Type A1 submarine

I-10 in Penang, 1942

The , also called were a trio of aircraft-carrying cruiser submarines built for the Imperial Japanese Navy (IJN) during the 1930s. All three participated in the Pacific War and were lost.

Design and description

The submarines of the A1 type were versions of the preceding J3 class with superior range, improved aircraft installation. Unlike the earlier boats, they were equipped with extensive communication facilities to allow them to serve as squadron flagships. They displaced surfaced and Template:Cvt submerged. The submarines were long, had a beam of and a draft of . They had a diving depth of .

For surface running, the boats were powered by two diesel engines, each driving one propeller shaft. When submerged each propeller was driven by a electric motor. They could reach on the surface and underwater. On the surface, the A1s had a range of at ; submerged, they had a range of at .

The boats were armed with six internal bow torpedo tubes and carried a total of 18 torpedoes. They were also armed with a single 40-caliber deck gun and two twin Type 96 anti-aircraft guns.

Unlike the J3 class, the aircraft hangar was integrated into the conning tower and faces forward; the positions of the deck gun and the catapult were exchanged so the aircraft could use the forward motion of the ship to supplement the speed imparted by the catapult. The hangar could be accessed from inside the pressure hull and the floatplane was stowed with its wings folded.

Boats

• was sunk by destroyer USS Frazier in the Aleutians on 11 June 1943.
• was sunk by destroyer USS David W. Taylor and destroyer escort USS Riddle east of Saipan on 4 July 1944.
• disappeared south of Funafuti after 11 January 1944. The I-11 probably struck a mine laid by USS Terror.

Two more boats were ordered under the 1942 Naval Program, but were later cancelled.