India’s 6,000 tonne INS Arighatprototype SSBN launch on November 19, 2017 is less of a surprise when one considers GhalibKabir’s adviceon December 12, 2017 that INS Arihantand another 6,000 tonne nuclear sub (now known as Arighat) were under construction since 2006. Their reactor specifications were apparently frozen at 83MW, meaning they could not be built much larger than 6,000 tonnes - if a cruising speed around 20kt was maintained.
Perhaps the need for a continual high level of SSBN budgetary funding prompted Indian SSBN builders to disseminate large Aridhaman propaganda for so long. Propaganda could also be seen as public relations (PR). As early as July 14, 2014 Aridhamanwas to be “launched into water soon”. Submarine Matters as early as August 24, 2014 doubted the ambition of India's SSBN and SSN programs.
So the non-appearance of a much larger INS Aridhaman SSBN may be due to India’s current inability to produce a reactor much more powerful than 83MW. Another limitation seems to be the immaturity of any 7,000km range SLBM (called K-5 or K-6). So India is not indulging in a rush program to produce a 13,000 tonne SSBN large enough to mount K-6s.
India’s SSBN Program at its most basic seems to have several requirements including sufficient reactor power, SSBN size to accommodate large enough SLBMs to carry a sufficient payload over a sufficient range. More specifically:
A. Develop, test and fine tune 2 x 6,000 tonne prototypes (INS Arihant and INS Agrihat) and
then
B. launch 2 small 7,000 tonne SSBN by 2022 which will have 8 x (very limited 3,500km range K-4s) 1.3m diameter, 10m long. The medium range K-4 can reach only a limited number of significant targets within China– these include:
Suspected Chinese IRBM hardened silos and TEL hiding places
The PLA’s Western and Southern Theatre Command HQs and troop concentrations
See Southwest China map for provincial capitals with comparatively large southwest Chinese populations, including:
For a 7,000 tonne SSBN it is preferable to use a slightly uprated 90 MW reactor. This is possible, assuming 6,000 tonne Arihant of 83MW reactor is a development of the Russian 70MW - 90MW VM-4 reactor. Hydronamic improvements can be made to the sail/fin and pump jet propulsor or a slower cruising speed may be acceptable
and/or
C. skip the 7,000 tonne SSBNs and go straight to 13,500 tonne SSBNs powered by an Indian-Russian development of Russia’s well used Russia 190 MWt OK-650 reactor. A 13,500 tonne SSBN needs the capability to launch, from Bay of Bengal bastion waters, a true 7,000km intercontinental SLBM with warheads in range of Beijing. Specifically 12 x K-6 SLBMs, 12m long, 2m diameter.
Maybe the above US SLBM comparitive image is useful if K-4 can be equated to a light warhead Polaris A2 and the K-6 equated to a Trident I C4. This would mean the K-6 would be over twice the overall K-4 SLBM weight. (Image and broader data is at the FAS website).
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SLOW PROJECT?
India may not need to develop SSBNs at a cracking US vs Soviet Union Cold War pace because India's main SSBN opponent, China, is not developing SSBNs quickly. This is as far as overt sources can know. Also one must remember China launched the first of its nuclear submarines (Type 091s) in 1970. Balanced spending, that satisfies Indian civilian expectations, is essential in that democracy.
Pete