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

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Those are S4 and S4* models with different configurations, not S5

No they're not. Addressed it before:

 
Not long enough to carry even 10 slbms

The Arihants (including S4/S4*) carry missiles in a single-file stack, one behind the other, with the side on which the missile hatch is hinged kept alternating. Here you can see it clearly, look at the alternating placement of the hinges (indicated by the white lines):

INS Arihant S-73 & INS Arighat S-74 on November 13, 2020.jpg

With the hatches open, clearly you can see that it's a single-file stack:

EqUQi5nUYAQAsfV.jpg

Whereas S-5 is pretty much guaranteed to have them in a double-file arrangement like this:

USS_Sam_Rayburn_(SSBN-635)_missile_hatches.jpg

So the overall length needed for 12 tubes will actually be lesser than what is needed for 8 tubes in an alternating single-file arrangement like on S4.

The Type-094's arrangement is probably the closest match as it has a similar 6x2 layout as what S-5 is expected to get:

e0zeiuec.jpg
 
Based on the most recent reliable information, the size & shape of the Project-77 SSN program becomes clearer:

What is confirmed by reliable sources so far:

  • It will indeed displace around 10,000T (one figure quoted by an older source states a very specific 9,800T figure). So very much in the league of Russia's Yasen, China's future Type-095 & upcoming AUKUS boats, and significantly bigger than UK's Astute, France's Suffren or the earlier blocks of US' Virginia-class boats.
  • It will be powered by a 190-200 megawatt PWR known as CLWR-B2. A shore-based prototype of which is known to have been in existence at least as of 2018.
  • It will have VLS capability. Described as having "close to a dozen" VLS cells of the 'large' variety, so would be capable of launching likes of BrahMos/future Scramjet-based Hypersonics & possible ASBMs.

What has not been confirmed so far:

  • Whether it will be a single-hulled or double-hulled design.
  • Whether it will have an X-form rudder or conventional rudder/tail planes.
  • Whether Nuclear-Electric Propulsion (NEP), aka Turbo-Electric Drive will be implemented or not.
  • Whether the boat will have a Pump-Jet Propulsor (PJP) or not. The PJP & NEP might be tied to each other, and will have implications on whether we follow the Russian doctrine of speed over stealth or if we choose to go with Western doctrine. This is the most interesting part to look forward to as Pumpjet & NEP is pretty much guaranteed to find application on the S-5 SSBN program, which is in a much more advanced stage than the SSN (first 2 boats already in construction). So we know that whether we put it on the SSN or not will come down to doctrinal choices.

What has not been confirmed, but is extremely likely nevertheless:

  • It will make use of conformal sonars. Especially a Conformal Bow Array (CBA) along with flank arrays integrated into the hull. Provision of towed array will anyway be there.


@Ashwin @Gautam @Rajput Lion @randomradio @suryakiran @Amarante @BMD @Optimist @ShiroBarks
 
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The budget ? Coming from Pmo or MoD annual expenditure

CCS approved $4.8 billion for the first 2 SSNs back in October 2024. The remaining 4 haven't been funded yet. The money will come from the MoD's Navy outlay. PMO will only look after SSBN funding.

That's awesome, so approximately parallel to P-75I. What do they expect the construction timeline to be?

I would expect a first-of-class SSN to take no less than 10-12 years of build, fitting & trials.

So expect first boat to be commissioned by 2038-2040.
 
Based on the most recent reliable information, the size & shape of the Project-77 SSN program becomes clearer:

What is confirmed by reliable sources so far:

  • It will indeed displace around 10,000T (one figure quoted by an older source states a very specific 9,800T figure). So very much in the league of Russia's Yasen, China's future Type-095 & upcoming AUKUS boats, and significantly bigger than UK's Astute, France's Suffren or the earlier blocks of US' Virginia-class boats.
  • It will be powered by a 190-200 megawatt PWR known as CLWR-B2. A shore-based prototype of which is known to have been in existence at least as of 2018.
  • It will have VLS capability. Described as having "close to a dozen" VLS cells of the 'large' variety, so would be capable of launching likes of BrahMos/future Scramjet-based Hypersonics & possible ASBMs.

What has not been confirmed so far:

  • Whether it will be a single-hulled or double-hulled design.
  • Whether it will have an X-form rudder or conventional rudder/tail planes.
  • Whether Nuclear-Electric Propulsion (NEP), aka Turbo-Electric Drive will be implemented or not.
  • Whether the boat will have a Pump-Jet Propulsor (PJP) or not. The PJP & NEP might be tied to each other, and will have implications on whether we follow the Russian doctrine of speed over stealth or if we choose to go with Western doctrine. This is the most interesting part to look forward to as Pumpjet & NEP is pretty much guaranteed to find application on the S-5 SSBN program, which is in a much more advanced stage than the SSN (first 2 boats already in construction). So we know that whether we put it on the SSN or not will come down to doctrinal choices.

What has not been confirmed, but is extremely likely nevertheless:

  • It will make use of conformal sonars. Especially a Conformal Bow Array (CBA) along with flank arrays integrated into the hull. Provision of towed array will anyway be there.


@Ashwin @Gautam @Rajput Lion @randomradio @suryakiran @Amarante @BMD @Optimist @ShiroBarks
That's great. I hope NEP & Pumpjet Propulsion are included in it. In future number of these SSN should be increased beyond the proposed number.
 
  • Whether Nuclear-Electric Propulsion (NEP), aka Turbo-Electric Drive will be implemented or not.
  • Whether the boat will have a Pump-Jet Propulsor (PJP) or not. The PJP & NEP might be tied to each other, and will have implications on whether we follow the Russian doctrine of speed over stealth or if we choose to go with Western doctrine. This is the most interesting part to look forward to as Pumpjet & NEP is pretty much guaranteed to find application on the S-5 SSBN program, which is in a much more advanced stage than the SSN (first 2 boats already in construction). So we know that whether we put it on the SSN or not will come down to doctrinal choices.

We did see the 35 MW motor EOI. The EOI clearly stated that this motor is to be paired with a pumpjet propulsor. EOI had weight & shaft length of pumpjet propulsor. It also had aft & fwd bulkhead sizes, proposed motor component size data. IN was certain about pumpjet propulsor before the motor development started.

The fwd bulkhead is 11m in dia. This would be equivalent to the max length of missiles it can accommodate. The LR-AShM is 13 m in length, going to need a smaller booster if these missiles are to be mounted on to these subs.

It will have VLS capability. Described as having "close to a dozen" VLS cells of the 'large' variety, so would be capable of launching likes of BrahMos/future Scramjet-based Hypersonics & possible ASBMs.
How large are we talking? 1 Brahmos per VLS cell large? Or Arihant class like large (3-4 Brahmos sized missiles per tube)?

If it is the former that would be disappointing. If later, that would be great. 12 VLS cells x 3 missiles per VLS = 36 missiles in VLS. Then 25-30 charges for the torpedo magazine.

Given these subs are a decade away, it needs to have this VLS setup to be relevant in the future threat scenario.

What has not been confirmed, but is extremely likely nevertheless:

  • It will make use of conformal sonars. Especially a Conformal Bow Array (CBA) along with flank arrays integrated into the hull. Provision of towed array will anyway be there.
Yep. We will also see the non-hull penetrating integrated optronics mast.
 
The Arihants (including S4/S4*) carry missiles in a single-file stack, one behind the other, with the side on which the missile hatch is hinged kept alternating. Here you can see it clearly, look at the alternating placement of the hinges (indicated by the white lines):

View attachment 51850

With the hatches open, clearly you can see that it's a single-file stack:

View attachment 51851

Whereas S-5 is pretty much guaranteed to have them in a double-file arrangement like this:

View attachment 51852

So the overall length needed for 12 tubes will actually be lesser than what is needed for 8 tubes in an alternating single-file arrangement like on S4.

The Type-094's arrangement is probably the closest match as it has a similar 6x2 layout as what S-5 is expected to get:

View attachment 51853

Type 094 is smaller than our upcoming SSN. S5 will be about 50% heavier.
 
That's great. I hope NEP & Pumpjet Propulsion are included in it. In future number of these SSN should be increased beyond the proposed number.

I had said way back that eventually we'll need 12-18 SSNs. The recent Sandeep Unnithan report also says that up to 12 SSNs could be needed. Let's hope we'll pursue a follow-on 6 boats after the first 6. We're certainly building up the infrastructure needed for producing a large number of hulls if needed: Project-76 Indigenous Diesel-electric Submarine (SSK) Program

We did see the 35 MW motor EOI. The EOI clearly stated that this motor is to be paired with a pumpjet propulsor. EOI had weight & shaft length of pumpjet propulsor. It also had aft & fwd bulkhead sizes, proposed motor component size data. IN was certain about pumpjet propulsor before the motor development started.

The fwd bulkhead is 11m in dia. This would be equivalent to the max length of missiles it can accommodate. The LR-AShM is 13 m in length, going to need a smaller booster if these missiles are to be mounted on to these subs.

Yea, I remember that document. But given the configuration changes we're seeing in N-sub programs (the evolution of S-5's design is insane) I think we can't call it yet. It's also possible we might go for a staggered technology-insertion (first 2 boats without NEP, last 4 with it).

If you ask me to bet on it, I'd say all P-77s and all S-5s will have NEP + PJP, but I'm just being ultra-conservative with my statements is all. I just hate to be disappointed.

How large are we talking? 1 Brahmos per VLS cell large? Or Arihant class like large (3-4 Brahmos sized missiles per tube)?

If it is the former that would be disappointing. If later, that would be great. 12 VLS cells x 3 missiles per VLS = 36 missiles in VLS. Then 25-30 charges for the torpedo magazine.

Given these subs are a decade away, it needs to have this VLS setup to be relevant in the future threat scenario.

Don't know for sure, but the way Sandeep describes them in that video (quoted as being able to carry ballistic missiles), I'm assuming they'll be of the latter type i.e. can take multiple BrahMos-sized rounds per cell.

I think the overall size of the boat holds the key - it's not clear if 9800T is the surfaced or submerged displacement, but typically when Indian media talks about N-sub displacement they're always referring to the surfaced figure. 9800T surfaced will make the P-77 even heavier than Yasen/Yasen-M which displace around 8600-8800T surfaced.

...and Yasen carries 8 x of those large VLS (which can take 4 x Kalibre/Oniks per cell). So P-77 having 'close to a dozen' (let's say 10-12) of that kind of VLS sounds very feasible given it could be a bigger vessel than Yasen overall.

Yep. We will also see the non-hull penetrating integrated optronics mast.

Dang, forgot about that. Yea, that'll be a given.

Type 094 is smaller than our upcoming SSN. S5 will be about 50% heavier.

Yea, I just mentioned the 094 as I couldn't get a nice illustrative picture of a 6x2 missile tube array anywhere else. The Dreadnought is probably a closer comparison.

Though our missile tubes will have to be bigger than any of those boats as we have to accommodate 2.4m-diameter SLBMs compared to JL-2/3's 2.0m or the Trident-IID5's 2.11m. The Typhoon's tubes are probably the closest match in terms of diameter (R-39 Rif was 2.4m). Of course all the figures are before we take the missile container into account, so the tubes will have to be bigger than that.

Ohio's were 2.2m as far as I could gather. Probably same for Columbia & Dreadnought unless they're making space for possible future missiles.
 
Yea, I just mentioned the 094 as I couldn't get a nice illustrative picture of a 6x2 missile tube array anywhere else. The Dreadnought is probably a closer comparison.

Though our missile tubes will have to be bigger than any of those boats as we have to accommodate 2.4m-diameter SLBMs compared to JL-2/3's 2.0m or the Trident-IID5's 2.11m. The Typhoon's tubes are probably the closest match in terms of diameter (R-39 Rif was 2.4m). Of course all the figures are before we take the missile container into account, so the tubes will have to be bigger than that.

Ohio's were 2.2m as far as I could gather. Probably same for Columbia & Dreadnought unless they're making space for possible future missiles.

Ah, I thought you were referring to the hump-design based on previous posts.

But yeah, 12 is comparatively unique compared to others.