DRDO to develop technology to help submarines remain under water for long

The Defence Research Development Organisation (DRDO) is in the process of developing ‘air independent propulsion (AIP)’ technology that would ensure future Indian-built submarines stay underwater for longer periods than a conventional submarine.

“Every 24 hours or so a conventional submarine has to surface in order to replenish its oxygen supply,” explained an official at the DRDO, a defence research agency, adding that new technology under consideration at DRDO’s unit, Naval Material Research Laboratory, at Ambernath, near Mumbai, would help the submarine stay underwater for a longer duration.

Submarines tend to be battery operated, since generators cannot be used under water. In order to recharge the battery, submarines have to surface, for taking in air and throwing out the exhaust, making the stealth vehicle vulnerable to detection.

However, with the AIP “that is based on a fuel cell which converts methanol-like substances to produce hydrogen, which in turn produces electricity,” submarines can remain longer under water, said the official, adding that the technology would help boost its combat operation capability.

Meanwhile, the sea trials of the first of six Scorpene submarines has got underway, and are likely to continue until the commissioning of the submarine next year.

The first of the six Scorpene submarines, the INS Kalvari is part of a $3.6-billion contract signed in October 2005 with French firm DCNS, which is currently assembling the Scorpenes at the Mumbai port.

Though the Scorpene submarines (Project-75) were conceived as non-AIP vessels, DCNS had offered to fit the last two submarines under the six-vessel project with the AIP technology. Sources indicated that the DRDO-developed AIP system could be fitted in the last two submarines, if the “timeline matches the delayed production timelines of Project 75,” which is running four years behind schedule.

“Late last year, the government issued a RFI (request for information) for six more conventional submarines as a follow-on project for Project-75 and has codenamed it Project-75-I. Under Project-75-I, the six submarines to be built by India will have AIP technology, since it is an auxiliary system that will increase the endurance of the boat’s sub-surface operability,” said the DRDO official, speaking about the $12-billion tender for six conventional AIP submarines.

Germany’s Thyssenkrupp Marine Systems with its HDW Class 214 submarine, the Russian Rubin Design Bureau’s Amur 1650, the Spanish Navantia S-80 class, France’s DCNS with its Scorpene platform, and the Swedish Saab Kockums’ with its A26 submarines have all displayed interest in the project.

In an earlier interaction with BusinessLine , Gurnad S Sodhi, Managing Director, ThyssenKrupp Marine Systems India, said the HDW Class 214’s “proven fuel-cell based AIP system is the best available in the market”.

Meanwhile, DRDO has already demonstrated its AIP technology on a land based prototype, and trials on a land based submarine section are to commence soon. “While the DRDO AIP can be reconfigured for the submarines to be acquired under Project-75-I, the four Scorpenes under Project-75 could also be retrofitted under an upgrade programme,” pointed out the DRDO official, adding that the Defence Acquisition Council's approval has already been accorded for Project-75-I.

Apart from AIP, the new submarines will have advanced detection range and combat management systems and better sensors for optimum performance on the new submarines. The weapon system would be a mix of torpedoes and missiles.

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