Japanese Submarine Developments Continue

The Japanese Ministry of Defense’s (MoD’s) ATLA research organisation is studying a significantly different prototype submarine shape (see last line in this MoD (in Japanese) document). The shape is similar to the old Soviet Alfa-class which had a streamlined fin/sail. Shape differs in having modern X-plane rudders. It was exhibited at the ATLA Technical Symposium 2016. 

It could be the Japanese are talking to TKMS which also features a highly streamlined fin/sail in the Type 212A (photo of model below). These fin/sail styles can provide improved hydrodynamic motion efficiency, noise reduction against passive sonar and the rounded shape may be  more stealthy against active sonar. 

29SS will be the first submarine of a new Japanese class (see this Table). It will probably be named after a famous ship in Japanese naval history. 29SS will charge Lithium-ion Batteries (LIBs) only and will likely be contructed at the MHI shipyard, Kobe with launch in 2023. It will be equipped with 2  advanced, more powerful, diesel engines and a high pressure air tank [for what?]. The diesel engines' possible modifications to increase power may be increased bore, stroke and/or charging pressure, and reduction in vibration/noise, etc.

The current Soryu diesel is KAWASAKI-12V/25/25SB
It is a V12, with bore 250mm, stroke 250mm, volume 147L, piston speed 10m/s, power 2280 kilowatts/minute [?] kWm, power/volume 15.4kW/L. This is considered adequate for the Lead-acid Battery (LAB) Soryu Mark 1.

The future diesels need to be more powerful to take advantage of the quick battery charging ability of LIBs. More powerful diesels might include:

-  Kawasaki-12PA6V-280CLV12, bore 280mm, stroke 350mm, volume 258L, piston

   speed 8.4m/s, power 3540kWm, power/volume 13.6kW/L or

-  Wärtsilä 26, 12V26 V12, bore 260mm, stroke 320mm, volume 204L, piston speed 10.7m/s, power 

   4080kWm, power/volume 20.0kW/L or

-  a Kawasaki modified MTU 4000?

On February 17, 2017 Submarine Matters reported on the two types of LIB (“NCA” and “LTO”) that Japan is considering for its new submarines. It may be likely that Japan prefers NCA (Lithium Nickel Cobalt Aluminium Oxide (LiNiCoAlO2)) produced by GS Yuasa (GSY). GSY’s cells have coatings that reduce the fire risk.

  

Note the Soviet Alfa class 1971-1990 (above) had a highly streamlined fin-sail (Photo courtesy findmodelkit). The fin/sail of the TKMS Type 212A (below) (Photo courtesy HobbyBoss) seems to owe much to the Alfa. Japan, when considering future hull shapes, might seek TKMS' advice on the fin-sail.

Future Submarine Matters articles this week will be:

-  June 15, 2017 on Sub Diesel Stresses & Requirements from comment on 10/6/17 10:16 AM and

-  June 16, 2017 carrying comments on Japan's future 29SS submarine and LIBs (GS Yuasa) etc.

Pete