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A torpedo is a self-propelled projectile carrying a warhead which detonates against a ship's side below the waterline. It was the most destructive naval weapon of the Second World War and the best of these was the Japanese IJN Type 93 'Long Lance' Torpedo.
In 1941 the Japanese Navy was the third largest navy in the world, after the US Navy and the Royal Navy. It had 100 destroyers, 18 heavy cruisers and 18 light cruisers. Most destroyers and cruisers were fitted with the 24-inch Long Lance torpedo. This oxygen-powered weapon could deliver a 1,000lb warhead at 49 knots over almost 11 miles.
At the outbreak of the war, the Japanese Navy possessed some of the world's finest torpedoes, including the fabled Long Lance. The quality of these weapons was no accident, but rather the result of Japan's intensive efforts during the 1920's and 30's to make good the shortcomings of her battle fleet during ww1. Laboring as she did under the unfavorable 5:5:3 ratio of capital ships imposed by the Washington Naval Treaty, Japan realized she would most likely be at a disadvantage in any Pacific conflict with the United States. She also knew well enough that the U.S. modeled its fighting doctrine on the famous 'Plan Orange', which called for an advance of the American battle fleet across the Pacific to relieve the Phillipines. It was anticipated that at some location in the Western Pacific a decisive battle would be fought. In Japan's view, some means must be found to offset its disadvantage in capital ships before this battle occurred, or its inferior batle line would be destroyed by the American force. Torpedo tactics and night combat were seized upon as one way to whittle down the American battle line as it made its way across the Pacific. Accordingly, Japan worked diligently to develop the tactics needed to implement this new doctrine, and also to create the weapons with which to carry it out. The result was that Japanese torpedoes showed a steady progression of improvements throughout the 1930's, culminating in the devlopment of the famous 'Long Lance' in 1935.
Designing and perfecting the Long Lance required solving some extremely difficult technical problems, most of which centered around the usage of pure oxygen as a fuel (rather than compressed air). Compressed air is nearly 77% nitrogen, which is useless for combustion, and also contributes to the visibility of the torpedo by leaving a bubble track on the surface. The usage of pure oxygen promised far greater power and propulsive efficiency, but it came with certain costs. The most glaring of these was how to use pure oxygen safely aboard a ship or submarine, given its inherently inflammable nature. Premature detonation of the torpedo upon firing was also a problem. However, the Japanese overcame these hurdles. Further, through meticulous live-testing of their weapons against ship targets, they perfected a warhead detonator that was rugged and reliable (The U.S. Navy's BuOrd could certainly have taken a lesson or two here). The resulting weapon, the Type 93 torpedo, was fantastically advanced in comparison with its Western counterparts, possessing an unequaled combination of speed, range, and hitting power. This weapon, coupled with the flexible battle tactics practiced by Japan's cruisers and destroyers, led to victory after victory in the early stages of the war. Only as American radar and gunfire control became increasingly sophisticated would the Japanese advantage in night battles begin to disappear, and even then a Long Lance-armed Japanese destroyer was still a thing to be feared.
Bottom line: the US fish had a decent-sized warhead, but nowhere near the range of the Long Lance, and the reliability was not as good. I know which one I'd rather be shootin', pardner...
Japanese warships mounted their torpedoes in several different types of mounts, ranging from dual-tube configurations, all the way up to quintuple(x5) tube mounts . Destroyers most often carried triples (in the Fubuki's (1928) thru the Hatsuharu's (1935)) and quads (Shiratsuyu (1936) on) thereafter (except for Shimakaze, which carried three quintuple mounts). Many ijn Cruisers carried doubles, triples, or quadruples.
The Type 93 was a 610 mm (24 inch) diameter torpedo of the Imperial Japanese Navy. Called the "Long Lance" by most modern English language naval histories (a nickname given by 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's development (in tandem with the submarine model, Type 95) began in Japan in 1928, under the auspices of Rear Admiral Kaneji Kishimoto and Captain Toshihide Asakuma. At the time, the most powerful potential enemy of the Japanese Navy was the United States Navy's Pacific Fleet. U.S. doctrine, presuming a move by Japan against the Philippines (then a U.S. possession), called for the U.S. battle line to fight its way across the Pacific Ocean, relieve or recapture the Philippines, and destroy the Japanese fleet. Since Japan possessed fewer battleships than the United States, the Japanese Navy planned to use light forces such as cruisers and destroyers to whittle down the U.S. fleet in a succession of night actions. After U.S. numbers were sufficiently reduced, Japan would commit her own fresh and undamaged battleships to finish off the U.S. remnants in a climactic engagement. (Curiously, this is essentially what American War Plan Orange expected.)
The Japanese Navy invested heavily in developing the torpedo; it was one of the main naval weapons capable of damaging a battleship. Japan's research focused on using compressed oxygen instead of compressed air for its propulsion oxidizer, feeding this into an otherwise normal wet-heater engine. Air is only about 21% oxygen, so a torpedo using compressed oxygen instead of air would hold about five times as much oxidizer in the same size tank. This meant that the torpedo could travel further and faster. Additionally, uncombusted normal air, principally nitrogen, bubbled to the surface and left a trail pointing back at the launcher. With oxygen, the gas was almost completely burned and left an almost invisible bubble trail.
However, compressed oxygen is more dangerous to handle and it required lengthy testing and experimentation for operational use to be possible. Finally, engineers discovered that by starting the engine with compressed air and gradually switching over to pure oxygen, they were able to overcome the uncontrollable explosions that had hampered its development. To conceal the use of oxygen, the oxygen tank was named Secondary Air Tank. It was first deployed in 1935.
The Type 93 had a maximum range of 40,000 m (21.5 nm) at 38 knots (70 km/h) with a 1,080 lb (490 kg) warhead. By contrast, the standard U.S. destroyer-launched torpedo of World War II, the Mark XV, had a maximum range of 15,000 yards (13,500 m) at 26.5 knots (49.1 km/h), or 6,000 yards (5,500 m) at 45 knots (83 km/h), with a 825 lb (375 kg) warhead.
Too large to fit in the standard 21-inch (533 mm) torpedo tubes on submarines, the Type 93 was usually launched from 24-inch (610 mm) tubes mounted on the decks of surface ships. A 21 inch (53 cm) version for use by submarines was designated Type 95 and was highly successful.
The Japanese Navy outfitted many of its destroyers and cruisers with Type 93s. The long range, speed, and heavy warhead of the Type 93 gave these warships a formidable punch
