Project 75 India Diesel-electric Submarine Programs (SSK) : Updates and Discussions

Who will win the P75I program?

  • L&T and Navantia

    Votes: 12 40.0%
  • MDL and TKMS

    Votes: 5 16.7%
  • It will get canceled eventually

    Votes: 13 43.3%

  • Total voters
But having to open a submarine every 6 or 7 years to replace the core and its fuel load is also disastrously expensive.

Isn't that the case with LEU reactors?

The Arihant (and subsequent Indian N-subs) are fueled with 40% enriched HEU - which should deliver somewhere between 10-15 years at least.

Either way, going to LEU would be way too prohibitive at this stage.
Isn't that the case with LEU reactors?
I think he meant LEU subs do not need to cut open and are easier to refuel. But obviously frequency is higher.
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I think he meant LEU subs do not need to cut open and are easier to refuel. But obviously frequency is higher.
My remark was not intended to promote French submarines, it was about a US rather than a Russian solution. ;)
Don't know if this was known before (certainly not to me):

Seems that inclusion of Lithium-Ion Batteries (LIB) technology is going to be a mandatory requirement under P-75I, alongside AIP.


@Gautam @Ashwin @randomradio
Don't know if this was known before (certainly not to me):

Seems that inclusion of Lithium-Ion Batteries (LIB) technology is going to be a mandatory requirement under P-75I, alongside AIP.

View attachment 21504

@Gautam @Ashwin @randomradio

It's not just mandatory, but it's also supposed to be indigenous.

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Very good read

Some excerpts :
Here is where the Russians and some of our allies have us beat. For our surface navy, we need to come up with a system similar to the Russian RBU-6000 anti-submarine rocket launcher. Better yet, we should support our friends and purchase Sweden’s ASW-601, or bring back a simple, inexpensive system like the ol’ Hedgehog. The benefits of this system also include mine countermeasures and an anti-torpedo defense, both of which our warships need.

For our aircraft, we need a simple, inexpensive depth charge that is similar to a Hedgehog device — bomblets, perhaps, such as an ASW version of the Mk 20 Rockeye cluster bomb. This would also mean developing a more effective magnetic anomaly detector (MAD) boom/bird to deal with a submarine in this environment. Funny how we seem to need to go back-to-the-future in 21st-century ASW.

Lithium-Ion Batteries

The lithium-ion battery (LIB) is the latest technology being applied to diesel submarines. More than just a much-desired replacement for the standard lead-acid battery (LAB), Japan has been working to perfect the LIB for much of the 21st century.

Clearly, with the launch of the second Taigei ("Big Whale") class submarine, the Hakugei ("White Whale"), a few weeks ago, the JMSDF is comfortable with the performance and safety of the technology; so much so, that it will no longer rely on the cumbersome Stirling engines that provide AIP propulsion for their previous boats, the Sōryūclass.

Indeed, lithium-ion batteries could allow some navies to dispense with all the complexity, weight, and, in some cases, the detectability of AIP machinery altogether. In essence, the LIB technology represents the dream of what a diesel-electric boat could possibly be. Depending on the needs of the navy, they offer their own kind of replacement for AIP technology, allowing for much longer dives than their LAB-equipped brethren, all without the complexity of having a separate AIP propulsion technology on board, although they do have unique fire suppression and other requirements.

Compared to AIP and LAB submarines, LIB cells can also take up considerably less space, allowing for more cells in compartments already allocated for batteries. Or, since space is always at a premium on a submarine, the area planned for an AIP plug can now be used for additional sensors, special operations capability, crew spaces, additional weapons, or even more batteries.
ASW crews love to interrupt a diesel boat that is surfaced or snorkeling to recharge its batteries. A LAB submarine needs, ideally, an uninterrupted half an hour — up to several hours — to obtain a full charge, depending on the quality of the batteries. Forcing the submarine to completely submerge when it has only attained, say, a 36 percent charge creates a difficult environment for the skipper. How long will the ASW force keep me down? Will I be interrupted again? With only a 36 percent charge, can I realistically get away from a determined hunter? If a torpedo is in the water, how long can I maintain speed to evade the weapon?

Unfortunately, “interrupting” a submarine with lithium-ion batteries is very unlikely. LIB cells recharge at a significantly faster rate than LAB cells. They also can discharge a greater amount of energy, which translates into higher speeds, and the batteries will maintain that high level of energy even as the charge is depleted. This allows the skipper to get away from or pursue a threat, even a nuclear submarine — if the conditions are right. Also, the investment a navy makes into lithium-ion technology is rewarded by the fact that the batteries keep most of their fast-charging ability and high-energy output throughout their lives.
LIBs can also be paired with existing AIP technology to dramatically increase the capabilities of these already remarkably capable boats. This is exactly what South Korea is doing with their KSS-III Batch 2 submarines. reports that Moon-hee Jang of Hanwha Defense says the new configuration will last 300 percent longer at full speed and 160 percent longer in cruise mode, also adding:
“Batch-2 submarines will have both AIP propulsion systems and lithium-ion batteries, which will increase the submerged endurance to more than 20 days at sea.”
And it's possible that the AIP system can charge the batteries while submerged. That is a stunning performance boost for a diesel-electric submarine, and the pairing of the technologies offers incredible flexibility that would greatly complicate a submarine hunter's mission.
Finally, a very critical point is made by the authors of this article encouraging the U.S. Navy to have a serious talk with the Japanese regarding LIBs: “All navies are rapidly developing and integrating large fleets of battery-powered [unmanned] submersibles.” As the U.S. Navy pursues unmanned air, surface, and subsurface vehicles, the use of Japanese-developed LIB technology can only enhance their performance and reliability.
Of course, AIP or advanced battery technology alone is not enough for submariners! Advances in propellor-blade technology and hydrodynamic hull designs (which, added to fuel cells’ capability for high speeds, allows for excellent sprint-drift operations), demagnetized hull materials, anechoic coatings, and sensor and weapons capabilities (including the submarine-fired SAM), and I think today’s ASW crews might be *censored*ed.

So, for P75I we are looking for LIB and AIP
There was a time when I would talk about economics ,tech , etc etc. French, German , Korean etc etc.

It's cool, I have done some of it.

But now all I want is to this program start, asap.

We need replacement for Kilos and Type 209.

The program started in 2019.

The field trials will delay things somewhat, but the RFP went out in July last year.

EoIs came out in 2019, which is the program start. This is when SPs are nominated and OEMs are qualified by the MoD. So two Indian companies were chosen, and Sweden and Germany dropped out. Germany dropped out in the RFP stage due to lack of time. Sweden dropped out in the EoI stage complaining about ToT. It's only in the RFP stage that the tie-ups happen, followed by field trials. But I think this time the process has been reversed, with OEMs expected to qualify at sea before the tie-ups. Post which the SP responds to the RFP.

So basically, when SPs get the MoD's RFP, the SPs create RFIs and send it over to the OEMs. Then they hold an internal competition, and this is where the AIP field trials are happening, at least MDL has confirmed this, not L&T. L&T probably doesn't care. Post which selected OEMs get RFPs and a tie-up happens, all this before the SPs respond to the MoD's RFP and the IN makes the shortlist.

MDL seems to be unnecessarily delaying it, and the funny thing is I don't think any of their OEM options have a functional sub with AIP (France, Spain and Russia). While France doesn't seem to have a sub with fuel cell AIP, the Spanish one will be ready only by the end of next year, whereas the Russians claim they have one design in the water already. I am guessing Korea is tying up with L&T as usual. And I don't believe the IN is also expecting field trials. So I get the feeling that if they don't find an OEM with AIP, they will hold the tender up for ransom and force more delays. Which can also easily end up being a ploy to force the IN to go for more Scorpenes.

Anyway, as far as I have understood about the SPM process, the SPs will have already finished the contract process with their OEMs before responding to the RFP. So the bid amount in the RFP is the final cost the forces have to pay. Which means, the minute the cheapest bidder is discovered, the forces can sign on the dotted line immediately, if it meets the MoD's benchmark pricing, or push for a discount on the final price before giving the L2 the opportunity.

Doesn't matter. Only SoKo, France and Spain have the tech we need. So 3 OEMs and 2 SPs.

SoKo's DSME-3000 comes without VLS though, that's a major drawback.
Only SoKo, France and Spain have the tech we need. So 3 OEMs and 2 SPs.
The Spanish design reportedly has weight issues.
SoKo's DSME-3000 comes without VLS though, that's a major drawback.
Given that the DSME 3000s parent design, the KSS 3, has 6-10 VLS cells, it may be safe to assume that the Koreans would have made provisions to modify the final design to fit in VLS cells. Not to mention, the Korean offer is the most proven of the 3.

Also, is there any chance for L&T to win against MDL, given the former's relative inexperience?

And in any case, it will be a surprise if the first submarine is launched within this decade as planned.
France's offer doesn't have AIP. The Spanish design reportedly had weight issues.

France has offered AIP to India.
The SMX 3.0 incorporates the latest digital technologies for improved responsiveness and functionality resulting to operational efficiency and versatility. It has better power management with the use of the Air Independent Propulsion Fuel Cell Second Generation (AIP FC2G) anaerobic propulsion system.

The Spanish will presumably fix whatever issues crop up due to the long gestation period.

In any case there are three OEMs to choose from.

Since the original design upon which its based, i.e. the Dosan Ahn Changho has VLS cells, this design would, most probably, be configurable to accomodate VLS cells.

No, they have officially not offered VLS to India.
We haven’t finalized the exact design for India, but the removal of the VLS cells behind the sail of the submarine will allow for greater flexibility. We will be able to add new features to meet the Indian Navy’s needs. Moreover, there is a possibility that we will offer submarine rescue vessels alongside our subs as part of a large ‘package’ deal.

So only the French are offering VLS. The other two are suspect. One's definitely not offering VLS, while the other hasn't commented on it. The only way VLS will be abandoned is if the IN allows it.

Apart from MDL, who else is bidding from the Indian side? GRSE and CSL have 0 experience in submarine building, HSL has a history of *censored*ing up, and L&T has so far built only the hulls for the Arihant class.

MDL and L&T are the only SPs. The rest are out.

It doesn't matter if L&T has less experience, it's a license production program so it comes with OEM hand-holding. Plus the ToT expectation is only 50%, the rest has to come from the OEM.
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