carriers

carriers.

1. Design and development

Before the Second World War, aircraft carrier design was driven by naval aircraft characteristics and by the constraints of the 1922 Treaty for the Limitation of Armament (known as the Washington Treaty). In the 1920s and 1930s, aircraft became faster, larger, and heavier, and their combat ranges and weapon loads increased. The treaty, however, set an upper limit of 121,500 metric displacement tons on the carrier tonnage allowed the US Navy (USN) and the Royal Navy (RN). The Imperial Japanese Navy (IJN) was allowed 72,900 metric tons. These three were the only combatant powers to build and operate fleet carriers during the war, though the Canadian Navy provided the crew for two escort carriers. The French did have one under construction (Joffre) while Germany's ‘Z’ Plan of 1938 included the construction of four by 1948, and ultimately eight (see Germany, Table 11). But only one, Graf Zeppelin, was launched, in December 1938, but work on completing her stopped in 1943. A second, unnamed, was started, but was broken up in 1940. Inter-service rivalry was the principal reason for the demise of the German carriers for Göring never allowed the German Navy to have a separate air arm, nor did he encourage naval–air co-operation, and the Luftwaffe therefore never developed a suitable aircraft for carrier warfare. Italy's lack of carriers was also caused by inter-service rivalry; Mussolini's veto on his navy's having a separate air arm was only lifted after its defeat at the battle of Cape Matapan in March 1941. The transatlantic liner Roma was then converted into a carrier but she had only just been completed at the time of Italy's surrender in September 1943. Work on converting another liner, Augustus, remained unfinished.

The Washington Treaty limited any individual carrier to 24,300 metric tons, but allowed the USA and Japan to convert two uncompleted battle-cruisers or battleships each to large carriers displacing no more than 29,700 metric tons. Improvements in aircraft, based on more powerful engines, made larger carriers more attractive. But the limits on overall carrier tonnage kept the three major navies from having many carriers at all, which increased the risk that, in wartime, the few available carriers would quickly be put out of action. There was a conflict between size and numbers. Advancing technology pushed up size, which reduced the numbers of carriers built. The desire to put more carriers to sea pushed the other way.

In 1939 the RN, USN, and IJN had several basic kinds of carriers afloat or building (see Table 1). There were small, slow experimental types, such as HMS Argus, USS Langley, and the IJN's Hōshō; there were converted cruisers and battle-cruisers such as HMS Courageous, USS Lexington, and the IJN's Akagi; and there were also some effective carriers designed on the basis of experience with the older ships: HMS Ark Royal, USS Enterprise, and the IJN's Hiryu. All three navies also studied variations of the flying-deck cruiser (half-cruiser, half-carrier) and of merchant ship conversions (see CAM, fighter catapult, and MAC ships) as ways of increasing the numbers of aircraft which their fleets could take to sea. For the Allies there was also the need to give some kind of air cover to convoys during the battle of the Atlantic.

In 1940 the RN completed the first of a series of heavily armoured carriers (Illustrious class), with reduced aircraft complements. The US and Japanese navies, on the other hand, continued to build lightly armoured vessels (Essex, Shokaku) with more than double the number of planes carried by ships such as Illustrious. War experience suggested to the British that they needed more aircraft, but the armoured decks of the British Pacific Fleet (see Task Force 57) did give some protection against Japanese kamikaze attacks. The Americans and Japanese, now freed from treaty restrictions, opted for more armour and size, producing Midway ( 1945: 42,650 metric tons) and Taiho ( 1944: 30,300 metric tons).

All three navies also built many war emergency types: converted liners, light carriers based on cruiser hulls, and escort carriers based on merchant ship designs. The Imperial Navy converted three submarine tenders to produce Zuiho and Shoho (10,170 metric tons each) and Ryuho (12,060 metric tons). Two seaplane carriers (Chitose and Chiyoda, 10,080 metric tons each) and seven liners were also converted. The largest liner conversions were Junyō and Hiyo, each of 21,720 metric tons. In the mid-1930s, the USA had also planned passenger liner conversions, but these were never pursued because of their cost and the time it would have taken to make the conversions. Instead, the USN co-operated with the RN to produce ‘auxiliary aircraft carriers,’ or merchant ship conversions. Basic types were Casablanca (8,400 metric tons; 50 built) and Commencement Bay (17,000 metric tons; 19 built). Most RN escort carriers were obtained through Lend-Lease, such as the eleven Attacker type (10,360 metric tons), but there were also very austere additions of flight decks and three or four aircraft to each of nineteen grain and oil bulk carriers.

Carriers, Table 1: Royal Navy, US Navy, Imperial Japanese Navy

Class/Type	Number	Commissioned	Tonnage	No. of A/C	Overall Length (in metres/feet)
All displacements are standard (that is, with 2/3 stores, no ammunition, and no aviation fuel or lubricating oil, aircraft were included) and in metric tons (.99 cu m=one imperial displacement ton). All USN, RN, and IJN carriers at sea on 3 Sept. 1939, used as carriers during the war, or meant to be used during the war are included. Langley had been converted to a seaplane carrier before the war. Her figures are included so that she can be compared with Argus and Hosho.
Source: Contributor.
Royal Navy
Argus (experimental)	1	1918	13,000	20	172.2 (565)
Eagle ”	1	1924	20,340	23	203.3 (667)
Hermes ”	1	1924	9,765	25	181.8 (600)
Furious (converted)	1	1925	20,205	36	239.5 (786)
Courageous ”	2	1928–30	20,250	48	239.5 (786)
Ark Royal (fleet)	1	1938	19,800	60	243.8 (800)
Illustrious ”	3	1940–1	20,700	33	225.5 (740)
Indomitable ”	1	1941	20,700	45	229.5 (763)
Implacable ”	2	1944	21,105	60	233.4 (766)
Unicorn (light)	1	1943	13,275	35	195.0 (640)
Colossus (light)	7	1944–6	11,871	37	211.2 (693)
Escort Carriers (9 classes)	44	1941–4	9,180–17,685	6–24
US Navy
Langley (experimental)	1	1922	11,430	24	165.2 (542)
Lexington (converted)	2	1927	33,840	63	270.6 (888)
Ranger (fleet)	1	1934	13,120	76	234.4 (769)
Yorktown ”	3	1937–41	17,900	96	246.6 (809)
Wasp ”	1	1940	13,230	76	219.4 (720)
Essex ”	24	1942–50	24,480	91	265.8 (872)
Independence (light)	9	1943	9,600	30	189.5 (622)
Midway (fleet)	3	1945–7	42,660	137	295.0 (968)
Saipan (light)	2	1946–7	13,050	48	208.2 (683)
Escort Carriers (5 classes)	86	1941–6	7,380–17,000	16–36
Imperial Japanese Navy
Hosho (experimenatal)	1	1922	6,730	26	167.9 (551)
Akagi (converted)	1	1927	32,850	91	260.6 (855)
Kaga ”	1	1928	34,380	90	238.3 (782)
Ryujo (light)	1	1933	9,000	37	179.8 (590)
Soryu (fleet)	1	1937	14,400	63	227.4 (746)
Hiryu ”	1	1939	15,600	64	227.1 (745)
Shokaku  ”	2	1941	23,130	72	257.5 (844)
Zuiho (converted)	2	1940–2	10,170	30	204.5 (671)
Ryuho ”	1	1942	12,060	31	215.4 (707)
Junyo ”	2	1942	21,720	53	219.1 (719)
Taiho (fleet)	1	1944	26,370	53	260.6 (855)
Chitose (converted)	2	1943–4	10,080	30	192.3 (631)
Shinano	1	1944	55,800	70	265.8 (872)
Unryu (fleet)	3	1944	15,435	65	227.4 (746)
Escort carriors (3 classes)	5	1941–3	12,240–16,050	24–33

2. Warfare

Carrier forces revolutionized war at sea. In the Pacific war they were the principal maritime offensive weapon; in the battle of the Atlantic, where escort carriers eventually helped tip the scales against the U-boat, and in the battle for the Mediterranean, where they fought Axis air power to break the siege of Malta, their presence was vital. Before the war, the three major navies (the Royal Navy (RN), the United States Navy (USN), and the Imperial Japanese Navy (IJN)) foresaw the carrier's major roles: (1)strikes against other carriers to gain air superiority over the battle area,(2)reconnaissance,(3)attacks against warships and shipping,(4)fixing the enemy's battle line so that friendly battleships could engage it,(5)attacking targets ashore, and(6)convoy escort. It was not clear, however, just which role or roles would matter the most. British pre-war experiments and exercises suggested to the RN that carrier bombers and torpedo planes could not by themselves eliminate battleships. American and Japanese trials, on the other hand, indicated that, suitably armed, carrier aircraft could be the decisive weapon. Those uncertainties, and the fact that the Washington Treaty of 1922 restricted the number of carriers (and hence also the number of carrier aircraft) which navies could field, made war experience the final arbiter of the carrier's status.

Carriers, Table 2: Carrier aircraft (fighters, unless indicated otherwise in left-hand column)

Type	Span	Length	All-up Weight	Power Plant	Armament (Cannon/Machine guns)	Weapons (Max) Bomrbs or rockets (or torpedoes)	Optimum Performance	Radius	Crew	Year of entry into service
NB All the above aircraft, while designed to operate from carriers, could also operate from land.
Source: E. A. Munday.
UK
Fulmer 1	14.1 m	12.3 m	4,636 kg	1 × Merlin	8 × .303 in mg	—	438 kph @ 2,133 m	644 km	2	1940
	(46 ft 4 in)	(40 ft 2 in)	(10,200 lb)	1,300 hp			(272 mph/7,000 ft)	(400 mi)
Firefly 1	13.7 m	11.6 m	6,364 kg	1 × Griffon	4 × 20 mm	909 kg	508 kph @ 4,267 m	805 km	2	1943
	(44 ft 6 in)	(37 ft 7 in)	(14,000 lb)	2,245 hp		(2,000 lbs)	(316 mph/14,000 ft)	(500 mi)
	or 8 rockets
Swordfish	14 m	11.1 m	4,205 kg	1 × Bristol	1 mg (forward)	1 × torpedo (18 in)	222 kph @ 1448 m	1,280 km	2/3	1936
Torpedo/	(45 ft 6 in)	(36 ft 4 in)	(9,250 lb)	Pegasus	1 mg (rear)	736 kg (1,620 lb),	(138 mph/4750 ft)	(795 mi) (in
strike A/c				750 hp		or equivalent in bombs,		recce role)
	mines, depth charges
Baracuda II	15.1 m	12.2 m	6,410 kg	1 × Merlin	2 mg (rear)	1 × torpedo (18 in)	365 kph @ 534 m	805 km	3	1944
Torpedo/	(49 ft 2 in)	(39 ft 9 in)	(14,100 lb)	1640 hp		736 kg or equivalent	(227 mph/1,750 ft)	(500 m)
strike A/c						in bombs or depth
	charges
Skua	14.1 m	10.9 m	3,740 kg	1 × Perseus	4 mg (forward)	1 × 227 kg (500 lb)	362 kph @ 1,982 m	805 km	2	1938
Dive bomber	(45 ft 11 in)	(35 ft 7 in)	(8,228 lb)	905 hp 1 mg (rear)	bomb	(225 mph/6,502 ft)
Japan
Mitsubishi A6M2	12.1 m	9.1 m	2,414 kg	1 × Sakae 12	2 × 20 mm	114 kg	540 kph @ 5,791 m	965 km	1	1940
Zero-Sen	(39 ft 4 in)	(29 ft 9 in)	(5,313 lb)	925 hp	2 mg	(250 lb)	(336 mph/19,000 ft)	(600 m)
(‘Zeke’ 22)
Mitsubishi A6M5	11 m	9.1 m	2,749 kg	1 × Sakae 31	2 × 20 mm	114 kg	554 kph @ 6,000 m	1,126 km	1	1944
Zero-Sen	(35 ft 10 in)		(6,047 lb)	1,130 hp	cannons		(344 mph/19,685 ft)	(700 mi)
(‘Zeke’ 52)					2 × 13.2 mn mg
Aicni D3A2	14,5 m	10.2 m	3,658 kg	1 × Mitsubishi	2 × mg (forward)	363 kg	397 kph @ 2,317 m	1,126 km	2	1940
(‘Val’)	(47 ft 2 in)	(33 ft 5 in)	(8,047 lb)	kinsei	1 mg (rear)	(800 lb)	(247 mph/7,600 ft)
Dive bomber				1,300 hp
Nakajima B5N2	15.6 m	10.3 m	4,109 kg	1 × Sakae 21	2 mg (forward)	1 × torpedo 18 in	378 kph @ 3600 m	980 km	3	1938
(‘Kate’)	(50 ft 11 in)	(33 ft 9 in)	(9,039 lb)	1,115 hp	1 mg (rear)	802 kg (1,765 lb)	(235 mph/11,810 ft)	(609 mi)
Torpedo/						or equivalent in
strike A/c						bombs
Nakajima B6N2	15 m	10.9 m	5,662 kg	1 × Mitsubishi	1 mg (forward)	1 × torpedo (18 in)	480 kph @ 4,877 m	1,126 km	2	1944
(‘Jill’)	(48 ft 10 in)		(12,456 lb)	Kasei 25	1 mg (rear)	802 kg (1,765 lb)	(299 mph/16,000 ft)
Torpedo/						or equivalent in
strike A/c						bombs
USA
Brewster F2A-3	10.7 m	8.1 m	3,254 kg	1 × Wright R-1820	4 mg	91 kg	516 mph @ 5,029 m	724 km	1	1939
Buffalo	(35 ft)	(26 ft 4 in)	(7,159 lb)	1,200 hp		(200 lb)	(321 mph/16,500 ft)
Grumman F4F-3	11.7 m	8.8 m	3,705 kg	1 × Pratt & Whitney	4 mg	91 kg	528 kph @ 6,400 m	676 km	1	1941
Wildcat	(38 ft)	(28 ft 9 in)	(8,152 lb)	R-1830 1,200 hp		(200 lb)	(328 mph/21,000 ft)	(420 mi)
Grumman F6F-5	13.2 m	10.3 m	5,682 kg	1 × Pratt & Whitney	6 mg	909 kg	621 kph @ 5,273 m	322 km	1	1943
Hellcat	(42 ft 10 in)	(33 ft 7 in)	(12,500 lb)	R-2800 2,000 hp		or 6 rockets	(386 mph/17,300 ft)
Grumman F7F-3	15.8 m	13.1 m	11,691 kg	2 × Pratt & Whitney	4 × 20 mm	—	700 kph @ 6,767 m	1,207 km	1	1945
Tigercat	(51 ft 6 in)	(45 ft 4 in)	(25,720 lb)	R-2800 2,100 hp	4 mg		(435 mph/22,200 ft)	(750 mi)
Grumman F8F-1	11 m	8.7 m	5,885 kg	1 × Pratt & Whitney	4 mg	909 kg	677 kph @ 6,005 m	1,529 km	1	1945
Bearcat	(35 ft 10 in)	(28ft 3 in)	(12,9471 lb)	R-2800 2,100 hp		or 4 rockets	(421 mph/19,700 ft)	(750 mi.)
Vought F4U-1D	12.6 m	10.3 m	5,964 kg	1 × Pratt & Whitney	6 mg	909 kg	684 kph @ 6,096 m	1,207 km	1	1942
Corsair	(40 ft 11 in)		(13,120 lb)	R-2800 2,250 hp		or 8 rockets	(425 mph/20,000 ft)	(750 mi)
Vought F4U-4	12.6 m	10.4 m	6,668 kg	1 × Pratt & Whitney	6 mg	909 kg	718 kph @ 7,986 m	1,207 km	1	1945
Corsair			(14,670 lb)	R-2800 2,450 hp		or 8 rockets	(446 mph/26,200 ft)
Goodyear F2G-1	12.6 m	10.3 m	7,010 kg	1 × Pratt & Whitney	4 × mg	909 kg	693 kph @ 4,998 m	1,529 km	1	—
Corsair			(15,422 lb)	R-4360 3,000 hp		or 8 rockets	(431 mph/16,400 ft)
(development		All US mg .5 in
of F4U-4)		(12.7 mm)
	except where
	shown
Douglas SBD	12.7 m	10.1 m	4,934 kg	1 × Wright R-1820	2 × 0.50 mg	1,023 kg (max)	394 kph @ 4,815 m	965 km	2	1941
Dauntless	(41 ft 6 in)	(33 ft)	(10,855 lb)	1,000 hp	(forward)	(2,250 lb)	245 mph @ 15,800 ft	(600 mi)
dive/scout		1 × 0.30 mg
bomber		(rear)
Grumman	16.6 m	12.3 m	8295 kg	1 × Wright R-2600	1 mg (forward)	1 × torpedo or	429 kph @ 4,572 m	1,448 km	3	1942
TBF-1/TBM-3	(54 ft 2 in)		(18,250 lb)	1,700 hp	2 mg rear	909 kg in bombs	267 mph @ 15,000 ft	(900 mi)
Avenger
Torpedo/strike A/c
Curtiss SB2C-4	15.3 m	11.3 m	7,553 kg	1 × Wright R-2600	2 × 20 mg	909 kg max	475 kph @ 5,090 m	1,440 km	2	1943
Helldiver	(49 ft 9 in)	(36 ft 8 in)	(16,616 lb)	1900 hp	Cannon (forward)		295 mph @ 16,700 ft
dive-bomber		2 × 0.30 mg
	(rear)

The three major navies designed and built carrier forces to deal with what they thought would be their primary tactical problems. For Japan and the USA, the challenge was to mass as many strike aircraft as possible so as to overwhelm the opposing side's defensive fighters and wipe out their aircraft carriers early in an engagement. Consequently, their carriers sacrificed armour protection for large, strike-heavy air groups. The British worried about endurance in the face of damage. The RN wanted damage-resistant carriers that could stay with its battle line and aircraft that could scout, attack, and spot shellfire for its surface formations. As a result, British carriers designed immediately after Ark Royal, completed in 1938, had armoured flight decks and reduced air complements (33 planes for Illustrious, 60 for Ark Royal, and 96 for the USN's contemporary, Hornet).

Different fleet doctrines led to different types of aircraft as well as different carrier designs. As Table 2 shows, the RN, constrained by limited hangar capacities and committed to the role of supporting its battle line, procured multi-purpose aircraft. The USN and IJN, on the other hand, developed highly specialized fighters, scout bombers, and torpedo planes. Japanese carrier aircraft, such as the Zero, were designed with very great ranges, and this gave the IJN not only a tactical advantage in carrier-versus-carrier clashes, but also a strategic edge as Japanese naval formations accompanied by carriers had the advantage of finding Allied ships before they themselves were found. Zeros could also keep Allied reconnaissance planes at a distance, so that Japanese commanders usually knew more about Allied movements than the Allies knew about theirs. This strategic advantage was the key to the great success of Japanese naval forces in the first six months of the Pacific war. Even in 1944, most Japanese carrier aircraft outranged their US opponents. The pre-war plan of the IJN was to combine carrier strikes with attacks by long-range, land-based bombers. The carrier planes would strike by day, the bombers by night. Japanese tactics were foiled through the USN's effective application of radar to tactical fighter control and by the growing power of its fighters. Just before the war, the USN sponsored the development of large, powerful radial aircraft engines. The fighters built with these engines, such as the famous F4U Corsair, outmatched their Japanese contemporaries and gave the USN the ability to eliminate Japan's naval pilots even if its bombers and torpedo planes could not find and sink all Japan's carriers.

War experience demonstrated how important and how vulnerable carriers were. Of the seven carriers which the RN had on hand in September 1939, two (Courageous and Glorious) were lost in less than a year, Ark Royal was sunk in 1941, and two more of the remaining five (Eagle and Hermes) were sunk in 1942. The USN also started its war with seven carriers. After one year of operations, only three of the seven (Enterprise, Saratoga, and Ranger) were still afloat. The IJN suffered even more. Four of its six large carriers were lost at the battle of Midway in June 1942.

Carrier warfare varied with the theatre. In the Atlantic and Mediterranean, RN carriers fought submarines and land-based aircraft. In the Pacific, US and Japanese carriers first fought each other; then, when US carriers had virtually wiped out Japan's carrier pilots (at the battle of the Philippine Sea), US carrier forces went after Japanese naval and merchant ships and also fought successfully against Japanese land-based air forces. In the Okinawa campaign ( April– June 1945), USN carriers (supported by an RN carrier task force) were primarily fighting land-based Japanese kamikaze aircraft. By the end of the war, US carrier aircraft were ranging over Japan's home islands.

In the summer of 1940, with France in German hands and Italy a declared enemy, the RN's fleet carriers acted with other ships to protect the UK from surface blockade and to contest control of the Mediterranean with Italian forces (see Taranto, and Cape Matapan). In such actions, British carrier aircraft, acting in support of RN forces, successfully attacked ships which lacked effective air cover at sea. Around Malta, however, in support of the struggle to resupply British forces there, in which the US carrier Wasp also took part on two occasions, RN carriers fought sustained battles against land-based air units. The cost was high. Apart from the loss of Ark Royal, Illustrious was severely battered by German dive-bombers in January 1941; Formidable was similarly damaged in May 1941; and Victorious and Indomitable were also hit during a resupply effort in August 1942. The fact that their armoured deck carriers could not carry many aircraft at all, let alone many high performance fighters, placed British carriers at a grave disadvantage when assaulted by repeated waves of experienced German land-based dive-bomber squadrons. There were just not enough effective fighters to defend against German attacks or to escort British strike aircraft on raids against Axis airfields.

Escort carriers, designed to provide air cover for convoys and for amphibious landings, lacked the speed to stay with the larger fleet carriers, but they performed invaluable service for the Allies in both the Atlantic and the Pacific. Poorly protected internally, they were suited to combat in areas where the enemy air threat was weak or non-existent. In the Atlantic their aircraft hounded German submarines in areas beyond the reach of land-based patrol bombers, and one was instrumental in the capture of U-505 in June 1944. In October of that year, sixteen escort carriers (designated CVEs in the US Navy) and their destroyer guard were caught in a surprise daylight surface engagement with a force of four Japanese battleships, six cruisers, and many destroyers in the battle of Leyte Gulf. One CVE was lost, and others were damaged (several by kamikaze aircraft), but the Japanese force was driven off with the loss of three cruisers. Such ship-to-ship combat was the exception for escort carriers. Most provided air cover for units fighting ashore or defending themselves against submarines.

In the Pacific war, carrier warfare began with a massed carrier raid by Japan on Pearl Harbor (which caught none of the US carriers in port) and the retaliatory Doolittle raid, then progressed to violent carrier-against-carrier duels—one of them, the battle of the Coral Sea, was the first-ever naval encounter in which neither side's warships were visible to the other's—and finally circled back to massed raids by US carriers against Japan. When the Pacific war began, both USN and IJN carrier aircraft complements were heavily weighted towards bombers and torpedo planes. Both sides understood the need to attack first, with overwhelming power, and at the longest possible range. In pursuing this doctrine, the IJN went so far as to deprive its pilots of adequately armoured planes. In addition, US carriers faced a special dilemma once US forces began to invade Japanese-held islands: whether to establish and maintain air supremacy during an amphibious assault (see amphibious warfare) or to hunt Japanese carriers, and by failing to solve it Vice-Admiral Fletcher very nearly turned initial success into disaster, at Guadalcanal.

The 1942 carrier battles were decided by which side found the other first, and by the striking power each side could deliver before suffering its own losses. By 1944, however, things had changed. Radar-directed air patrols and radar-directed ships' anti-aircraft guns downed Japanese pilots faster than the IJN could train them, allowing the USN simultaneously to cover amphibious landings and defeat Japanese carrier attacks.

US carriers survived massed kamikaze attacks at Okinawa because, unlike the RN at Malta, their fighter complements were large and their fighter-control system based on improved radars. Despite these advances, however, eight large, one light, and three escort carriers were seriously damaged by suicide aircraft. Massed kamikaze raids were such a threat to the carriers and the amphibious forces that B29 bombers were ordered to crater the airfields where the Japanese aircraft were organized for their assaults. However, despite the damage they sustained at Okinawa, US carriers demonstrated that carrier aviation could wage sustained campaigns against land targets. That understanding formed the basis for the development of modern carrier battle groups armed with nuclear weapons. See also sea power.

Tom Hone

Bibliography

Friedman, N. , British Carrier Aviation (London, 1988).
—— Carrier Air Power (London, 1981).
—— U.S. Aircraft Carriers (Annapolis, Md., 1983).
Hone, T. C.,, Friedman, N.,, and and Mandeles, M. D. , American and British Aircraft Carrier Development, 1919–1941 (Annapolis, Md., 1999).