Three New Scorpene Submarines That India Is Buying From France To Get AIP Propulsion As Naval Group Commences Integration

The three additional submarines that Indian Navy is buying from France's Naval Group will come installed with the new DRDO-built Air Independent Propulsion (AIP) system.

The deal to buy these three submarines estimated to be worth €4 billion was announced on 14 July, when Prime Minister Narendra Modi visited France.

A day earlier on 13 July, the Defence Acquisition Council (DAC) headed by the Defence Minister Rajnath Singh has also approved an Acceptance of Necessity (AoN) worth approximately €9.5 billion, for acquiring 26 Rafale Marine fighter jets and three Scorpene submarines for the Indian Navy.

These three additional submarines will be installed with the DRDO-lab Naval Materials Research Laboratory (NMRL)-designed AIP systems.

It is worth noting that the Indian Navy already operates six Scorpene submarines which were acquired from France, under a $3.5 billion contract in 2005, and under the contract the last two submarines were to equipped with DRDO-built AIP propulsion system.

However, due to delays in the development of the system, the AIP was not installed.

The Mazagaon Docks Limited (MDL) and Naval Group, on the other hand, has signed an agreement to install the AIP system on all the six scorpene submarines, on the sidelines of Aero India, held at Bengluru in February 2023.

According to reports, the first scorpene submarine, INS Kalvari will undergo AIP installation when it goes for its first refit, by the end of 2024.

According to a report by The Hindu, Naval Group has commenced work to integrate these AIP systems on the submarines and has already invested more than Rs 100 crore for establishing three workshops and procuring tools and infrastructure necessary for the integration.

“We are actively supporting the DRDO in qualifying indigenous supplier of liquid oxygen tank and preparation of the future stage of 'jumboisation' (making the new hull, integrate safely the AIP, cut the submarine and join it with new AIP section) during submarine’s normal refit,” said Pierre Éric Pommellet, CEO of Naval Group.

"The AIP system will increase the underwater endurance of submarines from three days to a week to more than two to three weeks".

The integration of an AIP module requires cutting the host submarine hull in half, adding the AIP module in the middle and welding the hull back, after rejoining all the pipings, mechanical and electrical systems.