Kaichen

(Japanese, “heavenly change”), a torpedo guided by a volunteer suicide pilot.

Kaichens were used in World War II by the Japanese armed forces to attack enemy surface ships. Work on the kaichens began in the second half of 1942 based on ordinary torpedoes. A kaichen was up to 16.5 m long, carried an explosive charge of over 1, 360 kg, could go up to 74 km/hr (40 knots), and had a range of up to 74 km (40 miles). Piloted by one man, kaichens were classified as naval ammunition. In 1944, Japan began producing kaichens carrying between 4 and 8 tons of explosives. Japan also built the wooden Shine cutters, which had a similar mission, were driven by an automobile engine, and had an explosive charge of up to 2 tons; the midget Kairyu submarines, with a crew of two men and an explosive charge of up to 20 tons; and the Koryu submarines, with a crew of five men and an explosive charge of up to 50 tons. Kaichens were used for the first time in November 1944 against US ships in the Pacific Ocean.

After spotting an enemy ship, the submarine armed with kaichens took up a position on the ship’s intended route and the suicide pilots took their place in the torpedo. The submarine commander launched the torpedo after instructing the pilot on the necessary course and speed. After traveling some distance, the torpedo pilot surfaced and directed the torpedo at the enemy ship. A total of 80 kaichen pilots died in combat operations.