Indian Nuclear Attack Submarine (Project 77) - Updates & Discussions

[Photon Vish]

Playing around with AI image generation using ChatGPT-5.5 to try and visualize the Project-77 SSN. Here's the WIP result:

View attachment 51783

This is done keeping in mind the latest Sandeep Unnithan report which confirmed the ~10,000T displacement and inclusion of VLS.

====

I started off with this side-on drawing of a Project-885M Yasen-M sourced from the web. The 885M is somewhat similarly sized to our boat (and may have some design influence carried over as well, with emphasis on the may):

View attachment 51784

The only modification I requested at this point was the inclusion of a pumpjet (which is a possibility for P-77, though not yet officially confirmed). That gave me this output originally:

View attachment 51785

View attachment 51786

I then asked all the masts to be removed (representing them in their retracted position) and also added an X-form rudder (again, there's no official indication of P-77 having an X-rudder, I just added it because that's how most new SSNs are turning out at least in the West & also China's Type-095), which ultimately gave me the result you see at the top of this post.

I tried my best to get GPT to change the number of VLS cells from 8 to 12 (but occupying the same amount of space as before) but the outputs were all wrong. Tried Gemini but it can't seem to grasp it either. Maybe my prompt-engineering skills are just trash.

So the VLS compartment remains with 8 hatches, just like on the Yasen for now. Anyone else is free to give it a try if they can speak to AI better than I could.

The next steps would be to try and get it to bring the torpedo tubes closer to the front of the bow (as P77 would most likely have a conformal bow array like on the Astute, and not a spherical array like on Yasen. Judging from the fact we've seen R&D being conducted on CBAs, but nothing on spherical arrays). Oh, and get it to show the diveplanes as well. Will share the updated results if they're any good.

Unfortunately, official graphics of the P77 or S5 may never really appear due to GOI's weird secrecy apprehensions, so we have to settle for these fan-made creations as a visualization tool. Too bad.

Are we compromising on SSN by making it hybrid with SSGN ?

USN or PLAN has much advanced and reliable and every where available ISR, they have large satellite constellation.

Hence for them, guiding AShM to target, anywhere is the world is not difficult.

But for us ? Our ISR is quite poor, we can not guide AShM to target reliably, as we dont have our own large satellite network.

Hence should we focus on smaller SSN, so that they are very menurable, as adding VLS and making it 10000 tonnes makes it bad for menurabality.

Just hunter killer, with amazing speed, menurabality, should be our choice V/S an hybrid SSN+SSGN.

(Offtopic: infact i doubt how are we gonna use 800km brahmos range and >1500km LRAShM range ?

Our AWACS or ISTAR plateform for navy is very low and with limited range, chinese CBG will target our ISR plateform before our ISR plateform even came close to their CBG to track it.

We dont have hundreds of satellite in LEO, so that we can move at the same place on earth within minutes.

LRAShM us hypersonic, and CBG is a moving target, we need hundreds of satellite to reliably target their CBG, or extremely long range ISR plateform.

But we have none )

 

[Batman]

Are we compromising on SSN by making it hybrid with SSGN ?

USN or PLAN has much advanced and reliable and every where available ISR, they have large satellite constellation.

Hence for them, guiding AShM to target, anywhere is the world is not difficult.

But for us ? Our ISR is quite poor, we can not guide AShM to target reliably, as we dont have our own large satellite network.

Hence should we focus on smaller SSN, so that they are very menurable, as adding VLS and making it 10000 tonnes makes it bad for menurabality.

Just hunter killer, with amazing speed, menurabality, should be our choice V/S an hybrid SSN+SSGN.

(Offtopic: infact i doubt how are we gonna use 800km brahmos range and >1500km LRAShM range ?

Our AWACS or ISTAR plateform for navy is very low and with limited range, chinese CBG will target our ISR plateform before our ISR plateform even came close to their CBG to track it.

We dont have hundreds of satellite in LEO, so that we can move at the same place on earth within minutes.

LRAShM us hypersonic, and CBG is a moving target, we need hundreds of satellite to reliably target their CBG, or extremely long range ISR plateform.

But we have none )

I don't think having a 10k ton vs 6k ton submarine is gonna make that much difference in maneuverability anyway, but having a larger nuclear reactor will help us gain unmatched speed and endurance which is a much more important requirement for missions than maneuverability I believe, also heard it may incorporate X shaped rudder for better maneuverability.

US/UK/Russian/Chinese large SSNs/SSGNs (e.g., Virginia ~10k tons, Ohio SSGN conversions, Type 093/095) successfully balance this. A "very small" SSN sacrifices payload, endurance, and versatility.

Hybrid capability adds strategic flexibility (e.g., long-range strikes from stealthy positions). India is also pursuing conventional subs (P-75I) and considering SSGN derivatives from SSBN designs as interim options. Pure hunter-killers alone would limit India's ability to project power against surface fleets

I largely agree with your ISR Limitations and Missile Guidance problem you mentioned unless anyone can correct me. Plans for a 52-satellite military surveillance constellation (SBS-III, by ~2029, with SAR/optical for persistent coverage) and Naval Constellation are underway, but it's not yet at US/China scale.

 

[Parthu]

Are we compromising on SSN by making it hybrid with SSGN ?

USN or PLAN has much advanced and reliable and every where available ISR, they have large satellite constellation.

Hence for them, guiding AShM to target, anywhere is the world is not difficult.

But for us ? Our ISR is quite poor, we can not guide AShM to target reliably, as we dont have our own large satellite network.

Hence should we focus on smaller SSN, so that they are very menurable, as adding VLS and making it 10000 tonnes makes it bad for menurabality.

Just hunter killer, with amazing speed, menurabality, should be our choice V/S an hybrid SSN+SSGN.

(Offtopic: infact i doubt how are we gonna use 800km brahmos range and >1500km LRAShM range ?

Our AWACS or ISTAR plateform for navy is very low and with limited range, chinese CBG will target our ISR plateform before our ISR plateform even came close to their CBG to track it.

We dont have hundreds of satellite in LEO, so that we can move at the same place on earth within minutes.

LRAShM us hypersonic, and CBG is a moving target, we need hundreds of satellite to reliably target their CBG, or extremely long range ISR plateform.

But we have none )

There will be some effect on maneuverability, but nothing too drastic. A ~200 MWth powerplant is sufficient to drive a boat of this size to meet all required speed & maneuverability criteria. All nuclear navies are converging toward this ~10,000T ballpark (+/- 20%) w/ VLS for their contemporary attack submarine requirements. This goes for the Virginia (US), Yasen-M (Russia), SSN-AUKUS (UK/Australia) and Type-095 (China).

France with their Suffren is the only exception. But it's also the only one which has a significantly less powerful reactor (~150 MWth), so there's your reason for why that is so.

As of ISR, you must understand that our P-77s will only be operational by around the late 2030s at the earliest. So you must think on the basis of what we are working toward having by the next ~15 years, not what we have right now. So the SBS Phase-III constellations will be fully implemented by that point.

That said, it's not true that we have no ISR capability at the moment. There are multiple SAR & other ISR-capable satellites in orbit (RISAT series, CARTOSAT-series) that can cover significant portions of the IOR if needed. And these inputs will be used alongside coastal, shipborne & airborne radar inputs, transmitted to command via datalinks/SATCOM and fed to the submarines via VLF & ELF communication facilities in Tamil Nadu (new ones coming up in Telangana as well).

Additionally, watch this video from 9:00 onwards:

Reading between the lines, it would appear that integrating inputs from the 'Fish Hook' SOSUS/IUSS hydrophone array have been integrated into our detection/kill chains (at least as of 2023) as a 'tripwire' against PLAN assets (even subsurface ones) crossing over into the IOR.



There is also talk that the SOSUS network could be extended till Mainland India (somewhere in TN), essentially placing another tripwire for those seeking to cross into the Bay of Bengal (where our INS Varsha submarine pens would be located).

This portion of the array will most likely be our own equipment.

 

[FalconSlayers]

Are we compromising on SSN by making it hybrid with SSGN ?

USN or PLAN has much advanced and reliable and every where available ISR, they have large satellite constellation.

Hence for them, guiding AShM to target, anywhere is the world is not difficult.

But for us ? Our ISR is quite poor, we can not guide AShM to target reliably, as we dont have our own large satellite network.

Hence should we focus on smaller SSN, so that they are very menurable, as adding VLS and making it 10000 tonnes makes it bad for menurabality.

Just hunter killer, with amazing speed, menurabality, should be our choice V/S an hybrid SSN+SSGN.

(Offtopic: infact i doubt how are we gonna use 800km brahmos range and >1500km LRAShM range ?

Our AWACS or ISTAR plateform for navy is very low and with limited range, chinese CBG will target our ISR plateform before our ISR plateform even came close to their CBG to track it.

We dont have hundreds of satellite in LEO, so that we can move at the same place on earth within minutes.

LRAShM us hypersonic, and CBG is a moving target, we need hundreds of satellite to reliably target their CBG, or extremely long range ISR plateform.

But we have none )

An SSN/SSGN would usually carry land-attack cruise missiles for large scale salvo attacks on enemy ground targets in their cells.

 

[South block]

Future ?

 

[Parthu]

Isn't this initial design of P77 ?

I've seen this before, but no way to know for sure if that's the actual design. My take on it is that this is just a generic model that they might be testing - one among many.

To calibrate the procedure more than anything.

As I guessed, this is a generic design they pulled from the web, specifically it seems to be the DARPA SUBOFF, a CFD-ready baseline model that's
widely used by researchers. They (NSTL) made some modifications though (like adding pumpjet).

The same model, but without pumpjet, was used by some Chinese author in a research paper years ago:

https://www.researchgate.net/figure/elocity-distribution-of-the-middle-longitudinal-section-at-typical-times-in-a-period-of_fig1_380483247

NSTL model:



Sail placement, rudder placement, everything is the same. Even the reflection near the stern is the exact same. It's most certainly the DARPA SUBOFF baseline design.

I've found over a decade-old research papers that use the same model (but with other modifications, like a highly blended sail):

https://www.semanticscholar.org/paper/Resistance-performance-of-submarine-under-different-Wang-Cui/be1b1caf374463b58b5ee96db6e8757543dfbd2f

The one important takeaway however is this: we now know for a fact that NSTL is/was certainly engaged in pumpjet research. As the original SUBOFF baseline (pic below) does not come with a pumpjet (or any propulsor for that matter), that is something that NSTL specifically added:

Future ?

View attachment 53073

Yep, that's how OK-650B is configured on a lot of Russian boats (including Akula). The reactor itself (central cylinder in the pic) is called VM-5, the whole package (including the steam generators, pumps etc. around it as seen here) is called the OK-650B.

It is my presumption that CLWR-B2 is 'inspired' by this design. To what extent, nobody can say.

 

[Ashwin]

It is my presumption that CLWR-B2 is 'inspired' by this design. To what extent, nobody can say.

My bet is that this "inspiration" is part of the original Akula (K-152) deal from the late 90s. All coming together now.

 

[RationalGuy]

As I guessed, this is a generic design they pulled from the web, specifically it seems to be the DARPA SUBOFF, a CFD-ready baseline model that's
widely used by researchers. They (NSTL) made some modifications though (like adding pumpjet).

The same model, but without pumpjet, was used by some Chinese author in a research paper years ago:

https://www.researchgate.net/figure/elocity-distribution-of-the-middle-longitudinal-section-at-typical-times-in-a-period-of_fig1_380483247

View attachment 53231

View attachment 53232

NSTL model:

View attachment 53233

Sail placement, rudder placement, everything is the same. Even the reflection near the stern is the exact same. It's most certainly the DARPA SUBOFF baseline design.

I've found over a decade-old research papers that use the same model (but with other modifications, like a highly blended sail):

https://www.semanticscholar.org/paper/Resistance-performance-of-submarine-under-different-Wang-Cui/be1b1caf374463b58b5ee96db6e8757543dfbd2f

View attachment 53234

The one important takeaway however is this: we now know for a fact that NSTL is/was certainly engaged in pumpjet research. As the original SUBOFF baseline (pic below) does not come with a pumpjet (or any propulsor for that matter), that is something that NSTL specifically added:

View attachment 53237



Yep, that's how OK-650B is configured on a lot of Russian boats (including Akula). The reactor itself (central cylinder in the pic) is called VM-5, the whole package (including the steam generators, pumps etc. around it as seen here) is called the OK-650B.

It is my presumption that CLWR-B2 is 'inspired' by this design. To what extent, nobody can say.

I know a person who worked on Arihant class (a supplier for the program) and he didn't say much but he did strongly deny that we outright copied even CLWR B1 from the Soviet subs for Arihant.

Now who am I for him to say the truth, but in my opinion, considering the time and effort we have put into this field, I believe this is more like the Lavi - J10 relationship. A clear "inspiration" from Soviet subs but the major work was done by us.

 

[Bon Plan]

but having a larger nuclear reactor will help us gain unmatched speed and endurance which is a much more important requirement for missions than maneuverability I believe,

The problem of speed is noise.
Modern SSN can't run at more than 15 knots (more or less) in a relative silence. Si the need of a powerfull reactor is relative. It is even more the case in a deterrence sub !
The only interest of high power is to evade a torpedo attack, in a last chance rush because once detected your are nearly already dead.

The Alpha russian SSN were able to run at nearly 40 knots more or less, but can be heard from half the ocean !

endurance : the people will be exhausted well before the reactor...

France with their Suffren is the only exception. But it's also the only one which has a significantly less powerful reactor (~150 MWth), so there's your reason for why that is so.

the french choice is an economic one. Barracuda SSN cost in the 1 billion, where a Virginia cost the double.