Project 77 Alpha Class SSN: News & Discussion

[Aditya G]

Chakra-II had a lot of maintainability problems, with was making it operationally very costly to manage. Cheaper to just lease a new submarine.

Chakra-III is reportedly coming in with a number of Indian sub-systems on-board. So like a test bed for the first pair of Project 75/77 SSNs.

I don't know how feasible Chakra-II (Nerpa) is. The last I heard she was docked in Russia, but reportedly awaiting disposal. Used extensively by the Indian navy during the 10 year lease period.

Do we know which sub is the Chakra-3? Last reports suggested Bratsk but that was denied by Saturnax

[Snehashis]

Do we know which sub is the Chakra-3? Last reports suggested Bratsk but that was denied by Saturnax

K-331 Magadan will most probably become Chakra-3.

On 10 October 2019, a decision was made instead of K-322, India plans to lease K-331 Magadan.[12] The transfer, after repair and modernization, to the lease of the Indian Navy was scheduled for 2022.

[Rakesh]

https://x.com/livefist/status/1886404968711962842 ---> Much-needed clarity as India drops '3 aircraft carrier' plans, clears decks for BIG focus on homegrown nuclear-powered attack submarines.

3-Carrier Plan Shelved, India Wants Sharks ASAP
https://www.livefistdefence.com/3-carri ... arks-asap/
03 Feb 2025

The decision to throw everything at the SSN program signals a major doctrinal shift. Nuclear submarines provide greater stealth and endurance, making them more effective for power projection and deterrence in the Indo-Pacific region. Unlike aircraft carriers, SSNs are less vulnerable to anti-ship missiles and asymmetric threats such as drones and hypersonic weapons.

The green-lighting of India’s SSN project suggests that naval planners see submarines as a more cost-effective and survivable option for securing sea lanes and countering China’s expanding naval presence. This aligns with global trends where many modern navies are increasing their submarine fleets while reconsidering the viability of large aircraft carrier groups. With India commissioning its second nuclear-powered ballistic missile submarine (SSBN) INS Arighaat in August last year, there is confidence that the SSN program will build on the difficult gains made over decades on those programs.

[Rakesh]

https://x.com/livefist/status/1886404968711962842 ---> Much-needed clarity as India drops '3 aircraft carrier' plans, clears decks for BIG focus on homegrown nuclear-powered attack submarines.

https://x.com/Firezstarter1/status/1886472730121261567 ---> Prioritisation for once.

[Ankit Desai]

India clears two nuclear-powered attack submarines armed with supersonic, hypersonic missiles

India has cleared the development of two nuclear-powered attack submarines under Project-77, with L&T playing a key role. These next-gen submarines will be armed with BrahMos and upcoming hypersonic missile systems, enhancing India’s maritime strike capabilities.

-Ankit

[SRajesh]

Admiral Saar
The above ones are they true blue home grown variety or
are they Elaichi Souffle!!

[Rakesh]

Elaichi Souffle Saar

My post from last September...

Below is *MY* Guess:

Indian Origin Kit - Reactor + Sonar (updated USHUS) + Weapons (Varunastra Torpedo; BrahMos-S, SLCM, etc in VLS Cell)..
French Origin Kit - Propeller Design, Pump Jet Propulsion, Hull Design, X-Shaped Rudder, Combat Management System, etc, etc, etc....

[SRajesh]

^^
La vache!!!
Aprenons le français!!

[Rakesh]

Le français est facile à apprendre!

[Rakesh]

The lead boat in the Suffren Class - the Suffren - visited India in January 2025. Port calls like these are not just mere visits. You can clearly see the X-shaped rudder in the pictures below.

https://x.com/IN_WNC/status/1875584933663854654 ---> French Carrier Strike Group, which includes nuclear-powered aircraft carrier FNS Charles de Gaulle along with its escort vessels, a frigate, a submarine and supply ships, is visiting Goa from 03 - 09 Jan 25. The purpose of this visit is to enhance interoperability, foster mutual understanding & strengthen ties between the two navies.

[Prem Kumar]

Below is *MY* Guess:

Indian Origin Kit - Reactor + Sonar (updated USHUS) + Weapons (Varunastra Torpedo; BrahMos-S, SLCM, etc in VLS Cell)..
French Origin Kit - Propeller Design, Pump Jet Propulsion, Hull Design, X-Shaped Rudder, Combat Management System, etc, etc, etc....

Rakesh: any particular reason why we need French assistance for propeller, hull design or CMS? We have the Arihant class which was homegrown

Is it because we want the latest tech from the French to jump a few generations?

[maitya]

Below is *MY* Guess:

Indian Origin Kit - Reactor + Sonar (updated USHUS) + Weapons (Varunastra Torpedo; BrahMos-S, SLCM, etc in VLS Cell)..
French Origin Kit - Propeller Design, Pump Jet Propulsion, Hull Design, X-Shaped Rudder, Combat Management System, etc, etc, etc....

Rakesh: any particular reason why we need French assistance for propeller, hull design or CMS? We have the Arihant class which was homegrown

Is it because we want the latest tech from the French to jump a few generations?

I can be completely wrong, and Admiral obviously will know better, but isn't the propeller rpm regimes vastly different between SSNs and those on SSBNs?
And since rpm heavily influences amount of Cavitation (primary source of noise, impacting stealth), so careful propeller design is paramount, and needs to be tailored for the relevant use-case (dash-with-somewhat-compromise-to-stealth of SSNs vs stealth-and-only-stealth of SSBNs design considerations).

Also IIRC, there was some news-item, quite a few months back wrt indigenous capability of pump-jet tech etc - not sure what happened to that.

[Prem Kumar]

Our indigenous ASW Shallow Water Craft that was commissioned recently, uses a water-jet propulsion. Wiki tells me there is a difference between water-jet and pump-jet propulsion

[Rakesh]

Below is *MY* Guess:

Indian Origin Kit - Reactor + Sonar (updated USHUS) + Weapons (Varunastra Torpedo; BrahMos-S, SLCM, etc in VLS Cell)..
French Origin Kit - Propeller Design, Pump Jet Propulsion, Hull Design, X-Shaped Rudder, Combat Management System, etc, etc, etc....

Rakesh: any particular reason why we need French assistance for propeller, hull design or CMS? We have the Arihant class which was homegrown

Is it because we want the latest tech from the French to jump a few generations?

I made the above assumptions, based on the idea that Naval HQ wants to induct these boats sooner than later. Going at it alone, while eventually bearing fruit, will take time and time is not something the Indian Navy has. The Arihant Class will not be the baseline design for the upcoming pair of Project 77 vessels. The former is a SSBN, while the latter is a SSN. Design inputs will come from experience with the Akula Class (INS Chakra-II {ex-Nerpa} and the rumoured INS Chakra-III) and from France (Suffren Class).

* Propeller design is part of the pump jet propulsion. That entire critical section of the submarine is a science unto itself. Please see my post right below (replying to Maitya-ji).

* Hull design is crucial for a SSN (or any submarine) to maintain her stealthiness (i.e. acoustics). Any help that India gets in this area will go a long way. French submarines are eerily quiet and excelled only by the US.

* CMS is an area that India is working on her own. The three upcoming Scorpene boats (they reportedly go by the term Project 75AS) are expected to have an indigenious CMS system. Remains to be seen if such a system finds its way onto the P77 program. See here --->

India – France Joint Statement on the visit of Shri Narendra Modi, Hon’ble Prime Minister of India to France (10-12 February 2025)
https://www.mea.gov.in/bilateral-docume ... ruary+2025
12 Feb 2025

Both leaders commended progress in collaboration in construction of Scorpene submarines in India, including indigenization, and in particular the work carried out with a view to the integration of DRDO developed Air Independent Propulsion (AIP) into P75-Scorpene submarines and the analyses conducted regarding the possible integration of the Integrated Combat System (ICS) into the future P75-AS submarines.

[Rakesh]

I can be completely wrong, and Admiral obviously will know better, but isn't the propeller rpm regimes vastly different between SSNs and those on SSBNs? And since rpm heavily influences amount of Cavitation (primary source of noise, impacting stealth), so careful propeller design is paramount, and needs to be tailored for the relevant use-case (dash-with-somewhat-compromise-to-stealth of SSNs vs stealth-and-only-stealth of SSBNs design considerations).

Spot On! Propeller design is a carefully guarded secret, as revealing that puts the entire boat at risk for detection. Cavitation is a submarine's Achilles heel and serious maintenance is undertaken to ensure that the propeller operates in peak performance. SSBNs move silently under the seas and thus her rpm is not operated at high speeds, unlike a SSN which is a hunter killer.

Some reading / video material for Prem Kumar-ji....

Veteran Sonarman Explains Why Pump-jets Are Superior To Props On Modern Submarines
https://www.twz.com/31708/veteran-sonar ... submarines
03 Jan 2020

Submarine Secrets: A Deep Dive into Propellers and Pump Jets
https://christianbaghai.medium.com/subm ... 68fd62e01a
24 Aug 2024

Submarine Secrets: Pump Jets And Propellers Explained



And below is from Google Chacha's AI bot...

Submarine propeller maintenance is crucial for optimal performance and safety. It involves regular cleaning, inspection, and repair or replacement of damaged components. This includes removing marine growth, checking for damage like dents or cracks, and ensuring proper lubrication of moving parts.

Detailed Maintenance Procedures

Cleaning: Remove marine growth and debris from the propeller blades and hub. This can be done with specialized tools and cleaning agents, or even by divers for underwater maintenance.

Inspection: Carefully inspect the propeller blades for any signs of damage, such as dents, cracks, or bent blades. Even minor damage can affect performance and lead to further issues.

Repair or Replacement: If damage is found, the propeller may need to be repaired or replaced. Repairing stainless steel propellers can be more cost-effective than replacing them, but aluminum propellers might be replaced due to lower cost.

Lubrication: Proper lubrication of moving parts, like the propeller shaft and bearings, is essential to reduce friction and wear.

Balancing: Ensuring the propeller is properly balanced is critical to prevent vibrations and potential damage to the shaft and other components.

Shaft Seal Maintenance: Inspect and maintain the propeller shaft seal to prevent water leaks and ensure proper sealing.

Cavitation Prevention: Implement measures to prevent or mitigate cavitation, such as grinding down blades or applying anti-fouling coatings, which can improve propeller efficiency and reduce damage.

Regular Servicing: Depending on usage and conditions, underwater maintenance, including polishing, should be performed regularly (e.g., every six to twelve months) to prevent issues and maintain optimal performance.

Storage: If the submarine is stored for an extended period, the propeller should be removed and stored in a dry, safe place to prevent corrosion and damage.

Also IIRC, there was some news-item, quite a few months back wrt indigenous capability of pump-jet tech etc - not sure what happened to that.

Was it this you saw? The first two pictures below are from a pump jet torpedo.

https://x.com/Varun55484761/status/1444673978849628164 ---> DRDO developing pump jet propulsion for future submarines. Indian SSN is again in the spotlight and It will have pumpjet propulsion with electric motor drive. Most probably it will have a upgraded CLWR-2 reactor with 180-200MW. India may try to get help frm France to make both tech perfect.