During WW2 the Japanese developed a small, two manned, submarine. These were intended for local defense against the prospective invasion that confronted Japan in 1945. The "Kairyu" weighed just over 19 tonnes, and were around 17 meters long. The diameter of the sub was 1.5 meters, making it a very tight squeeze for the two-man crew. The subs were built to house two 45cm torpedoes on either side, and were also fitted with an internal warhead, for employment on suicide missions. Propulsion of the sub was by an 80 horsepower electric motor, this allowed for a submerged speed of 10 knots, and a surface speed of 7.5 knots.
Drawings of the plans of the Japanese "Kaiten" and "Kairyu" subs.
These subs were used on the 31st of May 1943 attacks of Sydney Harbor. This attack involved both larger subs, and the mini "Kairyu" and "Kaiten" (A one manned version of the sub), and were responsible for shelling around the harbour and eastern suburbs of Sydney.
"Kairyu" in production at Kure Naval Base, Japan, 19 October 1945.
Joe.
