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The ''Illustrious'' class was a class of aircraft carrier of the Royal Navy that included some of the most important British warships in World War II. They were laid down in the late 1930s as part of the rearmament of British forces in response to the emerging threats of Nazi Germany, Fascist Italy and Imperial Japan. The ''Illustrious'' class comprised four vessels: HM Ships ''Illustrious'', ''Formidable'', ''Victorious'' and ''Indomitable''. The last of these was built to a modified design with a second, half-length, hangar deck below the main hangar deck. Each of these ships played a prominent part in the battles of World War II. ''Victorious'' took part in the pursuit of the German battleship ''Bismarck'', ''Illustrious'' and ''Formidable'' played prominent parts in the battles in the Mediterranean during 1940 and 1941 and all three took part in the large actions of the British Pacific Fleet in 1945. The later two ships of the ''Implacable'' class were also built to modified designs in order that they could carry larger air wings. and both had two hangar levels, albeit with a limited head room. ==Design and concept== The ''Illustrious'' class was designed within the restrictions of the Second London Naval Treaty, which limited carrier size to an upper limit of 23,000 tons. They were different in conception to the Royal Navy's only modern carrier at the time, their predecessor HMS ''Ark Royal'', and what may be described as their nearest American contemporaries, the ''Yorktown'' and ''Essex'' class carriers. The ''Illustrious'' class followed the ''Yorktown'' but preceded the ''Essex''. Where other designs emphasised large air groups as the primary means of defence, the ''Illustrious'' class relied on their anti-aircraft armament and the passive defence provided by an armoured flight deck for survival; resulting in a reduced aircraft complement. Other carriers had armour carried on lower decks (e.g. the hangar deck or main deck); the unprotected flight deck and the hangar below it formed part of the superstructure, and were unprotected against even small bombs. However, the hangar could be made larger and thus more aircraft could be carried, but the differences in aircraft capacity between these carriers and their United States Navy (USN) counterparts is largely due to the USN's operational doctrine, which allowed for a permanent deck park of aircraft to augment their hangar capacity.〔Friedman, pp.18-19.〕〔Hone, Friedman, Mandeles, ''British and American Carrier Development, 1919–1941'', p125:'' "The 1931 edition of "Progress in Tactics" included a section on foreign tactics, including operating practices. The U.S. portion mentioned that "the number of aircraft in carriers is proportionately much higher than in our Navy, largely due to the practice of storing some aircraft permanently on deck."''〕 ''Illustrious's'' hangar was 82%〔Friedman, in his works on RN (p.154) and USN (P.392), aircraft carriers states that Enterprise's hangar measured 546 feet x 63 feet versus 456 x 62 feet for the Illustrious class, therefore Illustrious' hangar had 82% of Enterprise's hangar capacity.〕 as large as ''USS Enterprise'''s but ''Enterprise'' typically carried 30% of her aircraft capacity in her deck park. ''Indomitable's'' two hangars were actually larger than ''Enterprise's'' but she carried fewer aircraft because she did not have a large permanent deck park. In 1944/45 RN carriers began to carry a permanent deck park of similar size to their USN counterparts and this increased their aircraft complement to an eventual 57 aircraft in the single hangar carriers and up to 81 in the double hangar, 23,400 ton Implacable design, compared to 90–110 for the 27,500 ton US ''Essex'' class.〔Friedman 1988, p. 145〕〔''USS Bennington'', ''Action Report, OPERATIONS IN SUPPORT OF THE OCCUPATION OF OKINAWA INCLUDING STRIKE AGAINST KANOYA AIRFIELD, KYUSHU. 28 May to 10 June 1945'', p.18. On June 05 1945, ''USS Bennington'' reported that her maximum hangar capacity was 51 aircraft, 15 SB2Cs and 36 F4Us, and that 52 were carried as a deck park. At that time she carried 15 TBMs, 15 SB2Cs and the rest were a mix of F6Fs and F4Us. She was prompted to utilize, and report on, her maximum hangar storage due to a Typhoon.〕 In the ''Illustrious'' class, armour was carried at the flight deck level—which became the strength deck—and formed an armoured box-like hangar that was an integral part of the ship's structure. However, to make this possible without increasing the displacement it was necessary to significantly reduce the size and headroom of the hangar. The later three vessels, ''Indomitable'', ''Indefatigable'' and ''Implacable'', had re-designed two-level hangars which enabled them to carry larger air groups than the original design. The size of the air wings was also increased by using outriggers and deck parks. The original design was for 36 aircraft, but eventually the vessels operated with a complement of up to 72 aircraft. However, the smaller overhead height of the hangars (16 ft (4.88 m) in the upper hangars and 14 ft (4.27 m) in the later ships with lower hangars) compared unfavourably to the 17 feet 3 inches (5.3 m) of the ''Essex'' class, 17 ft 6 inches (5.38 m) in ''Enterprise'' and 20 ft (6.10 m) in ''Saratoga''. This restricted operations with larger aircraft designs, particularly post-war. This armour scheme was designed to withstand 1,000 pound bombs (and heavier bombs which struck at an angle); in the Home and Mediterranean theatres it was likely that the carriers would operate within the range of shore-based aircraft, which could carry heavier bombs than their carrier-based equivalents. The flight deck had an armoured thickness of 3 inches, closed by 4.5-inch sides and bulkheads. There were 3-inch strakes on either side extending from the box sides to the top edge of the main side belt, which was of 4.5 inches. The main belt protected the machinery, petrol stowage, magazines and aerial weapon stores. The lifts were placed outside the hangar, at either end, with access through sliding armoured doors in the end bulkheads. Later in the war it was found that bombs which penetrated and detonated inside the armoured hangar could cause structural deformation, as the latter was an integral part of the ship's structure. Pre-war doctrine held that the ship's own firepower, rather than its aircraft, were to be relied upon for protection, since in the absence of radar, fighters were unlikely to intercept incoming attackers before they could release their weapons. Accordingly, the Illustrious class was given an extremely heavy Anti-Aircraft armament. The armament was similar to ''Ark Royal'' with twin 4.5 inch turrets (in a new "between-decks" or countersunk design) arranged on the points of a quadrant. The guns were mounted sufficiently high so that they could fire across the decks; de-fuelled aircraft would be stowed in the hangar for protection during aerial attack. The ''Illustrious Class'' were fitted with four HACS controlled High Angle Director Towers, for fire control of her 4.5" guns. ''Illustrious'' pioneered the use of Radar to vector carrier borne fighters onto attacking or shadowing aircraft, and a Fairey Fulmar fighter from ''Illustrious'' achieved the first radar directed kill on 2 September 1940.〔Thomas, Andrew, ''Royal Navy Aces of World War Two'', p24.〕 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「Illustrious-class aircraft carrier」の詳細全文を読む スポンサード リンク
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