Sōryū class (aircraft carrier)

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Sōryū class
Japanese aircraft carrier Hiryu.jpg
Overview
Type: Aircraft carrier
Units: 2
Technical data
(original planning)
Displacement: Standard: 15,900-17,300  ts
Length: over everything: 227.5 m
Width: 21.3-22.3 m
Draft: 7.4-7.8 m
Speed: Top: 34.5 kn
Crew: about 1,100 permanent crew

The Sōryū class was a class of two aircraft carriers of the Imperial Japanese Navy . Although both ships were initially planned as identical units, the Hiryū built later received considerable modifications, so that in some publications the ships are not listed as a class, but as individual ships.

The aircraft carriers were the first of their kind to be envisaged as an independent class of ships during the planning phase, while the Japanese aircraft carrier construction had previously only produced the single ships Hōshō and Ryūjō and the conversions of the ships Kaga and Akagi .

Development history

The light aircraft carrier Ryūjō was planned by the Imperial Navy as the second aircraft carrier from the keel. However, since Japan had largely exhausted its total contingent of aircraft carrier tonnage after the Naval Conference in Washington in 1922, the option of building a ship that was not considered an aircraft carrier according to the treaty was chosen. A loophole in the contract ensured that only one ship over 10,000 ts counted as an aircraft carrier, so the Ryūjō was planned with a little less than 10,000 ts. The result in 1933 was a ship that had little tactical value, but highlighted numerous problems of the new type of ship.

While most of the problems were due to the tonnage restriction, another point of criticism had a lasting impact on later buildings:

  • The aircraft hangar , placed on a hull with a low freeboard, made the Ryūjō top-heavy and an enlargement of the hangar exacerbated the problem, so that the ship was unstable and, until a conversion in 1934, was hardly seaworthy.

Similar hangars had already been used by the Kaga and Akagi , but they had massive armor elements in the hull from their time as battleships and battle cruisers , so that their center of gravity was lower than that of the unarmored Ryūjō .

In the first plans, which were carried out from 1931 to 1932, the two new ships of the Sōryū class were still planned as a mixture of cruiser and aircraft carrier, which could fight with guns. With the emergence of Japan's exit from the international fleet contract system, the plans were revised and the ships designed as full aircraft carriers.

Based on the shape of the hull, armor protection and machinery that resembled those of a heavy cruiser, a high speed could be achieved, and the revised hangar system allowed the accommodation of significantly more aircraft than previous structures.

Planning differences

The Sōryū 1938
The hiryu . The higher freeboard compared to the sōryū can be clearly seen here from the smaller distance between the flight deck and foredeck. The larger bridge tower is also clearly visible.

Both ships of the class received a modified cruiser hull. The hull length of the Sōryū was 227.50 m with a maximum width of 21.3 m. As a direct result of the devastating damage that a severe typhoon inflicted on a Japanese fleet in 1935, all ships were revised and the Hiryū was completely rescheduled before her keel was laid in 1936. Her foredeck was pulled higher up to the tip of the bow and thus reached closer under the flight deck than with her sister ship. With a length of 227.35 m, it was somewhat shorter than the Sōryū . An increase in stability was achieved by widening the hull by about one meter to 22.32 m. The standard displacement consequently increased from the 15,900 ts of the Sōryū to 17,300 ts in the Hiryū , the draft rose by 30 centimeters.

The widening of the hull of the Hiryū made it possible to carry 73 aircraft, compared to 71 on her sister ship. However, both porters were only able to carry 57 ready-to-use machines, while the rest was partially dismantled and stored as a reserve.

While the tonnage differences between the two ships were hard to see from the outside, the different arrangement of the bridge tower on different sides of the flight decks of both ships was a clear distinguishing feature. While the first Japanese aircraft carriers did not have a bridge tower at all, it quickly became clear that the previous practice of a bridge below the flight deck offered too little overview for the ship's command. The Sōryū therefore received a small bridge tower on the starboard side of the flight deck. His weight rested on a support structure on the side of the fuselage, so that the area of ​​the flight deck was not reduced by the bridge. The Hiryū , however, received her tower in an enlarged form on the port side. This experiment had previously been carried out on the Akagi , as it had been calculated that the configuration would allow a larger bridge structure, because the weight of the funnels positioned on the starboard side would compensate for the weight of the bridge structure. However, the idea had similarly serious consequences on both ships. The hot exhaust gases from the starboard chimneys were now blown unchecked over the flight deck and the enlarged bridge structure of the Hiryū caused strong turbulence , which made flight operations more prone to accidents. No Japanese aircraft carrier ever received a bridge tower on the port side again.

Propulsion systems

The propulsion systems corresponded to those of the heavy cruisers of the Mogami class . They consisted of ten boilers fired with heavy oil, with which the steam for the operation of four steam turbines was generated. These turbines transferred around 152,000 SHP to four propellers. The Hiryū reached a speed of up to 34.5 knots , the top speed of the Sōryū was slightly higher due to its lower weight of 34.9 knots. The heavy oil supply of around 3750 ts carried by the Hiryū and 3400 ts Sōryū allowed a range of around 7750 nautical miles at a speed of 18 knots for the Sōryū , while the range of the Hiryū was slightly less.

The exhaust gases from the boilers were fed through pipes on the starboard side through the lower hangar deck and finally at the height of the upper hangar deck via two chimneys from the ship.

Armament and fire control system

Heavy anti-aircraft weapons

Each ship received six twin mounts with 12.7 cm Type-89 cannons , three on each side of the ship. The starboard carriage aft of the chimney outlets was of type 89 A1 model 2 and equipped with a housing to protect the gun crews from exhaust gases, while the remaining five carriage had no such protection. The guns on the Sōryū were initially controlled with three Type 91 fire control devices , while the Hiryū already received the more modern Type 94 control devices. A control unit was located on the port and starboard sides next to the flight deck, and a third on the top of the bridge structure.

Light anti-aircraft weapons

The anti-aircraft armament for the close range of the Sōryū consisted of 28 25 mm type 96 cannons . They were installed in eleven open and three closed mounts. Only the three twin mounts behind the chimney on the starboard side had a housing to protect the crew from exhaust gases. Three twin mounts were located on the bow directly below the leading edge of the flight deck, six were mounted on the port and five on the starboard side of the flight deck.

The anti-aircraft armament for the close range of the Hiryū consisted of 31 25 mm type 96 cannons. The 25 mm weapons were installed in eleven open and three closed mounts. The three twin mounts behind the chimney on the starboard side had a housing to protect the crew from exhaust gases. Two twin mounts were on the bow, directly below the leading edge of the flight deck, the three mounts with housings were mounted on the starboard side of the flight deck behind the funnel. Two 25 mm triplet mounts were on the starboard side in front of the funnel, and on the port side there were five 25 mm triplet mounts.

The light anti-aircraft weapons were guided by five Type 95 control devices, two of which were set up on the sides of the ship and one on the bow.

Facilities for flight operations

The wooden flight deck on both ships was almost 217 meters long with a maximum width of the deck of 26 meters. There were nine safety ropes on the flight deck.

The ships had three elevators to raise or lower aircraft from the two stacked hangars on deck. The two rear elevators were slightly smaller than the front; they were all integrated into the flight deck and not attached to the sides of the ship. The rear or front elevators could only be used when there was no landing or take-off operation.

Protection systems

Structural protection

The Sōryū class received a simple integrated, structural protection system without additional torpedo bulges , which was composed of the belt armor, a small expansion chamber and a thin inner bulkhead .

Armor protection

The protection of the vital parts of the ships against shelling with flat and steep trajectories was comparatively weak and sacrificed in favor of speed. The Sōryū had a 4.5 cm thick belt armor and a horizontal armored deck only 2.5 cm thick, which was located between the lower hangar deck and the engine rooms. Its thickness only increased to 5.5 cm above the ammunition chambers.

The Hiryū was equipped with modified armor protection and its protection system on the ship's sides was improved with belt armor with a thickness of 8.8 cm. To protect the sensitive magazines with the aerial bombs and torpedoes, the belt armor was additionally lined with armor at these points and thus reached a thickness of almost 15 cm at these points of the Hiryū , which made it far less susceptible to hits in these areas than its sister ship.

Ships of the Sōryū class

Sōryū

The Sōryū was laid down by the naval shipyard in Kure in November 1934 and launched in December 1935. In the Pacific War , she formed the 2nd aircraft carrier division with her sister ship. In December 1941 she was one of the porters in the attack on Pearl Harbor and later in action against American troops on Wake . In 1942 she carried out numerous operations around New Guinea and was finally hit by three heavy aerial bombs on June 4, 1942 in the Battle of Midway , whereupon she went down as a result of the damage that evening.

Hiryu

The Hiryū was laid down by the Yokosuka naval shipyard in July 1936 and launched in November 1937. She was the second ship of the 2nd Aircraft Carrier Division and took part in the Japanese attacks on Pearl Harbor and Wake. After operations in the South Pacific, she was the last operational Japanese carrier in the Battle of Midway in June 1942 and the attacks by her aircraft led to the sinking of the American carrier USS Yorktown . Later in the battle, however , the Hiryū received four hits from aerial bombs and was so badly damaged that it had to be abandoned by the crew.

Evidence and references

Remarks

  1. ↑ Other sources assume 72 aircraft for the Sōryū , in the configuration 56 operational + 16 reserve machines. So konjinsha number 6.
  2. ↑ The information about various control stations of both vessels is from the translation of Kojinsha point 6 on page 57, but the same document lists S. 30 Type-94-guide devices for the soryu , so that a retrofit or a fault in the Document must be assumed.

Individual evidence

  1. ^ Paul E. Fontenoy: Aircraft Carriers: An Illustrated History of Their Impact. P. 35.
  2. ↑ Kaigun: Strategy, Tactics, and Technology in the Imperial Japanese Navy, 1887-1941. P. 318.
  3. ↑ Midway inquest: why the Japanese lost the Battle of Midway. P. 47.
  4. ↑ a b c so in the translation of Kojinsha number 6 at combinedfleet.com, viewed on April 14, 2011
  5. ^ Aircraft Carriers: An Illustrated History of Their Impact. P. 37.

literature

  • Collective of authors of the Maru magazine: WARSHIPS OF THE IMPERIAL JAPANESE NAVY - Shokaku class, Soryu, Hiryu, Unryu class, Taiho. (yes: 空 母 翔 鶴 ・ 瑞鶴 ・ 蒼龍 ・ 飛龍 ・ 雲龍 型 ・ 大 鳳) Kōjinsha, Tokyo 1996, ISBN 978-4-7698-0776-6
  • Dallas Woodbury Isom: Midway inquest: Why the Japanese lost the Battle of Midway. Indiana University Press, 2007, ISBN 0-253-34904-4
  • 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
  • Paul E. Fontenoy: Aircraft Carriers: An Illustrated History of Their Impact. ABC-CLIO, 2006, ISBN 1-85109-573-X

Web links