Mark 13 torpedo

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A Mark 13 torpedo is loaded onto a TBF Avenger aboard the Wasp in 1944. The torpedo is fitted with breakaway wooden nose and tail protection which is shed upon hitting the water.

The Mark 13 torpedo was the U.S. Navy's most common air-launched torpedo of World War II. It was designed from the onset as an aircraft torpedo, with unusually squat dimensions for its type: diameter was 22.4 in (569 mm) and length 13 ft 5 in (4.09 m). In the water, the Mark 13 could reach a speed of 33.5 knots (39 mph) for up to 6,300 yards (5,760 m).^[1] 17,000 were produced during the war.^[2]

Early models—even when dropped low to the water at slow speeds—were prone to not starting or running on the surface. Later in the war the design was modified to allow drops from as high as 2,400 ft, at speeds up to 410 knots. The final Mark 13 weighed 2,216 lb (1,005 kg); 600 lb (262 kg) of this was the high explosive Torpex.^[3]

The Mark 13 was very similar in design to the Mark 14 and Mark 15 torpedoes 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.^[4]

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