Illustrious class aircraft carrier
Encyclopedia
The Illustrious class was a class
of aircraft carrier
of the Royal Navy
that were 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.
Each of these ships played a prominent part in the battles of World War II. Victorious took part in the chase 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 Illustrious class comprised four vessels: HM Ships
Illustrious
, Formidable
and Victorious
. Indomitable
was built to a slightly modified design with a second half-length hangar deck below the main hangar deck. The following 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 limiting 14 feet (4 m) head room.
, 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 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. Illustrious's hangar was 85% as large as USS Enterprise
's but Enterprise typically carried 50% 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.
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. 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 countersunk turrets 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 September 2 1940.
-era jet aircraft, and retired in 1968 after a fire. Indomitable was given an extensive refit, including new boilers, from 1948 to 1950, then served as flagship of the Homefleet and also saw service in the Mediterranean. She suffered a hangar deck petrol
explosion and fire, in early 1953. She was placed in reserve after Queen Elizabeth II's October 1953 Coronation Review and was then scrapped in 1955.
Ship class
A ship class is a group of ships of a similar design. This is distinct from a ship-type, which might reflect a similarity of tonnage or intended use. For example, the is a nuclear aircraft carrier of the Nimitz class....
of aircraft carrier
Aircraft carrier
An aircraft carrier is a warship designed with a primary mission of deploying and recovering aircraft, acting as a seagoing airbase. Aircraft carriers thus allow a naval force to project air power worldwide without having to depend on local bases for staging aircraft operations...
of the Royal Navy
Royal Navy
The Royal Navy is the naval warfare service branch of the British Armed Forces. Founded in the 16th century, it is the oldest service branch and is known as the Senior Service...
that were some of the most important British
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
warships in World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...
. They were laid down in the late 1930s as part of the rearmament
Rearmament
Rearmament is the third album by American singer-songwriter Happy Rhodes, released in 1986.-Overview:Rhodes' first four albums were not conceived and recorded as album releases, but were a gathering together of songs recorded at Cathedral Sound Studios from 1984 to 1986...
of British forces in response to the emerging threats of Nazi Germany
Nazi Germany
Nazi Germany , also known as the Third Reich , but officially called German Reich from 1933 to 1943 and Greater German Reich from 26 June 1943 onward, is the name commonly used to refer to the state of Germany from 1933 to 1945, when it was a totalitarian dictatorship ruled by...
, Fascist Italy
Kingdom of Italy (1861–1946)
The Kingdom of Italy was a state forged in 1861 by the unification of Italy under the influence of the Kingdom of Sardinia, which was its legal predecessor state...
and Imperial Japan.
Each of these ships played a prominent part in the battles of World War II. Victorious took part in the chase of the German battleship Bismarck
German battleship Bismarck
Bismarck was the first of two s built for the German Kriegsmarine during World War II. Named after Chancellor Otto von Bismarck, the primary force behind the German unification in 1871, the ship was laid down at the Blohm & Voss shipyard in Hamburg in July 1936 and launched nearly three years later...
, Illustrious and Formidable played prominent parts in the battles in the Mediterranean
Mediterranean Theatre of World War II
The African, Mediterranean and Middle East theatres encompassed the naval, land, and air campaigns fought between the Allied and Axis forces in the Mediterranean Basin, the Middle East and Africa...
during 1940 and 1941 and all three took part in the large actions of the British Pacific Fleet
British Pacific Fleet
The British Pacific Fleet was a British Commonwealth naval force which saw action against Japan during World War II. The fleet was composed of British Commonwealth naval vessels. The BPF formally came into being on 22 November 1944...
in 1945.
The Illustrious class comprised four vessels: HM Ships
Her Majesty's Ship
Her or His Majesty's Ship is the ship prefix used for ships of the navy in some monarchies, either formally or informally.-HMS:* In the British Royal Navy, it refers to the king or queen of the United Kingdom as appropriate at the time...
Illustrious
HMS Illustrious (R87)
HMS Illustrious , the fourth Illustrious of the British Royal Navy, was an aircraft carrier which saw service in World War II, the lead ship of the Illustrious-class of carriers which also included Victorious, Formidable, and Indomitable.-Construction:Illustrious was built by Vickers-Armstrongs at...
, Formidable
HMS Formidable (R67)
HMS Formidable was an Illustrious class aircraft carrier of the Royal Navy during World War II. She was constructed by Harland & Wolff, Belfast, and launched on 17 August 1939...
and Victorious
HMS Victorious (R38)
HMS Victorious was the second Illustrious-class aircraft carrier ordered under the 1936 Naval Programme. She was laid down at the Vickers-Armstrong shipyard at Newcastle-Upon-Tyne in 1937 and launched two years later in 1939...
. Indomitable
HMS Indomitable (R92)
HMS Indomitable was a modified Illustrious class aircraft carrier of the British Royal Navy. The Illustrious class came about due to the 1937 Naval Programme...
was built to a slightly modified design with a second half-length hangar deck below the main hangar deck. The following two ships of the Implacable class
Implacable class aircraft carrier
The Implacable class was a class of aircraft carrier employed by the Royal Navy in the second half of Second World War. The class design was derived from the .- Design :...
were also built to modified designs in order that they could carry larger air wings
Carrier air wing
A Carrier Air Wing is an operational naval aviation organization composed of several aircraft squadrons and detachments of various types of fixed wing and rotary wing aircraft...
. and both had two hangar levels, albeit with a limiting 14 feet (4 m) head room.
Design and concept
The Illustrious class was designed within the restrictions of the Second London Naval TreatySecond London Naval Treaty
The Second London Naval Disarmament Conference opened in London, the United Kingdom, on 9 December 1935. It resulted in the Second London Naval Treaty which was signed on 25 March 1936.- Description :...
, 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
HMS Ark Royal (91)
HMS Ark Royal was an aircraft carrier of the Royal Navy that served during the Second World War.Designed in 1934 to fit the restrictions of the Washington Naval Treaty, Ark Royal was built by Cammell Laird and Company, Ltd. at Birkenhead, England, and completed in November 1938. Her design...
, and what may be described as their nearest American contemporaries, the Yorktown
Yorktown class aircraft carrier
The Yorktown class was a class of three aircraft carriers built by the U.S. and completed shortly before World War II. They bore the brunt of early action in that war, and the sole survivor of the class was to become the most decorated ship in the history of the U.S...
and Essex
Essex class aircraft carrier
The Essex class was a class of aircraft carriers of the United States Navy, which constituted the 20th century's most numerous class of capital ships with 24 vessels built in both "short-hull" and "long-hull" versions. Thirty-two were originally ordered; however as World War II wound down, six were...
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
Comparison of armoured to unarmoured flight deck designs
An armoured flight deck is an aircraft carrier flight deck that incorporates substantial armour in its design.Comparison is often made between some of designs of the Royal Navy and the United States Navy...
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
Superstructure
A superstructure is an upward extension of an existing structure above a baseline. This term is applied to various kinds of physical structures such as buildings, bridges, or ships...
, 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 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. Illustrious's hangar was 85% as large as USS Enterprise
USS Enterprise (CV-6)
USS Enterprise , colloquially referred to as the "Big E," was the sixth aircraft carrier of the United States Navy and the seventh U.S. Navy ship to bear the name. Launched in 1936, she was a ship of the Yorktown class, and one of only three American carriers commissioned prior to World War II to...
's but Enterprise typically carried 50% 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
Implacable class aircraft carrier
The Implacable class was a class of aircraft carrier employed by the Royal Navy in the second half of Second World War. The class design was derived from the .- Design :...
design, compared to 90-110 for the 27,500 ton US Essex class.
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
British Home Fleet
The Home Fleet was a fleet of the Royal Navy which operated in the United Kingdom's territorial waters from 1902 with intervals until 1967.-Pre–First World War:...
and Mediterranean theatres it was likely that the carriers would operate within the range of shore-based aircraft. 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 countersunk turrets 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
HACS
HACS, an acronym of High Angle Control System, was a British anti-aircraft fire-control system employed by the Royal Navy from 1931 onwards and used widely during World War II...
controlled High Angle Director Towers, for fire control of her 4.5" guns. Illustrious pioneered the use of Radar
Radar
Radar is an object-detection system which uses radio waves to determine the range, altitude, direction, or speed of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. The radar dish or antenna transmits pulses of radio...
to vector carrier borne fighters onto attacking or shadowing aircraft, and a Fairey Fulmar
Fairey Fulmar
The Fairey Fulmar was a British carrier-borne fighter aircraft that served with the Fleet Air Arm during the Second World War. A total of 600 were built by Fairey Aviation at its Stockport factory between January 1940 and December 1942...
fighter from Illustrious achieved the first radar directed kill on September 2 1940.
Fate of the class
Illustrious and Formidable did not long survive World War II. Like their contemporary they had fought a long and consuming war and were worn out; overhaul and renovation would have cost more than replacement. They were broken up for scrap in the 1950s. The last of the class, Victorious, had a long postwar career with a very expensive reconstruction to enable her to operate Cold WarCold War
The Cold War was the continuing state from roughly 1946 to 1991 of political conflict, military tension, proxy wars, and economic competition between the Communist World—primarily the Soviet Union and its satellite states and allies—and the powers of the Western world, primarily the United States...
-era jet aircraft, and retired in 1968 after a fire. Indomitable was given an extensive refit, including new boilers, from 1948 to 1950, then served as flagship of the Homefleet and also saw service in the Mediterranean. She suffered a hangar deck petrol
Gasoline
Gasoline , or petrol , is a toxic, translucent, petroleum-derived liquid that is primarily used as a fuel in internal combustion engines. It consists mostly of organic compounds obtained by the fractional distillation of petroleum, enhanced with a variety of additives. Some gasolines also contain...
explosion and fire, in early 1953. She was placed in reserve after Queen Elizabeth II's October 1953 Coronation Review and was then scrapped in 1955.