VERVIEW: The Mk 48 Mod 1 is a heavyweight U.S. Navy submarine-launched torpedo introduced in 1972, designed for dual anti-submarine and anti-surface warfare. It uses wire guidance and active/passive acoustic homing, powered by Otto Fuel II.

DETAILS: “Mark 48” designates the U.S. Navy’s standard 21‑in heavyweight torpedo; “Mod 1” is the initial production variant following RETORC II development and trial selections. It measures 19 ft (5.79 m) in length, 21 in (533 mm) in diameter, and weighs ~3,434 lb (~1,558 kg). It carries a ~650 lb (~295 kg) high-explosive warhead and is propelled by a swash-plate piston engine with pump-jet, fueled by Otto Fuel II, achieving speeds up to ~55 kn and range exceeding 5 mi (~8 km) officially, with estimates of ~48,000 yd (~24 nm) at ~40 kn. Guidance combines wire control during mid-course and active/passive sonar homing terminally; dual-mode enables engagement of deep-diving submarines and fast surface vessels. Developed 1967–1971, Mod 1 was selected over Mod 2 and entered service in 1972 aboard U.S. submarines.

TYPE: Heavyweight submarine-launched wire-guided dual-purpose acoustic homing torpedo

FUNCTION: Launched via 21‑in submarine tubes, Mk 48 Mod 1 uses wire guidance to navigate during the initial and mid-course phases, then transitions to onboard active/passive sonar homing for final interception of submarines or surface ships. Upon target acquisition, it detonates via proximity or contact fuse.

NOTE:
IOC: 1972
Manufacturer: Gould, Inc. (later Honeywell), USA
Operators: United States; also adopted by Brazil, Canada, Australia, Netherlands, Taiwan
Platforms: U.S. Navy fleet and ballistic submarines equipped with 21‑in tubes
Conflict used in: No confirmed combat deployment

SOURCE: Mark 48 torpedo (Wikipedia); “MK 48 - Heavyweight Torpedo” (US Navy Fact File); FAS Mk‐48 specs; Naval‐Undersea Museum “Advanced Capabilities: U.S. Mark 48 Torpedo”; A Brief History of U.S. Navy Torpedo Development – Part 2