Mark 15 torpedo

Mark 15 torpedo
Mk 15 torpedoes aboard USS O'Brien (DD-725)
Type	Anti-surface ship torpedo
Place of origin	United States
Service history
In service	1938-1956
Used by	United States Navy
Wars	World War II
Production history
Designer	Naval Torpedo Station
Designed	1938
Manufacturer	Naval Torpedo Station Naval Ordnance Station Forest Park
Produced	1940-1944
No. built	9,700
Specifications
Weight	3,841 pounds
Length	288 inches
Diameter	21 inches
Effective firing range	6,000 yards at 45 knots (5,500 meters at 83 km/h)
Maximum firing range	15,000 yards at 26.5 knots (13,500 meters at 49 km/h)
Warhead	HBX
Warhead weight	825 lb (375 kg)
Detonation mechanism	Mk 6 Mod 13 contact exploder
Engine	Wet-heater combustion / steam turbine with compressed air tank
Propellant	Methanol
Speed	26.5 - 45 knots
Guidance system	Gyroscope
Launch platform	Destroyers

The Mark 15 torpedo, the standard American destroyer-launched torpedo of World War II, was very similar in design to the Mark 14 torpedo except that it was longer, heavier, and had greater range and a larger warhead. It was developed by the Naval Torpedo Station Newport concurrently with the Mark 14 and was first deployed in 1938. It replaced the Mark 8 torpedo on surface ships with tubes that could accommodate the longer Mark 15; this primarily included destroyers built after 1930. Older destroyers, primarily the Wickes and Clemson classes, continued to use the Mark 8, as did PT boats early in World War II. During the war 9,700 were produced at Newport and at the Naval Ordnance Station Forest Park, Illinois.

The Mark 15 had the same basic design problems that plagued the Mark 14 for the first 20 months following U.S. entry into the war, though this was not realized nearly as quickly by the destroyer crews as it was by the submariners. One major shared deficiency was the Mark 6 exploder, which usually caused duds. Surface-combatant torpedo attacks very often included confusing splashes from gunnery and aerial bombs, obscuring smoke screens, and quick maneuvering to evade counterattack. Rarely was a destroyer given a chance for a slow, careful surprise attack. Torpedo results were difficult to estimate under these circumstances. The correction of the Mark 15's problems would depend on the submariners solving theirs.

The Battle of Vella Gulf on the night of August 6–7, 1943, was the first in which a surprise torpedo attack by U.S. gave the Americans an overwhelming advantage in the following gun battle, though one Japanese warship was hit by a dud torpedo and escaped. By September 1943, effective methods of torpedo deployment were beginning to be distributed to all U.S. destroyers.