OVERVIEW: The Mk 48 Mod 3 is a heavyweight U.S. Navy submarine-launched torpedo introduced in 1977, designed for dual anti-submarine and anti-surface warfare. It incorporates two-way wire telemetry for real-time operator feedback and enhanced homing control.

DETAILS: “Mark 48” designates the U.S. Navy’s primary 21‑inch heavyweight torpedo; “Mod 3” denotes the addition of TELCOM two‑way communication to the earlier Mod 1 baseline. It retains the same physical dimensions approx. 5.79 m length, 533 mm diameter, and ~1 558 kg weight with a ~295 kg high-explosive warhead and Otto Fuel II powered swash‑plate piston engine achieving speeds up to ~55 kn. The TELCOM system transmits sonar and torpedo status data (e.g., depth, trajectory) back to the submarine at ~14 updates per second via wire guidance, allowing mid-course adjustments and enhanced acoustic homing performance. Certification and entry into fleet service occurred in 1977 following trials.

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

FUNCTION: Launched from 21‑inch submarine tubes, the Mk 48 Mod 3 uses wire guidance with two-way TELCOM during mid-course to relay sensor and trajectory data back to the submarine. Upon target detection or wire release, it transitions to active/passive sonar homing in the terminal phase to intercept and detonate via contact or proximity.

NOTE:
IOC: 1977
Manufacturer: Gould Inc. (later Honeywell), USA
Operators: United States and other Mk 48 users (e.g., Australia, Canada, Netherlands, Brazil)
Platforms: U.S. Navy submarines with 21‑inch torpedo tubes—fleet and ballistic types; also fitted to allied submarines of partner navies

SOURCE: Mark 48 torpedo – Nuclear Companion: variant info; Mark 48 torpedo (Wikipedia); Advanced Capabilities – U.S. Mark 48 Torpedo (thetidesofhistory.com); U.S. Navy Torpedoes functional data (Naval Submarine League Archive)