OVERVIEW: Type 73 torpedo is a Japanese light-weight, anti-submarine weapon adopted in 1973. It is electrically powered and designed to operate from surface ships and helicopters.

DETAILS: Type 73 (“Type” meaning the year 1973 in the Japanese Imperial calendar; project name G‑9B) is a 324 mm diameter, ~2.5 m long torpedo developed by Japan’s Technical Research and Development Institute and manufactured by Mitsubishi Heavy Industries. It features an electric motor powered by a silver chloride–magnesium–seawater fuel cell, capable of ~35 kt speed and ~6 km range. Armed with ~40 kg of HBX-3 explosive, it uses active acoustic homing guidance. A modernization in 1984 resulted in the Type 73B, which added torpedo counter-countermeasure (TCCM) functionality. 

TYPE: Lightweight anti-submarine torpedo

FUNCTION: Launched from ships, helicopters, or aircraft to detect and home acoustically on submerged submarines, engaging them with an explosive warhead. The system adapts to shallow or variable-depth targets within its acoustic envelope.

NOTE: IOC: 1973 (Type 73), 1984 (Type 73B)
Manufacturer: Mitsubishi Heavy Industries (Japan)
Operators: Japan Maritime Self‑Defense Force 

SOURCE: Jane's Underwater Warfare Systems 2006-2007; SDF Equipment Yearbook 2006‑2007; Japanese Maritime Self‑Defense Force Ammunition Disposal Project: https/www.link.com/model-reference