The, also called was a pair of large, aircraft-carrying cruiser submarines built for the Imperial Japanese Navy (IJN) during World War II.
The Type A Mod.2 submarines were versions of the preceding A2 class with the command facilities replaced by an enlarged aircraft hangar, which was fitted for a pair of Aichi M6A1 floatplane bombers.[1] They displaced 36030NaN0 surfaced and 47620NaN0 submerged. The submarines were 113.7m (373feet) long, had a beam of 11.7m (38.4feet) and a draft of 5.9m (19.4feet). They had a diving depth of 100m (300feet).[2]
The machinery was reduced in power from the A2-class boats. For surface running, the boats were powered by two 22000NaN0 diesel engines, each driving one propeller shaft. When submerged each propeller was driven by a 300hp electric motor. They could reach 16.75kn on the surface and underwater.[3] On the surface, the AMs had a range of 21000nmi at ; submerged, they had a range of 60nmi at .
The boats were armed with six internal bow 53.3cm (21inches) torpedo tubes and carried a total of a dozen torpedoes. They were also armed with a single 140mm/40 deck gun and two triple and one single mount for 250NaN0 Type 96 anti-aircraft guns.[4]
In comparison to the A2 class, the aircraft hangar was enlarged to accommodate two aircraft. It was offset to the right of, and was faired into the base of, the conning tower which protruded over the left side of the hull. A single catapult was positioned on the forward deck. Two folding cranes on the forward deck were used to recover the floatplanes.[4]
Sources also refer to this class of ships as the "Type AM" (standing for the "Type A Modified"), or "Type AM2" (for "Type A Modified 2"), contrasting with two other sub-classes of the type, the I-9-class (Type A/A1) and I-12-class (Type AM1/A2). As the I-12 submarine was only a minor evolution of the I-9-class as well as being the sole ship of its class, it may also be considered as part of the I-9-class, making the I-13-class the only sub-class of the type, hence the I-9-class "Type A" and the I-13-class of the "Type AM".
"Type AM" might also be a miss-translation of (equivalent to 2nd remodel/modification) being interpreted as "Mark 2" in the sense of the 1st remodel/modification.
As the original Japanese name is better translated as either "Type A Mod.2 Submarine Cruiser" or "Junsen Type A Kai 2 Submarine ", the "Type A Mod.2" designation is used here.
Seven units were ordered, but only two were completed, while construction of two more was abandoned in March 1945. Construction of the remaining three submarines never started.[3]