View source for Kairyū-class submarine

{{short description|Class of midget submarines of the Imperial Japanese Navy}}
{{Use dmy dates|date=January 2018}}
{{more citations needed|date=April 2010}}
{|{{Infobox ship begin}}
{{Infobox ship image
|Ship image=KairyuuSuicideboat.jpg
|Ship caption= A Kairyu "Sea Dragon" in the [[Aburatsubo]] inlet.
}}
{{Infobox ship class overview
|Builders=
|Operators={{navy|Empire of Japan}}
|Class before=
|Class after=
|Subclasses=
|Built range=
|In commission range=
|Total ships building=
|Total ships planned=760
|Total ships completed=200–213 (sources vary)
|Total ships cancelled=
|Total ships active=0
|Total ships laid up=
|Total ships lost=
|Total ships retired=
|Total ships preserved= 2
}}
{{Infobox ship characteristics
|Hide header=
|Header caption=
|Ship type='''Kairyu''' (海龍 "Sea Dragon") class [[midget submarine]]
|Ship displacement={{convert|19.3|tonne|ST|abbr=on}}
|Ship length={{convert|17.2|m|ftin|abbr=on}}
|Ship beam={{convert|1.3|m|ftin|abbr=on}}
|Ship height={{convert|1.3|m|ftin|abbr=on}}
|Ship draft=
|Ship propulsion=*Surface: {{convert|64|kW|hp|abbr=on}} diesel engine
*Submerged: {{convert|60|kW|hp|abbr=on}} electric engine
|Ship speed=*Surface speed: {{convert|13|km/h|kn|abbr=on}}
*Submerged speed: {{convert|19|km/h|kn|abbr=on}}
|Ship range=*{{convert|830|km|nmi|abbr=on}} at {{convert|10|km/h|kn|abbr=on}} surfaced
*{{convert|70|km|nmi|abbr=on}} at {{convert|5.5|km/h|kn|abbr=on}} submerged
|Ship endurance=
|Ship test depth=
|Ship complement=2
|Ship armament= 2 × 450mm torpedoes and a {{convert|600|kg|lb|abbr=on}} explosive charge
|Ship notes=
}}
|}

The {{nihongo|'''Kairyu'''|海龍|Kairyū|"Sea Dragon"}} was a class of [[midget submarine]]s of the [[Imperial Japanese Navy]], designed in 1943–1944, and produced from the beginning of 1945. These submarines were meant to meet the invading American naval forces upon their anticipated approach of [[Tokyo]].

==History==
More than 750 of these midget submarines were planned and by August 1945 about 210 had been manufactured. Most of them were constructed at the [[Yokosuka Naval Arsenal|Yokosuka shipyard]]. These submarines had a two-man crew and were fitted with two torpedoes along with a {{convert|600|kg|lb|abbr=on}} explosive charge intended to be used on a suicide mission.

Most of the ''Kairyu'' submarines were based at Yokosuka to defend the entrance of [[Tokyo Bay]] in the event of a United States invasion of mainland Japan. Some of these subs were also stationed in the [[Moroiso]] and [[Aburatsubo]] inlets on the southern tip of the [[Miura Peninsula]] where a training school had also been set up.

Due to Japan's [[Surrender of Japan|surrender]] in August 1945, none of these submarines ever saw action.

<gallery>
File:Kairyu class submarine.jpg|A Kairyu in the Yamato Museum, Kure
File:Kairyu_class_submarine_at_the_Yamato_Museum_Oct_2008.jpg|Rear-end of a Kairyū submarine
</gallery>

==Technical details==
[[File:Kairyu general arrangement sections.svg|thumb|200px|left|General arrangement of the Kairyu class midget Submarine]]

<ref name="Characteristics of Japanese naval vessels">{{cite book|title=Characteristics of Japanese naval vessels, Section 7. Supplement 2: Submarines|publisher=US Navy|year=1946}}</ref>
All members of the Kairyu class were constructed from 3 sections of welded steel bolted together. The sections were the fore (warhead), mid (diesel engine, ballast, fuel, controls and batteries) and finally the aft (motor and control planes).

The bow section could be installed with or without a warhead, followed by the forward trim tank.

Following on from the bow was the central section, first in this section was the [[Battery (electricity)|batteries]] for the [[electric motor]] and the air flasks. Next was the pilot area. He would have numerous controls including controls for the fore and aft [[dive planes]] and [[rudder]]s, valves for oil, fuel and water and the [[periscope]] raise/lower controls. Behind the pilot would be the main [[ballast tank]] and fuel tank.

Abaft the fuel tank and ballast tank in the aft section was an [[Straight-six engine|in-line six]] [[diesel engine|diesel]] engine, followed by the aft trim tanks, [[gearbox]] and reduction motors and finally the electric motor and [[propeller]]s.

In the [[conning tower]] there was usually a Type 4 [[magnetic compass]] however some early models had a Type 97 [[gyrocompass]] in the boat itself.<ref>Rekishi Gunzo, p. 119.</ref>

===Modification 3===
While both the original and second modifications were practically identical, the third modification of the class had some notable differences.

The overall length was {{convert|160|cm|inch|abbr=on}} longer. The forward dive planes were moved forward of the conning tower. There was no external magnetic compass and the fuel tank  was installed before the pilot's control area. There was also a second periscope aft of the conning tower.

This model could very well have been used for training purposes with a complement of 3.

==Survivors==
A Kairyū-class submarine, cutaway to show interior details, is on display at the US Navy Submarine School at [[Naval Submarine Base New London]] in [[Groton, Connecticut]].  It has been there since at least the mid-1960s. Another is known to survive at the [[Yamato Museum]], fully intact.

==References==
{{reflist}}
*''Rekishi Gunzo'', History of the Pacific War Volume 36, ''Kairyu and Kaiten'', [[Gakken]], [[Tokyo]], Japan, 2002, {{ISBN|4-05-602693-9}}.

==External links==
{{Commons category|Kairyu class submarine}}
*[http://www.history.navy.mil/photos/sh-fornv/japan/japtp-ss/kairyu.htm U.S. Naval Historical Center] {{Webarchive|url=https://web.archive.org/web/20131213065802/http://www.history.navy.mil/photos/sh-fornv/japan/japtp-ss/kairyu.htm |date=13 December 2013 }}
*[http://ww2photo.mimerswell.com/navy/japan/sub/mini/kairyu.htm Kairyu midget submarine]
*[http://pwencycl.kgbudge.com/ Pacific War Online Encyclopedia]

{{Imperial Japanese Navy}}
{{WWII Japanese ships}}

{{DEFAULTSORT:Kairyu Class Submarine}}
[[Category:Submarine classes]]
[[Category:World War II suicide weapons of Japan]]
[[Category:World War II submarines of Japan]]
[[Category:Midget submarines]]
[[Category:Japan campaign]]