Indian submarines set for indigenous edge in open seas

An indigenously developed air-independent propulsion (AIP) system that will significantly increase underwater endurance of conventional submarines is ready and will be fitted onboard the first submarine next year, a senior DRDO scientist in charge of the project has said.

An AIP system adds significant stealth to conventional submarines, greatly enhancing operational effectiveness. It increases the ability of a submarine to stay underwater from a matter of a few days to almost two weeks, giving it a big edge in the open seas.

DRDO chief Samir Kamat inaugurated an AIP Integration and Testing facility at L&T's AM Naik Heavy Engineering Complex on Saturday. The advanced system will be manufactured and tested at the complex over the next year, before being fitted onboard the submarine at Mazagaon Dockyard Limited (MDL).


Suman Roy Choudhury, programme director, AIP, Naval Materials Research Laboratory (NMRL), said the AIP would be fitted onboard INS Kalvari submarine when it comes in for its first major refit in September next year.

The Kalvari is the first of the Scorpene line of submarines made by MDL and has been selected for the complex procedure that will involve cutting the boat into two halves and inserting a new AIP section. The section will increase the length and weight of the submarines, requiring a procedure that will be done with the assistance of its original manufacturer, France's Naval Group.


Once proven successful, the AIP can be fitted onboard five more Kalvari class submarines as and when they come in for their major refit to MDL. Successful integration of the AIP on time could also mean that the additional three Kalvari class submarines that are currently under price negotiations with MDL could also have the system from the very beginning.

Developed by DRDO in partnership with private sector players like L&T, the AIP has undergone extensive trials and a shore-based version was demonstrated to the Navy. DRDO has gone for a fuel cell-based AIP, which has high safety margins and better performance than many other such systems available globally.