Sunday, 11 August 2013

INS Arihant - an analysis

On a blogging roll for a while, although I suppose it won't continue much longer that I have other things to do.

INS Arihant's 83 MW reactor just went critical after a whole lot of sea trials, according to the news. Extrapolating from known data on Russian submarines and their reactors - the Russian project 971 (NATO: Akula) class has a 190 MW reactor but turbines that are rated at just 32MW, and the blisteringly fast Project 705 (NATO: Alfa) class has a set of turbines rated at 30 MW for a 155MW reactor plant.

Going by the roughly 20 percent power rule here, the turbines on the Arihant are likely to be around 15 MW, or about 20,000 horsepower. Rating them at higher than that doesn't seem to make much sense, and the figures placing them at 47,000 hp just seem ludicrous - that sort of power would propel the Arihant's estimated 6000 ton bulk past 37 knots given known submarine performance figures.

A lower power rating and a speed in the range of 24-28 knots seems far more likely (and the figure listed on Wiki is indeed 24 knots). A ballistic missile submarine isn't meant to sprint across the oceans - it's meant to be a ghost, running silent and deep, popping up to deliver its apocalyptic cargo when the time calls.

One thing here intrigues me thoroughly -

This submarine is capable of carrying 12 K-15 missiles or four K-4s. This is indeed an unusual arrangement. Again, going by the publicly available figures on both missiles, the K-4 is 0.74 meters in diameter and 10 meters in length, with a weight of 6-7 metric tons. The K-15 is about 12 meters in length, 1.3 meters in width and with a weight of 17 tons. These figures are probably suspect or incorrect but they do give the size of the missiles away quite clearly. Arihant has just four missile tubes and seems fairly close to the old Soviet Hotel-class submarine (like the kind in the K-219 movie) in size. The K-15 is being stacked three in a tube, evidently. The small size results, logically, in a small warhead and short range.

From the perspective of a Naval nerd and an amateur with a little knowledge, I'd say that this submarine was created by the Indian Navy specifically to deal with the threat of nuclear war with Pakistan. The K-4 is a missile that really could offer credible destructive power against any target. The smaller K-15 is a missile that would bring Arihant dangerously close to the coast of any country it would want to strike - so it makes no sense to have such a missile on-board unless it really has substantial precision-strike capabilities. But then again, it's hard to say with these things. Whenever India gets larger, more powerful missile submarines, I'm pretty sure Arihant will land up as an underwater launch platform for cruise missiles the way the Americans are doing with the older Ohios.

All things said, Arihant looks to be a very interesting vessel. Given that all the other five countries that have nuclear submarines (The US, UK, France, China and Russia) are the five permanent members of the UN security council, will Arihant ease India's entry as a permanent member? Possibly. Just possibly.

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