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INS Khanderi: Dawn of new era for Indian Navy with Scorpene multi-purpose attack submarines

Huma Siddiqui

With intent to achieve supremacy by way of increasing underwater presence in the Indian Ocean Region (IOR) with various sea-based threat perceptions evolving in the region, the Indian Navy had taken up the production of six Kalvari class (Scorpene) diesel-electric attack submarines (SSKs) under Project 75 (P-75). And are being constructed with the support and technology transfer (TOT) from French company Naval Group (former DCNS) at the Mazagon Dock Limited (MDL).

Globally, different variants of Scorpene-class submarines are in the navies of countries including Chile, and in Brazil (with licensed production) and in the South Asian region — Malaysia. The P-75 submarine is a well-proven technology and their indigenization effort reduces its operating cost in the long term.

The first four submarines, christened Kalvari, Khanderi, Karanj, and Vela (names of erstwhile submarines decommissioned) are in various stages of construction and commissioning at MDL since 2015.

Indian Navy Scorpene class submarine INS Khanderi: It’s a deadly deep-sea predator

Submarine Warfare

It is expected Indian Shipyards shall leverage the knowledge and skill acquired from this French TOT to continue building a series of Scorpene-class submarines on a sustainable basis for the next few decades. The weaponry and sensors onboard `Scorpene' are French and may continue to be so for some time since indigenous replacements (like torpedoes Varunastra etc.) are still far from achieving the desired potency. With India showcasing itself as a regional power in the IOR, the underwater warfare maybe the primary weapon of 21st century's warfare, akin to the evolution of jet aircraft technology and supremacy witnessed in the last century.

More about Kalvari Class Submarine

Kalvari class submarines are advance conventional propulsion stealth submarines designed for longer ranges, while being submerged for weeks altogether. Such low noise long-range stealth submarines are force multiplier during hostilities and act as an invisible deterrence, establishing an area of supremacy. In peace time, the submarine's primary role shall be Intelligence gathering and Special Ops but during hostilities, the submarine shall play a crucial role in Surface Warfare tactics against merchant ships/warships and Anti-submarine warfare role in countering the enemy submarines, including mine laying activities.

The design of the boat is hi-tech with a high level of automation so as to keep the manpower onboard to a minimum. Systems like Platform Management System (PMS) provides automatic monitoring and control of primary machinery like PGD (Power Generation & Distribution), Steering, Propulsion & Stabilisation system, Safety system, etc. Onboard a submarine, it's floating and moving capabilities are integral to warfighting abilities and therefore, the PMS system is seamlessly integrated with submarine's Integrated Combat System. Further, to make the vessel a potent weapon against any hostile ship or submarine, it is designed with an acoustic advantage of remaining invisible to enemy's sonars. However, verification measurements on low acoustic signatures etc. to arrive at actual data are feasible only once Kalvari class submarines are exploited extensively under various sea conditions (as underwater characteristics are highly unpredictable model varying with seasons, temperature gradient profiles, etc.).

Weapon Punch Onboard

Scorpene submarines boast of a large payload of heavy weaponry, integrated with hi-tech electronic sensors and weapons through Integrated Combat System. It is understood that Scorpene-class submarines are armed with six torpedo launching tubes and precision-guided weapons. To support the Weapons and Navigation systems, various sonars are fitted onboard (viz. Bow sonar, Stern sonar, Side looking sonars, Towed array active sonar) for identifying the threats, including mines, in shallow and deep waters. The inputs from the Sonar suite are utilized in the Torpedo Fire Control computers for various attacks/counter-attacks measures. For above water Target detection, the submarine uses surveillance radar (when it is operating on sea surface level).

Exocet SM-39 Anti-ship Missiles

A top naval officer has indicated that the French EXOCET tube-launched MBDA SM-39 anti-ship missiles are fitted as an integral package onboard the Kalvari Class submarines. These are the submarine variant of Ship launched SSMs. Each is 4.69 m long SM-39 missile weighs approx. 655kg and has a 350mm diameter. The missile is housed in a water-tight capsule, which is launched from the submarine's standard torpedo tube and has a two-stage solid propellant. And uses onboard Inertial Navigation system to cruise towards the Target position at a sub-sonic speed, following a sea-skimming trajectory. The SM-39 is an all-weather missile and has an active RF seeker head to make it 'fire-and-forget' weapon. These missiles can be launched from shallow or deep waters and have a high-penetration probability against a heavily defended surface target with a high hit probability.

Air-independent Propulsion (AIP)

With an AIP system, a submarine can run its propulsion electric motor and other electrical systems bypassing the use of conventional batteries, thereby, allowing the submarine to remain submerged for a longer duration (by reducing the need to surface often to take in the air for running diesel engines for charging batteries). The Kalvari class submarine has the provision for fitment of AIP to achieve better capabilities; however, the AIP system to be indigenously developed by DRDO has been delayed. With the status of on-going progress made by DRDO, the AIP system on the submarine looks available for integration only by next scheduled major overhaul period of the submarines, which could be after six years or so.