Torpedo

Check out photos of torpedoes here.

A torpedo is an underwater, self-propelled, explosive weapon that can be launched from a submarine, a surface ship, an airplane, or a helicopter. It is a key naval weapon used against warships, merchant vessels, and submarines. Torpedoes can also be used against fixed targets, such as harbor installations. Like mines, torpedoes explode below the waterline.

Torpedoes designed for use against surface ships usually travel just below the surface of the water, to avoid passing under the hull of the target. Those designed to be used against submarines can follow and strike a target at depths of up to 2,500 feet. Many torpedoes travel at speeds of 40-50 knots. Conventional torpedoes may have ranges of less than 2,000 yards, while rocket-assisted torpedoes can strike targets more than 10 miles away.

Torpedoes are cigar-shaped devices containing an explosive with a detonation system, a guidance system, and a propulsion system. Torpedoes used by the U.S. Navy are generally from 8-21 feet long, 10-21 inches in diameter, and weigh as little as 265 pounds up to 4,000 pounds or more. Most contain conventional high explosives; a few carry nuclear warheads. The largest United States torpedoes carry about 650 pounds of conventional explosive.

Torpedoes are detonated by contact detonators, which set off the explosive when the torpedo strikes the target, or by magnetic detonators, which set off the explosive when the torpedo enters the magnetic field of a steel ship. They can be guided by any of several systems: straight-running torpedoes that are held on course by a gyrocompass; acoustic, or homing, torpedoes that are guided to their targets by sound; and wire-guided torpedoes that are electrically guided from onboard an attacking vessel.

Modern torpedoes are usually built multiple guidance systems, often combining active and passive acoustic homing capabilities. The United States Mk-48 heavy torpedo has not only active and passive acoustic homing guidance but also provisions for wire guidance.

Newer submarines launch torpedoes through tubes along the sides of the submarine, near the bow. Older subs have tubes in the bow and stern. Surface ships launch torpedoes from tubes on the deck. Compressed propels a torpedo free of its tube before its own propulsion and guidance systems take over. Most torpedoes are propelled by jet turbines, though some use battery-powered electric motors.