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The two aircraft carriers were built for the Imperial Japanese Navy (IJN) in the late 1930s. Completed shortly before the start of the Pacific War in 1941, they were judged by historian Mark Peattie as "arguably the best aircraft carriers in the world until the emergence of the American in 1943."〔Peattie, p. 243〕 With the exception of the Battle of Midway, they participated in every major naval action of the Pacific War, including the attack on Pearl Harbor, the Indian Ocean Raid, the Battle of the Coral Sea, and the Guadalcanal Campaign. Their inexperienced air groups were relegated to airfield attacks during the attack on Pearl Harbor, but they later sank two of the four fleet carriers lost by the United States Navy during the war in addition to one elderly British light carrier. The sister ships returned to Japan after the Battle of the Coral Sea, one to repair damage and the other to replace aircraft lost during the battle, so neither ship participated in the Battle of Midway in June 1942. After the catastrophic losses of four carriers during that battle, they formed the bulk of the IJN's carrier force for the rest of the war. As such they were the primary counterattack force deployed against the American invasion of Guadalcanal in the Battle of the Eastern Solomons in August. Two months later, they attempted to support a major offensive by the Imperial Japanese Army to push the United States Marines off Guadalcanal. This resulted in the Battle of the Santa Cruz Islands where they crippled one American carrier and damaged another in exchange for damage to and a light carrier. Neither attempt succeeded and the Japanese withdrew their remaining forces from Guadalcanal in early 1943 using the air group from to provide cover. For the next year, the sisters trained before moving south to defend against any American attempt to retake the Mariana Islands or the Philippines. ''Shōkaku'' was sunk by an American submarine during the Battle of the Philippine Sea in June 1944 as the Americans invaded the Marianas and ''Zuikaku'' was sacrificed as a decoy four months later during the Battle of Cape Engano. ==Background and description== The two ''Shōkaku''-class carriers were ordered in 1937 as part of the 3rd Naval Armaments Supplement Program. No longer restricted by the provisions of the Washington Naval Treaty, which had expired in December 1936, and with relaxed budgetary limitations, the IJN sought qualitative superiority over their foreign counterparts. Drawing on experience with their existing carriers, the Navy General Staff laid out an ambitious requirement for a ship that equaled the 96-aircraft capacity of the and , the speed of and the defensive armament of ''Kaga''. The new ship was also to have superior protection and range over any of the existing carriers.〔Lengerer, p. 90〕 The Basic Design Section of the Navy Technical Department decided upon an enlarged and improved ''Hiryū'' design with the island on the port side, amidships. After construction of the ships began, the Naval Air Technical Department (NATD) began having second thoughts about the location of the island because it thought that the portside location of the island on ''Hiryū'' and ''Akagi'' had an adverse impact on airflow over the flight deck. Another issue identified was that the amidships position shortened the available landing area, which had the potential to be problematic in the future as aircraft landing speeds increased with their growing weight. To verify these assumptions, the NATD filmed hundreds of takeoffs and landings aboard ''Akagi'' in October–November 1938 and decided to move the island over to the starboard side and further forward, about one-third of the length from the bow. ''Shōkaku'' was the furthest advanced by this point and the supporting structure for the bridge had already been built; rebuilding it would have delayed construction so it was left in place. The changes that had to be made consisted of a widening of the flight deck opposite the island and a corresponding narrowing on the starboard side and the addition of of ballast on the port side to re-balance the ship.〔Lengerer, pp. 91, 93〕 The ships had a length of overall, a beam of , a draft of at deep load, and a moulded depth of . They displaced at deep load. Based on hydrodynamic research conducted for the s, the ''Shōkaku'' class received a bulbous bow and twin rudders, both of which were positioned on the centerline abaft the propellers. Their crew consisted of 1,660 men: 75 commissioned officers, 56 special duty officers, 71 warrant officers and 1,458 petty officers and crewmen, excluding the air group.〔Lengerer, pp. 93, 107〕 The ''Shōkaku''-class ships were fitted with four Kampon geared steam turbine sets, each driving one propeller, using steam provided by eight Kampon Type Model B water-tube boilers. With a working pressure of , the boilers gave the turbines enough steam to generate a total of and a designed speed of . This was the most powerful propulsion system in IJN service, more than the ''Yamato'' class and the , respectively. During their sea trials, the sister ships achieved from . They carried of fuel oil which gave them a range of at . The boiler uptakes were trunked to the ships' starboard side amidships and exhausted just below flight deck level through two funnels that curved downward. The ''Shōkaku'' class was fitted with three turbo generators and two diesel generators, all operating at 225 volts.〔Lengerer, pp. 102–04, 106〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Shōkaku-class aircraft carrier」の詳細全文を読む スポンサード リンク
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