Indian Nuclear Attack Submarine (Project 77) - Updates & Discussions
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Should be submerged. I doubt our sub is gonna be larger than Yasen, and that's 8500+T surfaced. So my guess would be 7500T (+/- 500T) surfaced.
We need the length and beam numbers to put this to rest.
Seawolf is interesting. Both subgroups have a massive 12 m beam compared to Virginia, but the first 2 smaller subs max out at 9100T surfaced at 108 m length and the third sub is 138 m long but manages 12500T. Virginia B5 sits in between with these 2 subgroups, but the smaller 10 m beam means it maxes out at 10500T.
It's also possible the number released is fake or confused with the S5 class. Gotta wait for Sandeep Unnithan's article.
The number released are probably true....
Yasen Severodvinsk is around 9500 tonne surfaced.... Later Yasen-M class which are smaller have lower displacement.
India in all likely going for multi role capability both SSN & SSGN here. Higher displacement could also be due to more advance technologies which probably will go into this sub.
It's possible. Plus bigger size is easier to develop.
USN's SSN-X is also expected to be Severodvinsk class. And SSN-AUKUS is advertised to be above 10000T too.
I think I gotta agree with you.
@mamiam23 The magazine Mer&Marine has just published (11.Oct.) a long and very interesting article-report on board the Dugay-Trouin, second SSN of the Suffren class. I am not reproducing it in full because it would be off-topic here, however it addresses answers to the questions you are asking yourself about discretion. Excerpt:
The Bravo section then houses the "electric vertical", with all the main electricity distribution panels and in the depths one of the two battery banks of the building (the other is at the front), while the Charly section is that of the nuclear boiler room. Designed by TechnicAtome, it produces steam which turns two Thermodyn-Jeumont turbo-alternators generating electricity stored in the form of energy in the batteries, which then power two electric propulsion motors supplied by Exail (ex-ECA). These MEPs drive via a reducer the shaft line at the end of which is the "pump-propeller", a shrouded propeller specially designed to reduce the effects of cavitation, these air bubbles created by mixing the water which are a major source of acoustic indiscretion. The submarine therefore benefits from electric propulsion, in particular for tactical speeds, which makes it very quiet. But its propulsion architecture is hybrid, with another mode for evolving at the highest speeds. "In this case, it is a mechanical drive, we have a third turbine that is directly connected to the reducer and the shaft line," says the commander. In this case, the vessel is obviously less discreet. But the challenge is not so much, then, to be silent as to be able to reach a remote area at high speed. (…) /deepl
Full paper:
Duguay-Trouin : à bord du nouveau sous-marin nucléaire d’attaque français | Mer et Marine
Increased acoustic discretion thanks to a larger size than the Rubis
(…) At the new dock of the Brest naval base specially designed to accommodate the Suffren-class SSNs, where we found it, the Duguay-Trouin is imposing. "I didn't think it was that big," sighs an officer, used to the Rubis and who is discovering the beast for the first time. It must be said that the new French submarines are significantly larger than their elders. While the Rubis measure 73.6 meters long by 6.4 meters in diameter and have a displacement of 2,670 tons when submerged, their successors have a length of almost 100 meters, a diameter of almost 9 meters and a displacement of more than 5,000 tons under the surface of the water. "It is almost twice as big as the first-generation SSNs. This larger size allows for a lot of things, including gains in terms of acoustic discretion," explains Commander Pierre. An essential aspect for a submarine, whose efficiency and survivability depend precisely on this factor. The vessel must in fact be as quiet as possible to avoid being detected by an adversary, this discretion also improving the performance of its own listening means and therefore its ability to detect an enemy. "The indiscretions come in particular from the machines that vibrate and must not be in communication with the thick hull to prevent these vibrations from radiating outwards and being detected. To do this, the machines are placed on pads that absorb the vibrations, the pads being fixed to a frame that is itself decoupled from the hull". Rotating machines, pumps, auxiliaries... everything that can make noise is isolated from the decks and bulkheads, via these elastic pads, a second "barrier" being obtained from the fact that the equipment itself is integrated on suspended cradles isolated from the hull.Legacy of the Le Triomphant-class SSBNs
This architecture comes directly from the four Le Triomphant-class ballistic missile submarines (SNLEs), commissioned between 1997 and 2010 and which marked a major advance for the French fleet in terms of acoustic discretion. "It takes up a considerable amount of space, hence the increase in the size of the Suffren to allow them to have the highest standards in terms of acoustic discretion. But we are not as big as the Triomphants (the French SNLEs measure 138 meters long by 12.5 meters in diameter and have a displacement of more than 14,000 tons when submerged, editor's note). However, there have been technological improvements over the past 25 years, for example on elastomer pads and new absorbent materials." Improvements that make it possible to obtain equivalent results, or very close ones, by optimizing space.The propulsion system
The Duguay-Trouin has three decks (from 1 to 3 from bottom to top) and five sections (Alfa, Bravo, Charly, Delta and Echo from rear to front), separated by bulkheads and watertight doors. The Alfa section houses the MAM (Motor Engine Module) with in particular three turbines, two electric propulsion motors (MEP), the shaft line and the steering gear mechanisms, consisting of four “X” shaped bars. The latter allow for greater maneuverability, particularly at very low speeds, compared to the traditional “+” stern rudders. Unlike previous French submarines, the diving bars are no longer on the bulkhead but integrated into the forward third and foldable into the hull, so as not to impact the submarine’s hydrodynamics when it is submerged. This is also a guarantee of discretion.The Bravo section then houses the "electric vertical", with all the main electricity distribution panels and in the depths one of the two battery banks of the building (the other is at the front), while the Charly section is that of the nuclear boiler room. Designed by TechnicAtome, it produces steam which turns two Thermodyn-Jeumont turbo-alternators generating electricity stored in the form of energy in the batteries, which then power two electric propulsion motors supplied by Exail (ex-ECA). These MEPs drive via a reducer the shaft line at the end of which is the "pump-propeller", a shrouded propeller specially designed to reduce the effects of cavitation, these air bubbles created by mixing the water which are a major source of acoustic indiscretion. The submarine therefore benefits from electric propulsion, in particular for tactical speeds, which makes it very quiet. But its propulsion architecture is hybrid, with another mode for evolving at the highest speeds. "In this case, it is a mechanical drive, we have a third turbine that is directly connected to the reducer and the shaft line," says the commander. In this case, the vessel is obviously less discreet. But the challenge is not so much, then, to be silent as to be able to reach a remote area at high speed. (…) /deepl
Full paper:
Duguay-Trouin : à bord du nouveau sous-marin nucléaire d’attaque français | Mer et Marine
Size comparison between Severodvsink & Virginia SSN/SSGN.....displacement shown are when submerged.
Everyone is going bigger..... US future SSN will be 11% bigger than seawolf class when comes to displacement....... 9,800 tonne surfaced displacement will make our SSN not just bigger than Severodvsink in size but also future US Navy SSN.
So we've developed our own Pumpjet propulsion for SSNs. No wonder why our great European friends are "sincerely" offering their help to us
"Developed" means that it has already been tested successfully in some form. We dont have any submarine with pumpjet. Nothing validated.So we've developed our own Pumpjet propulsion for SSNs. No wonder why our great European friends are "sincerely" offering their help to us
If this is the bar for developed then we have lasers, rail guns and EMALS and what not.
Extrapolating from the difference in unit cost - Rs 16,000 crore reported by Sandeep Unnithan (2021) and the latest figure of Rs 20,000 cr (CCS approved figure of Rs 40,000 cr/2) - we can be fairly certain the SSN has gotten around 20%-30% bigger in size.
Infra costs should be minimal considering SBC has been running for decades.
India's nuclear sharks
A long-delayed project nears CCS clearance even as India's submarine force gets long in the tooth. Why the N-powered attack submarine project has taken so long
Whenever we start our own program, we are offered an alternative by one or the other FOEM.
Even looking down on the inflation front, mere high LD provision (~ 5-15% ) and 18% GST rate is enough for the cost to soar.Extrapolating from the difference in unit cost - Rs 16,000 crore reported by Sandeep Unnithan (2021) and the latest figure of Rs 20,000 cr (CCS approved figure of Rs 40,000 cr/2) - we can be fairly certain the SSN has gotten around 20%-30% bigger in size.
Infra costs should be minimal considering SBC has been running for decades.
India's nuclear sharks
A long-delayed project nears CCS clearance even as India's submarine force gets long in the tooth. Why the N-powered attack submarine project has taken so longwww.indiatoday.in
Great news. Initially I thought that we shall ask France to transfer technology when we Nuke Sub deal.
France offered collaboration on nuclear submarine. No actual report is saying they offered pumpjet. So, its a Straw man.
Probably not appropriate to share the DMs here but word from a well-established source who reported on N-sub program for over a decade is this:
The bit about the SSN having 190MWt reactor is correct. However, 10k ton displacement figure is wrong - it's closer to 6k tons.
Now, this is my further analysis based on what he said:
So it would seem BARC has indeed fully absorbed the production-engineering knowledge of the OK-650B PWR that our Akula crews trained on. There were hints all the way back in 2018 that a land-based version of the CLWR-B2 reactor (Indianized OK-650) was under some stage of construction and/or limited operation by that time itself:
^^ From BARC publication:
Secondly, the bit about it being around 6k tons leads me to believe that we need to entertain the possibility of an entirely new hull design at this point. Because Arihant itself is believed to be 6k tons (the Stretch variant probably 7k) and with the missile silo section removed there's no way an SSN design based around the same bulkheads would also displace the same amount.
I think we cannot rule out that our SSN is going to be Barracuda/Suffren-sized. There are other offline sources saying that the French have indeed parted with the hull design of the Barracuda itself (all those visits to Naval Group by Indian Navy officials probably weren't for nothing), just withholding the reactor tech. But that's not an obstacle because our HEU-based program is incompatible with their LEU ecosystem anyway. However this would also entail us having to relearn a lot of stuff wrt hull-forging as we'd be going from Soviet-style double-hull to Western-style single-hull construction.
We'll see if that indeed turns out to be the case.
Either way, with a 190MWt reactor (meaning a total possible electrical output of around ~60MWe assuming 33% efficiency) on a 6k ton boat, expect an SSN that is P-O-W-E-R-F-U-L. Will run circles around any existing Chinese N boat, plus with lots of power on tap to operate some truly powerful next-gen sensors. A real hunter-killer.
Oh, and there's no confirmation from that source regarding pumpjet status, at least for the first 2. Fingers crossed.
Fingers crossed about NEP as well (didn't ask him about that though).
P.S.
There are also people saying we'll be going for a 150MWt reactor for SSN. If that turns out to be true, it would probably mean it's still the same CLWR-B2 reactor (because I sincerely don't think B1 can be scaled that high), just in a lower state of tune so to speak. A reduced output like this would probably have to be a result of the SSN's hull not having enough space for the kind of shielding or heat-exchanging capacity that the reactor would require for the full 190MW thermal output. It probably serves to know that the K15 reactor France uses on Suffren is also 150MWt.
The S5-class SSBN would however have all the space it needs for full 190MWt. Again, we'll see how it goes.
@Ashwin @Gautam
The bit about the SSN having 190MWt reactor is correct. However, 10k ton displacement figure is wrong - it's closer to 6k tons.
Now, this is my further analysis based on what he said:
So it would seem BARC has indeed fully absorbed the production-engineering knowledge of the OK-650B PWR that our Akula crews trained on. There were hints all the way back in 2018 that a land-based version of the CLWR-B2 reactor (Indianized OK-650) was under some stage of construction and/or limited operation by that time itself:
^^ From BARC publication:
Secondly, the bit about it being around 6k tons leads me to believe that we need to entertain the possibility of an entirely new hull design at this point. Because Arihant itself is believed to be 6k tons (the Stretch variant probably 7k) and with the missile silo section removed there's no way an SSN design based around the same bulkheads would also displace the same amount.
I think we cannot rule out that our SSN is going to be Barracuda/Suffren-sized. There are other offline sources saying that the French have indeed parted with the hull design of the Barracuda itself (all those visits to Naval Group by Indian Navy officials probably weren't for nothing), just withholding the reactor tech. But that's not an obstacle because our HEU-based program is incompatible with their LEU ecosystem anyway. However this would also entail us having to relearn a lot of stuff wrt hull-forging as we'd be going from Soviet-style double-hull to Western-style single-hull construction.
We'll see if that indeed turns out to be the case.
Either way, with a 190MWt reactor (meaning a total possible electrical output of around ~60MWe assuming 33% efficiency) on a 6k ton boat, expect an SSN that is P-O-W-E-R-F-U-L. Will run circles around any existing Chinese N boat, plus with lots of power on tap to operate some truly powerful next-gen sensors. A real hunter-killer.
Oh, and there's no confirmation from that source regarding pumpjet status, at least for the first 2. Fingers crossed.
Fingers crossed about NEP as well (didn't ask him about that though).
P.S.
There are also people saying we'll be going for a 150MWt reactor for SSN. If that turns out to be true, it would probably mean it's still the same CLWR-B2 reactor (because I sincerely don't think B1 can be scaled that high), just in a lower state of tune so to speak. A reduced output like this would probably have to be a result of the SSN's hull not having enough space for the kind of shielding or heat-exchanging capacity that the reactor would require for the full 190MW thermal output. It probably serves to know that the K15 reactor France uses on Suffren is also 150MWt.
The S5-class SSBN would however have all the space it needs for full 190MWt. Again, we'll see how it goes.
@Ashwin @Gautam
This is exactly why i said 10,000 ton could be a mistake.
We can be certain about two key factors: the new shared reactor (S5 & SSN) and the limitations in the size of the existing yard for constructing bigger designs. SSBNs do not need much speed as their responsibility is to carry missiles and hide, while SSNs, on the other hand, need to be speedy, requiring a huge power reserve. If S5 and SSN have the same reactor, then the SSN has to be smaller to take advantage of the power.
Also, it doesnt make sense to go for outlandishly expensive and big SSN when we are building one for the first time. We are going for true SSBN design only after we have mastered a mini design.
The approved funds appear to be expensive at ~$2.5 billion per boat. This cost could account for the 15-year inflation and potential foreign "consultancy" payments, not due to the fact that we are constructing a larger boat than originally anticipated. Great news that we have already sorted out the reactor tech.
Excellent.Probably not appropriate to share the DMs here but word from a well-established source who reported on N-sub program for over a decade is this:
The bit about the SSN having 190MWt reactor is correct. However, 10k ton displacement figure is wrong - it's closer to 6k tons.
Now, this is my further analysis based on what he said:
So it would seem BARC has indeed fully absorbed the production-engineering knowledge of the OK-650B PWR that our Akula crews trained on. There were hints all the way back in 2018 that a land-based version of the CLWR-B2 reactor (Indianized OK-650) was under some stage of construction and/or limited operation by that time itself:
^^ From BARC publication:
http://www.barc.gov.in/presentations/fddir18.pdf
Can you find a cross-section view of the OK-650B or the CLWR-B2? Just need to check something.
So, no VLS?
Isn't the Suffren/Baracudda less than 5000 tons surfaced? If we are going for a Suffren/Baracudda based design with 6k surfaced displacement, won't it need to be stretched?
I am asking if there is any scope for a VLS plug in there.
I agree, power to weight of such a boat would be incredible. But are we even working on any next gen sensors that can make use of this additional power? I cannot think of any new sonar that is under-development.
The only pumpjet prototype we have built is that with a NEP. So, either we get NEP pumpjet or we get open screw propeller driven by a steam turbine shaft.
I wonder where that 9,800-ton figure came from. Oddly specific number.
Unfortunately, no.
Check out this document though:
There's no cutaway of OK650 but there are diagrams of a few other Afrikantov designs that might be related. You might find what you're looking for.
I've asked about VLS & NEP. Will update if I get an answer.
I reckon anything feeding into overarching ATV program would be secret. That said, this reactor should at least give us the room to accommodate such sensors, assuming we are developing them.
Either alone or in cooperation with Thales.
We are developing the SSN in 3 different phases with each phase having 02 boats so who knows if with each phase we might see the increase in displacement or not. There is huge possibility though. The feedback from Navy and the requirements of the time might see increased size and displacement as well.
Are we actually going to know what's part of the collaboration?
Reports say DRDO has devleoped it for both P76 and SSN.