Brazil Navy Riachuelo class submarine conducts immersion tests.

According to information published by Defesa Aerea & Naval (Guilherme Wiltgen) on March 24, 2023, the second Riachuelo class submarine Humaita successfully conducted immersion tests.
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Brazilian Navy's Riachuelo class submarine Humaita. (Picture source: Brazilian Navy)

The Riachuelo class is a type of attack submarine developed by the state-owned shipyard Itaguaí Construções Navais as part of the Submarine Development Program (PROSUB), a naval modernization plan of the Brazilian Armed Forces. The class includes both diesel-electric and nuclear-powered submarines and is based on the French Scorpène class.

The conventional submarine has a displacement of 1,900 t and a length of 70.62 m, while the nuclear submarine has a displacement of 6,000 t and a length of 100 m.

The propulsion systems are different as well, with the conventional Riachuelo class submarine using four MTU 12V 396 SE84 diesels and one Jeumont-Schneider EPM Magtronic electric motor, while the nuclear Riachuelo class submarine has a pressurized water reactor and nuclear turbo-electric engine.

The Riachuelo class submarines also have different speeds, with the conventional submarine capable of 21 knots and the nuclear submarine capable of 25 knots.

The armament of the Riachuelo class includes six 533 mm torpedo tubes, eight cruise missiles, eight SM-39 Exocet or MANSUP anti-ship missiles, 18 F21 heavy torpedoes, and 30 naval mines.

The complement is also different, with the conventional Riachuelo class submarine having 32 crew members and the nuclear Riachuelo class submarine having 100.

The sensors and processing systems of the Riachuelo class include the DCNS Submarine Tactical Information and Command System, Thales DR 3000 ESM receiver, ITT AR 900, TSM 2233 Eledone, Safare & S-Cube, and DCNS Contralto-V. The electronic warfare and decoys of the Riachuelo class include the Thales DR 3000 ESM receiver, ITT AR 900, TSM 2233 Eledone, Safare & S-Cube, and DCNS Contralto-V.