NEW DELHI, — April 6, 2026 : The Defence Research and Development Organisation (DRDO) is preparing to initiate user-evaluation trials (UET) of the indigenous ‘Takshak’ electric heavyweight torpedo (EHWT) aboard the Indian Navy’s Kalvari-class submarines, with testing scheduled to commence in late 2026. The trials are intended to validate the system’s operational performance ahead of its planned induction into service.
The Takshak torpedo has been developed by the Naval Science and Technological Laboratory (NSTL), a Visakhapatnam-based laboratory under DRDO. It is designed as a submarine-launched heavyweight torpedo capable of engaging both enemy submarines and surface vessels. The system is positioned as an advanced electric-propulsion derivative of the Varunastra torpedo, optimized for deployment from standard 533 mm submarine torpedo tubes.
According to program details, the torpedo measures approximately 6.4 meters in length and weighs over 1,300 kilograms in its operational configuration. It is powered by an electric propulsion system using silver-oxide batteries, enabling low acoustic signature movement underwater. The estimated operational range is approximately 40 kilometers, with an operational depth capability of up to 400 meters.
Testing Roadmap and Schedule
The evaluation process will follow a phased testing structure aligned with the refit schedules of the Kalvari-class submarines.
Initial harbour-based trials will include both dry and wet testing procedures conducted while the submarine remains docked. These trials are intended to verify safe launch characteristics and ensure that torpedo deployment does not affect the submarine’s hull integrity, onboard sensors, or internal systems.
Following successful harbour validation, dynamic sea trials are scheduled for late 2026. During this phase, the torpedo will be deployed under operational conditions at varying depths and speeds. A key focus of this stage will be the validation of the fibre-optic wire guidance system, particularly its performance during high-speed underwater maneuvers.
A live-fire test phase is planned for 2027. This stage will involve the launch of a fully armed torpedo against a decommissioned ship or designated underwater target to assess warhead effectiveness and overall system reliability.
Guidance, Navigation, and Control Systems
The Takshak is equipped with a Ring Laser Gyroscope (RLG)-based inertial navigation system (INS), supported by satellite-based inputs from GPS and India’s NavIC navigation system. For tactical guidance, the torpedo uses a fibre-optic wire link, allowing real-time data exchange between the submarine and the weapon.
This fibre-optic guidance enables sonar operators onboard the submarine to transmit course corrections and targeting updates during the engagement. In the event that the wire link is severed, the torpedo is programmed to transition into an autonomous homing mode, allowing it to continue toward the target using onboard sensors.
The system also incorporates advanced sonar capabilities and resistance to electronic countermeasures, improving target acquisition and engagement reliability in contested environments.
Launch Mechanism and Submarine Integration
The Takshak torpedo is deployed using a “swim-out” launch mechanism, which allows the weapon to exit the submarine’s torpedo tube under its own propulsion rather than being expelled using compressed air. This method reduces the acoustic signature associated with launch, supporting the stealth characteristics of the submarine.
Integration of the torpedo with the Kalvari-class submarines is being carried out in coordination with ongoing submarine refit programs. During the refit of INS Kalvari, the lead vessel of the class, hardware required for the torpedo’s launch system is being installed along with other upgrades.
To support system integration, the Ministry of Defence signed a contract valued at ₹877 crore (approximately $102.4 million) with France’s Naval Group on December 30, 2024. The agreement covers the integration of the Takshak torpedo with the Submarine Tactical Integrated Combat System (SUBTICS), which is deployed across the Kalvari-class fleet.
The integration ensures compatibility between the torpedo and the submarine’s combat management system, enabling coordinated target tracking, fire control, and weapon deployment. The effort is being undertaken jointly by the Indian Navy, DRDO, and Naval Group.
Platform and Production Details
The Kalvari-class submarines, also known as Scorpene-class submarines, are being constructed in India by Mazagon Dock Shipbuilders Limited (MDL) under Project 75. These submarines form a key component of the Indian Navy’s conventional underwater fleet.
The Takshak torpedo is intended to be manufactured by Bharat Dynamics Limited (BDL) following successful completion of trials and acceptance into service.
As of late 2024, the torpedo had completed required redesign work, including modifications to its tail section, positioning it for the upcoming evaluation phase. Separate development activity related to an extended-range or deeper-strike variant of the EHWT has been reported, though it is not part of the current trial program for the Kalvari-class submarines.
Strategic Context
The development and planned induction of the Takshak torpedo form part of India’s broader efforts to enhance indigenous defence manufacturing under the “Aatmanirbhar Bharat” initiative. The system is expected to reduce dependence on imported heavyweight torpedoes while strengthening the operational capabilities of the Indian Navy’s submarine fleet.
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