I-11 was an Imperial Japanese Navy Type A1 submarine that served during World War II. Designed as a submarine aircraft carrier and submarine squadron flagship, she was commissioned in 1942. She participated in the Guadalcanal campaign and patrolled off Australia, New Caledonia, and the Ellice Islands before she disappeared in 1944 during her sixth war patrol. She badly damaged the Royal Australian Navy light cruiser in 1943. Design and description Type A1 submarines were versions of the preceding Type J3 with superior range and an improved aircraft installation, and they were fitted as squadron flagships. They displaced on the surface and submerged. The submarines were long and had a beam of and a draft of . They had a diving depth of . For surface running, Type A1 submaries 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 Type A1s had a range of at ; submerged, they had a range of at . Type A1 submarines were armed with four internal bow torpedo tubes and carried a total of 18 torpedoes. They were also armed with a single /40 deck gun and two twin Type 96 anti-aircraft guns. Unlike on the Type J3 submarines, the aircraft hangar was integrated into the conning tower and faced forward, and the aircraft catapult was forward of the hangar, while the deck gun was aft of the conning tower. Reversing the locations of the deck gun and catapult allowed aircraft launching from a Type A1 submarine to use the forward motion of the submarine to supplement the speed imparted by the catapult. Construction and commissioning Built by Kawasaki at Kobe, Japan, I-11 was laid down as Submarine No. 125 on 10 April 1939. Provisionally attached to the Kure Naval District on 5 February 1941, she was launched on 28 February 1941 and was named I-11 that day. She was completed and commissioned on 16 May 1942. Service history May–July 1942 I-11 was formally attached to the Kure Naval District on the day of her commissioning and also became the new flagship of Submarine Squadron 3 that day, replacing the damaged submarine in that role. She moved to Kure, Japan, in late May 1942 for work-ups, embarking an 11th Naval Air Arsenal Yokosuka E14Y1 (Allied reporting name "Glen") floatplane for