Scorpene subs to have system to stay longer under water

An indegenously-developed propulsion system that will allow Scorpene submarines to stay underwater for longer period is in final stages of development and trials could be held from March next year.
The Air Independent Propulsion (AIP) system, developed by DRDO, is to be fitted on the last two Scorpene submarines being built in India.
A conventional submarine (diesel-electric) has to resurface every 3-4 days for oxygen but those fitted with the latest generation of AIP can stay under water for as much as three-four weeks.
"It is an important and critical project for our country's submarine project and the trials are set to be held from March onwards next year," a senior DRDO official said here.

Six state-of-the-art Scorpene submarines are being built under the "Project 75" programme in collaboration with French defence major DCNS.
While the first Scorpene is likely to be inducted in 2016, the AIP will be fitted on the last two which would be ready some years later.

For the trials, a land-based compartment will be set, in which the tests will be carried out. The work on this projects was started in 2010, sources said.
The conventional submarine has to come to periscope depth and raise its snorkel, which makes it vulnerable to detection by the enemy.
AIP drastically improves stealth because it enables a submarine to generate electricity for services and battery charging and propulsion while being completely submerged.

Explaining the process of AIP, an official said the system, based on a fuel cell, converts methanol-like substances to produce hydrogen, which in turn produces electricity. While diesel engines need oxygen to function, these cells are air independent.
The DRDO has also tied up with both public and private firms for this project.
DRDO sources said the AIP is completely indigenous and the French company will be helping them to integrate the system to the Scorpene.
While giving a go-ahead for the indigenous production of another six submarines last month, the government has made it clear that all of them will have AIP technology.