The two Arihant Class ballistic missile (SSBN) submarines of India are among the world's least photographed submarines. In 2016, The first boat INS Arihant (S2), was commissioned and a second boat, INS Arighat (S3) is expected to enter service this year.
The Arihant is a one-of-a-kind design that can be described as a "pocket boomer." It is significantly smaller than other ballistic missile submarines and carries only four missile silos.
This does not negate the fact that a nuclear-powered submarine has been built in the country. In many ways, its modest size appears reasonable. Other countries, such as Brazil, who are considering nuclear submarines are opting for smaller models.
Some parts of Arihant have a strong resemblance to the Kilo Class, according to the limited photographs available. Many sections of the sail are visually identical, notably the upper sonar dome on top of the bow. The hull diameter looks to be the same. The front hull and sail are virtually identical to those of the Kilo Class.
This makes sense because India has 10 Kilos in service, designated as the Sindhughosh Class.
DRDO-developed ‘USHUS' sonar suites have been installed on several of India's Kilos. To take advantage of the USHUS sonar, the Arihant's forward hull is expected to be very similar. This system, which has now been upgraded to USHUS-2, was being developed at the perfect time to be fitted to her.
The USHS includes a cylindrical passive sonar under the chin, multiple intercept sonars, an obstacle avoidance sonar, and an active sonar.
Overall, the system is set up similarly to the Russian systems that were originally installed on the Kilo. The intercept sonars in the sail's trailing edge are layered one on top of the other. This could explain why Arihant's sonar window is shaped differently.
The torpedo tube configuration is one apparent difference between the bow of Arihant and the Kilo Class. Arihant's are set to a lower level. This reveals some fundamental variances and demonstrates that it isn't a Kilo hull in the literal sense.
The forward hydroplanes, commonly known as fairwater planes, have been relocated to the sail. The upper half of the casing has been lifted to clear the missile silos, which are located behind the sail as is customary.
The missile compartment begins the part of the submarine that is unlike anything else on a Kilo behind the sail. In a single line, four large-diameter missile silos are stacked. Initially, triple tubes for the K-15 ‘Sagarika' missile were installed. It can fire a 1,000-kg warhead and has a range of 400 nautical miles.
K-15 is considered a stopgap measure. A single K-4 missile should fit in each missile tube. It is a full-size SLBM that was released recently. The range is estimated to be over 1,900 nautical miles, nearly four times that of the K-15. While it has a lower range than the SLBMs used by more advanced nuclear navies, it will improve India's at-sea deterrent.
A second Arihant class submarine is unlikely to influence the Indian Navy's approach toward submarine secrecy. However, its commissioning may reveal new information about the classes capabilities. In addition, any variations between the two boats should be noted and the third class may shortly emerge from its construction hall.