Option of TKMS for Dutch Walrus Submarine Replacement Program

The Dutch Government has a Walrus Replacement Program calling for at least 4 medium-large conventional diesel-electric submarines for launch in the mid-late 2020s.

On October 9, 2018 Anonymous examined technical issues for a Saab A26 concept meeting the Walrus Replacement requirement. 

Now Anonymous, in comments from October 21-23 2018, is looking at technical details involved with Germany’s TKMS meeting the Walrus Replacement requirement.

Drawing from those comments Walrus replacement concept could be a very large version of the TKMS 212A/CD, 214 or non-AIP 209. Assuming the South Korean 3,000 ton KSS3 is based on a TKMS design (lets call it a TKMS Type 3000). A 2,900 ton (submerged) Walrus replacement could also be a Type 3000.

Within the 2,650 ton (submerged) current Walrus class’s double hull structure (light & pressure hulls) there are 3 x MAN Diesel & Turbo owned SEMT Pielstick 12 PA4 V 200 SM [1] diesels (width ca.1470mm, not 12 PA4 200 SMDS) could be installed in parallel. Distances (ca.400mm) between diesel-diesel and diesel-pressure hull are small (ca.400mm).

In the Walrus replacement concept, 3 x 12 PA4 V 200 SMSD diesels could be installed in parallel, but the separation distances could be somewhat greater (ca.600mm). These latter diesels could be more powerful to propel a larger 2,900 tons submerged Walrus replacement [and/or charge Lithium-ion Batteries (LIBs) more quickly]. As result of these exchange of diesels, Walrus-concept becomes more powerful. See Appendices [1], [2], [3] and [4] below.

MAN Diesel & Turbo or SEMT Pielstick (now operate as a brand by MAN Diesel & Turbo) has the following three generators which are sometimes confused. Correct data are as follows:

-  8 PA4 V 200 SM, cylinder bore 200mm, V8, single supercharger (mechanical output 700kW). A26; (2 starboard + 1 port) x 8 PA4 V 200 SM (2,100kW)

-  12 PA4 V 200 SM, cylinder bore 200mm, V12, single supercharger (1,060kW).  Walrus-class; 3 parallel x 12 PA V 200 SM (3,180kW)

-  12 PA4 V 200 SMDS, cylinder bore 200mm, V12, single supercharger + single turbocharger (1330kW), Walrus -concept; 3 parallel x 12 PA V200 SMDS (3,990kW)

  

The next Dutch submarine will need much space to accommodate some female crew, for additional quieting measures and additional weapons spaces (possibly for anti-ship missiles, land attack missiles and UUVs, etc). 

A double hull structure may be required for the stern drive sections (see red/blue in the 212A diagram above). This is if the Walrus replacement is an enlarged Type 212A/CD, 214 or 3000 equipped with LOx cylinders (diameter ca.1.7m) outside the pressure hull. To fit these cylinders the outer diameter of pressure hull in the drive sections would be considerably smaller (diameter ca.5.6m) than the 212s beam (of 6.8m) and would be an inefficient use of space. Also, the strength of pressure hull material for the 212A/CD is not high.

The Walrus replacement would need floating decks to insulate/isolate vibrations thereby reducing noise effectively, but, are not in 212A/CD or 214s. Floating decks also mitigate shock from outside thereby protecting equipment and crew. Floating deck are used in US nuclear submarines and already in the Stirling generator section of (LABs + AIP) Soryus.  Floating decks will also feature in the future Japanese Soryu with LIBs 29SS (to be launched in 2 to 4 years).

TKMS fuel cell AIP is more efficient than combustion type Stirling AIP. But fuel cell AIP, owing to its use of hydrogen is less safe than Stirling. For fuel cell hydrogen containers are placed out side the pressure hull (see red O2 Tanks and H2 Storage in diagram above). Meanwhile the Kawasaki Stirling AIP, licensed by Kockum’s Stirling, for use in LABs + AIP Stirlings, are very expensive.

[1] http://en.wikipedia.org/wiki/Walrus-class_submarine

3 diesels, diesel-electric, 5,430 shp (4 MW): They confuse 12 PA4 V 200 SM (right) with 12 PA4 V 200 SMDS (wrong)

[2] Electrical output = 0.8 x mechanical output

[3] https://marine.man-es.com/docs/default-source/shopwaredocuments/pa4-sm-smdsfba3ca1740b144429518d4e002fd7d6f.pdf?sfvrsn=6f128e3a_3

[4] Some discussion of a TKMS option

 https://www.defensenews.com/industry/2018/03/23/emerging-german-dutch-naval-tie-up-has-industry-abuzz/

Pete Comment

The Netherlands may not use any AIP (fuel cell or Stirling) due to the Walrus' replacement need to travel long distance missions (maybe 8,000nm) from the Netherlands to the Dutch Caribbean and back. This is similar to Australia’s and Japan’s long transit missions making AIP inefficient (especially with high weight and imbalances of LOX tanks). Thus Australia in the 1970s and Japan now have decided against future placing of AIP in their submarines.

But Japan is obviously attracted to the submerged range and speed advantages of LIBs. TKMS and Naval Group are also marketing the advantages of their LIB solutions. See discussion of this tomorrow. 

TKMS corporate ownership changes/problems may be of concern to the Dutch government. Hence this may favour the A26 solution raised by a SAAB-Damen consortium or Naval Group.

Anonymous and Pete