P-77 SSN: Indian Nuclear Attack Submarine Project

[mist_consecutive]

Really doubt the claims from Rajat Pandit report saying 10k tons & 190mwt PWR.

If the 190mwt reactor was ready, we wouldn't be considering extension of Arihant class production run. We'd have gone straight to S5 class.

Most likely he confused the S5 itself (widely believed to be between 10-13k tons) with upcoming SSN - which would without doubt be smaller than Arihant, not bigger. We're not going for a SSGN here.

And this is what our SSN will probably look like:

View attachment 12100

Picture from this event:


View: https://x.com/alpha_defense/status/1678784625223798784

I will say go through this tweet thread -


View: https://x.com/Parthu_Potluri/status/1444631861502767109

Second thing this thread failes to mention (coz it is old) is the new Submarine facility created at Vizag has dimensions of being able to produce Virginia-class subs parallely.

 

[Gessler]

I will say go through this tweet thread -


View: https://x.com/Parthu_Potluri/status/1444631861502767109

Second thing this thread failes to mention (coz it is old) is the new Submarine facility created at Vizag has dimensions of being able to produce Virginia-class subs parallely.

I'm the one who made that thread.

There isn't any concrete info to say yet as to which class the new facility is meant for. It could be for the S5s (as they're larger) or it could be for SSNs.

It's also possible they would accommodate subs being built one ahead of the other (that's how Arihants are built at the existing facility, two boats can be fitted out simultaneously. The one that began construction first would be at the rear), which would also explain the length.

 

[darkflame]

I assume the new facility is for the S5-class submarine, while the older one will be used to construct ~6000-ton SSNs after the Arihant-class submarine. A 190 MW reactor seems unlikely since no prototype has been built yet; perhaps they won't build any prototype at all [looking towards full russian assistance]

 

[AYoungBrotchen]

I assume the new facility is for the S5-class submarine, while the older one will be used to construct ~6000-ton SSNs after the Arihant-class submarine. A 190 MW reactor seems unlikely since no prototype has been built yet; perhaps they won't build any prototype at all [looking towards full russian assistance]

On forums and articles scattered here and there, it has been mentioned quite often that the IN is looking at a near copy of the Akula reactor for its SSN. Indeed, it would make sense to equip both the SSN, and the SSBN with the same reactor to drive down the costs.

 

[Gessler]

Not sure if it's 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

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 others saying that the French have indeed parted with the Suffren hull design, 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's indeed the case.

Either way, with a 190MWt reactor (meaning an electrical output of around ~60MWe) 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).

 

[SlayingHell]

Not sure if it's 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:

View attachment 12444
^^ From BARC publication:

http://www.barc.gov.in/presentations/fddir18.pdf

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 others saying that the French have indeed parted with the Suffren hull design, 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's indeed the case.

Either way, with a 190MWt reactor (meaning an electrical output of around ~60MWe) 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).

My worry is about two things 1. Silent Drive at 20 Knots as I don't think 30 Knots or 35 Knots is less priority. Its about Machinery, Turbines, Pumps etc. The Chinese were having trouble with their SSN because they were unable to do Precision Manufacturing on scale of West. We may be in worse position than Chinese in regarding Precision Manufacturing unless we import those from France
2. About Sensors- In regarding both Capability and also Chickening out on a large array. The British Astute class was able to track Virginia Class at longer range than Virginia could track it because of its larger side array. So, I hope they fit on a array that runs entire hull in length and breadth and not small array.

 

[Gessler]

My worry is about two things 1. Silent Drive at 20 Knots as I don't think 30 Knots or 35 Knots is less priority. Its about Machinery, Turbines, Pumps etc. The Chinese were having trouble with their SSN because they were unable to do Precision Manufacturing on scale of West. We may be in worse position than Chinese in regarding Precision Manufacturing unless we import those from France
2. About Sensors- In regarding both Capability and also Chickening out on a large array. The British Astute class was able to track Virginia Class at longer range than Virginia could track it because of its larger side array. So, I hope they fit on a array that runs entire hull in length and breadth and not small array.

1) There is a critical difference though. The Chinese did not have Russian hand-holding in a lot of fields (and now going ahead, possible French assistance). Also, they did not have the benefit of operating & observing an Akula II-class boat and all the noise-mitigation techniques it entails (Akula is still much quieter than any in-service Chinese N-boat). But, how well we managed to absorb all these lessons & techniques remains to be seen.

2) Agreed. With Scorpene in hand, we've gotten a taste for what the extended FoV of flank-array sonars can do wrt situational awareness as opposed to bow-only setups like on all our previous boats. Here's hoping we'll implement that on our SSN.

 

[Aaj Ka Hero]

Not sure if it's 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:

View attachment 12444
^^ From BARC publication:

http://www.barc.gov.in/presentations/fddir18.pdf

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 others saying that the French have indeed parted with the Suffren hull design, 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's indeed the case.

Either way, with a 190MWt reactor (meaning an electrical output of around ~60MWe) 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).

Man, it should be pump jet, I already knew that 10,000 ton story was fishy when I read "as said by source", anyway, if it is new design, then it should be based around pump jet, otherwise it is such a drag.
Regarding hull forging, I think scorpene deal should help there.
Interesting time, not for chowmeins though.
France and India should form an alliance that can show it's power from time to time to 5eyes Anglo-saxons, so that these 5eyes can remain in limit.

 

[Hari Sud]

One good questions stays unanswered in all this thread and that is that 190mw reactor fully operational or is underdevelopment. That is the key to the whole attack submarine project.

 

[Gessler]

Got some further updates from a follow-up conversation:

• Appraently we're indeed going for a SSN with VLS as per the source. He only mentions LACMs though (Nirbhay/ITCM), no AShM.

Just as well, if we're getting a 190MWt reactor, we might as well onboard additional mission sets i.e. long range land-attack.

No info regarding numbers but I personally don't expect too many on a 6k ton boat...maybe in the region of 12-16 missiles, triple- or quad-packed in 4 tubes. Enough to strike a specific target from a survivable platform on short notice but no sustained volleys like a true SSGN a-la converted Ohio or Virginia Block-5.

If we want an SSGN in that league, we're gonna have to wait till S5-class completely takes over the deterrence role and then convert the Arihant Stretch into SSGNs with 5-6 Nirbhay per tube for a total of 40-48 LACMs.

• Oh, and no specifics regarding NEP but says that should be the way to go considering the timeframe in question.

Personally, with around 60MWe on tap, I think we can safely assume that the 35MWe motive setup (Pumpjet-NEP) who's diagrams we've seen earlier (pic below) will become a reality on the SSNs. If not in the first 2, then definitely in the next 4.

For comparison, the Barracuda SSN (5.3k tons) uses a 20MWe NEP setup with a 150MWt LEU reactor.

 

[AGNI 6 ICBM]

Our SSN will depend on design philosophy of P76 & S4 class


View: https://x.com/Manish_K_Jha1/status/1765973135801860329

If navy wants pumpjet even in P76 SSK then high chance of our SSN having pumpjet

Recent news/rumour says that 2 Arihant class and 3 S4 class will be built

So once S5 SSBN's come active then 3 x S4 might be converted into SSGN's with SMART missile and ...so our SSN will not have those bulky SLBM VLS .....

Bulky VLS and its supporting structures effects agility of submarine so they aren't suitable to SSN

what are our upcoming next gen antiship cruise missile ? It's 🕉VISHNU HCM in similar VLS like this



Reactor might be 180-190 MW to maintain Commonality with 6 x S5 SSBN's & upcoming Aircraft carriers....
6 SSN + 6 s5 = 12+ (190 MW Reactors) so cost will go down

recent S5 hydrodyanamic model showed + shaped rudder "similar to borei SSBN" so no X shaped rudder

So conclusions "high probability"

1.Pumpjet propulsion
2.190 MW
3.+ shaped rudder
4.VLS present

Arihant class and S4 class look similar to DELTA (if russian gave any assistance in development)

We were to lease russian SSN in 2019 so my assumption our SSN will look similar to severodvinsk class with pumpjet propulsion (if russians are giving any assistance in development)

 

[fire starter]

Some info regarding our SSN.

1) A new steel has been developed & certified apparently it is more powerful than the existing steels used by France & USA, it will allow submarine to dive at much greater depths.


2) SSN will have plethora of sensors such as.

Conformal bow mounted sonar.



Fiber optic flank array.


Multiple information & processing technologies.



Two types of integrated masts are being developed.

One will house optics, ESM & SATCOM where as another one will have multi function antenna to support wide band communication.


surface surveillance radar.


Underwater navigation system.


View: https://x.com/indiannavy/status/1704314588622381106?t=6aFeiTDxBgM4QN7q-3nvSQ&s=19

 

[fire starter]

Now coming to signature part



Various vibro-acoustic counter measure technologies are being developed in project which includes decoys, Noise Counter measures, C mounts, R Mounts, RAVM-220,CAVM1200, CAVM220, MRM Mk3, Engine Mount and STF based Autonomous mount.

 

[fire starter]

Part 2.

It will also have metamaterial based acoustic reduction.


Active vibration control.


Tuned damper.




Magic tiles.


Coupled with pumpjet & NEP our SSN will have very low acoustic signature probably at the level of french & American submarines.

Hard kill based torpedo defense system will provide full proof protection.


Other capabilities may include under water launched vehicle & drone.

 

[darkflame]

 

[Gessler]

A nearly definitive compilation of everything we know about P77 so far. Quite a bit of information & inference is available here:


View: https://x.com/Parthu_Potluri/status/1861371602736386397

 

[GodEmperorDoom]

A nearly definitive compilation of everything we know about P77 so far. Quite a bit of information & inference is available here:


View: https://x.com/Parthu_Potluri/status/1861371602736386397

No way you need another Turbine based Propulsion after putting a 35MW Motor. The Seawolf class needs 43,000shp/34MW at 9000-Tons to reach 35-Knots. The Astute which is fully NEP need 20-MW at 7000-Tons to reach 30-Knots and they didn't bother with a hybrid setup. Only the French looking to save costs resorted for a Motor and Turbine setup.

 

[Gessler]

No way you need another Turbine based Propulsion after putting a 35MW Motor. The Seawolf class needs 43,000shp/34MW at 9000-Tons to reach 35-Knots.

35MW is the input power. It does not translate into shaft power. And then there's the efficiency problem, 35MW input =/= 35MW output.

The document clearly states it's only expected to drive a forward speed of 25 knots. End of story.

The Astute which is fully NEP need 20-MW at 7000-Tons to reach 30-Knots and they didn't bother with a hybrid setup. Only the French looking to save costs resorted for a Motor and Turbine setup.

Astute is not fully NEP. The turbo-gens it has are a back-up to the conventional setup. Currently, the only NEP boats are Triomphant & Sufrren.

First Submarine To Use New Stealth Technology - Naval News

The Royal Navy’s new Dreadnought Class submarine promises to be the stealthiest yet. The first two boats, HMS Dreadnought and HMS Valiant, are already under construction. They are destined to take over Britain’s nuclear deterrent from the 2030s. They incorporate significant changes in the design...

www.navalnews.com

Dreadnought will be the first British boat with full NEP.

 

[Rynzl3r]

Just an observation of mine. The older S5 model looks similar to the Type 094 SSBNs of PLAN, specifically the hump and transition from hump - upper hull. Any opinions?

 

[SwordOfDarkness]

View attachment 16641View attachment 16642
Just an observation of mine. The older S5 model looks similar to the Type 094 SSBNs of PLAN, specifically the hump and transition from hump - upper hull. Any opinions?

Convergent design I would guess. Its the only way to fit large missiles in small diameter hull.

Ofcourse, due to the poor streamlining, it has acoustic and speed drawbacks. Having a larger hull is the solution, but with cost drawbacks.


IN seems to have accepted the cost of larger sub to have better performance in S5.