The development of these very large-scale submarines before the war engaged spetsy Head marine arsenal at Yokosuka and designers state shipyard in Kure. Despite the complexity of the goal, work is progressing quite rapidly, and a year later the first 5 submarine aircraft carriers (I-400, I-401, I-402, I-403 and I-404) were laid at the shipyards in Sasebo and towns Kure. Boat I-400 was ordered under the «Fifth applets by substitution ships» in 1942, and I-401, I-402, I-403 and I-404 — for «modified by the substitution of the fifth programmke ships» in 1942. In addition, for the same program there was supposed to build 14 more such submarines, but their orders canceled in March 1945.
To fulfill the requirements laid down in the tactical and technical requirements, the designers had to apply a lot of unique technical solutions. First it came to form the submarine’s hull. With this displacement of 50 000 tonnes ordinary design robust tubular housing proved to be unacceptable because of the very high rainfall. Because for him was adopted dvuhkor-pusnaya design — strong housing middle part consisted of 2-cylinders joined together sides.
A distinctive feature of this design is strong longitudinal bulkhead at the junction of the cylinder along all compartments and sealed deck. In the cross-sectional shape such body had laid horizontally eights. Inside the body was laid out flat bulkheads into eight compartments. Thanks to such design has been achieved and of sufficient width to provide the required boat stability and reducing rainfall, which, nevertheless, reached 7 meters.
To keep the length of the boat within reasonable limits, all four diesel engines placed side by side, grouped two by two, with each pair worked on their line shaft. Disconnecting through the gears and couplings were associated with diesel power generators and compressors located in the fifth compartment. Main machinery (diesel engines, generators, motors and compressors) were mounted on rubber shock absorbers. There was a device for diesel engines under water — snorkel. 5 groups of tanks head ballast, fuel tanks and aviation gasoline tanks were located outside the body strong.
Diving and surfacing system allowed the boat to go under water for 70 seconds, which helped small and comparable to the Japanese navy in store buoyancy. Hangar for 3 aircraft, which had the shape of a cylinder (inner diameter — 3.5 m, length — 37.5 m) is located over a strong body in the central part of the boat. Hangar and shifted to the left side cutting had fencing overall development. Ahead of the hangar door hermetically locked strong-lid opening in the starboard side. Through a hatch in the floor of the hangar was reported with a strong body, allowing the aircraft to start preparing for the start before surfacing. Yet since surfacing submarine surfaced and to lift into the air all 3 planes more than 45 minutes.
Cellar aviation ammunition, which was located in the fourth compartment accommodates four aircraft torpedoes, three 800-kg and 250-kg twelve bombs.
Onboard torpedo bomber for I-400, developed by Aichi, was designated M6A1 Seiran. It was a float inline engine monoplane with liquid cooling. To organize planes in the hangar were developed starting special carts that could be moved on rails laid on the hangar floor, and then the track catapult. The cart was integrated hydraulic lift, which allows you to omit the plane while rolling into the hangar and tilt, giving bombers additional angle of attack of 3.5 degrees when it is installed on the launcher position catapult. In the hangar cart rails fixed to special terminals, and on the launch pad clung to hook the power piston catapults.
Floats aircraft stored below deck in 2-sealed cylindrical containers, three in each of the float. Floats were mounted on carts ipoparno served on the deck on the rails if necessary. The tarmac at the bow of the boat was installed specially designed catapult Type 4 modes. 10, with a track length of 27 m, an elevation angle of 3 degrees and a track width of 1.2 m, calculated on the launch aircraft weighing up to 5 tons. It provided the acceleration of aircraft to a speed of 34 m / s and the start of the overload to 2.5 d
The left side was set folding 12-ton crane, retractable deck into the recess, which was intended to take on board the aircraft after splashdown.
Not counting the main aircraft armament boat had eight 533 mm bow torpedo tubes with 20 torpedoes supplies, feeding the 140-mm gun and 10 25mm anti-aircraft machine — three triple-and single-barreled one installation. The submarine was equipped with radars detection of surface and air targets. To reduce the radar and acoustic visibility, lightweight hull covered with special rubber compound. However, despite all the measures taken (use of rubber shock absorbers, rubber coating). noise STo boats remained relatively the highest.
The submarine crew were provided with excellent habitability conditions, supplies of fresh water and provisions consistent with the autonomy of 90 days, although the supplies of fuel submarine could be in the sea more than 100 days (range navigation economic progress-37 500 miles). Operating depth is 100 meters. STo boats built in the criteria of extreme secrecy, and measures taken by the Japanese crowned with success. After the war, the South American command was forced to admit that the emergence of the Japanese submarine aircraft carriers was complete surprise to him.
First underwater aircraft carrier I-400 was delivered to the Navy 30 December 1944 and 8 January 1945 was adopted and the second — 1-401. Third submarine I-402 being completed at Sasebo, but in March 1945 had actually finished the boat returned to the dock to rebuild it into a tanker. It was then discontinued and the construction of I-403, at the time it was over 60 percent readiness. At the end of the same month the order rescinded, and the boat was dismantled at the shipyard in Sasebo Navy. Not lucky and last mortgaged underwater aircraft carrier I-404. Excellent disguised I-404 readily more than 95 percent, located at the shipyard in Kure, the next raid case sank a South American aviation.
Submarine I-400 and 1-401 formed the basis of 1st submarine flotilla shock, the main task of which was combat attack locks of the Panama Canal, appointed in July — August 1945.
In the mountains in the north-western part of Honshu Island residents Japan built models depicting Panamanian gateways on which the pilots practiced bombing. Training bailout carried directly from the boats at quay, with all this with them whenever necessary to remove the masking (haystacks and even mowing), hid the boat from the bombing by U.S. aircraft, which has reigned supreme in the skies over Japan.
Training very complicated fuel shortages, the 1st submarine flotilla shock considered in reserve, and is available on the basis of a small fleet in Kure in store fuel intended, first, to combat units. Because the middle of June I-400 and 1-401 were sent to campaign in Chinese Dairen to get the right fuel and food. But in the Sea of Japan 1-401 encountered South American magnetic mine and received severe injuries, then she had to return to base.
By July 1945 1st submarine flotilla shock also achieved combat readiness (having lost all this in two accidents M6A1 Seiran together with crews) was approved and plan to strike on the Panama Canal — the flotilla was to sail to the islands of Japan to the south, pass through Indian ocean, circumnavigating Africa at Cape of Good Hope, enter into the Atlantic Ocean, and then ascend to the north to the Caribbean to strike over a channel with sudden hand, from the Pacific Ocean, where the South American fleet waited attack and from the Atlantic, where the Japanese ships did not expect. 6 of 10 aircraft fleet had to storm the gates gateways torpedoes, and four — to bombard them with a dive.
But at the last moment Naval General Staff postponed the attack channel, decided to use the 1st shock flotilla more pressing, from his point of view, the operation codenamed «Hikari» to destroy American aircraft carriers are at Ulithi atoll. In this case for the application of the greatest harm to the aircraft carriers fleet pilots were instructed to act in ways kamikaze — all M6A1 Seiran had to run from boats without floats (landing was not assumed) and refueling only the path to the goal.
Pilot with I-400 Kazuo Takashi recalls that for a day or two before going to the base commander of the boat Captain 1st rank Arid the zoom gave each pilot individually samurai sword (small blade Toko) with an engraved signature Combined Fleet commander Admiral Toyeda a symbol that now they are brave kamikaze pilots.
To ensure operation «Hikari» July 3 boats 1-13 and 1-14 were sent to Truk atoll, still held by the Japanese forces to deliver there disassembled reconnaissance aircraft C6N1, which had to clarify the deployment of U.S. aircraft carriers. But on July 16 1-13 was sunk by airplanes with South American escort carrier Anzio 500 miles east of Yokosuka.
July 27, 1945 Kure out the main strike force — the submarine I-400 and 1-401, which had on board three bombers M6A1 Seiran, and also went to Truk atoll. U.S. aircraft carrier attack was scheduled for August 17, but on August 15 it was announced on the radio on the surrender of the Land of the Rising Sun, and submarines was handed an order — follow the progress of freeboard in the near Japanese port, raising flags dark (vplen signal of surrender, white flags of the same color as with the national flag of the Land of the Rising Sun), all documents and weapons, including aircraft, ordered to kill. Atsushi’s memoirs Asama-ry, commander of the bombers M6A1 Seiran submarine 1-401, August 22 evening, all three onboard aircraft with folded wings were mounted on a catapult and thrown into the sea. So Makar, the only military operation in which involved huge Japanese submarine aircraft carriers and bombers, over, and it began.
August 25, 1945 I-400 was intercepted by South American destroyer «Weaver» and its commander Toshivo Kusaka handed boat landed on its board prize party.
Paul Witmer, party capture 1-400, recalled how they landed on the submarine in full armor, waiting for that at this point in their start shooting, despite the fact that the boat destroyer held at gunpoint own guns. Japanese team were ordered to line up on the top deck (formerly residents of the country of the rising sun do so makarom when sunk an enemy ship), with all this pilot Ka-ZUO Takashi was sure that they would all be shot. But South American sailors were assured to follow the Japanese port, claiming that if they do not comply, then the Americans themselves would be taken the boat — it was a frank bluff, because South American mariners not versed in unit 1-400.
After a day or two submarine entered Tokyo Bay, where moored alongside American mother ships. On August 31 and entered Tokyo Bay 1-401, its commander Ryunosuke Aridzumi, although not to surrender, and considering that the loss of honor pravitelskogo submarine fleet from putting to wash off the blood of its senior commander, killed himself before ordering wrap his body naval flag and throw into the ocean.
In September 1945, I-400 and 1-401 transferred to South American naval base on the peninsula Guam (according to other sources, the Hawaiian Islands), where they were subjected to the study of South American naval spices.
May 31, 1946 I-400 and 1-401 Yankees were flooded in the western approaches to the island of Oahu.
I-402 after the war Americans towed together with other captured Japanese submarines (I-47, 1-14, I-58, 1-156, 1-158, etc.) in Sasebo Bay on the west coast of the country, to study them in all details. 40 professionals in the Navy was focused on I-402, so investigating the structure. Japanese crew promised that as Americans learn to control your ship, release them to their homes, because they are willing to cooperate with the Yankees. But in March the bay were brought thousands of military explosives kg C-2, and the main mechanisms and torpedo all Japanese submarines laid explosive charges. Thus began the preparations for the operation to destroy submarines, code name «Dead End.»
April 1, 1946 I-402, together with other 23 captured Japanese submarines sank at about. Goto. Such hasty liquidation Yankees Japanese submarines was due to the fact that the part of the Japanese Navy claimed the USSR, and the Americans did not want anyone to share the secrets of the underwater aircraft carriers, which were capable of striking areas of the United States.
It is not so long ago, when the documents relating to the operation «Deadlock» were declassified in Japan sent an expedition led by Brad F-nave of Texas A & M Univerrsity. Within 10 days, the expedition led searches submerged submarines in 1946, which were crowned with complete success. The examination of the seabed 200 miles northwest of Nagasaki at a depth of 182 m of the expedition managed to find a cemetery Japanese submarines, including bolshennuyu I-402.