Naval warfare during WWII was often done with stealthy sneak attacks on unsuspecting vessels. Submarines firing off torpedos were among the most common ways to launch sneak attacks but they came with many risks. The Imperial Japanese Navy found a method of avoiding the dangers of submarine combat by creating a new type of torpedo that was deadlier than any other.
It went by many names including Thunder Fish, Long Lance but it was formally known as the Type 93. It was originally developed in the 1920s with an immense 30-feet in length and equipped with a warhead weighing over 1,000 lbs. This torpedo led to the destruction of over 20 Allied vessels and was extremely dangerous because it could be fired from long range distance of about 6 miles.
Many would assume that such a big torpedo would be easy to detect, however, this used an oxygen-based propulsion system in order to reduce visibility by eliminating most of its bubble trail. The downside of a compressed-air torpedo is that it was more likely to detonate early due to shocks and vibrations underwater.
“The compressed air launch ensured that Allied ships in night engagements were not aware they under torpedo attack until the first torpedoes hit. The mounts included 3mm (0.118″) shields around the warheads to give them light splinter protection. Torpedo depth and gyro angle were set manually using a plunger and handwheel, but running speed could be adjusted only by removing an access plate in the torpedo tube.”
The Type 93 Torpedo was a stealthy weapon but it definitely made its presence known during the Battle of Guadalcanal. This video shows a brief demonstration of how the biggest torpedo of WWII functions.