OVERVIEW:  The L5 Mod 4 is a heavyweight French ship‑launched torpedo designed for anti‑ship and anti‑submarine warfare. It uses electrically driven propulsion and active/passive sonar homing, launching from surface combatants.

DETAILS:  L stands for Lourde (heavyweight) and Mod 4 denotes the surface‑launched, ASW‑specialised variant of the DTCN L5 series. It is 4.40 m long, 533 mm diameter, and weighs about 920–935 kg. It carries a 150 kg high‑explosive (HBX‑3/TNT) warhead, powered by a silver‑zinc electric motor achieving 35 kn speed with a range of approximately 9.25 km, and operating to depths around 500 m. Its Thomson‑CSF active/passive sonar enables both anti-submarine and anti-surface target engagement. First introduced in 1976, Mod 4 remained in service on French frigates and destroyers until being replaced by the F17 series.

TYPE: Heavyweight surface‑launched acoustic homing torpedo

FUNCTION:  Fired from 533 mm tubes on surface vessels, the torpedo initially follows a programmed search pattern or gyroscopic course, then shifts to active/passive sonar homing when a submarine or surface ship is detected. It maneuvers underwater to intercept and detonates its warhead on or near the target.

NOTE:
IOC: 1976
Manufacturer: Direction Technique des Constructions Navales (DTCN), France
Operators: France
Platforms: Suffren‑class, Tourville‑class, Georges Leygues‑class and Cassard‑class frigates, F70‑class destroyers
Conflict used in: No confirmed combat deployment

SOURCE: Torpille DTCN L5 (French technical data); Wielingen: ECAN L5 Mod 4 specifications; Naval‑Encyclopedia: Tourville/Suffren armament; Cassard‑class frigate armament data