[dragracer567]

Originally Posted by ads11

While it seems the bulk of the help came from the UK, I did find it interesting that some Indian expertise was involved in this project. I wonder to what extent any Indian personnel being involved would need to be greenlit at GoI level rather than it being retirees going in an individual consulting capacity.

As far as I am aware, Indian service personnel would almost surely need approval from the GoI to be involved in defense-related activities oversees (unlike Western countries like UK & Australia). The fact that Indian personnel were present should mean tacit support from GoI even though ostensibly they are supporting at a personal capacity.

[V.Narayan]

https://swarajyamag.com/defence/thre...on-with-france

Looks like France is going to help us integrate an AIP power unit with our Scorpene class starting with INS Kalvari later in 2024. It seems DRDO has developed this AIP.

[ads11]

Originally Posted by V.Narayan

https://swarajyamag.com/defence/thre...on-with-france

Looks like France is going to help us integrate an AIP power unit with our Scorpene class starting with INS Kalvari later in 2024. It seems DRDO has developed this AIP.

This has to be the AIP plug that's been doing the rounds on the blogosphere for a while now. Think we have a schematic of it earlier on the thread. I guess it's in Naval Groups interest to see how well it integrates into their design. I imagine as the OEM they still get access to a fair bit of data from the license built boats.

What's more interesting in the announcement is the potential 3 boat follow on order. Question is, wording makes it sound like they'll come from French yards which doesn't do anything for preserving the production base at Mazagon Docks from the Kalvari build programme.

[V.Narayan]

Originally Posted by ads11

What's more interesting in the announcement is the potential 3 boat follow on order. Question is, wording makes it sound like they'll come from French yards which doesn't do anything for preserving the production base at Mazagon Docks from the Kalvari build programme.

Good news is these 3 will be built at Maz Docks Mumbai. How I wish it was 6 or 8 and not 3. 5 out of our 7 Kilo class boats and all 4 HDW's are 40 years old now. That is a lot of age for a pressure hull. Sadly we are being compelled to keep this ageing fleet going because of indecision and lack of budgets in the 1990s and early 2000s.

[V.Narayan]

Indian Navy launches Rs 60,000 crore tender for AIP equipped submarines to be built in India.

https://www.msn.com/en-in/money/tops...a33916ebb&ei=4

With the aim of modernising the country's existing conventional submarine fleet, the Indian Navy has kicked off trials for making highly advanced submarines by floating a Rs 60,000 crore tender. The Rs 60,000 crore contract is to build six stealth submarines equipped with Air Independent Propulsion (AIP) technology, enabling prolonged underwater operations.

The Indian Navy has started trials of the competing teams including Larsen and Toubro and Mazagaon Dockyard. The trials of the German submarine's Air Independent Propulsion system were conducted in Kiel in the last week of March in Germany, defence officials informed India Today. The next series of trials would be held in June at the Spanish Navy facility. Spanish Navantia and India's Larsen and Toubro are partners for this mega project.

This is clearly the most important step in 20 years in the Indian submarine world.

Over the weekend I'll post on the two families of submarines that are most likely in this race.

[ads11]

I mean this is good but I'm confused. If the Kalvari follow on got greenlit using an AIP module, why does it sound like there's a fresh tender with totally new designs being floated? Surely just tack on further orders of the AIP Kalvari.

What am I missing here?

[V.Narayan]

Originally Posted by ads11

I mean this is good but I'm confused. If the Kalvari follow on got greenlit using an AIP module, why does it sound like there's a fresh tender with totally new designs being floated? Surely just tack on further orders of the AIP Kalvari.

What am I missing here?

To tack on an AIP on a Kalvari boat will be a retrofit job - a little bit like taking your ICE Honda City car and retrofitting an EV+ICE hybrid powerpack. Might also require cutting the hull in two and inserting a section to create the extra volume. Can be done but a highly inelegant solution and any cutting and rejoining of a submarine hull is a job fraught with risk. The whole hull every square inch will need to be surveyed with ultrasound devices for microscopic cracks that could rupture explosively at depth.

The new tender represents submarines in my opinion of a half generation beyond the Scorpene ie designed to be long distance EVs from day one without the cut and patch jobs of our example above. The German designs at least has variants in the 3000 tonne category with extraordinary submerged loitering times.

[Gansan]

Just a doubt. If the French subs are so good, why doesn't the French Navy use them at all?

[ads11]

Originally Posted by V.Narayan

To tack on an AIP on a Kalvari boat will be a retrofit job - a little bit like taking your ICE Honda City car and retrofitting an EV+ICE hybrid powerpack. Might also require cutting the hull in two and inserting a section to create the extra volume. Can be done but a highly inelegant solution and any cutting and rejoining of a submarine hull is a job fraught with risk. The whole hull every square inch will need to be surveyed with ultrasound devices for microscopic cracks that could rupture explosively at depth.

True, on the current spec design, the AIP module was to be a retrofit job to existing hulls, I thought there was a follow on order where the AIP module would be integrated into the hull from the onset - thereby negating the justifiable risks associated with cutting an existing pressure hull to add a new module. This was basically the B spec of the Kalvari class order right?

The new tender represents submarines in my opinion of a half generation beyond the Scorpene ie designed to be long distance EVs from day one without the cut and patch jobs of our example above. The German designs at least has variants in the 3000 tonne category with extraordinary submerged loitering times

I guess my confusion and reticence here is to do with timelines and the inevitable delays a fresh Indian defence tender process introduces. If the current Scorpenes are all being brought up to have the domestic AIP, I just feel that maybe in the interests of budget and time constraints it makes sense that we just tack on further Kalvari-B boats so to speak. Sure they're a smaller weight class than this proposed new tender design but it'll likely be cheaper by far too and surely fielding more of the Kalvari boats is in the interests of logistics and the shipbuilding industrial base. By the time additional orders are placed India could be well on its way to multiple decades of operating the type with a robust system for not just spares but yards with expertise in operating the type.

I guess where I'm going with this is the IN's surface vessel template, where they took one hull type and essentially incrementally iterated from it. In the undersea domain the presence of the SSBN project sort of throws that philosophy out the window somewhat but that was driven by strategic needs. For the conventional boat fleet I don't see why the Scorpene platform can't form the genesis point for similar iterative conventional boat classes down the line, building off a nascent but present domestic shipyard base.

But let's hash it out, I want to understand what the differences in the mission profile of these new boats will be from the Kalvari-B spec, ie, what will they be envisioned to do that the AIP equipped boats can't currently offer? Because if we can get 80% of the way with the Kalvari's, then is it worth it from a time, cost, industrial base and force structure view point to add another hull type to the mix?

Presumably the main differences will likely be enhanced range, ability to have some sort of VLS system for lobbing stand off munitions (cruise missiles) and potentially the flexibility to operate special forces modules.

• a) How much further do these new boats need to go on sorties compared to AIP Kalvaris? There's an argument to be made that if being able to chase let's say PLAN boats further out into the IOR or beyond is the aim, then surely that's the remit of the SSN programme boats. But, SSNs are an order of magnitude more expensive than a conventional boat and therefore this could be that cost consideration compromise option. But why then do we not look at forward basing Kalvari boats further out in the IOR (in a scenario where we can afford more of them should we go down that route). With more boats available IN planners would be afforded more flexibility in tasking the boats across the entire purview of the IN's security committments.
• b) Where it breaks down somewhat for the Kalvari is the inclusion of that VLS cells for launching cruise missiles. You'd need to potentially design yet another add on module for this, which again adds time and risk to the existing design, not to mention the Kalvari C-spec now could end up weighing in around that 3000 ton mark for the new boat tender.

Originally Posted by Gansan

Just a doubt. If the French subs are so good, why doesn't the French Navy use them at all?

Think the Marine National opted for an all nuclear fleet like the other two nuclear NATO powers. Never thought about why they'd do it - not like the French to go in lockstep with the Americans or Brits. The French not opting for SSKs is likely a strategic decision as to the make up and roles of their submarine force rather than any other reason. That being said it does raise an oddity in that they have a fairly robust SSK pipeline on offer for export but with no usage domestically.

[dragracer567]

The Indian Navy has finished the first round of trials for the P75I contract. The operational AIP was showcased by both the contenders - the German company TKMS demonstrated the technology at sea in an operational Type 212 submarine while the Spanish Company Navantia showcased this on land though they didn't have it integrated into a boat. The Navy is preparing the report on the trials though many seem to think that the Germans would come out on top. Further, the Indian Navy already operated Type 209 subs. The Germans aren't particularly reliable these days as arms suppliers but then the Spanish have also been doing strange things. If you want a reliable Western arms supplier, stick French though the Americans & Brits (if they make anything these days) are better than they used to be!

This will be interesting and if the recent Naval fighter trials are anything to go by, the Navy should move relatively fast.