Type 93 torpedo
The Type 93 was a 610 mm (24 inch) diameter torpedo of the Imperial Japanese Navy. Called the "Long Lance" by US sailors (a nickname attributed to Samuel E. Morison, a historian who spent much of the war in the Pacific theater), it was the most advanced torpedo in the world at the time.
The Type 93 was quietly developed in Japan in the 1930s. It used compressed oxygen instead of compressed air for its propulsion oxidizer. Oxygen had a couple of advantages, it did not leave an obvious track of bubbles and it was more efficient as a fuel. However, compressed oxygen is dangerous to handle and required lengthy testing and experimentation to make it possible to use operationally. It was first deployed in 1935.
The Type 93 had a range of 40,000 meters. Too large to fit in the standard 21-inch torpedo tubes, it was usually launched from the decks of surface ships, but some submarines also had deck-mounted launchers.
Its capabilities were not recognized by the Allies until one was captured in 1943.
A 17.7 inch version designated the type 97 torpedo was later developed for use by midget submarines, but was not a success and was replaced operationally by the type 91 torpedo.
