Japanese Submarine Developments through to 2030, Soryu Table.

As can be seen in the SORYU TABLE below 21SS was a test submarine or test program equivalent.

Given 21SS’s 2010 timing Pete believes 21SS signified the concerted beginning of Japan’s 

Lithium-ion Batteries (LIBs) for submarine program. The actual LIBs testbed submarine used may have been Harushio class TSS-3601(launched as SS-589 in 1995, converted to AIP testbed in 2002, converted to LIBs testbed in 2010, decommissiond in 2017).

The LIBs development program continues to this day in the shape of 27SS (Japan’s first soon-to-be operational LIBs submarine) launched in 2018 and due to be commissioned this year (see Table below). Also see the Japanese Ministry of Defense (MoD) Acquisition, Technology & Logistics Agency (ATLA) LIBs development activity by scrolling half way down here.

The description of Japanese submarine 29SS research/testing below draws from Anonymous's comments on Japanese submarines on February 19and 21, 2020 

Submarine prototype and tests conducted during MoD budget financial years FY2017-2018 and FY2019-2022 concerned prototype research on submarine hull forms. This was aimed at significantly reducing hydrodynamic noise with the long term aim of permitting Japanese submarines to face ASW threats through the year 2030.

Anonymous believes optimization of hull form research was conducted to reduce noise caused by bubbles, hydrodynamic flow, vibration and by the propulsor – see [1] and [2].

Japanese researchers at ATLA built a [29SS] scale model for various tests conducted in large naval test tank (length 247m, width 12.5m, depth 7m). The findings of this research together with other research findings will influence Japan’s future (post Soryu) submarine design designated 29SS. [Pete comment: 29SS likely also exists as a complex mainframe computer simulation shared between MoD central, its ATLA agency and submarine builders MHI and KHI (see Key to Table below the Table).]

29SS may be the first submarine of a new class following the Soryus. A formal report by the MoD indicates 29SS is being used as a test submarine for various research technologies. 29SS has the same shape and dimensions as the Soryus. Further design modifications will take place in operationally deployed 30SS and 31SS (etc) as is usual in Japan’s yearly continuous build of submarines practice.

[Pete comment: There may be increased blending of the sail. There is some blending of the Soryu sail’s leading edge. Further blending may be not as extreme as depicted in Alfa and Type 212A submarines at Submarine Mattershere. There will be ongoing research for quieter diesel engines, improved LIBs and “Improved Snorkel”].

[1]“Terminology for underwater acoustics – Phenomena (Y0011B)” by Standard for Ministry of Defense (NDS), page 22, terminology number 1561. “Definition of hydrodynamic noise: noise caused by hydrodynamics.”

[2]ibid, page 67, “Classification Table”

Hydrodynamic noise is classified into i) bubble noise (1562, noise caused by generation, vibration or collapse of bubbles underwater), ii) flow noise (1564, noise caused by turbulence flow such as turbulence flow boundary, separating flow and wake), iii) flow induced vibration noise (1568, noise caused by vibration of structure or part of it which is induced by water flow), iv) wave-breaking noise (1569, noise caused by collapse of wave) and v) propulsor noise (1571, noise caused by propulsor*1-2).

*1 Propulsor includes propellers, water jets, etc.

*2 Causes of propulsor noise include cavitation, "wing" [rudder and sail-plane?] vibration by lift fluctuation, local vibration of [rudder] induced by tailing vortex.

Note: Pricing issues will be discussed next week using Anonymous’ comment of February 24, 2020 .This is on the issue of Australia possibly choosing a LIBs Soryu if the current Naval Group Attack class submarine program collapses.