Japan's 29SS Submarine Research Program - Land Attack Missiles, etc.

Based on what I've read so far, likely, but cannot be proven. The Japanese Navy has formalized its submarine testing:

- from testing new technologies on several operational Oyashio and Soryu submarines.

- to a formal testing program called 29SS (with 29SS being a Japanese Ministry of Finance to
  Ministry of Defense research funding designation, rather than an actual operational submarine).

The 29SS Program apparently begun in 2017 (see SORYU TABLE below). 29SS apparently involves testing of such new technologies as:

-  new, higher sea state (storm) snorkel system http://gentleseas.blogspot.com/2018/01/japanese-
   soryu-higher-power-snorkel.html

-  new pumpjet? propulsor

-  new 12V25/31S diesels

-  new diesel-to-LIB and LIB-to-propeller/propulsor transmissions.

-  further LIB testing (eg. new LIB types/formulas)

-  more broadly an updated combat system which would include:
   :  new "G-RX6" torpedoes, see https://en.wikipedia.org/wiki/Type_89_torpedo which contains
      sentence "A succeeding design is in development under the development name of "G-RX6" still
      using Mark 48 torpedo technology.
   :  new mines and decoys,
   :  possible Japanese successor to the Harpoon ASM
   :  consideration of Tomahawk or more advanced Land Attack Missiles
   :  such sensors as hull and towed sonars, radars, other submarine motion detectors
   :  optronic (non-hull piercing) masts,
   :  new central processing computers.

Even though 29SS does not mean a new submarine, the technologies above could be tested on existing "training" submarines. "Training" can be a cover for "testbed" submarine.

Japan's 2 known training submarines are the 2 earliest Oyashios
https://en.wikipedia.org/wiki/Oyashio-class_submarine#Boats namely:

-  SS-590. Converted to training submarine (TSS-3608) on 6 March 2015, and

-  SS-591. Converted to training submarine (TSS-3609) on 27 February 2017.

So TSS-3608 and/or TSS-3609 could be the full scale testbeds for 29SS Submarine Research Program. Meanwhile there is a great deal of on-shore testing of 29SS technologies, eg. electronics, weapons and test pools (for miniature scale models to test the hydrodynamics of slightly altered hull shapes).

A new sail/fin, less exaggerated than the German Type 212A's, may eventially be adopted. A much lower, muc more blended sail/fin than the Soryu's is unlikely because Japanese submarines still need to be tall/perpendicular enough to operate, surfaced, without being swamped, in the higher sea states of the open Western Pacific Ocean.

As is Japan's usual practice the new technologies will be steadily incorporated into individual submarines on an iterative, continuous-build basis, rather than a US/European style batch basis.

Looking at the SORYU TABLE below, 30SS may be the first new-build submarine to begin incorporating 29SS Program features (eg. 2 x 12V25/31S diesels). Some Oyashios and Soryu's may be retrofitted - especially with updated combat system electronics and perhaps the G-RX6 torpedo.

Pete