DRDO To Equip Indian Navy Submarines With Lethal ‘AIP Technology’

Indian Navy is set to receive a boost through Air Independent Power (AIP) for its submarines much after its regional foes – China and Pakistan. Defence Research and Development Organisation (DRDO) has announced that India’s AIP system will eventually be fitted aboard all Kalvari-class submarines.

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Initially, the 5th and 6th submarine were supposed to receive an AIP plug. However, due to delays, it was decided that the AIP plug will be retrofitted to each Kalvari-class submarine during their first normal refit that occurs every 7 years.

The AIP technology allows a non-nuclear submarine to stay underwater for a longer period which makes it harder to detect and patrol in high-risk areas.

According to H.I. Sutton, an author and expert on underwater warfare, it would be mounted in a hull extension that is inserted between the crew area and the engine space. The locally designed system is expected to extend the endurance of the submarines by two weeks.

“AIP has a force multiplier effect on the lethality of a diesel-electric submarine as it enhances the submerged endurance of the boat, several folds. Fuel cell-based AIP has merits in performance compared to other technologies,” said a government press release.

The Chief of the Naval Staff, Admiral Karambir Singh appreciated the breakthrough accomplishments achieved in this programme and said that the programme is of great value to the nation and the Indian Navy in particular. He urged DRDO and the Indian Navy to continue the partnership to meet the timelines set for short and long-term goals.



India’s adversaries, China and Pakistan already possess the AIP system. Pakistan’s Agostas have an added advantage. “Unlike the Indian subs, which will use fuel cells, the Pakistan Navy submarines use the MESMA (Module d’Energie Sous-Marine Autonome) system.



This burns ethanol with stored oxygen to produce steam, which turns a turbine similar to a nuclear power plant,” explained Sutton.

He further wrote that Pakistan is buying eight Type 093B submarines from China that will come with another type of AIP called a Stirling generator, which uses a closed-cycle diesel engine. He explained that those are same as Chinese AIP submarines, 17 of which are believed to be in service.

“The Stirling generator is famous because of the Swedish Navy’s use, and it is also the type used by Japan,” he added.

According to Aaron Amick, author of the Sub Brief podcast, AIP will give the Indian Navy strategic advantages over the current non-nuclear submarines. He said that it will “force their closest rival, Pakistan, to be more vigilant over a wider area.

Improving their Scorpene submarines with AIP will balance India with Pakistan’s new Type 093B Chinese subs that are due in 2023.” He further added that AIP is “essential in the 21st century, open water battlespace. Submarines only get one chance to attack from stealth and AIP gives them the best opportunity for success”.

Sutton concluded by saying that for some time Pakistan’s AIP submarines will continue to out-number India’s as the Indian project is still several years away. “But the indigenous fuel cell technology will allow India to increase the usefulness of their conventional submarines.

Add to this India’s nuclear-powered submarines and the Indian Navy should be able to retain a competitive edge,” he stated. “And India’s next-generation Project-75I boats will get AIP from the get-go”.