A torpedo tube is a cylindrical device for launching torpedoes. There are two main types of torpedo tube: underwater tubes fitted to submarines and some surface ships, and deck-mounted units (also referred to as torpedo launchers) installed aboard surface vessels. Deck-mounted torpedo launchers are usually designed for a specific type of torpedo, while submarine torpedo tubes are general-purpose launchers, and are often also capable of deploying mines and cruise missiles. Most modern launchers are standardized on a 12.75 in diameter for light torpedoes (deck mounted aboard ship) or a 21 in diameter for heavy torpedoes (underwater tubes), although torpedoes of other classes and diameters have been used.

Submarine torpedo tube

A submarine torpedo tube is a more complex mechanism than a torpedo tube on a surface ship, because the tube has to accomplish the function of moving the torpedo from the normal atmospheric pressure within the submarine into the sea at the ambient pressure of the water around the submarine. Thus a submarine torpedo tube operates on the principle of an airlock.

Torpedo tube operation

The diagram illustrates the operation of a submarine torpedo tube. The diagram is somewhat simplified but does show the working of a submarine torpedo launch. A torpedo tube has a considerable number of interlocks for safety reasons. For example, an interlock prevents the breech door and muzzle door from opening at the same time. The submarine torpedo launch sequence is, in simplified form: Spare torpedoes are stored behind the tube in racks. Speed is a desirable feature of a torpedo loading system, but safety is paramount. There are various manual and hydraulic handling systems for loading torpedoes into the tubes. Prior to the Ohio-class submarine, US SSBNs utilized manual block and tackle which took about 15 minutes to load a tube. SSNs prior to the Seawolf-class submarine used a hydraulic system that was much faster and safer in conditions where the ship needed to maneuver. The German Type 212 submarine uses a new development of the water ram expulsion system, which ejects the torpedo with water pressure to avoid acoustic detection.