Human torpedo

Human torpedoes or manned torpedoes are a type of rideable submarine used as secret naval weapons in World War II. The basic design is still in use today as a type of diver propulsion vehicle.

The name was commonly used to refer to the weapons that Italy, and later Britain, deployed in the Mediterranean and used to attack ships in enemy harbours. A group of a dozen countries used the human torpedo, from Italy and the United Kingdom to Argentina and Egypt, and there are some museums and movies dedicated to this naval weapon. The human torpedo concept is used recreationally for sport diving.

The first human torpedo (the Italian Maiale) was electrically propelled, with two crewmen in diving suits riding astride. They steered the torpedo at slow speed to the enemy ship. The detachable warhead was then used as a limpet mine. They then rode the torpedo away.

In operation, the Maiale torpedo was carried by another vessel (usually a normal submarine), and launched near the target. Most manned torpedo operations were at night and during the new moon to cut down the risk of being seen.

The idea was successfully applied by the Italian navy (Regia Marina) early in World War II and then copied by the British when they discovered how powerful this new weapon was after three Italian SLC's successfully forced the harbour of Alexandria and damaged the two British battleships HMS Queen Elizabeth and HMS Valiant, and the tanker "Sagona." The official Italian name for their craft was "Siluro a Lenta Corsa" (SLC or "Slow-running torpedo"), but the Italian operators nicknamed it "Maiale" (Italian for "pig"; plural "maiali"), after their inventor Teseo Tesei angrily called the SLC thus, when it had just been difficult to steer. The British copies were named "chariots".

A typical manned torpedo has a propeller and hydroplanes at the rear, side hydroplanes in front, and a control panel and controls for its front rider. It usually has two riders who sit facing forwards. It has navigation aids such as a compass, and nowadays modern aids such as sonar and GPS positioning and modulated ultrasound communications gear. It may have an air (or other breathing gas) supply so its riders do not have to drain their own apparatus while they are riding it. In some the riders' seats are enclosed; in others the seats are open at the sides as in sitting astride a horse. The seat design includes room for the riders' swimfins (if used). There are flotation tanks (typically four: left fore, right fore, left aft, right aft), which can be flooded or blown empty to adjust buoyancy and attitude.

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