Military Review

Submarine aircraft carriers of the Japanese Empire

During the First World War, many types of weapons showed and proved their importance. For example, Tanks demanded to reconsider the doctrine of positional war, and submarines became a real miracleweapons sea ​​battles. Naturally, quite original ideas of “crossing” several new types of weapons began to arrive in some heads. So, already in 1915, the first projects of a submarine capable of carrying an aircraft appeared. Naturally, the airplane was planned to be used for reconnaissance purposes. Further, this idea will be repeatedly reviewed and developed, but in the overwhelming majority of cases, the projects of new “submarine aircraft carriers” will largely repeat the original idea.

Of all the projects of submarine aircraft carriers created between the world wars, the work of Japanese designers deserves special attention. At a certain point, the military leadership of the Land of the Rising Sun offered to make the plane not only with the eyes of a submarine, but also with its long arm with a sword. Indeed, the carrying capacity of even purely reconnaissance light aircraft made it possible to take a couple of small bombs on board. It is quite clear that for full bombing this will not be enough, but sometimes two or three bombs are enough. True, the effect of such an attack would rather be psychological.

The first Japanese submarine with the ability to transport aircraft was built in 1932 year. Boat I-2 project J-1M had a sealed hangar for transporting aircraft. Hangar dimensions allowed to keep it light reconnaissance Caspar U-1 - German 20-s aircraft, produced in Japan under license. Only one instance of the J-1M submarine was built. Despite the preparations for the coming expansion, which were in full swing, the Japanese were in no hurry to build an underwater carrier fleet. The submarine I-2 was equally military and test: the construction of an aircraft carrier submarine associated with many specific problems. For example, it is much easier to seal a small manhole for the crew than to prevent water from entering through the slots in the large manhole of the hangar. In addition, it was necessary to create a compact and load-lifting crane: in the J-1M project there was no take-off springboard, so the plane had to take off and land from the water. For transfer to the surface of the water and lifting onto the boat, the latter had to have a crane. At first, with a crane, we had to suffer - salty sea water had a very bad effect on its mechanisms and at times the parts were wedged. However, the crane and the design of the hangar eventually brought to mind. The fundamental possibility of creating a submarine aircraft carrier, carrying strike aircraft, has been proven.

By 1935, the fleet of submarine aircraft carriers in Japan has replenished with another boat. This was the J-6 I-2 project. From its predecessor, it is distinguished by a number of design changes. It was slightly larger, had better running characteristics, and in a larger hangar, one reconnaissance aircraft such as Watanabe E9W could be transported. Although he made the first flight simultaneously with the launch of the boat on the water, then it was E9W that later became the basis of the I-6 aircraft armament. Thanks to a reasonable approach to testing the previous submarine aircraft carrier, Japanese engineers managed to create a more advanced design and did not repeat a number of errors. However, the plane still took off from the water. If landing on the floats did not cause any complaints to anyone - it is not difficult to imagine the size of a submarine equipped with a full-fledged flight deck - then the need to launch the plane first, after which it could take off, was the cause of complaints. In particular, this fact was the reason that the project J-2 was able to "generate" only one submarine-aircraft carrier.

Submarine aircraft carriers of the Japanese Empire

The next project of the Japanese submarine aircraft carriers was the J-3. It was a more serious submarine: the hangar already contained two aircraft, and for their takeoff there were a springboard and a catapult. In 1939, the first boat of the series, I-7, was launched. A little later, I-8 was also completed. Aviation the armament of these two submarines were Yokosuka E14Y aircraft. These seaplanes were much better than the previous ones, although by their characteristics they still could not compete with other Japanese bombers. And the payload of four 76-kilogram bombs was clearly insufficient. However, as an armed scout for submarines, the E14Y was pretty good.

A few months before the attack on Pearl Harbor in the Japanese naval system fleet boat I-9 entered. She became the lead submarine of the A1 project. Subsequently, two similar submarines were built, which received the designations I-10 and I-11. With a solid displacement of about 4000 tons and six torpedo tubes, these boats also had on board one Yokosuka E14Y aircraft and a stock of various weapons for them. It is noteworthy that the A1 was the first Japanese project of an underwater aircraft carrier, which did not have any operational restrictions associated with the design of the hatch of the hangar. The designers successfully coped with the problem of sealing it, and Project A1 could safely walk at depths of up to 100 meters without the risk of flooding the room for the aircraft. At the same time, the outer contours almost did not spoil the streamlining of the submarine and did not "eat" speed and range. The lead boat of the project, which bore the designation I-9, namely its plane, on December 7, 1941, made a photo and filming of the results of the attack on the American naval base Pearl Harbor.

The A1 project to some extent became the basis for the subsequent series of Japanese submarine aircraft carriers. So, in a matter of months, the following projects were designed and put into a series of boats:
- A2. In fact, it was an upgrade of A1 with the addition of a number of new systems. The equipment associated with the aircraft has not undergone any changes. Built one boat;
- AM. Deep upgrade A1. The length of the hull was reduced, which, however, did not prevent the increase of the hangar to accommodate the second E14Y aircraft. The boats of this project I-13 and I-14 were ready only for 44-th year.

Developments on the projects of the “J” and “A” families allowed us to gather all the necessary experience and already in the summer of 42, an even more sophisticated I-15 submarine from the B1 project was launched. Before 44, 20 of such submarines with symbols from I-15 to I-39 will be built. It was the submarine of the B1 project that became one of the first Japanese submarine-aircraft carriers that had a chance to take part in striking the United States. 9 September 1942, the crew of the Yokosuka E14Y aircraft, composed of pilot N. Fujita and arrow S. Okuda dropped several incendiary bombs on a forest in Oregon. Shortly before the operation, later called “Lookout Air Raid”, rain and high humidity of foliage, soil, etc. took place in that area. did not let incendiary bombs do their work. The only strike of the aircraft carrier boat to the continental United States was unsuccessful.

The B1 project, like the previous A1, became the basis for the whole family. Thus, several of its upgrades were carried out: B2, B3 and B4. From each other, they differed in technical features and the number of manufactured boats. After twenty submarines of the B1 variant, only six B2 submarines and three B3 / 4 submarines were made. The construction of eight B2 and twelve B3 / 4 was canceled. By the end of 43, when this decision was made, Japan needed other weapons for its fleet.

However, the reduction in construction did not affect the overall plans of the Japanese command. Back in 1942, the design of a new type of submarine aircraft carrier, designated I-400, was started. Submarines with a submerged displacement of more than 6500 tons and a length of about 120 meters should have a submarine range of 110 kilometers and a surface more than 60 thousand kilometers. In doing so, they had to carry 20 torpedoes and 3-4 aircraft. Especially for boats I-400 developed aircraft Aichi M6A Seiran. This aircraft could already carry serious weapons in the form of two 250-kilogram or one 800 kg caliber bomb. In addition, the possibility of using special containers with rodent vectors of diseases was seriously considered. Only one discharge of such a container on the continental territory of the United States could lead to serious consequences. And the range of the submarine allowed to go beyond the Pacific.

The photo depicts the head submarine of the I-400 series on the day after it was handed over to the Americans. Japanese submarines of the I-400 series were the largest submarines before the appearance of atomic submarines. Their design was launched by Admiral Yamamoto, who needed an underwater aircraft carrier capable of carrying seaplanes armed with 800-kg bomb or a pilot. This aircraft was the Aichi M6A "Seiran" (Mountain Haze), which, by the way, did not receive a nickname from the allies, among the few late Japanese cars. Of the 18 boats planned for construction, the entire 3 was completed, but they also did not take part in the hostilities.

The head boat of the I-400 project was laid in February of the 43. The fleet wanted to get 18 such submarines. However, just a few months after laying the first submarine of the series, the plans had to be cut in half. The constant deterioration of the situation on the fronts led to the fact that until the end of the war of the planned six submarines, the Japanese managed to lay only six. As for the completion of construction, four boats were launched, and only three were put into operation. Of particular interest is the design of these boats. The hull lines were non-standard for such equipment of Japanese and foreign production. So, to ensure the required internal volume and preserve acceptable dimensions in the bow, the hull of the boat had an 8-shaped section. To the central part, the section smoothly turned into a semblance of the “∞” sign, and the feed again looked like a figure eight. Such a profile of a double-hull boat was due to the fact that the technical task required a large amount of fuel on board, and a separate hangar led to an increase in the vertical dimensions of the structure. Therefore, a tubular sealed hangar with a diameter of about 3,5 meter was placed in the middle of the boat, under the wheelhouse. Due to the shape of the middle part of the hull, it did not lead to a significant increase in the height of the boat. In a ready for use form on the boat could be three M6A aircraft. Before the submarine took off, the sailors opened the hangar doors, installed the aircraft on a catapult (on the bow of the boat), laid out its plane and the pilot took off. The plane landed on water, from where it was raised by a crane. In addition to the three airplanes ready for departure, a fourth could be transported in a disassembled form, but the volume of the room was only enough for three assembled ones.

The Japanese aircraft carrier submarine I-401 is moored at Pearl Harbor. US military experts are studying the internal structure of the boat, one of three aircraft-carrying boats of the I-400 series, surrendered to the Americans

Due to persistent problems with resources, the head boat of the I-400 project was commissioned by the Japanese Navy only on December 30 of the year 1944. The 8 of January of the next 45 was followed by the I-401 of the same project, and the third I-402 became a warship only at the end of July. Of course, these submarines did not have time to do something to change the situation at the front. In August, the month of 45, a few days before the end of the Second World War, the crews of the boats decided to surrender to the Americans. Boats I-400 and I-401 for a few months of their combat work did not have time to war up properly. So, first they received an order to attack the locks of the Panama Canal. However, the leadership of the fleet soon realized the futility of such an operation and canceled its order. Now, submarine aircraft carriers had to go to the atoll of the Uliti and attack the American ships stationed there. On August 6, the boats went out to sea, but after a couple of days they returned - a fire occurred on I-400 and repair was necessary. I-401, in turn, could not cope with the task on their own. Repeated exit was first planned on the 17-th number. Then the beginning of the operation was transferred to August 25, but in the end the 20 of the boat commanders received an order to destroy all offensive weapons. Execution of this order meant only one thing - aircraft carrier boats could no longer do anything to save Japan from defeat. The crew of I-400 shot the torpedoes into the sea and dropped the planes into the water. The captain of the boat I-401 Aridzumi, giving the order to do the same, shot himself.

Japanese aircraft carrier submarine I-401, surrendered to the Americans, moored in Tokyo Bay

History Japanese submarine aircraft carriers ended in the spring of 1946. After putting the I-400 boats to the Americans, they were taken to Pearl Harbor, where they were carefully studied. In March, 46, the Soviet Union, in accordance with the available agreements, demanded that the United States provide access to Japanese miracle weapons. Not wanting to share trophies, the US command issued an order to destroy them. On April 1, not far from Pearl Harbor, I-402 was shot by torpedoes, and on May 31 I-400 and I-401 set off to the bottom.

Information sources:
The Maritime Collection and Technology Youth Magazines
Secret weapon Japan - submarine aircraft carrier (US, UK) 2009 year

In the spring of 1946, after 8 months after the end of World War II, the decision was made at the highest government level in the United States: one of the most advanced systems of Japanese weapons was sent to the seabed to avoid its falling into the hands of the Soviet Union. We will learn how the course of the Second World War could have changed if the Japanese had carried out their project ...

How could change the course of the Second World War, if the Japanese had carried out their project to create a giant submarine aircraft carrier.

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  1. altman
    altman 31 May 2012 08: 19
    Not such a stupid idea .. the only thing is that the development of technology at that time did not give the desired effect
    1. 755962
      755962 31 May 2012 14: 17
      Quote: altman
      Not such a stupid idea.

      Especially in our time, which has continued.
      Next year, the US Navy is going to test a new UAV (unmanned aerial vehicle), launched ... from a submarine located at periscope depth. Raytheon Corporation received a contract to supply five submerged launch vehicles (SLVs) for launching the AeroVironment Switchblade UAV.
      SLVs are fired from the DUK systems (for shooting waste), drop ballast and open a miniature lifebuoy, bringing the UAV to the surface. Then there is a tilt of the “launcher” at 35 ° to the surface of the water and the UAV “shoots” into the air - in the direction of the wind.

      This is not the first year that Raytheon has been working on this project: in 2008, they already demonstrated the launch of the SLV and a drone hidden inside a conventional ship. A full-fledged underwater launch is planned for next year. This is such an unexpected continuation of the story.
      1. M. Peter
        M. Peter 31 May 2012 21: 17
        And if you take into account their kamikaze experience ...
        Here is a submarine equipped with cruise missiles. smile
    2. Kassandra
      Kassandra 31 December 2014 16: 05
      if the "bombs" were bacteriological, the psychological effect of destroying up to 25% of the US population would be even greater.
      artillery with submarines, too, could, but delivered not far into the coast, on which almost all the main cities, except Detroit and Chicago, are located.
      As far as we know, Detachment 731 was not only tested by rodent kontainers, and the USA was saved from such a development of events only by seizing the arsenals of Detachment 731 in Manchuria by Soviet paratroopers less than a day before shipment of weapons to these submarines, and also to Japanese long-range bombers (which are in Japan in the amount of 6 units were still).
  2. Rus_87
    Rus_87 31 May 2012 08: 52
    Once again I am convinced that the amers are still bastards: In March of the 46th, the Soviet Union, in accordance with the existing agreements, demanded that the United States provide access to Japanese miracle weapons. Not wanting to share trophies, the American command gave the order to destroy them. On April 402, near Pearl Harbor, I-31 was shot by torpedoes, and on May 400 I-401 and I-XNUMX went to the bottom.
    1. Vadivak
      Vadivak 31 May 2012 09: 10
      Of the six planned submarines, the Japanese managed to lay only six.

      1. beech
        beech 31 May 2012 22: 39
        pure oxymoron !!))
    2. Pimply
      Pimply 31 May 2012 15: 30
      Amer is not. At that time, both the USSR and the USA feverishly received the maximum from victory, and were well aware of who their future adversary would be.

      The USSR at that time sharply made claims against Turkey, sponsored the Greek communists in the civil war and actively invaded the zone of interests of English-speaking countries. Which is true, however, in the opposite direction. The difference of ideologies of cooperation did not suggest further. In March of the same year 1946, the USSR refused to withdraw the occupation troops from Iran (with great difficulty this was finally done in May). Well, and other cute little things that did not imply the unconditional fulfillment of obligations - they were broken by both parties.
      1. Kassandra
        Kassandra 31 December 2014 16: 01
        however, Greece in 1944 freed itself from the Germans, but then British troops landed, which in the course of three-week battles captured it and killed it more than the Germans in several years.
        The United States violated the Yalta plans to divide Japan between several winning countries. The USSR didn’t break anything.
  3. Sakhalininsk
    Sakhalininsk 31 May 2012 10: 07
    Very interesting ships, it’s interesting how real the chances of connecting these boats were to clog the Panama Canal.
    1. mga04
      mga04 31 May 2012 10: 58
      There was no chance of blocking the canal at 45m, and there was no point either. This had to be done at 41, at the same time as the Pearl Harbor attack.
  4. Zerstorer
    Zerstorer 31 May 2012 10: 30
    From a technical point of view, the project is very interesting. But I don't understand what tasks it was all built for? The air group is too small to cause serious damage. To carry out intelligence activities is too difficult. It is better to use a specialized long-range reconnaissance agent for reconnaissance, for example, the Ki-46. An example of such a successful interaction was demonstrated by the Germans.
    1. mga04
      mga04 31 May 2012 10: 48
      I think the main purpose of these products is reconnaissance and target designation under the action of a submarine detachment at a great distance from coastal bases. All the same, the range of 2400 km at the Ki-46 for the Pacific Ocean is not enough. At the same time, the detachment should have one reconnaissance aircraft carrier and three to four strike boats. And throwing planes from submarines into an attack on ships is already out of hopelessness.
      Although it is even possible to use them for sudden point (sabotage) strikes, primarily against coastal targets.
      1. Zerstorer
        Zerstorer 31 May 2012 16: 01
        As far as I remember, the Ki-46-III (and IV) has a range of 4000 km.
        1. mga04
          mga04 31 May 2012 18: 04
          Yes, I agree. Here are just cruising submarines of the Japanese during the Second World War had a range of 25000 km. An exception is the KD7 type, they have about 15000km, if I'm not mistaken. I-400 type boats described in this article
          power reserve of more than 60000km. Not a single serial reconnaissance aircraft was capable of supporting the operation of these boats.
    2. Kibb
      Kibb 31 May 2012 10: 51
      The Japanese "samurai" spirit is inscrutable. But the only ones in history bombed the continental United States
  5. Dust
    Dust 31 May 2012 12: 53
    Yes, the idea of ​​using aircraft for reconnaissance and guidance of submarines with the development of equipment and technology in the vastness of the Pacific Ocean is more than a good idea!
  6. Kars
    Kars 31 May 2012 14: 27
    original idea. But for me anyway, from the submarines of the Second World War nothing will be more original than Surkuf.
    1. Kibb
      Kibb 31 May 2012 14: 36
      I agree, especially since the plane was also on it
      Photo true M2
    2. Glenn witcher
      31 May 2012 14: 43
      And "Surkuf" just did not have time to really fight.
      1. Kibb
        Kibb 31 May 2012 15: 15
        And still a rather stupid boat, although very interesting technically, and the French, like the Italians, "always built their ships better than they fought on them."
        1. Mut Anthony
          Mut Anthony 1 June 2012 23: 36
          Yes, the original submarine, only a dozen of them could make such a rustle to the Amers in the 42nd that the entire east coast, and the west would be in horror. Only in my opinion, at sea, our Komsomol members (and K21) are better.
    3. Kibb
      Kibb 31 May 2012 16: 21
      Still there was such a miracle - X1
      1. Glenn witcher
        31 May 2012 17: 30
        Oh yes, the cooler 5,2-inch guns are just torpedoes. wink

        In case anyone knows, you ist X-1:
  7. Deniska999
    Deniska999 31 May 2012 20: 32
    The Japanese were always inventive. Yes, and we had enough craftsmen.
    1. 755962
      755962 31 May 2012 23: 45
      Oh, remember the project 661 submarine with an underwater speed of 44,7 knots.