: the New Class will likely be assigned a name of a Japanese mythological creature (eg. a mermaid or a different dragon than "Soryu", etc)] 

02SS will also equip with improved LIBs. The electrical system for LIB-submarines is summarized as follows:

-  Soryu (27SS, 28SS): LIBs type SLH (see SLH explationation below); with 2 x Kawasaki 
   12V25/25SB or 12V25/31 diesels

-  first 3 subs of the New 3,000 ton Class (29SS, 30SS, 01SS): LIBs type SLH and
   2 x 12V/25/31 diesels

-  4th sub of 3,000 ton class (02SS): LIBs type improved SLH [1], new diesel [2]

[1]  According to the ex-Minister of Defense, improved SLH LIBs with better performance had been
       developed but was not immediately adopted due to defense budget shortfalls.

[2]  As an item for a new diesel was not found in R&D planning for submarine, a new diesel might be
       based on an existing diesel (e.g., the 12V25/25SB) being a largely modified version of the
       12V/25/31.

Noise testing by KHI, for new or modified diesels took place in a simulated pressure hull, which was constructed by KHI in 2019. This strongly suggests that the new diesel 02SS is made by KHI.

Judging from specifications of the NDS (National Defense Standard), output of 12V25/25S is 2,000kW  and it may be an evolution from the diesel for 29SS (12V25/31). Output of a new diesel for 02SS is expected to be more than that of 12V25/31 (2,500-2,800kW) and to be 3,000kW or more.

In this case of a 3,000kW-output, the indiscretion ratio (IR) of 02SS might be 4%-5%. As ex-Vice Admiral Masao Kobayashi [see his photo and biodata here] suggested charging of LIBs would be conducted outside the operational sea area. Then the real IR of 02SS may be considerably lower (less than 1%?). [Pete Note: "A submarine’s indiscretion rate [or ratio] is defined as the percentage of time a submarine spends snorting. This indiscretion rate depends strongly on the energy discharged from the batteries and the diesel generators’ capacity to recharge the batteries. Typical snorting indiscretion rates [of LAB submarines] are between five and twenty per cent"]

[1] NDS F80182D [General Rules of Rotating Electric Machine for Ship] 4.1 a) and 4.1 g) specify rated output of AC generator and rated speed AC generator driven diesel, respectively, as follows:

4.1 a) 80, 100, 160, 200, 300,400, 500, 600, 800, 1000, 1200, 1500, 1800, 2000, 2500, 2800, 3000 [kW]

and

4.1 g) 900, 1200 or 1800 [rpm]

[2] SHIPS OF THE WORLD 2020, No930, Page109

“Output of KAWASAKI 12V25/25S for Oyashio is 3400PS (=2040kW)”

Latest information on battery arrangement for Oryu (27SS), a Soryu Mk II, was reported at [1] below. There, additional LIBs are loaded in a double deck arrangement in place of LOx for AIP tanks [as there is no AIP on Mk IIs] see [2] below. 

Then, amount of batteries in Oryu (27SS) and Toryu (28SS) seem to be twice as much as those in Soryu Mk Is [which have LABs and much space taken up by AIP chemicals and Stirling engines], suggesting loading of 960 LIB-arrays (total energy, 70MWh?). 27SS and 28SS might show better performance previously reported here, in Submarine Matters.

[1] SHIPS OF THE WORLD 2020, No935

[2] at http://gentleseas.blogspot.com/2016/09/pressure-hull-alloys-debate-titanium.html see the “Cutaway diagram of a Soryu submarine”

In the Oryu (27SS), LOx tanks in section 10 are removed, doubled decker structure is adopted for section 10 and filled with additional LIBs (240 LIB-arrays x 2).

SLH

Japan’s Ministry of Defense (MoD) discloses purchasing information in detail but not perfectly. SLH is a model name of a LIB for submarine. SLH is made by GS YUASA. Specifications of equipment are classified as “old”, “revised” and “new” for existing, revised and new models, respectively.

Specification class of SLH for 02SS in FY2020 is “revised”, suggesting that LIB for 02SS is an  improved version of LIBs (“old” SLH) for 01SS. If LIB is fully model changed, new model name is selected and specification is “new”.

Specification of the 2 diesels for 02SS in FY2020 are classified as “new”, suggesting that they are a new model.

 In 27SS, improvements other than LIBs are achieved, and 28SS Toryu improves 27SS somewhat.

By the way, an ex-Vice Admiral (not Kobayashi) of JMSDF said nuclear submarine is needed in future, because even LIB-submarine is still powerless (10% energy of nuclear submarine). RAN might have the same idea for Australia."

[See most of the diesel and battery details incorporated in the revised SORYU TABLE below.]

Anonymous and Pete