As this is a developing story of significant importance, I've started a new thread to compile the various reports & images. After a while this thread will be merged into the existing Nuclear submarine thread.
For a long while, there were reports & speculations that the last 2 of the 4 x Arihant-class nuclear-powered ballistic missile submarines (SSBNs) sanctioned for construction would be considerably bigger & carry more missile armament than the first two. Some dismissed these reports as hearsay, but now tangible proof has emerged in the form of satellite images obtained by open-source intelligence (OSINT) and by major Defence publications like IHS Janes.
It started with a report by Chris Biggers of Janes who stated that the S4 hull (3rd boat in class) was quietly launched last month without any fanfare:
However, this image in of itself could not substantiate the size (or comparative difference) of this boat as opposed to the first two (S2 INS Arihant & S3 INS Arighat). And then another OSINT handle Deadtrap777 obtained more recent imagery showing the three submarines docked at the Ship-Building Centre (SBC, a ubiquitous name for the facility in Vizag on east coast that builds India's nuclear submarines):
This image proved beyond a shadow of a doubt that the 3rd boat was indeed larger - and considerably so. Further analysis was done by Submarine expert H.I. Sutton of Covert Shores (also writes for Forbes) in his article:
He states:
"Analysis of high resolution satellite images seen by me (I got them via OSINT, but I am unsure whether the satellite provider intended them to be public so I am not posting them here) suggests that it is about 20 meters longer overall. The forward hull, sail and stern appear, overall, largely unchanged. The hull diameter does not appear to have increased and the missile deck remains narrow. Taken together, this supports reports that the new submarine has 8 instead of 4 missile tubes. These will be arranged in a single row down the centerline.
The newest boat may also have an improved reactor."
A little of background on the "Arihant Stretch", and the executive-level decisions that shaped it, from an article by Sandeep Unnithan appearing in a 2017 issue of India Today:
"...the design got another tweak a decade ago after an intervention from then finance minister P. Chidambaram who was on the political committee which monitors the classified programme. The minister questioned the billions being spent on a boat launching just four nuclear tipped missiles. The ATV project team came back with an 'Arihant-stretch'-an additional 10-metre-long plug for four K-4 SLBMs to be integrated into the S-4, then on the design board. The plug would increase the weight of the submarine by nearly 1,000 tonnes..."
Information about the ATV project is meagre. It operates directly under the supervision of national security advisor Ajit Doval and is now wrapped in deep levels of secrecy.
www.indiatoday.in
The plug (reported by Unnithan as 10-meter but analyzed by Sutton as being ~20 meter) would increase the submarine's displacement from 6,000 to 7,000 tons (surfaced), which means up to 8,000 tons submerged. It could possibly be more because an addition of ~1,000 tons was made against the backdrop of a 10-meter module, not a ~20 meter one.
With 8 missile tubes, the two boats of the Stretch variant could carry either:
8 x intermediate/intercontinental missiles like K-4/K-5 SLBMs
or up to 24 x medium-range ones like K-15 SLBMs (triple-packed in every tube, already done on S2 & S3)
In the future (mid/late 2030s) when the much larger 13,500-ton (initial estimate) "S-5" class SSBNs take over the deterrence role, the Arihants & Arihant Stretchs could be converted into a less demanding role i.e. SSGN. If the silo that can take 3 x 0.74m diameter K15 missiles can handle 5 or 6 x 0.52m diameter missiles like Nirbhay LACM, the Arihants could carry 20-24 vertically launched long range cruise missiles...while the Stretch variants can carry up to 40-48 such LACMs, a truly significant land-attack capability rivalling that of the Oscar II-class SSGN or even Virginia Block-V in terms of number of payloads.
I had already included the Arihant Stretch class into my Composition of Future Combatants of the Indian Navy:
Future of the Indian Navy This is a list I'm making using purely open-source information regarding the fleet composition of the Indian Navy in the foreseeable future (confirmed programs seen through to their logical end, alongside existing vessels expected to serve till a reasonably distant...
defencehub.live
Further posts will be made as more details emerge. Tagging you
@Nilgiri
@Anmdt @Cabatli_53 @Bilal Khan(Quwa)
www.iiss.org
www.indianarrative.com
