Kaiten

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Kaiten I
Longitudinal profile of the Kaiten I
Longitudinal profile of the Kaiten I
Ship data
country JapanJapan (naval war flag) Japan
Ship type Manned torpedo
Construction period March 1944 to August 1945
Units built 330
From 1944
length
14.50 m ( Lüa )
width ∅ 1.00 m
displacement 8.0 t
 
crew 1

The manned torpedo Kaiten ( Japanese 回 天 ) (also Kaiten igyo ) was a small-scale maritime weapon used by the Imperial Japanese Navy towards the end of the Second World War .

It followed the functional principle of the submarine , but provided that the pilot rammed his vehicle against a target ship and caused a large explosive charge to explode. The explosion destroyed both the target and the small ordnance and killed the pilot.

prehistory

The co-developers of the Kaiten: Sekio Nishina and Hiroshi Kuroki 1943

Idea and planning

Two Japanese officers, Ensign Nishina and Lieutenant Kuroki, who had been trained on mini-submarines, had recognized their design-related weaknesses in terms of armament and speed. They developed the plan to design a vehicle based on the Type 93 torpedo , which would combine the advantageous abilities of mini-submarines, such as their maneuverability and good protection against detection by sonar and enemy observers, with the speed and destructive power of the Torpedoes should connect.

The plan was worked out with the help of a navy engineer in 1942, but initially rejected by the naval staff. Only when the Pacific War developed significantly to the disadvantage of Japan in 1944 was the construction of a prototype approved. Concerned that the Kaiten's plan did not include the pilot's survival, the staff requested the installation of an escape hatch in the Kaiten prototype.

construction

The Kaiten prototype was built in the workshops of the Kure naval shipyard . Components were also built by other naval shipyards for subsequent series production. The construction of the engines, which was quite complex, especially for the Kaiten II, was spread over several manufacturers. In 1946, for example, the Americans listed the naval shipyards in Kure, Yokosuka , Sasebo , Maizuru and Hikari , together with the private companies Mitsubishi and Kawasaki as producers.

Personnel and training

The pilots for Kaiten missions were recruited partly from volunteers for the Shimpū-Tokkōtai missions of the Air Force, who were retrained on the Kaiten due to a lack of available aircraft. The requirements were significantly higher than, for example, for crews of the Shin'yō-class explosive devices , since the Kaiten pilots had to deal with minor technical defects while they stayed in the small capsule for a long time with no outside view. The high physical and psychological demands then also meant that many applicants were not suitable for the program. The age of the pilots was between 17 and 28 years. After the aptitude tests, the pilots were given extensive theoretical training and then transferred to another base for practical training. By the end of the war, 1,375 soldiers had been trained as Kaiten pilots.

Models

Kaiten I

Schematic structure type 1

For details on the propulsion system, see: How the Type 93 Torpedo Works

The Kaiten I was developed based on the Type 93 torpedo. However, with 1550 kg of explosives in the front, it had significantly more destructive power than the original unmanned torpedo. For the pilot there was a small steering position in the middle of the vehicle, which he could climb through two hatches. One hatch was at the top, and another, for use from the deck of large, submerged submarines, was recessed at the bottom. The control units and a periscope were located in the steering position , which could be retracted or extended up to 70 cm if necessary.

Since the original torpedo had no oxygen supply for a pilot, the Kaiten pilots had to carry sodium peroxide in a tin can in the control stand, which filtered carbon dioxide from the air and released oxygen in the process . This principle corresponded to that of the diving rescuer as it was used on submarines.

The Type 93 torpedo engine was operated with around 550 hp. The maximum range was 78 kilometers at 12  knots (kn), at the top speed of 30 kn it sank to 23 kilometers. At an average speed of 20 knots, 43 kilometers could be achieved.

The Japanese engineers had to make changes to the torpedo mechanics of the Type 93 in order to keep the components functional even for the longer operating times of the Kaiten. They exchanged the simple gyroscope , which was operated with compressed air, for a counterpart with an electric motor. The pilot could steer a course manually or let the gyro to follow a certain course. The depth control allowed presets from 0 to 35 meters, which were controlled by a depth gauge. As in the Type 93 torpedo, compressed air was used to operate the rudder for depth corrections. The maximum diving depth should be 100 meters, however, various leaks occurred during tests at this depth. 60 meters was finally given as the maximum diving depth. The control surfaces, i.e. the down and rudder rudders, which the pilot could operate, were made larger on the Kaiten compared to the torpedo, so that the Kaiten responded much more quickly to manual steering commands. The control surfaces, which were automatically controlled by the gyro instrument, were smaller, on the other hand, so that the pilot could simply override the effects of the automatically generated rudder movements with his control commands.

The length of the Kaiten I was 14.50 m, the cylindrical hull was one meter in diameter and the weapon weighed 8.0 tons.

The Kaiten I was produced from June 1944. A modification of the Kaiten I was produced from 1945. This version was 14.74 m long and weighed 8.3 t, carried 40 liters of additional compressed air to operate the control surfaces, but otherwise corresponded to its predecessor.

The production figures for the Kaiten Type 1 were around 100 and around 230 of the modification produced from 1945 onwards.

Kaiten II

Schematic structure type 2
Drawing of the generator in Kaiten II with the combustion chamber and details of the mixing system for liquids A and B.

While the Kaiten I went into series production, the prototype of the Kaiten II was already being made at the same time . After Japan had received technical data, drawings and photos from the allied German Reich containing details on the use of hydrogen peroxide in the Walter HWK 109-509 rocket drive of German aircraft such as the Me 163 or the Ba 349 "Natter" , the Navy decided to to use this drive also for the Kaiten. The development of its own peroxide drive for the J8M Shūsui interceptor began at Mitsubishi in Nagasaki in mid-1944. The navy sent its engineers to Mitsubishi to develop the drive for the Kaiten II based on the findings .

After several tests, it was decided to mix and then burn the following substances:

  • Liquid A hydrogen peroxide with a consumption of 17.8 kg / min
  • Liquid B hydrazine hydrate with a consumption of 1.53 kg / min
  • Fuel ( petroleum ) with a consumption of 3.57 kg / min
  • Water with a consumption of 33.6 kg / min

The Kaiten pilot first opened a valve for compressed air during takeoff, which began to move the eight-cylinder engine. When the gas lever was activated, oil was slowly let into the engine, which opened the switches for the valves for liquids B , A , fuel and water one after the other as the level rose , and finally closed the compressed air valve . The liquids were then first fed from their tanks through their valves to the generator and introduced at the top. Used quantities were replaced with water in their tanks to ensure constant pressure and trim.

In a first step in the generator, the components hydrogen peroxide and hydrazine hydrate, which were introduced in a ratio of around 10: 1, reacted at the upper end. This created oxygen. This oxygen had a high temperature of 700 to just under 1000 ° C and was now enriched with the petroleum and the water, which were injected a little deeper into the generator. The extremely hot gas mixture was fed through two specially cooled pipes with an inner diameter of 92.5 mm on the underside of the generator to the two engine blocks of the Type 6 engine, where it then operated the cylinders .

The speed reached in this way was 20 knots in the basic position, when the throttle lever was pressed again to a higher level (30 or 40 kn), up to two additional valves were opened for each component, thus increasing the flow of liquids to the generator and increasing the power increased to up to 1600 hp. The energy was transferred to an inner and an outer shaft, each of which had a three-bladed propeller attached. The propellers, the front with 1060 mm diameter, the rear with 970 mm diameter, were made of bronze and worked like those of the Type 93 torpedo.

By the end of the war, only two ready-to-use Kaiten IIs were produced. The weapon weighed 18.307 metric tons, carried a 1.55 tonne explosive charge, which, like its predecessor, could be triggered with two separate detonators. The maximum range was 83 kilometers at 20 kn.

The drive of the Kaiten II thus took up the functional principle of the “hot process” in the Walter drive from 1936, even if the Japanese engineers did not connect a turbine to generate electricity, but operated a conventional piston expansion machine with the hot gas.

Kaiten III

No pattern called Kaiten III was produced.

Kaiten IV

Schematic structure type 4

Because of the difficult supply of hydrogen peroxide for the Kaiten II , the Navy decided to develop the Kaiten IV , which retained the dimensions of the Kaiten II , but was to be powered with oxygen, petroleum and water for a modified Kaiten II engine. The prime mover with the designation "Type 6", which was similarly used in Type 2, was modified under great time pressure. Several engineers opposed wasting resources on this project because they believed the Kaiten I was sufficient and believed that the "Type 6" machine was consuming too much oxygen, making the Kaiten IV's range too short .

After several tests, the fears were confirmed and the Kaiten IV was not pursued further after testing finished models.

The 1500 HP engine did not work efficiently with a top speed of only 25 knots and emitted a large part of the fuel unburned as exhaust gas. At 1800 kg, the weapon was supposed to carry a significantly larger warhead than the Kaiten II . By using oxygen instead of the two liquids A and B, it was hoped that a significant weight saving would be achieved, whereby the Kaiten IV with 18.17 t, despite its heavier warhead, should weigh 200 kg less than the Kaiten II .

The maximum range was 62 kilometers at a speed of 20 kn.

Kaiten V

The Kaiten V was a slightly modified version of the Kaiten IV with a modified compressed air supply.

Kaiten VI

The Kaiten VI was a slightly modified version of the Kaiten I with a modified compressed air supply.

Kaiten X

Schematic structure type 10

With the ever increasing fear of an invasion of the Japanese home islands, the amount of Kaiten torpedoes produced should be increased in the short term. The only option was to convert existing Type 92 torpedoes .

The original torpedo was divided for this purpose and an additional section with a steering position was used. The Kaiten X was the only member of the Kaiten family to have an electric drive. A maximum of six were produced by the end of the war. The weapon had a 300 kg warhead, weighed 3 t, was 9 m long with a cylinder diameter of 70 cm. The electricity for the electric motor came from two lead-acid batteries . At 7 knots, the Kaiten X could cover up to 3.5 km.

Calls

Mission sequence

Kaiten I on the deck of the carrier submarine I-361 in May 1945
Map of the Japanese islands with the positions of planned Kaiten bases

The Kaiten I should be used from submarines, ships or from bases on land. Although several ships had been converted to transport Kaitens, this combination was never used in a battle. On the other hand, they were used several times from submarines.

The Kaiten pilot stayed with the rest of the crew in the pressure hull of the carrier submarine during the approach to the target area. Once the target area was reached, the submarine went to periscope depth of approximately 9 meters and a hatch to the upper deck of the submarine was opened. There was an entry port above the hatch that connected the hatch in the submarine to a hatch on the underside of the Kaiten. The pilot's cabin of the Kaiten was initially ventilated from the carrier submarine. Then the pilot climbed into the kaiten and the hatches were closed. The pilot could now speak to the crew in the submarine via a simple telephone. He received final instructions for his attack and the clamps connecting the submarine and the Kaiten were loosened. If the kaiten was stored in front of the tower of the carrier submarine, the pilot had to raise the drive before releasing the retaining clips so as not to collide with the tower.

The pilot set the course to the target on the electric gyro and selected a speed and depth for his attack. The Kaiten now ran independently towards the target and automatically made the necessary corrections to maintain course and depth. Around 1000 m in front of the calculated position of the target, the speed was reduced manually and the kaiten emerged so far that the pilot could aim at his target via the periscope. The reduced speed at this stage of the attack made the detection more difficult as less water was thrown up. At the same time, it was easier to observe the surroundings, as the water that was thrown up at higher speeds could also obstruct the pilot's view.

The pilot then changed course in accordance with his observation and dived to attack to the desired depth, which depended on the draft of the target ship. He accelerated to the top speed of 30 knots and unlocked the two detonators for the explosive charge in the Kaiten's nose. One detonator was an impact detonator , which was also used in the Type 93 torpedo and which was triggered by the abrupt braking on impact at the target. The second detonator was electric and was operated directly by the pilot by holding a pistol grip installed in front of him in his steering position during the attack. On impact, the pilot was thrown forward and so also pushed the handle forward, closing a circuit that triggered the ignition.

Carrier submarines and ships

The following submarines, which could each transport 4 to 6 Kaiten I , were converted as carrier ships : I 8 , I 36 , I 37 , I 44 , I 46 , I 53 , I 47 , I 48 , I 53 , I 56 , I 58 , I 156 , I 157 , I 159 , I 162 , I 165 , I 361 , I 363 , I 366 , I 367 , I 368 , I 369 , I 370 , I 372 and I 373 . In addition, several surface units were modified as carrier ships, such as the express transporter LST I , the Japanese cruiser Kitakami of the Kuma class , and the destroyers Namikaze and Shiokaze .

However, in the course of naval battles, the submarines I 8 , I 37 , I 44 , I 48 , I 56 , I 165 , I 361 , I 368 , I 370 and I 378 were sunk by American units with their Kaiten .

Land bases

While the use of submarines was of an offensive nature, a significant part of the Kaiten produced was withheld for use of a defensive nature. Kaiten were seen as an important means of defending particularly threatened stretches of coast in the expected invasion of the Japanese home islands by Allied ground forces.

The plans envisaged that all small arms, in addition to explosives and mini-submarines, including the Kaiten, should launch an attack on the anchored invasion fleet from their hidden bases along the coasts of the Japanese islands on the first night of an invasion. Since the Kaiten were the most difficult to fend off the available small arms, their targets would have been the escort ships that were most dangerous for the other small arms.

In July 1945, a total of 118 Kaiten were assigned to various bases at Yokosuka, Osaka, Kure and Sasebo, and further deployments were planned.

Occupied missions

The USS Mississinewa sinks after the "Kaiten" of Sekio Nishina hit her in the early morning of November 20, 1944

In November 1944, three carrier submarines with four Kaiten I each were set off against a US Navy anchorage in Ulithi Atoll . I-37 was sunk by American destroyers on the approach, I-36 could only drop one Kaiten, but it did not hit a target. The rest were broken. I-47 launched all of the Kaiten, but only one, likely the torpedo piloted by the gun's co-inventor, Sekio Nishina, found a target and sank the tanker USS Mississinewa . The other three were lost.

In addition, only the USS Underhill , an escort destroyer, was sunk by a kaiten on July 24, 1945 before the war ended.

The Japanese side overestimated the weapon’s effectiveness. A post-war questioning of the Kaiten School's head of training by the Americans revealed that he believed his Kaiten pilots had sunk two to three aircraft carriers , two battleships , 25 to 30 cargo ships and four to six destroyers .

Losses and reception

losses

A total of 162 American soldiers died in Kaiten attacks. 106 Kaiten pilots were killed, 15 of them were killed in accidents while training. Over 600 Japanese sailors died when their carrier submarines were sunk during Kaiten missions.

Commemoration

A museum was set up near Shūnan at the training site of the Kaiten crews on the island of Oodu ( Japanese 大 津 島 ). The plant was expanded several times and is next to the museum and a monument and a 1: 1 model of a Kaiten I .

Exhibits

A preserved Kaiten I can be seen in the Yūshūkan Museum of the Yasukuni Shrine in Tokyo , a Kaiten X can be seen in the Yamato Museum in Kure and a copy is at the Tokuyama Ferry Terminal. The Bowfin Museum in Honolulu has a Kaiten IV on display .

Movie and TV

The story of a Kaiten pilot is portrayed in the film (Japanese 出口 の な い 海 ) (in German: "See without return") from 2006 based on a book by Hideo Yokoyama.

In the US-American television history produced infotainment - television series "Dogfights" the second season was sent in March 2008, reports on various secret projects during World War II in the 17th episode, in which, among other things Kaiten was also discussed. The report consists mostly of computer animation , but also contains excerpts from an interview with Harumi Kawasaki, a former Kaiten pilot.

Remarks

  1. ↑ This includes both the course arsenal and the one in Hiro (Hiro Kaigun Kosho) at Kure.
  2. ↑ 1,500 PS according to USNTMJ O-01-1, p. 335
  3. ↑ The components for up to 50 Kaiten IV could have been produced, according to USNTMJ O-01-1, p. 403
  4. ↑ The original unmanned torpedo Type 92 was supposed to reach a range of nearly 7 km. USNTMJ O-01-1, p. 31
  5. ↑ Naturally, the identity of the pilot could not be ascertained by the Americans, so that the statement must be based on Japanese sources, as described by Robin L. Rielly in "Kamikaze Attacks of World War II", p. 349

Individual evidence

  1. ↑ USNTMJ O-01-1
  2. ↑ Kamikaze Attacks of World War II: A Complete History of Japanese Suicide Strikes on American Ships, by Aircraft and Other Means. P. 90
  3. ↑ USNTMJ O-01-1, p. 402
  4. ↑ Making sense of suicide missions. P. 12
  5. ↑ USNTMJ S-02, p. 22
  6. ↑ USNTMJ S-02, p. 24
  7. ↑ USNTMJ S-02, p. 22
  8. ↑ USNTMJ O-01-1, p. 326
  9. ↑ USNTMJ O-01-1, p. 324
  10. ↑ USNTMJ O-01-1, p. 343
  11. ↑ USNTMJ O-01-1, p. 380
  12. ↑ USNTMJ S-02 p. 29
  13. ↑ USNTMJ O-01-1, p. 398
  14. ↑ USNTMJ O-01-0 p. 413
  15. ↑ a b USNTMJ S-02, p. 28
  16. ↑ USNTMJ O-01-1, p. 415
  17. ↑ USNTMJ O-01-1, p. 323
  18. ↑ Kamikaze Attacks of World War II: A Complete History of Japanese Suicide Strikes on American Ships, by Aircraft and Other Means. Pp. 308 and following
  19. ^ Proceedings, Volume 81, 1962, US Naval Institute, p. 61
  20. ↑ Kamikaze Attacks of World War II: A Complete History of Japanese Suicide Strikes on American Ships, by Aircraft and Other Means. P. 182 and following
  21. ↑ USNTMJ O-01-1, p. 424
  22. ↑ a b Bill Gordon's homepage with information from the Kaiten Museum, viewed on February 6, 2011
  23. ↑ Private homepage that documents the expansion of the memorial over the decades with numerous photos, viewed on February 9, 2011 (Japanese)

literature

  • Diego Gambetta (Ed.): Making sense of suicide missions. 1. published in paperback, expanded and updated. Oxford University Press, Oxford u. a. 2006, ISBN 0-19-929797-5 .
  • Harald Fock: Naval small weapons. Manned torpedoes, small submarines, small speedboats, explosives yesterday - today - tomorrow. Nikol, Hamburg 1996, ISBN 3-930656-34-5 .
  • Michael Mair: Oil, Fire, and Fate. Seven Locks Press, Santa Ana CA 2007, ISBN 978-0-9790950-1-6 ( excerpt online ; PDF; 1.5 MB).
  • Robin L. Rielly: Kamikaze Attacks of World War II. A Complete History of Japanese Suicide Strikes on American Ships, by Aircraft and Other Means. McFarland, Jefferson NC et al. a. 2010, ISBN 978-0-7864-4654-4 .
  • US Naval Technical Mission to Japan, Report O-01-1: Ship and Kaiten Torpedoes. 1946.
  • US Naval Technical Mission to Japan, Report S-02: Japanese Sucide Craft. 1946.

Receipts Kaiten-kai (Association of Japanese Kaiten Pilots)

  • Toshiharu Konada, (“Chairman” Kaiten-kai), Tokko (Special Attack) , Interview “How did they feel?” , May 1999
  • Kaiten bases Kabajima and Sokodo on the island of Hachijō-jima (English)
  • Kaiten group "Kikusui" November 1944, Japanese submarines I-36, I-37, I-47 (English)
  • Kaiten group "Congo" December 1944 - January 1945, Japanese submarines I-36, I-47, I-56 (English)
  • Kaiten group "Kongo" December 1944 - January 1945, Japanese submarine I-53 (English)
  • Kaiten group "Congo" December 1944 - January 1945, Japanese submarines I-48, I-58 (English)
  • Kaiten group "Chihaya" February 1945 - March 1945, Japanese submarines I-44, I-368, I-370 (English)
  • Kaiten group "Hakuryu" March 1945, Japanese "Troopship No.18" (T-18), sunk on March 18 by the US submarine USS Springer (SS-414) (English)
  • Kaiten group "Shinmu" March 1945 - April 1945, Japanese submarines I-36, I-58 (English)
  • Kaiten group "Tatara" March 1945 - April 1945, Japanese submarines I-44, I-47, I-56, I-58 (English)
  • Kaiten group "Tenmu" April 1945 - May 1945, Japanese submarines I-36, I-47 (English)
  • Kaiten group "Shinbu" May 1945 - June 1945, Japanese submarine I-367 (English)
  • Kaiten group "Todoroki" May 1945 - June 1945, Japanese submarines I-36, I-165, I-361, I-363 (English)
  • Kaiten group "Tamon" July 1945 - August 1945, Japanese submarines I-47, I-53, I-58, I-363, I-366, I-367 (English)

Web links

Commons : Kaiten  - collection of images, videos and audio files