I-400-class submarine

Japanese submarine I-400
I-401, with its long plane hangar and forward catapult
Class overview
OperatorsEmpire of Japan Imperial Japanese Navy
Cost28,861,000 JPY in 1942[1]
Built18 January 1943–24 July 1945
In commission1944–45
Planned18
Completed3
Cancelled15
Retired3
General characteristics
TypeSubmarine aircraft carrier
Displacement
  • 5,223 long tons (5,307 t), surfaced
  • 6,560 long tons (6,670 t), submerged
Length122 m (400 ft)
Beam12.0 m (39.4 ft)
Draft7.0 m (23.0 ft)
Propulsion
  • 4 diesels: 1,680 kW (2,250 hp) each, surface
  • 2 electric motors: 1,600 kW (2,100 hp) each, submerged
Speed
  • 18.7 kn (34.6 km/h; 21.5 mph), surfaced
  • 6.5 kn (12.0 km/h; 7.5 mph), submerged
Range43,123 mi. (69,400km)
Test depth100 m (330 ft)
Complement144 officers and men
Armament

The I-400-class submarine (伊四百型潜水艦, I-yon-hyaku-gata sensuikan) Imperial Japanese Navy (IJN) submarines were the largest submarines of World War II, with the first one completed just a little over a month before the end of the war. The I-400s remained the largest submarines ever built until the construction of nuclear ballistic missile submarines in the 1960s. The IJN called this type of submarine Sentoku type submarine (潜特型潜水艦, Sen-Toku-gata sensuikan, Submarine Special). The type name was shortened to Toku-gata Sensuikan (水艦, Special Type Submarine). They were submarine aircraft carriers able to carry three Aichi M6A Seiran aircraft underwater to their destinations. They were designed to surface, launch their planes, then quickly dive again before they were discovered. They also carried torpedoes for close-range combat.

The I-400 class was designed with the range to travel anywhere in the world and return. A fleet of 18 boats was planned in 1942, and work started on the first in January 1943 at the Kure, Hiroshima arsenal. Within a year the plan was scaled back to five, of which only three (I-400 at Kure, and I-401 and I-402 at Sasebo) were completed.

  1. ^ Senshi Sōsho #88 (1975), p.37
  2. ^ Campbell, John Naval Weapons of World War Two ISBN 0-87021-459-4 p.191