Mark 39 torpedo

The Mark 39 torpedo was the first homing torpedo in United [States Navy] service to use a trailing wire for mid-course guidance through the submarine's fire control system. In 1946, shortly after the Mark 37 Mod 0 had been prototyped, the wire guidance system was reverse-engineered from the List of [World War II torpedoes of Germany|G7ef(TX) "Spinne"] following the arrival of technical documentation from Germany. This resulted in the development of a wire-guided prototype the same year. The Mark 39 was a Mark [27 torpedo|Mark 27] Mod 4 torpedo converted for development of wire guidance techniques, which were eventually incorporated into the Mark 37 Mod 1 and the Mark 45. Due to this development, the Mark 39 was considered obsolete and the remaining inventory was scrapped.