What Happened
- Raksha Mantri Rajnath Singh laid the foundation stone of a state-of-the-art Large Cavitation Tunnel (LCT) at the Naval Science & Technological Laboratory (NSTL), a premium DRDO laboratory in Visakhapatnam, on April 3, 2026.
- The LCT is conceived as a strategic national asset that will significantly enhance India's indigenous capabilities in hydrodynamic research, supporting the design and development of next-generation ships, submarines, and underwater platforms.
- The facility will strengthen capabilities in advancing propulsion systems, enable focused efforts on noise reduction, and enhance stealth capabilities of naval platforms.
- The event was attended by Chief of Defence Staff General Anil Chauhan, Chief of the Naval Staff Admiral Dinesh K. Tripathi, and Flag Officer Commanding-in-Chief, Eastern Naval Command, Vice Admiral Sanjay Bhalla.
- The project marks a major step towards achieving technological self-reliance (Aatmanirbharta) in critical naval defence technology.
Static Topic Bridges
Cavitation and Its Significance in Naval Warfare
Cavitation is a hydrodynamic phenomenon where rapid fluid flow around an object (such as a submarine propeller) causes localised pressure drops that form vapour bubbles. When these bubbles collapse, they generate intense noise, vibration, and can erode metal surfaces. For submarines, cavitation is a critical concern because it directly compromises stealth, the most vital tactical advantage of undersea platforms.
- Cavitation occurs when local fluid pressure drops below the vapour pressure of water, forming bubbles that collapse violently
- Cavitation inception speed (CIS) is the highest speed at which a vessel can operate without any propeller cavitation, a key design parameter for submarines
- There is a step-change in noise levels between non-cavitating and cavitating propeller operation, making cavitation avoidance essential for submarine stealth
- Cavitation tunnels are variable-pressure water tunnels that simulate real-world hydrodynamic conditions for testing propeller and hull designs
- Hydro-acoustic tunnels are specialised variants that enable precise noise measurement of propeller designs under controlled conditions
Connection to this news: The Large Cavitation Tunnel at NSTL will enable India to indigenously test and optimise submarine propeller designs for noise reduction and stealth performance, reducing dependence on foreign facilities for critical hydrodynamic testing.
Naval Science & Technological Laboratory (NSTL)
NSTL, established on August 20, 1969, is DRDO's premier laboratory for underwater weapons and systems, headquartered in Visakhapatnam. Over five decades, it has evolved from an initial staff of 10 to 674 personnel (including 186 scientists), developing indigenous torpedoes, mines, and autonomous underwater vehicles for the Indian Navy.
- Key achievements include the Varunastra heavy-weight torpedo (1,500 kg, 40 km range, 40+ knots, inducted 2016) and the Advanced Lightweight Torpedo (ALWT, ~300 kg, 25 km range)
- Currently developing high-speed supercavitation torpedoes capable of exceeding 80 knots (~148 km/h)
- Developed the Multi-Influence Ground Mine (MIGM) for detecting submarine and stealth ship signatures
- Partnering with Cochin Shipyard on the HEAUV autonomous underwater vehicle
- Varunastra torpedo successfully completed combat trials on June 5, 2023
Connection to this news: The LCT complements NSTL's existing underwater weapons portfolio by providing a world-class testing facility for propulsion and hull hydrodynamics, enabling the laboratory to test its torpedo, submarine, and underwater vehicle designs domestically.
Defence Self-Reliance and Make in India (Defence)
India's push for defence self-reliance has been accelerated through the Make in India initiative in defence, with the Defence Acquisition Procedure (DAP) 2020 prioritising indigenous design, development, and manufacturing. The defence indigenisation percentage has increased from approximately 54% in 2019 to over 68% in FY2025, with a positive indigenisation list restricting imports of 500+ defence items.
- Defence Production value crossed Rs 1.27 lakh crore in FY2024, with exports reaching Rs 21,083 crore
- Five defence corridors established in Uttar Pradesh and Tamil Nadu to anchor domestic production ecosystems
- DAP 2020 categories: Buy (Indian), Buy & Make (Indian), Make, and Strategic Partnership — all prioritise indigenous content
- India's naval shipbuilding sector is already largely indigenous: INS Vikrant (aircraft carrier), Kalvari-class submarines (Scorpene), and Project-75I are landmark programmes
- A cavitation tunnel is a foundational testing infrastructure that no amount of imports can substitute — it enables continuous indigenous design iteration
Connection to this news: The LCT represents a strategic infrastructure investment that underpins long-term defence self-reliance: without indigenous hydrodynamic testing capability, India would remain dependent on foreign test facilities for every new submarine and warship propulsion design.
Key Facts & Data
- Foundation stone laid: April 3, 2026, by Raksha Mantri Rajnath Singh
- Location: NSTL, Visakhapatnam, Andhra Pradesh
- NSTL established: August 20, 1969; current strength: 674 personnel (186 scientists)
- Varunastra torpedo: 1,500 kg, 40 km range, 40+ knots speed, inducted 2016
- Supercavitation torpedo under development: target speed 80+ knots (~148 km/h)
- Defence Production (FY2024): Rs 1.27 lakh crore; exports: Rs 21,083 crore
- Positive indigenisation list: 500+ items restricted from import
- CDS General Anil Chauhan, CNS Admiral Dinesh K. Tripathi present at ceremony