Unryū-class aircraft carrier

The Unryū-class aircraft carriers (雲龍型航空母艦) were World War II Japanese aircraft carriers. Sixteen ships of the class were planned under the Maru Kyū Programme (Ship #302 in 1941) and the Kai-Maru 5 Programme (#5001–5015 in 1942). However, only three of the Unryū-class carriers were completed.

Design
In the lead-up to the Pacific War the Imperial Japanese Navy (IJN) attempted to build a large number of fleet carriers. For them to be built quickly, the design for these ships was based on the aircraft carrier JAPANESE AIRCRAFT CARRIER Hiryū rather than the newer and more sophisticated JAPANESE AIRCRAFT CARRIER Taihō or the Shōkaku-class aircraft carrier.

The Unryū-class aircraft carrier design was very similar to that of Hiryū. The ships were lightly built, and the main difference from Hiryū was that the carriers' island was placed on the starboard side of the ships. The carriers were capable of carrying 63 aircraft in two hangars, and were fitted with two elevators. The Unryū class carried a smaller quantity of aviation fuel than Hiryū with fuel tanks protected by concrete. The ships were fitted with the same propulsion system used in the aircraft carrier JAPANESE AIRCRAFT CARRIER Sōryū to reach 34 kn, though JAPANESE AIRCRAFT CARRIER Katsuragi was instead fitted with two turbines of the same type used in destroyers and had a maximum speed of 32 kn. The carriers also had a similar armament as Hiryū and were equipped with two Type 21 radars and two Type 13 radars.

Construction
The first three Unryū-class aircraft carriers were laid down in 1942 and construction of a further three began the next year. Eventually, only three (JAPANESE AIRCRAFT CARRIER Unryū, JAPANESE AIRCRAFT CARRIER Amagi, and JAPANESE AIRCRAFT CARRIER Katsuragi) were completed and construction of the other three carriers (JAPANESE AIRCRAFT CARRIER Kasagi, JAPANESE AIRCRAFT CARRIER Aso and JAPANESE AIRCRAFT CARRIER Ikoma) was abandoned in 1945.

Unryū class
Project number was G16. General production model of the Unryū class. 3 carriers were completed. The IJN unofficial designation for Unryū and Amagi were Modified Hiryū class (改飛龍型), Ship Number 5002–5006 were Modified Unryū class (改雲龍型) also.
 * Unryū (built by Yokosuka Naval Arsenal used the same boilers and turbines as the heavy cruiser Suzuya.
 * Amagi and Kasagi (built by Mitsubishi, Nagasaki Shipyard) were equipped with surplus stock of the Ibuki-class cruiser machinery.
 * Katsuragi and Aso (built by Kure Naval Arsenal) were equipped with two sets of the Kagerō-class destroyer machinery, because Japanese industry power became scarce. Dead space was replaced by fuel tanks.
 * Ship Number 5002 and 5005 (built by Yokosuka Naval Arsenal) were to have been built simultaneously using JAPANESE AIRCRAFT CARRIER Shinano's dock. However, they were cancelled because Shinano was continued.

Ikoma class
The Ikoma subclass was a simplified and sped-up construction model of the Unryū class. They were equipped with shift-arrangement machinery (four sets of parallel boilers and one turbine). Therefore, their funnels were intended to be spaced out. The IJN unofficial designation for this class was Modified Ship Number 302-class (改第302号艦型).