India’s submarine fleet gets big boost as desi AIP system to enhance underwater capability achieves key milestone

NEW DELHI: A significant milestone towards enhancing Indian Navy’s underwater capabilities has been achieved with the inauguration of ‘Setting to Work Phase (STW)-2’ activity of the Air Independent Propulsion (AIP) system energy module developed indigenously by Naval Materials Research Laboratory of Defence Research Development Organisation (DRDO).STW is the critical transition phase between building a machine and actively operating it. The AIP system boosts the underwater endurance of the diesel-electric submarines by reducing its dependence on atmospheric oxygen. It allows conventional diesel-electric submarines to remain under water for weeks at a time—typically 2 to 4 weeks.In the next phase, the AIP energy module will be energised for power production and tested rigorously as per Indian Navy’s protocols before handing over to Mumbai-based Mazagon Dock Shipbuilders Limited for integration on Kalvari-class submarine in early 2027. India has built 6 Kalvari-class (Scorpene-design) submarines under Project-75 at Mazagon and has a proposal on the table to build 3 additional submarines.The inauguration ceremony took place at Larsen and Toubro’s, AM Naik Heavy Engineering Complex at Hazira in Gujarat on Saturday.Defence secretary and DRDO chairman Rajesh Kumar Singh, who led the ceremony as chief guest virtually, congratulated DRDO and industry partners and appreciated the scientific perseverance and industrial cooperation in the indigenous AIP programme, which has culminated into productive reality on the shop floor. He also acknowledged the cooperation rendered by the Indian Navy to DRDO throughout the course of this programme, including testing and validating at every stage of the trials.He emphasised on working towards next phases of the programme towards achieving the Navy’s induction timelines for the AIP system while maintaining the exacting safety culture that hydrogen and fuel cell systems require without compromise.