Shōkaku class (aircraft carrier)
| Shōkaku class | |
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| Overview | |
| Type: | Aircraft carrier |
| Units: | 2 |
| Technical data (original planning) |
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| Displacement: | Standard: 25,675 ts |
| Length: | over everything: 257.5 m |
| Width: | 26 m |
| Draft: | 8.87 m |
| Speed: | Top: 34 kn |
| Crew: | about 1160 permanent crew |
The Shōkaku class ( Japanese 翔 鶴 型 航空母艦 Shōkaku-gata kōkubokan ) was a class of two aircraft carriers of the Imperial Japanese Navy . In this class, the previous experience from Japanese warship building was combined, so that the ships received a synthesis of speed, armor protection and aircraft capacity that had not been achieved before . Until the introduction of the American Essex class in 1943, the Shōkaku-class ships were considered the most powerful aircraft carriers in the Pacific War .
Development history
After the announcement by the Japanese government in 1934 that the international fleet contracts were to be terminated, the naval planners no longer had to observe the tonnage limits for the construction of aircraft carriers.
The most successful design to date was the Sōryū class , whose second ship, the Hiryū , formed the basis for the new aircraft carrier class. The speed of the Hiryū should be maintained, but the aircraft capacity should be the same as that of the larger Kaga . However, the experiment with the Hiryū's bridge structure positioned on port side should not be repeated.
The 227 m long hull of the Sōryū class was extended to 257.50 m for the new ship class, the width increased by almost 5 meters to 26 meters. The length at the waterline reached 250 m.
Propulsion systems
The drive system consisted of four steam turbines , which were fed by eight steam boilers. The steam boilers burned heavy oil . Each boiler was housed in its own watertight compartment.
The turbines transferred around 160,000 SHP to four propellers. The Shōkaku class reached a speed of up to 34 knots . In a load test of the machinery on the Shōkaku , 161,280 SHP and 34.5 knots were achieved.
The exhaust gases from the boilers were led through pipes on the starboard side under the lower hangar deck and finally led out of the ship via two chimneys at the level of the upper hangar deck. With 18 knots, the ships could reach ranges of up to 10,000 nautical miles.
A rudimentary form of bulbous bow was integrated into the hulls of Shōkaku-class ships . It did not extend beyond the front perpendicular so that its exact degree of efficiency is unknown. The same applies to the spare rudder, which, similar to the spare rudder built into the Yamato class, was installed in front of the main rudder.
Armament and fire control system
Heavy anti-aircraft weapons
Each ship received eight twin mounts with 12.7 cm Type-89 cannons , four on each side of the ship. The two starboard mounts at the aft, behind the chimney outlets, were of the Type 89 A1 Model 2 and equipped with a housing to protect the gun crews from exhaust gases, while the other six mounts had no such protection. The guns were controlled with three Type 94 fire control devices.
A Type 94 control unit stood on the roof of the bridge structure, two on the port side and two more on the starboard side.
Light anti-aircraft weapons
The anti-aircraft armament for the close range of the Shōkaku class consisted of 36 25 mm L / 60 cannons type 96 . They were installed in ten open and two closed mounts. Only the two triplet mounts behind the chimney on the starboard side had a housing to protect the crew from exhaust gases.
The light anti-aircraft weapons were guided by six Type 95 control devices, three of which were set up on the sides of the ship.
Facilities for flight operations
The wooden flight deck on both ships was almost 242 meters long with a maximum width of 29 meters for the deck. In order to be able to take off modern and therefore heavy aircraft, the carrier had to drive against the wind so that the airflow reached under the wings of the aircraft and generated lift as soon as it took off. The distance for the take-off run of a B5N2 bomber, for example, was 226 meters with no wind and the aircraft naturally could not use the entire length of the deck for take-off, so that a certain wind speed was absolutely necessary as a starting aid. When there was no wind, the Shōkaku-class ships had to run at at least 26 knots in order to artificially generate the same effect and the required 13 meters per second of airflow and to enable their aircraft to take off.
The ships had three elevators to raise or lower aircraft from the two hangars on deck, one above the other. At 13 × 12 meters, the two rear elevators were slightly smaller than the front one with 13 × 16 meters; they were all integrated into the flight deck and not attached to the sides of the ship. The rear elevators or the front elevator could only be used when there was no landing or take-off operation.
72 operational and 12 reserve machines per ship were required for the aircraft carried. These figures were implemented and so the ships each carried in 1941:
- 18 (+ 2 reserve) Mitsubishi A6M2 - Type 0 Model 21
- 27 (+ 5 reserve) Nakajima B5N2 - Type 97 model 12
- 27 (+ 5 reserve) Aichi D3A1 - type 99 model 22
While the largest of these types of aircraft, the B5N2 torpedo bomber, with a wingspan of 15.51 meters in the hangar, could be shortened to only 7.5 meters wide by folding up the wings, only the wing tips could be folded down on the wings of the smaller D3A1 dive combat aircraft and the A6M2 fighters so that they were still 10 meters wide in the hangars.
| Conversions and modernizations on Shōkaku-class aircraft carriers | |||
| Drawing of the Shōkaku as it was built in 1942. The anti-aircraft armament had already been reinforced to four 25 mm Type 96 triplets at the bow and stern and in June 1942 the ship was equipped with a Type 21 radar on the bridge tower been. On the flight deck you can see 10 safety ropes, two folded net safety systems and the hinged windbreak, which protected the deck crew when preparing for take-off when the porter ran against the wind.
Three rectangular covers for retractable headlights are embedded in the flight deck. The wooden deck is interrupted by eight expansion joints to stabilize it. The three aircraft elevators and the top of the deck are not planked with wood, but are made of steel that was painted with a coat of anti-slip paint. Shortly behind the tip of the flight deck, the Katakana character for "Shi" is painted on to identify the ship for its own pilots. The Zuikaku had applied at the time the letters "SU" on their deck. |
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| Drawing of the Zuikaku under construction from October 1944. She received the massive upgrade with machine weapons and the camouflage paint before her last mission. In addition, a platform for four 28-tube rocket launchers was installed on the starboard side of the fore and on the port side of the stern, which fired unguided rockets with a caliber of 12 cm. The searchlight number 3 was removed and another type 21 radar was installed in its position. A Type 13 radar for searching for aerial targets was also retrofitted in 1944, the Yagi Uda antenna of which is mounted on the main mast. Ten type 96 25 mm single mounts and numerous machine guns were also taken on board before their last use, so that finally 96 25 mm cannons were set up on board.
The Imperial Japanese Navy began experiments in March 1944 to develop effective camouflages for aircraft carriers. When viewed from the side, the pattern was intended to simulate the outline of a cargo ship and obscure the conspicuous flight deck when viewed from above. The Navy itself did not consider the measure to be particularly effective, but in their opinion it was better than no camouflage. |
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Protection systems
Armor protection
The designers of the Shōkaku-class were instructed to construct the armor protection of the ships in such a way that the machinery should be protected from hits from 250 kg aerial bombs and 127 mm artillery projectiles . The magazines of the ships containing bombs and torpedoes were even supposed to be protected against hits from bombs up to 800 kg dropped from a horizontal bomber and 203 mm shells fired from up to 20 km away. The flight deck itself was not armored and, as was almost always the case at the time, was made of wood.
To implement their armor concept, the developers selected the following types of steel :
NVNC - New Vickers Non Cemented, also known as nitsukeru kurōmu kō (hardened chrome steel) by the Japanese , was the standard steel grade for armor in Japanese battleship construction and was also used for belt armor and the armored deck of the Shōkaku class . The belt armor was 8.5 "(21.6 cm) thick over the vital ship systems and thinned to 5.9" (15 cm) over the other areas. The armored deck was 17 cm (6.7 inch) thick.
DS - Ducol Steel, was not real armor steel, but steel with high yield strength , originally developed in Great Britain for mechanical engineering . They were homogeneous steel plates without case hardening, the production of which was not very resource-intensive and therefore inexpensive, but which had nevertheless proven to be useful in the role of armor. It was used for the structural protection system.
Structural protection
The Shōkaku class received an integrated, structural protection system without additional torpedo bulges . The system was nevertheless deeply staggered and reached in the middle of the ship about 5 meters from each side inwards. The exact requirements of the Imperial Navy for the designers for this protection system are controversial. They range from protection against the effects of a 200 kg TNT underwater explosion to a 450 kg TNT explosion. The most effective structural protection system, as shown by experiments with the battleship Tosa of 1924, consisted of a mixture of empty spaces (to soften the pressure wave of an underwater explosion) and those filled with liquid (water or oil) (to slow down the splinters, which also occurred in such an explosion). These findings were implemented in the Shōkaku class , so that a system was created that was structured as follows:
The protection system had four watertight compartments at the level of the boiler rooms, which were supposed to absorb the energy of an explosion before one of the boiler rooms was affected by it. The outer skin of the fuselage, below the belt armor, was followed by an empty expansion space, which was closed off by a 25 mm thick inner wall made of DS steel. This was followed by an approximately 2-meter-wide heavy oil tank, which could be pumped empty as a precaution in the event of anticipated battles. The inside of the tank formed another 25mm DS plate. Another oil tank was connected inboard, which was finally followed by the torpedo bulkhead. Another watertight compartment was located between the torpedo bulkhead and the boiler room.
Hangars and flight deck
A significant part of the dangerous substances on board an aircraft carrier is in the form of highly flammable aircraft fuel and in the form of bombs, torpedoes and automatic cannon ammunition in the hangars of the ships. Although the stocks of gasoline and ammunition are relatively well protected deep inside the ship under armor protection - as soon as flight operations take place, certain quantities must be brought into the hangars as part of the preparations for take-off.
The porters' hangars were not below an armored deck, but were above the armored deck. In order to survive explosions from enemy or own bombs within a hangar as unscathed as possible, the outer walls of the upper hangar were made very thin so that the explosion energy should be directed outwards and not upwards towards the flight deck. But that didn't work: the hangars on all Japanese aircraft carriers were completely closed, with the elevator shafts of the aircraft elevators as the only direct connection to the outside. After the Shōkaku was hit by several aerial bombs in October 1942, which exploded in the upper hangar, their explosive energy was directed against the flight deck, which buckled and tore, which initially made further flight operations impossible.
As a further measure, the space inside the upper hangar was divided by two gates, which were intended to limit splinters and pressure in the event of an internal explosion to one of three hangar segments.
Another problem was fumes from leaked aviation fuel, which could spread and ignite. Due to the closed hangar system, artificial ventilation of these areas was absolutely necessary, so that air was sucked in from the outboard on the port side and sucked out again via fans on the starboard side. Aspiration on both sides was not possible, as otherwise the exhaust gases from the chimneys would have been forced into the hangars from the starboard side.
Shōkaku-class ships
Shōkaku
The Shōkaku was laid down by the Yokosuka naval shipyard in December 1937 and launched in June 1939. In the Pacific War, she formed the 5th aircraft carrier division with her sister ship. In December 1941 she took part in the attack on Pearl Harbor . In May 1942 she was damaged by aerial bombs during the Battle of the Coral Sea and was initially canceled for further operations. In August 1942 she was involved in the Battle of the Eastern Solomon Islands , followed by the Battle of the Santa Cruz Islands in October. In June 1944 she was sunk by the submarine Cavalla by several torpedo hits during the battle in the Philippine Sea on the 19th .
Zuikaku
The Zuikaku was laid down in May 1938 by the Kawasaki shipyard in Kobe and was launched in November 1939. She was the flagship of the 5th Carrier Division and took part in the attack on Pearl Harbor, the battles in the Coral Sea and the Santa Cruz Islands. It was damaged by an aerial bomb in the Battle of the Philippine Sea in June 1944 and its flying formations suffered heavy losses when attacking American warships. Unable to compensate for the losses of pilots, it was decided to use the Zuikaku with other carriers as bait for American carrier groups during the sea and air battles in the Gulf of Leyte in October 1944. This plan succeeded, but the Zuikaku was so badly damaged by American carrier aircraft that it went down on October 25, 1944.
Remarks
- ↑ An exception to this rule was the British aircraft carrier HMS Ark Royal from 1938, which had a steel flight deck.
- ↑ in the translation of Kojinsha number 6 at combinedfleet.com a thickness of 132 mm is given for the armored deck.
Evidence and references
Individual evidence
- ^ Kaigun: Strategy, Tactics, and Technology in the Imperial Japanese Navy, 1887-1941 p. 319
- ↑ a b c so in the translation of Kojinsha number 6 at combinedfleet.com, viewed on April 14, 2011
- ↑ a b USNTMJ A-11 p. 16
- ↑ USNTMJ A-11 p. 8
- ↑ USNTMJ, X-32, Camouflage of Japanese Ships and Naval Installations, p. 17 and following
- ^ Sunburst: The Rise of Japanese Naval Air Power, 1909-1941 , p. 60
- ↑ Article by Kent G. Budge on kgbudge.com, viewed January 3, 2010
- ↑ USNTMJ, Japanese Heavy Armor, O-16, p. 7
- ↑ Nathan Okun ARMOR PROTECTION OF THE BATTLESHIP KM BISMARCK on combinedfleet.com, viewed April 16, 2011
- ↑ USNTMJ, Underwater Protection, S-01-9, p. 74
- ↑ USNTMJ, A-11, pp. 12-14
literature
- Collective authors of the Maru magazine: WARSHIPS OF THE IMPERIAL JAPANESE NAVY - Shokaku-Klasse, Soryu, Hiryu, Unryu-Klasse, Taiho (Japanese: 空 母 翔 鶴 ・ 瑞鶴 ・ 蒼龍 ・ 飛龍 ・ 雲龍 型 ・ 大 鳳 ) Kōjinsha, Tokyo, 1996, ISBN 978-4-7698-0776-6 .
- Mark R. Peattie: Sunburst: The Rise of Japanese Naval Air Power, 1909-1941 . US Naval Institute Press, 2007, ISBN 978-1-59114-664-3 .
- David C. Evans: Kaigun: Strategy, Tactics, and Technology in the Imperial Japanese Navy, 1887-1941 . US Naval Institute Press, 2003, ISBN 0-87021-192-7 .
- United States Naval Technical Mission to Japan, Report A-11, Aircraft Arrangements and Handling Facilities on Japanese Naval Vessels
- United States Naval Technical Mission to Japan, Report X-32, Camouflage of Japanese Ships and Naval Installations
