[Maveryq]

Originally Posted by V.Narayan

The picture posted by you is correct.

Thank you Sir.



I was intrigued by the different pictures that were floating around of the INS Arihant where the tail pod of the Akula was quite common in several ones. Those pictures could only be of the INS Chakra.


I was curious about that and hence read up. Your thread was amazing in depth. Would be great if you could share nuggets about the miniturisation programme on the IN. I was reading up on Adm. Rickover and his efforts in nuclearising the US Navy was amazing. Thank fully we have a lot of unclassified literature available and books written about him which provide a lot of the background details and the amazing history. Wonder if we will hear anything about the heroes who did the same for the IN?


One thing that piqued my curiosity was the space behind the main sail tower. I looked at several submarine profiles and only the Delta IV Class of the Russians and the Vanguard Class of the British Navy have that gently sloping fairing.


Picture source: seaforces.org website






You can see the fairing is similar to the Arihant.


Another one of the Vanguard. Picture Source: Seaforces.org





The Chinese submarine fairing is pretty sharp in its downward slope towards the tail mast. Please see the silouhettes comparison below.


Picture source: Popular Mechanics.

[V.Narayan]

Originally Posted by Maveryq

I was curious about that and hence read up. Your thread was amazing in depth. Would be great if you could share nuggets about the miniturisation programme on the IN. I was reading up on Adm. Rickover and his efforts in nuclearising the US Navy was amazing. Thank fully we have a lot of unclassified literature available and books written about him which provide a lot of the background details and the amazing history. Wonder if we will hear anything about the heroes who did the same for the IN?

I guess things will remain under wraps for some years. The Rickover stories came out in the US in the 1980s about 3 decades after his nuclear debut with the USS Nautilus.

One thing that piqued my curiosity was the space behind the main sail tower. I looked at several submarine profiles and only the Delta IV Class of the Russians and the Vanguard Class of the British Navy have that gently sloping fairing

As you may know the ballistic missiles are placed immediately abaft the main sail in all SSBN's except the Russian Typhoon. The height of the ballistic missiles relative to the circumference (and therefore height) of the main hull determines the bulkiness of the fairing. The ability to design short fat missiles is a function of higher technology. The Americans are the most advanced in this. Also different nations follow differing philosophies of how many warheads per missile and what its range needs to be. That also influences size.

The two SSBNs in service today with the largest humpback are the Chinese Type 094 and the Russian Delta IV. The Chinese Type 094 SSBN is reported to carry the JL-2 missile with a height believed to be ~13 metres. The Delta IV carries missiles believed to be ~15 metres in height.
[/quote]

[Maveryq]

Came across this infographic from Livefist showing the proposed the plan of growth for Indian submarine fleet.


Will be interesting to see how this pans out.


Picture Source: Livefist website.

[V.Narayan]

Indian Navy in talks to lease a second Russian nuclear attack submarine to replace INS Chakra in 2023

https://www.thequint.com/news/india/...al-with-russia

The Indian Navy is planning to sign a long term lease of a Russian Akula class attack boat to replace INS Chakra whose lease expires in 2022. The boat to be selected will undergo a 6-year refit prior to induction.

The Akula boats have a submerged displacement of ~12,500 to 13,000 tonnes, a official diving depth of 480 to 600 metres and a top speed estimated between 28 to 35 knots. They are armed with both 533 mm torpedoes and submarine launched anti-ship missiles.

File photo of a Russian Akula I (Improved) Submarine; Photo Source:Wikipedia

[AlphaKilo]

Originally Posted by V.Narayan

Indian Navy in talks to lease a second Russian nuclear attack submarine to replace INS Chakra in 2023

https://www.thequint.com/news/india/...al-with-russia

...

Why do we need another lease? Would they start the retrofit only after the lease period starts or would the refit be completed by 2023?Based on the previous experience with INS Vikramaditya, hopefully our people have formulated a binding and strict agreement this time around.

Wouldn't Arihant and its brother be battle ready by 2023? I understand this would be an extension to the INS Chakra but when we can have our own, why spend the extra cash on foreign players? Also, the Scorpenes (all 7 of them) would be ready by then (According to my sources). IMHO, we "could" be better off spending this cash on local product. It would be interesting to see if commissioning something (a used product with some retrofit) in 2023, make it the state of art (for that time) product or would it serve as a platform for our Soldiers to get trained for long submerge times and the art of stealth etc.

[V.Narayan]

Originally Posted by AlphaKilo

Why do we need another lease?

This is to ensure, I would think, that after 2022 we have at least 1 SSN ie nuclear powered attack submarine in commission. If INS Chakra's lease is extended then I suspect she would go for a refit and re-join the fleet sometime later.

Would they start the retrofit only after the lease period starts or would the refit be completed by 2023?

I guess is the refit would start now after agreements are signed and the submarine ready to commission by 2022-23.

Based on the previous experience with INS Vikramaditya, hopefully our people have formulated a binding and strict agreement this time around.

In INS Vikramaditya we postponed our decision for way way too long by which time the hull had deteriorated and a much more complex and lengthy build back was needed. If we had decided in 1992-93 when the Russians had offered her the story on cost over runs would have been different.

Wouldn't Arihant and its brother be battle ready by 2023?

Arihant is already operational. She is a SSBN, ballistic missile armed, nuclear powered. INS Chakra and the new vessel are SSNs.

Also, the Scorpenes (all 7 of them) would be ready by then

Sounds reasonable. SSKs like Scorpene and SSNs like Akula are complimentary and not replacements for each other. I wish we build another 10 Scorpene's albeit with some upgrades.

IMHO, we "could" be better off spending this cash on local product.

It is said that we are developing our own SSN. See post #89. I don't know the schedule - not in the public domain. But I suspect as all efforts are on getting INS Arihant's sister boats ready the SSN maybe 10 years away. INS Arighat the second of class of Arihant SSBNs is expected to commission in 2019 and two more are said to be under construction.

INS Chakra, Akula class SSN, Indian Navy. Photo Source: Livefist

[AlphaKilo]

Originally Posted by V.Narayan

..In INS Vikramaditya we postponed our decision for way way too long by which time the hull had deteriorated and a much more complex and lengthy build back was needed. If we had decided in 1992-93 when the Russians had offered her the story on cost over runs would have been different.

Thanks! Wasn't there more to this story? If I remember correctly even here in TBHP there was a discussion relating to quality issues during the refit being the cause for additional (apart from our delay in making decisions and the usual Armed forces Requirement being way too much of an ask) delay and cost overruns?

Originally Posted by V.Narayan

Sounds reasonable. SSKs like Scorpene and SSNs like Akula are complimentary and not replacements for each other. I wish we build another 10 Scorpene's albeit with some upgrades.

If we are going to do so, AIP would be my preferred choice. I believe only Germans have mastered this skill properly although there are others who do similar technology but to their standards. But our friendly neighbourhood already posses this technology and I have heard from my sources that they are quite happy with the technology.

Originally Posted by V.Narayan

It is said that we are developing our own SSN. See post #89. I don't know the schedule - not in the public domain. But I suspect as all efforts are on getting INS Arihant's sister boats ready the SSN maybe 10 years away. INS Arighat the second of class of Arihant SSBNs is expected to commission in 2019 and two more are said to be under construction.

Can't wait for the Fleet review with a full arsenal of Indian made Vessels both on, above and in the water.

[V.Narayan]

Originally Posted by AlphaKilo

If we are going to do so, AIP would be my preferred choice. I believe only Germans have mastered this skill properly although there are others who do similar technology but to their standards. But our friendly neighbourhood already posses this technology and I have heard from my sources that they are quite happy with the technology.

As you would know, three modern day solutions exist:-

A) The Swedish answer is a small stirling engine in the 50 to 75 kw range that combusts ethanol and compressed oxygen (carried in cyrogenic cylinders at very high pressures). So at depth the little stirling starts to chug at a low RPM and re-charge the main batteries enabling the sub to increase its endurance. The fuel density of ethanol is far greater than any battery so for the same weight of energy source the sub sails longer.

B) The French came up with a similar concept expect the small stirling got replaced by a not so small high RPM steam turbine.

C) The Germans developed fuel cells that compliment the traditional batteries. The traditional batteries can be charged and discharged rapidly while the fuel cells with greater energy density can discharge only slowly and hence suited for slow speeds while the traditional batteries are used for high speed dashes.

#A and #C are in service and relatively proven. #B is considered by most experts to be the laggard and has only been adopted by our western neighbour. Even the French don't use it!

#A and #B need to discharge their gaseous exhausts underwater at 40 bars or more. They do that be conducting the combustion at a higher pressure. High pressure oxygen, super high pressure combustion underwater in a confined space filled with a few hundred tonnes of fuel on the whole seems a less elegant and more risky solution than fuel cells in option #C. Discharge of gas is also a source of noise. Avoidance of noise makes subs stealthy. So I would put my money in the long run on #C i.e. Fuel Cells.

Figures of endurance are never published. Indicatively from what is in the public domain subs on traditional batteries could patrol (at very low speeds) for 7 to 10 days. With the AIP systems that figure goes up 2X or so. AIP subs are a natural evolution from traditional battery subs and will dominate the navies of tomorrow. Sweden & Japan have gone down the stirling engine path and Germany, Greece, Israel, Italy, Norway, Portugal, Singapore, Spain, South Korea, Turkey have gone the fuel cell route.

An AIP does not improve the killing power of a sub. But it does give the commander tactical flexibility provided by endurance.

If we had stayed with our HDW Type 1500 programme as Turkey did we could have built 10 more subs under German license by now and be building the AIP versions (called Type 212/214) today. I'll save that rant for another day.

DRDO do say they are developing an AIP. Not sure why we need to reinvent everything when ready made technology is available under license. The Swedes could sell the know-how the same way they did to the Japs.

Can't wait for the Fleet review with a full arsenal of Indian made Vessels both on, above and in the water.

One normally happens under the tenure of each President. So maybe we'll have one soon.

[Jeroen]

Originally Posted by V.Narayan

B) The French came up with a similar concept expect the small stirling got replaced by a not so small high RPM steam turbine.
.

Interesting information. So the French run a small steam turbine underwater to charge the batteries? How do they generate the steam?

Thanks

Jeroen

[V.Narayan]

Originally Posted by Jeroen

Interesting information. So the French run a small steam turbine underwater to charge the batteries? How do they generate the steam?

Jeroen, you, I know are familiar with this but for the benefit of all readers I am explaining it with some background.

Closed Cycle Steam Turbines

As most readers know steam turbines make use of a source of energy to heat water and convert it into steam in order to the run the turbine. In nuclear powered submarines, the reactors provide the heat in order to convert water into steam. But in conventional closed cycle steam propulsion, a non-nuclear energy source is used to do the same. The French MESMA (Module d’Energie Sous-Marine Autonome / Autonomous Submarine Energy Module ) is the only such system available of this kind and it makes use of ethanol and oxygen as energy sources. The combustion of ethanol and oxygen under high pressure is used to generate steam. The steam generated is the working fluid and is used to run the turbine. Because the combustion is at a high pressure it becomes possible for the carbon dioxide to be expelled outside into the sea at any depth without making use of a compressor. This is one advantage the closed cycle steam turbine has over the closed cycle Stirling engine.

Further the advantage of MESMA is it’s higher power output when compared to the alternatives which allows higher underwater speeds but it’s major drawback is it’s lower efficiency. Also the rate of oxygen consumption is said to be very high and these systems are very complex and might be high on maintenance. These drawbacks make several navies opt for sterling cycle and fuel cell alternatives.

Stirling Cycle Engines

A Stirling Engine is a closed cycle engine with a working fluid which is permanently contained in the system. A source of energy is used to heat this working fluid, which in turn moves the pistons and runs the engine. The engine is coupled to a generator, which generates electricity and charges the battery. The source of energy used here is typically LOX as oxidizer and diesel fuel, which is burnt in order to generate heat for the working fluid. The exhaust is then scrubbed and released into the seawater.

The advantage of using Stirling engines is they are quieter than MESMA and hence preferred by the Japanese for their Soryu class, Sweden for their Gotland and Västergötland class and now being developed by China for its Yuan class. The Swedes are the world leaders in this type of AIP and put it in operation by the early 1990s – the first fully successful AIP submarine.
The main drawback is that they are relatively noisy when compared to Fuel Cells due to the presence of a large number of moving parts. They are also bulky when compared to Fuel Cells.

The operating depth of a submarine using Stirling AIP is said to be limited to 200 m when the AIP is engaged. This means if the Sub needs to go deeper it must switch off the Stirling, move to the conventional batteries only and then dive deeper. For Subs depth is safety and increase in stealth.

Fuel Cells

Germany the world leader in developing and fielding this type of AIP, which is backed by the large number of export orders they have received. France is developing a new generation Fuel Cell AIP as a successor to its MESMA. India is another country which is developing a Fuel Cell AIP to be integrated on their submarines.

Fuel cells are the most advanced and preferred AIP technology today. This is because of the major advantages they offer in stealthiness and power generation. They contribute to the stealthiness of the sub as Fuel Cells have almost no moving parts, which significantly reduces the acoustic signature of the sub. They can also be scaled easily into large or small sizes depending on the displacement of the submarine. This is easier than developing different systems for each submarine class.

Advantages of the AIP

The use of AIP on a diesel-electric submarine, greatly increases their underwater endurance, allowing them to continuously stay submerged for weeks without surfacing. Although the submarine eventually needs to surface to charge its batteries and their endurance is nowhere on-par with nuclear powered submarines, the vast increase in endurance offered by AIP gives them an advantage over non AIP equipped diesel-electric submarines. However AIP doesn’t give any advantage other than increased underwater advantage and it should not be assumed that AIP-equipped submarines will always defeat their non-AIP equipped counterparts. The underwater endurance of an AIP equipped sub is also largely limited to a single digit speed in knots much like its conventional diesel-electric battery powered sister.

In April 2006, a German Navy submarine U-32, equipped with a Siemens proton exchange membrane (PEM) compressed hydrogen fuel cell AIP, made a 1500 nautical miles (~2800 km) uninterrupted underwater journey without surfacing/snorkeling! It did this in about 2 weeks making it an average speed of ~4.5 knots. This is in stark contrast to non-AIP equipped submarines which can cover only 500-800 km before they have to surface and recharge their batteries by running noisy diesel generators. Again in 2013, U-32 set a record by traveling underwater continuously for 18 days without surfacing! Comparatively, a non-AIP diesel sub has an underwater endurance of just 4-9 days before it has to surface.

The U-32, Type 212 of Germany

[AlphaKilo]

Originally Posted by V.Narayan

...

In April 2006, a German Navy submarine U-32, equipped with a Siemens proton exchange membrane (PEM) compressed hydrogen fuel cell AIP, made a 1500 nautical miles (~2800 km) uninterrupted underwater journey without surfacing/snorkeling! It did this in about 2 weeks making it an average speed of ~4.5 knots....
The U-32, Type 212 of Germany

A documentary about the U-32 (although in German) can be interesting read.

https://www.youtube.com/watch?v=HTrC4EnMKx0

Thanks for the info sir. The current generation of AIP is even more advanced and the companies associated with this are making great progress. The U-36, latest of the U-32 sister ships enhanced capabilities that exceed beyond the numbers mentioned here for U-32. The operational concept of such boats are rather more for recon/snooping data and less of attack or counter strike. These are used more like the ELINT aircrafts, just under water they can get real close to shores or snoop on the underwater fibre optic cables.

[Sutripta]

Anyone knows how much a nuke in a sub weighs?

Regards
Sutripta

[Jeroen]

Originally Posted by Sutripta

Anyone knows how much a nuke in a sub weighs?

a

The tridents weigh about 58 tonnes

http://news.bbc.co.uk/2/hi/uk/4438392.stm

But a cruise missile with a nuclear head weighs in at just a few tonnes I believe!? And these get launched from subs as well

Jeroen

[ads11]

AIP is truly the present and future of submersible warfare for most nations. It's telling that there's a small but increasingly vocal group in the US who are finally making noises about the need for non nuclear boats in the USN but I'm afraid the doctrines of Admiral Rickover, the interests of the builders and the need for global reach of the US have stubbornly shot down any argument made in favour of AIP subs.

I find it really interesting the super sized Barracuda AIP sub by DCNS that the French pitched for Australia's Collins Class replacement programme. (http://www.thedrive.com/the-war-zone...-on-the-planet)
Clearly it shows that the concept is scalable to much higher levels.

Honestly for IN usage, I would imagine the pressing need now is to have sufficient boats to not only combat Pakistani boats to the west but the encroaching PLAN boats coming in through the east. To that end I wonder if the ranges of the Scorpenes and any future AIP equipped Indian sub type to be sufficient to operate in the blue water IOR and not just littoral waters off our coast.

Originally Posted by V.Narayan

DRDO do say they are developing an AIP. Not sure why we need to reinvent everything when ready made technology is available under license. The Swedes could sell the know-how the same way they did to the Japs.

This. I can't agree enough. I get the need to develop skill in house but when the Swedes are happy to let us build under license and there is a pressing need and not enough time for the IN to replenish and enlarge its sub surface fleet why are we handicapping ourselves?! I'm sure there's plenty that can be learned through license manufacture.

Coming back to the 2nd Akula lease I guess another reason to lease a 2nd boat just as the current lease expires isn't only to keep a IN flagged SSN but I suppose to keep the skill set developed by such an SSN crew from atrophying. If the IN had been that bravado in their expectations of a domestic SSN coming onstream in a similar time frame, they could've made an incredibly ballsy call of relying on the newly minted indigenous SSN. Instead to my eyes they're making the pragmatic choice.
Now, of course I pray the refit contract terms are set in stone and any process is put underway yesterday given the sterling reputation for tardiness any procurement contract involving either India or Russia has.

Personally I would hope that the focus is on getting the Indian SSBN watertight with the entire set of boats before looking into our own SSN.

[V.Narayan]

Originally Posted by ads11

AIP is truly the present and future of submersible warfare for most nations.

Yes. And with time it will get better.

in the USN but I'm afraid the doctrines of Admiral Rickover, the interests of the builders and the need for global reach of the US have stubbornly shot down any argument made in favour of AIP subs.

The speed, endurance and phallic status of a nuke boat over rides all.

I find it really interesting the super sized Barracuda AIP sub by DCNS that the French pitched for Australia's Collins Class replacement programme. (http://www.thedrive.com/the-war-zone...-on-the-planet)

The Japs are building just what we need. Big, quiet and AIP.

Honestly for IN usage, I would imagine the pressing need now is to have sufficient boats to not only combat Pakistani boats to the west but the encroaching PLAN boats coming in through the east.

Can't agree more. Scuttling the HDW relationship and delaying the start of the Scorpene contract by several years has brought us to this spot of inadequate force levels.

This. I can't agree enough. I get the need to develop skill in house but when the Swedes are happy to let us build under license and there is a pressing need and not enough time for the IN to replenish and enlarge its sub surface fleet why are we handicapping ourselves?! I'm sure there's plenty that can be learned through license manufacture.

Our DRDO etc have had a sad history of scientific territory marking by constantly claiming that this or that can be developed indigenously and in the process put off license production and delay the Armed forces getting the equipment they need. <Rant Over>