Before World War II, the Type 93 oxygen torpedo was the pinnacle of the world's torpedo technology development, and its range and speed far exceeded that of similar weapons in other countries in the world. The power is also unprecedented, its charge from the Type 89 torpedo 295 kg and the Type 90 torpedo 400 kg to 490 kg, greatly exceeding the torpedo charge of the underwater protection design of the warships of various countries, it is difficult to imagine that any ship can withstand the explosive impact of half a ton of explosives. All these advantages made the Type 93 torpedo, once equipped, immediately become the "unique weapon" of the Japanese Navy, listed as top secret, and kept strictly confidential, and even the word "oxygen" was not allowed to be revealed
German g7 series torpedoes have two models of internal combustion engine drive G7a and motor drive G7e, the G7A type will leave a trail mixed with bubbles and oil traces during sailing, which is easy to be found and avoided by enemy ships, and the biggest advantage of the G7e torpedo is that the wake is not obvious, but it is not as good as the former in terms of speed and range, and the most troublesome thing is to charge every few days. Torpedoes use magnetic fuzes that sense changes in the magnetic field to explode and destroy the keel when passing through the bottom of the ship, and although powerful, there are technical flaws that often fail until the middle of the war
The American MK.14 torpedo was the worst quality torpedo in World War II, with a failure rate of up to 70%, the submarine captain simply hated this thing, either exploded in advance or could not be hit at all, the torpedo was inaccurately set at depth, often passing through the bottom of the ship, so that the depth was uniformly set to 0 meters for safety. It was not until the post-war United States obtained torpedo technology from Japan and the United States that it completely improved