Mark 13 torpedo
The Bliss-Leavitt Mark 13 torpedo was the U.S. Navy's most common aerial torpedo
Aerial torpedo
The aerial torpedo, airborne torpedo or air-dropped torpedo is a naval weapon, the torpedo, designed to be dropped into water from an aircraft after which it propels itself to the target. First used in World War I, air-dropped torpedoes were used extensively in World War II, and remain in limited...

 of World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

. It was designed with unusually squat dimensions for its type: diameter was 22.4 inches (56.9 cm) and length 13 in 5 in (4.09 m). In the water, the Mark 13 could reach a speed of 33.5 knots (18.2 m/s) for up to 6300 yards. The Mark 13 ran 12.8 knots (7 m/s) slower than the Mark 14 torpedo
Mark 14 torpedo
The Mark 14 torpedo was the United States Navy's standard submarine-launched anti-ship torpedo of World War II.This weapon was plagued with many problems which crippled its performance early in the war, and was supplemented by the Mark 18 electric torpedo in the last 2 years of the war...

. 17,000 were produced during the war.

Originating in a 1925 design study, the Mark 13 was subject to changing USN requirements through its early years with resulting on-and-off development. Early models—even when dropped low to the water at slow speeds—were prone to running on the surface, or not running at all. By late 1944, the design had been modified to allow reliable drops from as high as 2400 ft (731.5 m), at speeds up to 410 knots. The final Mark 13 weighed 2216 lb (1,005.2 kg); 600 lb (272.2 kg) of this was the high explosive Torpex
Torpex is a secondary explosive 50% more powerful than TNT by mass. Torpex is composed of 42% RDX, 40% TNT and 18% powdered aluminium. It was used in the Second World War from late 1942. The name is short for Torpedo Explosive', having been originally developed for use in torpedoes...


The Mark 13 was very similar in design to the Mark 14 and Mark 15 torpedo
Mark 15 torpedo
The standard U.S. destroyer-launched torpedo of World War II, the Mark 15 was very similar in design to the Mark 14 torpedo except that it was longer, lighter, and had longer range and larger warhead. 9,700 were produced during the war....

es which suffered from problems such as submerged running approximately ten feet lower than set, contact exploder duds and magnetic trigger premature explosions. The Mark 13 design avoided these problems with its larger diameter, lesser mass, lesser negative buoyancy, slower running speed and the lack of a magnetic influence feature in its Mark IV exploder.

At the close of the war, the Mark 13 was considered one of the most reliable air-dropped torpedoes available.
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