Kaiten Facts for Kids

Designs for a Japanese Kaiten type 1.

Designs for a Japanese Kaiten type 2.

The Kaiten (Japanese: 回天, translated "Change the World" or "Reverse Destiny") was a torpedo that was changed to become a suicide weapon, and used by the Navy of the Empire of Japan in the last months of the Second World War. It was basically a torpedo with a pilot, and it could be thrown from a submarine or a ship.

Kaiten Type 1 periscope at the Tokyo Yasukuni War Memorial

Development
Deployment
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Development

The very first Kaiten was nothing much more than a Type 93 torpedo engine compartment attached to a cylinder that would become the pilot's compartment with trimming ballast in place of the warhead and other electronics and hydraulics. The torpedo's pneumatic gyroscope was replaced by an electric model, and controls were installed which gave the pilot full control of the weapon.

The original designers and testers of this new weapon were Lieutenant Hiroshi Kuroki and Lieutenant Sekio Nishina. They both died at the controls of Kaiten, Lieutenant Kuroki in a very early training prototype.

In total six models of Kaiten were designed, Types 1, 2, 4, 5, and 6 were based on the Type 93 torpedo. Type 10 was the only model based on the Type 92 torpedo. Types 2, 4, 5, 6, and 10 were only manufactured as prototypes and never used in combat.

Early designs allowed the pilot to escape after the final acceleration towards the target. There is no record of any pilot attempting to escape or intending to do so, and this provision was dropped from later Kaiten, so that, once inside, the pilot could not unlock the hatches. The Kaiten was fitted with a self-destruct control, intended for use if an attack failed or the impact fuze failed.

Deployment

Map of known Kaiten base locations at the end of World War II

Kaiten were designed to be launched from the deck of a submarine or surface ship, or from coastal installations as a coastal defense weapon. The cruiser Kitakami was equipped to launch eight Kaiten and took part in sea launch trials of Type 1s. In addition, two destroyers of the Minekaze-class were converted to Kaiten carriers. Shiokaze could carry four, and Namikaze two. Twelve destroyers of the Matsu-class were to follow with capacity for one Kaiten, however only one, Take, was completed.

In practice, only the Type 1 craft, using the submarine delivery method, were ever used in combat. Twenty-one specially equipped submarines carried two, four, five, or six Kaiten, depending on their class. The Kaiten were lashed to the host vessel on wooden blocks with a narrow access tube connecting the submarine to the lower hatch of the Kaiten. This allowed the Kaiten crew to enter from the host submarine while submerged.

A Kaiten Type 1 being trial-launched from the light cruiser Kitakami

Kaiten had a very limited diving depth, which in turn limited the diving depth of the host submarine. This is one of several factors blamed for the very poor survival rate of submarines using them, eight submarines being lost for the sinking of only two enemy ships and damage to several others.

Once the target was acquired and the host submarine was within range the pilot was briefed, the Kaiten's starting air bottles were charged and the cockpit was ventilated. The pilot then entered the vessel, the gyroscope was programmed with the correct bearing and depth and the pilot was given his final briefing.

The Kaiten separated from the host submarine and headed at speed in the direction fed into the gyroscope. Once within final attack range the Kaiten would surface and the pilot would check his range and bearing via periscope and make any adjustments necessary. He would then submerge to a suitable depth, arm the warhead and proceed on his final attack run. If he missed he could make adjustments and try again. If the mission failed he would detonate his vessel as a last resort.