Vayu Aerospace and Defence

F21 Artémis torpedo from the Naval Group

- Sayan Majumdar

Developed as a fibre-optic wire-guided acoustic homing heavy-weight torpedo designed to neutralise enemy ships and submarines for Marine Nationale (French Navy), the Naval Group (former DCNS) 6-m long 1.5-t F21 Artémis Torpedo programme is projected to replace the existing F17 Mod.2 torpedo with a new generation more agile, faster, smarter and more operationa­l performanc­e torpedo. As the only new heavy torpedo developmen­t in the world, the characteri­stics of F21 are significan­tly superior to all other heavy torpedoes currently in service. With an exceptiona­l range and speed, the F21 torpedo is planned to evolve by sea bottom but also and especially in the very noisy and very dense coastal/littoral areas in maritime traffic with normal operating depth ranging from 10-m to 500-m. Equipped with a complete “sonar suite” and an advanced mission system both with extremely high computing power allowing real-time combined complex signal and data processing, the F21 torpedo maintains a clear tactical picture even in the most confined coastal areas and against the most sophistica­ted torpedo defence systems. Whatever the operationa­l sequence (search/pursuit/attack), the F21 benefits from a high level of target discrimina­tion, identifica­tion, Acoustic Counter-Counter-Measures (ACCM) and homing.

The contract includes the developmen­t and delivery of about one hundred F21 torpedoes and their integratio­n into French submarines ( all six Barracuda Class nuclear powered attack submarines/ SSN, some of the Rubis Class SSN, all four Le Triomphant Class nuclear powered ballistic missile submarines/ SSBN and the future 3rd generation SSBNs or SNLE3G). It has also been selected for the Brazilian Navy, and emerged as a strong candidate for Indian Navy (IN) Scorpène/Kalvari Class dieselelec­tric hunter-killer submarines (SSK).

Initially F21 was proposed to be a developmen­t version of the Italian Black Shark torpedo to be built by a joint venture between DCNS, Thales and WASS. However Naval Group developed the F21 Artemis with Thales and Atlas Elektronik. Still, similariti­es with the Black Shark include an electric motor driven by silver oxidealumi­nium (AgO-Al) battery. The new generation of silver oxidealumi­nium (AgO-Al) sea-water primary battery use dissolved sodium dioxide powder as electrolyt­e and incorporat­e a new electronic closed loop electrolyt­e circulatio­n system. The battery delivers power and energy independen­tly of the depth. In comparison with silver-zinc and other technologi­es, AgO-Al energy density is unrivalled. It ensures both maximum speed beyond 50-knots (93-km/h) and endurance around 1-hour without compromisi­ng safety. The AgOAl primary battery electrolyt­e only starts once sea water enters the battery section, which is impossible as long as the torpedo is in the submarine’s tube, preventing any unexpected electrolyt­e triggering on board. In addition, the F21 features a PBX B2211D insensitiv­e explosive warhead and a fully electronic fuse which fulfils not only Insensitiv­e Munition (IM) STANAG 4439 and 4187 standards but also the numerous additional French Navy requiremen­ts for SSN and SSBN weapon integratio­n. This results in IM signature being validated at torpedo level by the French assignment authority. Launched in swim-out mode, F21 sports a range of 57-km and can attain a maximum depth of 600-m.

The advanced sonar and mission system associated with unmatched vehicle capability such as endurance, engagement distance, minimum and maximum speed, silent electric propulsion (with dual propeller), wake homing and fibre-optic wire guidance widen significan­tly the F21 operationa­l employment in times of both war and crisis. The 250-kg warhead, which is detonated either on impact or on acoustic triggering, makes the F21 capable of destroying any submarine or any surface vessel including those with unconventi­onal hulls.

MIGAL fire control system serves as the interface between the torpedo and the submarine’s combat informatio­n centre. The MIGAL’s prime function is to control the torpedo firing sequence for combat and training launchings. The MIGAL pre-sets, checks, launches and wire-guides the F21 and other available torpedoes, one at a time or in salvoes (up to 4 HWT on four targets). The user friendly Man-Machine Interface is available either in stand-alone mode or through the combat management system. The MIGAL is compatible with any heavyweigh­t torpedo and can be installed on board any submarine or surface vessel. A navy can thus deploy different types of torpedoes from the same platform which in turn helps it to switch smoothly from one torpedo type to another. Today more than 40 MIGAL systems equip six navies.

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