DRDO develops AIP technology, Indian subs to be more silent and lethal

A boost for Atma Nirbhar Bharat campaign, AIP-fitted submarines remain sub-surface for a longer period and are quieter than nuclear-powered submarines.

Updated on: Mar 9, 2021, 13:45:05 IST

By Shishir Gupta, Hindustan Times, New Delhi

Prefer HTon Google

Share via

Copy link

A day before INS Karanj attack submarine is inducted into Indian Navy, the Defence Research and Development Organization (DRDO) conducted the final development test of Air Independent Propulsion (AIP) in Mumbai on Monday night, 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. (Photo: Indian Navy)

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 Dockyards Limited in collaboration with French Naval Group and is based on Scorpene design. INS Karanj, third of the class, is expected to be commissioned tomorrow.

The development of AIP technology is a major boost for the Atma Nirbhar Bharat 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 on Monday night, the last of a series of tests.

The AIP or marine propulsion technology allows non-nuclear submarines to operate without access to atmospheric oxygen (through snorkel or surfacing) and augments the diesel-electric propulsion system of attack submarines. This means that the AIP fitted submarine does not have to surface for charging its batteries and remains underwater for long periods. The AIP is retrofitted into existing submarine hulls by adding an additional hull section. The AIP equipped submarines are identified as SSP while classic diesel attack submarines carry the SSK classification.

While the nuclear submarine generates noise due to the ship’s reactor constantly pumping coolant to maintain temperatures of the engine, the AIP-equipped submarine maintains a lethal silence. The new technology will add to lethality of Indian submarines, which also take advantage of internal refraction in equatorial waters due to differences in temperatures on the surface and within the ocean.

The DRDO’s AIP technology has also got a pat in the back from the French, who were in touch with the Indians in the context of Kalvari class manufacturing. Despite urgent requests, the French have decided not to upgrade the Pakistani Agosta 90 B submarines with AIP technology, forcing Islamabad to either go to China or Turkey.

ABOUT THE AUTHOR
Shishir Gupta
Shishir Gupta is Executive Editor at Hindustan Times and one of India's top journalists covering national security, strategic affairs, foreign policy and geopolitics. Over the past three decades, he has extensively reported on India's military, diplomatic and security landscape, covering every major conflict and national security challenge, from the 1999 Kargil War and the 2020 East Ladakh standoff to Operation Sindoor in 2025. He has also covered major terror attacks, including the IC-814 hijacking, the 26/11 Mumbai attacks and the 2025 Pahalgam terror strike, along with numerous Pakistan-backed terrorist incidents in the Kashmir Valley and across India. He has reported on national and state elections for more than three decades. A recognised authority on strategic affairs, Gupta has covered India's nuclear programme since the Pokhran-II (Shakti series) tests in May 1998 and has written extensively on global nuclear issues, Indian diplomacy and the country's expanding global outreach. He has also reported widely on international conflicts and terrorism, with a special focus on the Indian subcontinent. Gupta has interviewed Prime Minister Narendra Modi more than four times, including Modi's first interview with the print media after becoming Prime Minister in May 2014. His other interviews include three with the Dalai Lama, as well as conversations with Benjamin Netanyahu, Amit Shah, Yogi Adityanath, S. Jaishankar, Nirmala Sitharaman and Piyush Goyal. He is the author of Indian Mujahideen: The Enemy Within (Hachette, 2011) and Himalayan Face-off: Chinese Assertion and Indian Riposte (Hachette, 2014). He was awarded the Chevening-Wolfson Joint Scholarship at Wolfson College, University of Cambridge, UK, in 1998 and participated in the International Visitor Leadership Program (IVLP) of the US State Department in 2006. He received the Ben Gurion Prize from Israel in 2011 and the K. Subrahmanyam Prize for Strategic Studies in 2015 from the Manohar Parrikar Institute for Defence Studies and Analyses (MP-IDSA). Since 2024, he has hosted Point Blank, Hindustan Times' weekly YouTube show on global geopolitics.Read More

Drdo Test

Get the latest India News, breaking headlines and real-time updates from across the country. Stay informed about politics, government policies, crime, weather and major national developments.