INS Arihant (ATV) News and Discussion -2

[Gagan]

Russians have the most number of VLF facilities, something like 2 dozen or so. At least 5-7 of them just broadcast time signals for the sub fleet.
Wikipedia lists the various frequencies, earth coordinates and purpose of the signals of all known VLF facilities
http://en.wikipedia.org/wiki/List_of_VLF-transmitters

[Gagan]

This report from Janes, April 2013.
(Sorry don't have the Janes Link)

India makes headway with ELF site construction
By James Hardy

3/4/2013

Imagery taken by DigitalGlobe in January 2013 provides an update on the construction of India's new Extremely Low-Frequency (ELF) facility in the south of the country.

The construction began in March 2012, when Admiral Nirmal Verma, chief of the naval staff of the Indian Navy (IN), laid the cornerstone for the ELF facility near the village of Vijaya Narayanam, about 23 km north of the Kudankulam Nuclear Power Plant in Tamil Nadu. It is co-located with the IN's Very Low-Frequency (VLF) communications station, which transmits at 18.2 kHz.

The ELF station, which is believed to be being built by Indian firm Larsen & Toubro, will have nuclear-hardened bunkers and is expected to be commissioned in 2015. Russia is closely associated with the research and development for the facility, which is expected to be similar to Russia's own ELF transmitter at the ZEVS facility near Murmansk.

ELF transmission is used to communicate very brief commands to submerged submarines. Such transmissions can travel thousands of miles and through extended depths of seawater. ELF transmissions are generally initiated during circumstances in which conventional communications channels have been disrupted or destroyed.

[member_20067]

http://theproblemwithwindpower.com/info ... estELF.htm

[shaun]

About the 1980's VLF facility -Project Skylark was initiated to give Navy VLF comm. facility with US help ,akin to the Omega system of Naval Communication Station Harold E. Holt , located on the northwest coast of Australia . Below are the two satellite pics of arrays of two different sites one in India other in Australia.





The INS Kattabomman facility have frequency of 18.2 kHz where as the one Exmount have 19.8 kHz

[dinesh_kimar]

Posers from DFI had elaborated on steps involved in building a nuke sub. The reactor is built and installed before the hull is even constructed. In 2009, when inaugrated by MMS, the reactor was already in place.

Also, before installation, reactors are first tested on land.

The reactor is based on a Russian design, and is expected to be a reliable and working unit.

Walchandnagar Industries built many parts of the 85 MW Nuclear reactor (incl. the heart of the reactor called "calandra") and integrated it with the Steam Turbine.

Here is the link:
http://www.dnaindia.com/india/report-pr ... nt-1277435

So if Arihant has a problem, it might be more to do with issues like hull construction and integration, rather than propulsion.

[shaun]

No one said Arihant have problem regarding Hull construction and integration , its only our folks at SCB is cautious and powering the reactor progressively to its full potential before commencing sea trials.

[deejay]

No one said Arihant have problem regarding Hull construction and integration , its only our folks at SCB is cautious and powering the reactor progressively to its full potential before commencing sea trials.

Sirs, with Arihant and those that will follow it, we will never know anything real time. A lot of assumptions and hypothesis will be required to reach exact conclusions.

[shaun]

Gaganji, there is no VLF/ELF station in W Bengal , there is LORAN-C Mast at Diamod Harbour. And the new VLF facilty at INS Kottabomman is a VLF station .

The new VLF station can transmit message to a submerged submarines at 300 bits/sec and can penetrate seawater to a depth of 8-10 meters according to some dated news.

[krishnan]

10-50 mtrs under water ..

[krishnan]

i am confused regarding this INS Kattabomman

http://indiannavy.nic.in/about-indian-n ... attabomman

Historical Background
INS Kattabomman was commissioned on 20 Oct 1990 by then President, Shri R Venkataraman. It is named after Veera Pandya Kattabomman, a famous warrior king, who laid down his life in the struggle for freedom from the British Raj. The vast base is rich in flora and fauna with rows of exotic trees and fruits. It is home to deer, hopping hare, peacocks and vast variety of migratory birds from Siberia.

Function/ Role

INS Kattabomman is the premier communication establishment, located at South Vijayanarayanam, near Tirunelveli in South Tamil Nadu. The primary role of the base is to provide continuous global communication link in the Very Low Frequency (VLF) spectrum to ships and submarines in the country’s areas of interest. The 3000 acre base enclosed in a 22 km perimeter wall hosts the VLF transmitting grid, which is the only one of it’s kind in the country. The antenna structure consists of 13 high raised cable-stayed steel masts in form of a 6-pointed star. The 301 m centre mast is the third tallest structure in the country, while the other 12 rank amongst the top ten.

so what did they commission this time ??

[ravip]

Gaganji, there is no VLF/ELF station in W Bengal , there is LORAN-C Mast at Diamod Harbour. And the new VLF facilty at INS Kottabomman is a VLF station .

The new VLF station can transmit message to a submerged submarines at 300 bits/sec and can penetrate seawater to a depth of 8-10 meters according to some dated news.

There is some VLF like facility in Charbatia Air Base, Odisa.

Here is the screen shot of it.

[Singha]

10-15mts underwater is a unhealthy place for submarine. vulnerable to all forms of detection including wake turbulence, algae luminance and even eyeballs in clear water.

so that indicates ELF is needed to call it up to VLF depth or a fixed schedule to come up and get VLF messages - which is not exactly useful for n-deterrent patrols.

so I guess ELF is a must for n-deterrence on-demand strike patrols.

[shaun]

ravip ,

actually I could not find any transmitter arrays. it can be a EW asset of ARC who currently operate this base or some navigation becon and it is newly built around 2011-12.

krishnaji ,
even I am confused about the new vlf facility , may be to agument the existing one .

[ramana]

I think the plan is to have the Arihant go out on deterrent patrol immediately after the first few launches. I expect about four or five launches from it.
One bird Proof the sub capability to launch underwater
one-two birds from adjacent tubes to proof cross tube issues
one -two - three birds from adjacent tubes to proof cross tube issues
one-two-three birds from same tube to proof one tube cross issues

[ravip]

ravip ,

actually I could not find any transmitter arrays. it can be a EW asset of ARC who currently operate this base or some navigation becon and it is newly built around 2011-12.

krishnaji ,
even I am confused about the new vlf facility , may be to agument the existing one .

Even I am not sure what it is... Only gurus can ponder over it...it was just a guess as it is very similar to VLF facilities.

[Ranjani Brow]

NDTV Exclusive: This is INS Arihant, first made-in-India nuclear submarine

[Pratyush]

if that is not an officially sanctioned Photo. The NDTV should loose its license and top brass ought to be tried for treason.

having said so. I was worried that the her hump would be similar to that of the Delta class

[Ranjani Brow]

if that is not an officially sanctioned Photo. The NDTV should loose its license and top brass ought to be tried for treason.
having said so. I was worried that the her hump would be similar to that of the Delta class

Ask this question to Vishnu Som in Indian Naval Discussion Thread.

[Surya]

now wait and watch for the Shiv aroor "first to" and exclusive

[tushar_m]

awesome

Would love to see if some changes are made to INS Arindaman (some people say more powerfull reactor & higher tonnage)

But who knows ????

[SagarAg]

Looks like Chinese Type 092 submarine

[partha]

now wait and watch for the Shiv aroor "first to" and exclusive

Nobody should get exclusive access to such pics. What's special about NDTV that they got it? All such pictures should be channeled through MoD which can release them to the media.

btw, great to see Arihant.

[chetak]

10-15mts underwater is a unhealthy place for submarine. vulnerable to all forms of detection including wake turbulence, algae luminance and even eyeballs in clear water.

so that indicates ELF is needed to call it up to VLF depth or a fixed schedule to come up and get VLF messages - which is not exactly useful for n-deterrent patrols.

so I guess ELF is a must for n-deterrence on-demand strike patrols.

That's the antenna depth.

The sub will be much deeper

[Indranil]

now wait and watch for the Shiv aroor "first to" and exclusive

Your wish is granted.

First Photo Of India's N-Sub 'Arihant' During Harbour Trials

In August 2009, friend and colleague Sandeep Unnithan scooped the first ever photograph of the Arihant. A year later, I happened to put out the first public photograph of the Arihant here, furtively published by the government in an official document. The photograph above, scooped by NDTV, is only the third.

[Surya]

thanks Indranil

[jamwal]

Is the conning tower covered with tiles or what ?

[Vishnu]

if that is not an officially sanctioned Photo. The NDTV should loose its license and top brass ought to be tried for treason.

having said so. I was worried that the her hump would be similar to that of the Delta class

Pratyush, thanks for the concern. Just enjoy the picture ...

[Austin]

The Hump does not make a sub more noisier but just reduces the speed at which broad band noise becomes more noticable. Having a curvy hump like Arhiant would reduce the flow noise compared to say the turtle back hump of Delta 4.

But the key noise parameter for Submarine that make submarine vulnerable to long range detection in narrow band are mostly internal related to its machinary and noise insulation measure adopted to curb those noises , reactors and moving parts makes more noise and are difficult and expensive to insulate , cant really make out by looking at the submarine.

So a smooth looking submarine externally is not necessarily a quite one.

[negi]

^ That is why both Ru and Germany have officially different designations for their export models be it U 209 or the Kilo class what buyers get are watered down versions and it is not too difficult just remove the gaskets from key machinery mounts and voila you have a noisier sub , digital equipment is even more easier to downgrade simply sell the buyer an older firmware.

That is why a noisy home made sub is far better than phoren one for you know what and where to improve .

[Singha]

the sinic Han class was supposed to be understandably the noisiest n-sub around given their tech level in 1970s, but had a very sleek shape.http://chinesemilitaryreview.blogspot.i ... 1-ssn.html

[Austin]

^ That is why both Ru and Germany have officially different designations for their export models be it U 209 or the Kilo class what buyers get are watered down versions and it is not too difficult just remove the gaskets from key machinery mounts and voila you have a noisier sub , digital equipment is even more easier to downgrade simply sell the buyer an older firmware.

That is why a noisy home made sub is far better than phoren one for you know what and where to improve .

All export level subs noise are moderated and even within subs of the same class the noise level varries depending how well they are maintained.

Having said that noise is just one of the matrix of the sub , due to Hollywood type propaganda the value of noise is over rated , having a good sonar , knowledge of the environment you are operating in ( acoustic condition ) , knowledge of weapons/semsor system of your own subs and that of your enemy ( sensor/weapons & tactics ) , having weapons that can match your sensor performance , good sub crew is as much as critical importance

In real world sub contacts appear and dissappear so a detection of sub and keeping track of it is a very challenging task and having weapons quality data to make a good case of it is much beyond that.

Recently when Virginia class was detected by Rus in barrent sea they could just keep contact with it for 27 mins before she vanished.

Check the interview use translator http://vpk.name/news/115405_Nikto_ee_ni ... snyal.html

[Austin]

the sinic Han class was supposed to be understandably the noisiest n-sub around given their tech level in 1970s, but had a very sleek shape.http://chinesemilitaryreview.blogspot.i ... 1-ssn.html

Yes and even the Alfa class is far more smooth & streamlined and made entirely from titanium but it was to be a very noise submarine.

[negi]

Austin those who can measure noise , resolve a type from another and filter it from background clutter are the ones who have better Sonars so noise is not overrated. It also happens to be the case that the ones who have mastered detecting and tracking the source of noise are likely to run the most silent submarines , you see one cannot reduce the acoustic signature of a platform unless you can detect and measure the noise emanated by it. Mapping seabeds, locating underwater thermal layers and war gaming all come naturally to those who run silent and can measure smallest source of noise.

[jamwal]

The speeds at which submarines travel, the amount of noise generated has little to do with shape.

[vsunder]

The speeds at which submarines travel, the amount of noise generated has little to do with shape.

Jamwal sahib: I beg to disagree. The issue is this, let us take a block of wood, or an oversized can of Kothari chaap paan ka masala, seems to be my model nowadays for all things. Let us fit a propeller to it and an engine and let us say move it at 8 knots underwater. Now do the same for a streamlined shape, both moving at 8 knots. Which engine will be running at faster rpm to achieve the same 8 knots? The issue is that there is an effect called cavitation and this is more pronounced at higher rpm. Cavitation was studied mathematically even in the 19th century, see I always say the works of the old masters are worthy of study. Countries with mathematical expertise and ocean going traditions have developed far better understanding of cavitation and know how to control it even at high rpm and thereby know how to build proper propellers which run silently whatever that means. For sure you may have systems to damp engine noise, but the propeller sticks outside and if you have marked cavitation effects you lose on two counts, telling the enemy where you are and worse low propeller life. Cavitation is an interesting free boundary problem. Here is a link:

http://en.wikipedia.org/wiki/Cavitation

You can see for sure the damage caused by cavitation in the link. It is like little sonic booms on the propeller.
The section on submarines in the link above and the connection with high rpm is of particular relevance to what I described above.
Personally I have found great value in studying the works of Kelvin and Helmholtz etc.

[Singha]

for unknown reasons, a country with such a strong tradition in maths and fluid dynamics like russia has still not gone for shrouded propeller on the Yasen, which the western n-boats enmasse moved to in their latest classes starting from mid 90s. there is some mojo in shrouded props , else ALL three of uk, france and usn would not move to it in lockstep.

[Philip]

Sub warfare is the most complex of all forms,as there are so many variables in the environment in which a sub lives,the oceans.Thermal gradients,silt,underwater characteristics,vary so much that along with the marine life ,detecting a quiet sub,tracking it and working out a firing solution is a complex task.As far as quieting is concerned,both the hull shape (Collins class "tusk" fix for the sail by the US) external (cavitation from the screw) and internal noise are the major contributing factors.Most machinery on subs for the last few decades are rafted,to reduce the noise transmitted to the hull.Russian double-hulled subs have been suspected for long to have acoustic applications internally as well as externally.In addition for silent running,they have auxiliary "creep" motors that swing out from special compartments in the hull when required. The number and size of free flood holes in the hull are also contributory factors.

As far as the Soviet titanium-hulled Alfa class is concerned,she was the world's fastest and deepest diving sub,where enemy torpedoes could not reach her.Test depths reached were supposedly in excess of 1000+m! But she was phenomenally expensive and was therefore replaced by the highly successful Akula class.Very interestingly,the Russians are renovating/modernising some surviving titanium hulled Soviet era subs say some reports,as their hulls can last 100 years! The Soviets caught up with US sub tech by 1990,according to some US analysts,and some even say that with the latest Borei and Severodvinsk classes, may have stolen a march in some crucial aspects,esp. in non-acoustic sensors.
It is a fallacy that milling tech and eqpt. acquired for propeller manufacture was the reason for Soviet subs getting quieter.The Sierra and Akula prop. designs were developed much earlier than the chronology for tech. acquisition.
By the end of the Cold War,US experts rated the Soviets ahead in wake generation,hull flow noise,magnetic signature and at low speeds noise levels were similar to US subs.

Our ATV class has depended heavily upon Russian assistance and one can speculate that many of the advances in sub tech that have been achieved in their subs exists on the ATV,esp. in machinery.Since the Chakra was supposed to be a platform for also training our N-submariners,it stands to reason that much of the internal eqpt. is common.The weaponry certainly is! Nevertheless,to build an SSBN at home ,plus develop its missile armament is a tremendous achievement. In fact once the second SSBN arrives,we would've achieved the capability of building an entire class of N-sub,why we should simultaneously begin a second line of SSGNs along with the SSBN line,instead of the P-75I conventional requirement, Acquiring Scorpenes and Amurs will be sufficient for our conventional sub needs,with tech from both east and west-and don't forget we also have German sub-tech in the form of our U-209s being modernised.Mastering the capability to build N-subs both attack and strategic boats is the holy grail of sub building capability.

PS:As Austin has said,ultimately its the training and tactics of the submariners that matter,not just the capability of the sub.In our own backwaters,where we have the most info on the maritime conditions,our subs and their crews have the advantage.

[Austin]

Austin those who can measure noise , resolve a type from another and filter it from background clutter are the ones who have better Sonars so noise is not overrated. It also happens to be the case that the ones who have mastered detecting and tracking the source of noise are likely to run the most silent submarines , you see one cannot reduce the acoustic signature of a platform unless you can detect and measure the noise emanated by it. Mapping seabeds, locating underwater thermal layers and war gaming all come naturally to those who run silent and can measure smallest source of noise.

The point I was trying to make is in the context of general impression in media that Noise is Everything and one sub considered better than other because its less noisy , Noise is just one factor among the other equally important factors to be considered in sub warfare.

Yes advanced country are better in this respect but sub warfare and submarine are great equaliser and Indian Submarine with competent crew and good knowledge about acoustic condition in its friendly waters will be more than a match with submarine of other country which would be advanced in other aspect.

[Manish_Sharma]

http://bharatkarnad.com/2014/08/21/arih ... ng-depths/

Anyone discussed this article yet? I wasn't aware the hull of arihant was Ti alloyed.

He is saying that Arihant has already done crush depth tests below 340 - 350 meters, and 1 and half hull is from severodvinsk, posting it in full:

http://www.ndtv.com/news/images/story_p ... _final.jpg.

What do you see?

The most obvious thing that has not been commented on is the humpback on the hull — the so-called “one and a half hulls””– that
permits the boat to slice through water, performing diving and other actions more efficiently. It is a design aspect, along with several other design features, taken from the Russian Severodvinsk and Borei class nuclear subs.

The less obvious but far more significant things to notice is that Arihant has apparently returned from a mission where it dived below crushing depths of well over 300 meters, around 340-350 metres, to see how well the hull would hold up. It has held up beautifully.

But how can this be deduced?Look closely at the smooth skin on the hull. The titanium alloyed hull has withstood the quite enormous pressures on it in the deep without crimping. But on the differently metalled conning tower there is evidence of the skin being crunched — see the wavy formations? — at great depths. It cannot be reproduced in labs or synthetically. And it couldn’t have happened because the Arihant dived to the 100 metre depth of the Vizag channel leading to the open sea. That the structure held up very well may be attributed to the extraordinary welding that fused the tower to the hull.

While it has been publicly put out that the Indian SSBN was working up its nuclear power plant to full power, etc., the fact is it takes no more than a month at the most, at a graduated pace, to reach the full 80 MW drive power. So for the rest of the last 8 months or so, it has been cruising and diving, including below crushing depths. After several more such deep dives the Arihant will have anechoic tiles — able to absorb sound waves, making detection by sonar more difficult — attached to its outer surface, and it will be ready for induction into fleet operations.

The most commendable aspect, other than the high-class technology and manufacturing skills of Indian welders, is the guts shown by the CO, XO, and the rest of the crew of the Arihant in making these repeated hazardous dives but required as a stern test for an SSBN.

The BIG QUESTION that arises is: With so much evidence of indigenous design and manufacturing skills on the Arihant, why is the Indian Navy still hankering for foreign submersibles and not trusting Indian capabilities to produce the Project 75i conventional submarine???


RV says:
August 21, 2014 at 1:16 pm

If one examines the picture on the India Today cover:

2DOTbpDOTblogspotDOTcom/_o_no4M2xEPY/SnraGGWlrzI/AAAAAAAAH4o/gFId3VIO0Xc/s1600/new%2Bcopy-707909DOTjpg

(please replace all instances of “DOT” with “.”) the “crimping” or “nodule” like effect/shape on the conning tower is clearly evident, and resembles that in the NDTV image. However, the same “rubbery coating” is also seen on the hull, which does not seem to be eminently evident in the NDTV image. Again, care should be taken to note the effects of resolution, angle, and lighting, and even effects of “touch ups” when judging from publicly available sources.

Further, from the image:

economictimesDOTindiatimesDOTcom/photo/4822916DOTcms

(please replace all instances of “DOT” with “.”) the hull shows a covering of a smooth silvery coating which appears to extend to the base of the conning tower. Unfortunately, the said image does not capture any details of the boat owing to the undesirable nature of the primary object/objective. Still further, from this image:

2DOTbpDOTblogspotDOTcom/_o_no4M2xEPY/TAUXIto0lwI/AAAAAAAAKh0/Il8lpGHIeXg/s400/ARIHANT-718188DOTJPG

(please replace all instances of “DOT” with “.”) the hull of the boat appears to have a rubbery coating. Thus, in a nutshell, the recent NDTV image provides no explicit/direct evidence to suggest that the boat was taken to “crushing depths”. This however does not in any way foreclose such a possibility.
Reply
RV says:
August 22, 2014 at 7:57 am

It does seem increasingly evident that the NDTV image depicting the INS Arihant does not reveal any explicit evidence that the boat was never taken to its crushing depth. The crimping/distortions and even some of the irregularities on the conning tower appears to be a consequence of optical occlusions of the anechoic tiles caused by angle, lighting, and resolution. In some cases, irregularities are deliberately induced to facilitate maximum acoustic damping. Stating my arguments in point form for the sake of brevity:

1. Given the image displayed by NDTV:

pbsDOTtwimgDOTcom/media/BvetA0GCMAAJgNFDOTpng

(please replace all instances of “DOT” with “.”) If the boat was taken to its crushing depth a likely place which would exhibit structural distortions would is the white vertical band on the rear of the conning tower. This does not appear to be the case. Further, the region where the conning tower joins the hull appears to be unaffected. This would be another region to examine for any structural distortions.

2. Comparing the NDTV image of the INS Arihant with not too common image of the boat in an article in India Today many years ago, one finds the same “nodule-like” shapes/formations on the conning tower:

iDOTimgurDOTcom/jXnyADOTjpg

please replace all instances of “DOT” with “.”.

3. Finally, examining the anechoic tiles of a USS New Hampshire on its induction ceremony:

xpdaDOTcom/virginiasubs/081025-N-6553L-022DOTjpg

(please replace all instances of “DOT” with “.”) irregularities in the anechoic tiles, though of a different type, possibly because of the different coloring and the composition/size of the tiles, and the image properties. Now, examination of the image of the identical boat taken just a few days prior to the one taken above during the rehearsals for its induction ceremony:

trbimgDOTcom/img-50b7b216/turbine/hr-dp-081023-n-7441h-0520100727043438/600/600x400DOTjpg

(please replace all instances of “DOT” with “.”) show differences in the anechoic tiles to that shown above, in a different conditions of resolution, lighting. angle, etc..

Thus, prima-facie the NDTV image does not exhibit any explicit evidence that the INS Arihant was taken to its crushing depth. However, one cannot entirely discount such a test(s) SINCE ABSENCE OF EVIDENCE IS NOT EVIDENCE OF ABSENCE!
Reply
satyaki says:
August 23, 2014 at 8:38 am

Bharat Sir,

But with just 4 K-4 missiles, isn’t the number of nuclear warheads on the Arihant class sub. bey low ? Unless the K-4 has a heavy MIRV payload, is constructing a SSBN for just 4 slums worth it?
Reply

RV says:
August 23, 2014 at 10:29 am

Take the worst case scenario of 2 K-4’s with one warhead each and the remaining 2 K-4 silos each fitted out with K-15’s in 3 pack “shooter” tubes with one warhead per K-15 (total 6 K-15’s). That makes it 2 warheads (from the K-4’s for targets at ~ 3500+ Kms.) + 6 warheads (from the K-15’s at ~ 1500 Kms.). That’s not bad for starters.

The main issues of concern now are:

1. Sound dampening – does India have: (1.) the engineering capability to do the necessary “soundproofing” of these boats, and (2.) the necessary talent possessing in-depth knowledge of instrumentation and the numerical tools to assess the quality of the “soundproofing” and identifications of possible sources of noise (such as ICA/BSS),

2. Obtaining the necessary amounts of supergrade Plutonium 239 to manufacture warheads for submarine operations.

3. SSBN operations require a different and higher level of skills than SSK and often even SSN operations. Many critical SSBN operations cannot be mimicked/emulated on a SSN (like the Akula-2). One of the finest example of such skills which are written in Letters of Gold in the annals of submarine operations was when on August 6, 1991, the Delta-IV submarine (Novomoskovsk), under the command of Captain (Second Rank) S. V. Egorov, performed a full salvo underwater launch of all 16 R-29RM SLBM’s.

The whole process took around 224 seconds. During this period, the submarine expelled more than 650 tons of weight. Launching SLBM’s in even the simplest of salvo modes is a very complex exercise for two primary reasons. First, tons of water is ingested for even a single launch . Stability control is usually achieved through a continuous process of ballasting and deballasting, while maintaining course through trimming (fins & screw). Next, while doing all the above, the submarine has to traverse a circular pattern called the “launch corridor” to minimize error. Reference is made to the Youtube clip:

wwwDOTyoutubeDOTcom/watch?v=ath0oT-4bns

please replace all instances of “DOT” with “.”.

Accomplishing the above tasks is not easy!
Reply
Bharat Karnad says:
August 24, 2014 at 7:53 am

The Arihant may benefit from a revolver-like contraption firing ballistic and cruise missiles; so the SSBN may carry more than just 4 K-4s/K-15s.
Reply
RV says:
August 24, 2014 at 8:33 am

The revolver like contraption that you mention are the “shooter” rotating tubes which carry up to 3 K-15’s per “shooter” tube placed in a single K-4 silo. These are ONLY for K-15’s. I believe follow-up boats will carry more tubes. Some of the Ohio-class are also being converted to SSGN’s where up to 7 Tomahawks in “shooter” tubes are placed in a single Trident silos. Further, even if the Arihant has 650 mm torpedo tubes, accommodating current BrahMos designs fired from the torpedo tubes would not be possible,

[Vivek K]

He says that hull design is used only. The hull is fabricated locally.