Japanese I-400 Class Submarine
Submersible Seaplane Carriers.
Specially built to attack the Panama Canal.
Five were built, three launched, none served the original purpose.
The Book Cover. Assembly Underway.
The Japanese built five (three were launched) giant, seaplane carrying submarines. One made a trip around the Horn of Africa to Germany. Another was converted as a tanker. A submarine fleet was formed intending its aircraft to torpedo the Gatun Locks, Panama Canal, but was diverted to attack the US anchorage at Ulithi just as the war ended. The I-400 series submarine had an energy absorbing skin, snorkel, radar, degaussing, and a range of 1-1/2 times around the world and four months duration.
Displacement 4760 tons, length 355 feet.
Two submarines hulls were welded together with a waterproof compartment on deck for three disassembled torpedo bombers.
Hanger deck is a watertight compartment.
Each plane to be assembled on deck.
This picture seems too perfect,
It might be a model.
The slightly smaller AM class of two large subs, I-13, I-14, could each carry two Seiran aircraft.
Aichi M6A1 Seiran . Specially build for torpedo bombing of the strategic Panama Canal.
Three carried by each submarine. The wings and tail folded for storage and the floats were removeable.
Photo courtesy of Roger Connor.
Aichi, builder of the D3A "Val" carrier bomber and the late-war B7A "Grace" torpedo bomber, also build the E13S "Jake" long range reconnaissance seaplane that flew at Pearl
Harbor and the purpose-built D4Y4 Kamikaze. A specially designed version was purpose-built for the I-400 class submarine to carry an aerial torpedo to attack the strategic Gatun Locks to stop
the flow of ships and supplies from the Atlantic needed to fight in the Pacific.
The design developed from the Yokosuka D4Y1 Suisei (early "Judy"); had two-seats and carried a torpedo or 1,800 pounds of bombs. Speed max 295 mph, cruise 184 mph; range 740 miles. 18 were built after six prototypes and two trainers.
About half of the Japanese fleet submarines at the start of the war carried a single scouting aircraft, 42 subs.
All of the WW2 belligerants had or experimented with sub launched seaplanes.
A Yokosuka E14Y "Glen" from I-25 twice dropped incendiary bombs on Oregon in Sept'42 to start forest fires, fortunately during a wet period.
This was the only manned air attack on U.S. mainland.
These photos were selected from the many by Google picture search.
The associated web pages and credits were not identified.
Return to: WW2 Menu About this page: I-400 - Japanese I-400 Class of submarine aircraft carrier.
Last updated on Dec 3. 2013 -- add details.
May 5, 2010 -- add notes on other Japanese aircraft carrying subs.
January 25, 2007 -- original