The Japanese submarine I-28 was one of 20 Type B cruiser submarines of the B1 sub-class built for the Imperial Japanese Navy (IJN) during the 1940s.
The Type B submarines were derived from the earlier KD6 sub-class of the and were equipped with an aircraft to enhance their scouting ability. They displaced 25890NaN0 surfaced and 36540NaN0 submerged. The submarines were 108.7m (356.6feet) long, had a beam of 9.3m (30.5feet) and a draft of 5.1m (16.7feet). They had a diving depth of 100m (300feet).[1]
For surface running, the boats were powered by two 62000NaN0 diesel engines, each driving one propeller shaft. When submerged each propeller was driven by a 1000hp electric motor. They could reach 23.6kn on the surface and underwater.[2] On the surface, the B1s had a range of 14000nmi at ; submerged, they had a range of 96nmi at .
The boats were armed with six internal bow 53.3cm (21inches) torpedo tubes and carried a total of 17 torpedoes. They were also armed with a single 140mm/40 deck gun and two single mounts for 250NaN0 Type 96 anti-aircraft guns.[3] In the Type Bs, the aircraft hangar was faired into the base of the conning tower. A single catapult was positioned on the forward deck.[3]
I-28 was commissioned at Kobe, Japan on February 6, 1942. The submarine participated in the Battle of the Coral Sea in May 1942. Returning to base at Truk in the central Pacific, I-28 was torpedoed and sunk with all hands (88 officers and men) by the United States Navy submarine at 6.5°N 152°W on 17 May 1942.