New Delhi: Ahead of the induction of INS Karanj attack submarine into Indian Navy, the Defence Research and Development Organization (DRDO) conducted the final development test of Air Independent Propulsion (AIP) in Mumbai, a major step that will make Indian submarines more lethal.

AIP allows a submarine to be submerged for longer periods under water and makes the sub-surface platform more deadly by making it quieter than a nuclear submarine.

The Indian Navy now plans to retrofit all its Kalvari class non-nuclear attack with AIP during their first upgrade, expected around 2023. The 1615 tonne Kalvari class submarine is being built by Mazagon Dockyard Limited in collaboration with French Naval Group and is based on Scorpene design. INS Karanj, third of the class, commissioned into Indian Navy on March 10.

The development of AIP technology is a major boost for the Atmanirbharbharat campaign since only the US, France, China, UK and Russia have this key technology. The DRDO’s AIP technology is based on a Phosphoric Acid Fuel Cell and the last two Kalvari class submarines will be powered by it. The AIP design was tested on land in Mumbai, the last of a series of tests.