India Navy Indian Nuclear Submarine Programs (SSBN & SSN)

Nilgiri

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@Nilgiri I almost know nothing about SSN propulsion technology.
But how much refueling LEU reactor cost on avarage? Does it require hull cutting?

Also I am wondering if india's first generation indigenous SSN would be as quiet ( in terms of hull and propulsion system ) and advanced ( in sensors and CMC package ) as Astute or Virginia boats.

Reactor costs are pretty much the same (given enrichment of fuel and reactor design difference accommodating for that is very small portion of the final lifetime cost, if its even any different in the end).

As to what those costs are like, I am unsure (given what gets allocated in funding to their RnD "backdrop" versus actual unit production costs leveraging those and how you would split that up in the economies of scale etc....though I have heard figures in the 100 million - 500 million range depending how you do this). Maybe @Anmdt or others know more about that.

If by hull cutting, you mean what needs to happen during say French reactor replenishment, then no as they have accommodated that need in the hull design itself:


i.e they already had certain requirements (by law regarding nuclear reactors and materials) to have their boats come in every 10 years, so they went with LEU to make maximum use of the time spent anyway along with harnessing LEU long term advantages (foresight largely tied into leveraging from what exists in commercial reactors long term given dedicated HEU RnD from joint-service weapons program was ended in the 90s).

If India collaborates with French and the West in general regarding everything else on the sub (and the various non-nuclear related mitigations for the reactor area itself concerning pumps and so on)...one would expect the end product to be among western acoustic profile in the end too. Depends on degree of cooperation in the end there I guess.
 

Gessler

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Hydrodynamic model of the 13,500-ton future SSBN class, commonly known as "S-5". Picture via Manjira Machine Builders' website

View attachment 54477

Some more pics of the models, via AlphaDefence

s5.JPG


image-36-1024x342.png


It's now more or less certain that the S-5 class SSBN will be having no less than 12 x ballistic missile tubes.
 

Gessler

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So apparently, NSTL is testing this design, lack of a missile hump implies this is an SSN:

IMG_20230703_141003.jpg


It does not necessarily mean that the upcoming Project-75A/76 SSN will have a pumpjet, or that this is indeed the indigenous SSN design (could just be a case-study of a generic modern SSN boat). But it's definitely interesting.
 

Gessler

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This is pretty surprising...the missile hump on this test model is much more streamlined with the hull compared to the older model:

photo_2023-02-26_14-19-18.jpg


Considering the size of the hump depends on the size of the SLBM you plan to use from it, unless our intended SLBM specifications have changed (read: better propulsion tech resulting in a shorter missile with the same range as before), I don't see how they can redesign the hump to be more blended without changing the Sub's beam diameter itself (which essentially means going back to the drawing board and starting from square one). Which I don't think they're doing.

Additionally, the models seen previously had the dive planes on the hull (like on Vanguard-class) and not on the tower. It seems we're testing various different configurations, as we should. Don't know which one we will eventually settle on (or maybe we already have?).
 

Gessler

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This is pretty surprising...the missile hump on this test model is much more streamlined with the hull compared to the older model:

View attachment 66371

Considering the size of the hump depends on the size of the SLBM you plan to use from it, unless our intended SLBM specifications have changed (read: better propulsion tech resulting in a shorter missile with the same range as before), I don't see how they can redesign the hump to be more blended without changing the Sub's beam diameter itself (which essentially means going back to the drawing board and starting from square one). Which I don't think they're doing.

Additionally, the models seen previously had the dive planes on the hull (like on Vanguard-class) and not on the tower. It seems we're testing various different configurations, as we should. Don't know which one we will eventually settle on (or maybe we already have?).

Another thing I'm noticing just now...

The length of the missile compartment has significantly increased in the new model. This was the old one:

s5.png


...compared to the new one, where the compartment is now going almost all the way to the tail section:

s5 3.jpg


Assuming the old model had 12 x missile tubes (two rows of six, side-by-side), it seems we are looking at 16-20 tubes for the new model!
 

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