Carrier Evolution V: War Games I

USN Carrier Evolution V: War Games 1

By Scot MacDonald. Fifth article in a series. Reprinted with permission: Naval Aviation News August 1962 pp. 28-33.

One of those whose untiring efforts helped shape the evolution of the “all big gun battleship,” ADML William S. Sims, did not immediately endorse Naval Aviation—especially ships carrying naval aircraft—upon its introduction as a weapon in the country’s arsenal. In 1909, for instance, he wrote: “According to the papers, one of the Wright brothers has stated that it would be impracticable to hit anything by dropping a projectile from his flying (machine). That Wright man is right, all right.” Sims had a deep appreciation and understanding of the merits of the battleship as a weapon system whose evolution he had fought to promote and he was not about to write it off, except on the basis of sound evidence.

During WW I and the years immediately preceding it, aircraft design improved spectacularly. By the end of the war the U.S. Navy still did not have an aircraft carrier. His observation of the limited use of such ships permitted him to state with justification, “All the aeroplane-carrying ships in the world could not make an attack upon a foreign country unless they were supported by a battleship force that was superior to that of the enemy.”

Build carriers, “the battleship is dead”

Not until the end of the war, when VADM Sims assumed leadership of the Naval War College at Newport, did his thinking undergo a profound change. At the game board there in 1921, he recognised not only the advantages and potentials of airpower but also the brevity of the future of battleships. “If I had my way,” he said, “I would arrest the building of great battleships and put money into the development of the new devices and not wait to see what other countries are doing.”

By March 1922, after witnessing the 1921 bombing tests off the Virginia Capes, he had written, “The battleship is dead.”

During Sims’ tenure at the War College, the Navy Department inaugurated a series of war games, fleet exercises, that were conducted during the next two decades. Through these Problems, the Navy obtained practical experience in testing the “new devices” under simulated combat conditions.

Naval Aviation had entered fleet manoeuvres as early as the winter of 1912-13 when the entire aviation element—pilots, student pilots, enlisted men and aircraft inventory (which then totalled five planes)—was transported to Guantanamo Bay to take part in planned exercises. From their camp at Fisherman’s Point where the present air station is located, they worked to achieve three goals: first, to prove the utility of the airplane as a scout under simulated war conditions; second, to test its usefulness in detecting mines and submerged submarines; and third, to stimulate interest in aviation among officers in the fleet.

Veracruz action, 1914

Naval Aviation next joined the fleet in 1914, in connection with actual hostilities in Mexico. At that time, an A-3 and a C-3, put aboard the Mississippi, saw action at Veracruz. Daily reconnaissance flights kept landing forces informed of the enemy dispositions inshore.

(Three planes placed aboard the Birmingham were taken to Tampico but did not see action.)

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This Curtiss C-3 “hydroaeroplane”, based in USS Mississippi (BB 23) and flown by LTJG (later VADM) P.N.L. Bellinger, was the first U.S. naval aircraft to see active service. Bellinger overflew Veracruz, Mexico, on 25 April, 1915, searching for enemy positions and mines. On 6 May, he became the first USN pilot to report damage by hostile fire (small arms) during another reconnaissance mission.

As a result of the experience at Veracruz, Naval Aviators judged the hydro-aeroplane more efficient than the flying boat type then in use. Recommendations were also made on the design of aircraft.

(Ed. note: There was considerable interchange, leading to confusion, but the term “hydro-aeroplane” gradually evolved into “seaplane” and craft such as the Curtiss C-3 became known as “flying boats”.)

Extraordinary expansion

The Navy’s air arm was still very small when the United States entered WW I. In the next year, seven months and four days, while war raged, its growth was extraordinary. By the time the Armistice was signed, the Navy had 2107 planes, 570 of which were overseas, 15 dirigibles, 205 kite balloons and 10 free balloons.

Thirteen bases were established in the U.S. and the Canal Zone, only one of which, at Galveston, was not yet in operation. In Ireland, the Navy had four seaplane stations, one kite balloon station, a receiving station and a supply station. Two stations, including a major assembly and repair base, were established at Eastleigh, England. Two more stations and a training school were built in Italy. There were 18 stations in France, including an assembly and repair base at Pauillac and a school at Moutchic. Additionally, the Navy had a base operating in the Azores, one in Canada, and a rest station in the British West Indies. There were fewer than 300 officers and men in Naval Aviation when the war started in April 1917. At war’s end, in November 1918, there were 39,871, of whom 19,455 were abroad.

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Flying boats, such as this WW I-era Curtiss H-16, provided the majority of the air component in USN fleet war games immediately after WW I. The H-16, built in the USA, was a derivative of a joint British/American project, the Felixstowe. The 29 x 14.1 x 5.4 metres craft had two Liberty 400 hp engines and a crew of four. It could carry five Lewis machine guns and four 104 kg bombs.

Naval air operations in this war were predominantly in support of allied shipping, launching aircraft from land bases for anti-submarine patrols. It was not until the years immediately following the war that the U.S. Navy returned to the theory of integrating aviation with the Fleet. Although aviation had proven itself, there was still resistance within the fleet toward the imminent merger. A CNO newsletter of July 30, 1919 carried a report on Fleet Air Operations:

Early in January 1919, it was decided to send a detachment of six H-16 flying boats to Guantanamo Bay, Cuba, to operate with the U.S. Fleet for the purpose of proving to it the use of aircraft in actual naval operations and of demonstrating the practicability of maintaining an air detachment with the fleet. It was accordingly decided to operate these flying boats from moorings and to quarter the aviation personnel on a ship carrying necessary repair personnel, necessary spare material, etc., for the upkeep of the squadron.

In addition to the six flying boats there was also an airplane division consisting of two Sopwith Camels and [a Sopwith] 1½ Strutter on board the USS Texas under the command of LCDR E. O. McConnell, USN.

Not once when the air detachment was called upon to send machines for operations with the fleet has it failed to send them, and not once when machines have been sent on a certain mission has the air detachment failed to accomplish that mission. This has required flying in all sorts and conditions of weather, high winds, rain, fog, and low visibility. It has required duty in spotting, bombing, scouting, passenger carrying, mail carrying, and all types of work which aircraft with the Navy can be called upon to do.

The air detachment also had a kite balloon division and the report ends with an optimistic, though probably inaccurate, note: The result has been that the officers of the seagoing Navy have been converted to the belief that aircraft are practicable and essential to a well rounded fleet.

Numerous training periods and exercises were conducted subsequently, in which aviation participated with the fleet, but it was with the annual Fleet Problem of the twenties and thirties that these manoeuvres were conducted on the largest scale.

Historian observation, analytical study

Historian LCDR James M. Grimes, USNR, said:

Taking an ever increasing role in these problems, Naval Aviation gradually developed and came of age. The Fleet Problem, therefore, serves as the measuring rod for this growth to maturity. It provides an annual check on what Naval Aviation was accomplishing and the reports and recommendations which grew out of each problem show how important the problems and their results were in development of aviation in the Navy.

A study of these problems can be made successfully by breaking them down into five groups, studying each to determine tactics employed and lessons learned. Basically, these groups are:

1. The days of the “constructive” (paper) carriers, when other ship types were designated aircraft carriers because of unavailability of the real thing.

2. The period when the USS Langley, a converted collier, joined the games as the only aircraft carrier in the U.S. Fleet.

3. The profound effects on tactical thought precipitated by entry of the USS Saratoga and USS Lexington into the games.

4. The addition of the USS Ranger, and

5. The years immediately prior to WW II when the U.S.Navy operated five aircraft carriers.

 

Fleet Problem I: 1923

The first of the Fleet Problems occurred in 1923, in the Panama-Pacific area. It was a resounding success for the Black Fleet, given the mission attacking the defences of the Panama Canal, and a shattering failure for the Blue, assigned the defence of the Canal.

Blue’s air forces consisted of the tenders Wright, Sandpiper and Teal, and the 18 patrol planes of Scouting Plane Squadron One (half the planes were based at Ballena Bay with the Sandpiper and Teal, the remaining at Bahia Honda with the Wright), the patrol planes based at Coco Solo and all the available Army planes.

The Black Fleet was assigned the battleships New York and Oklahoma as “constructive” carriers.

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USS Wright (AZ-1, left) was commissioned as an airship tender but employed mainly as a seaplane tender. She displaced 11,500 tons on a 136.5 x 17.7 x 7 metres hull and had a maximum speed of 15 knots. Her 228 crew also manned her two 127 mm (five-inch) and two 76.2 ( three-inch) guns. USS Teal (AM-23), like Sandpiper (AM-51) was a converted minesweeper displacing 840-950 tons.

Approaching the Canal, one of the battleship “carriers,” the Oklahoma, launched a seaplane by catapult to scout ahead of the force. Early the next morning, a single plane representing an air group took off from Naranyas Cays, approached the Canal from seaward, flew over Gatun Spillway, and dropped ten miniature bombs. This plane completed its mission undetected and theoretically destroyed the Spillway.

An official report submitted after the problem pointed up the susceptibility of vital parts of the Canal to destruction by air. The report urged, among other things, that air defences of the Canal be strengthened and that rapid completion of aircraft carriers be effected for offensive and scouting purposes.


Fleet Problem V: 1925

Naval Aviation played little part in the next three exercises. It was not until Fleet Problem V in March 1925 that USS Langley entered exercises off the California coast. The second phase of the problems began; a new element was introduced.

 

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USS Langley (CV-1) seen here in 1928, was the first, and for many years the only, aircraft carrier to participate in US war games.

Basically, the supposition for this problem was that strained relations existed between Blue (the U.S.) and Black, an imaginary country in the area of the Hawaiian Islands. When Black declared war, its Commander-in-Chief was ordered to Guadalupe Island where he was to occupy an unfortified anchorage from which he was to operate against Blue in the Eastern Pacific.

Langley BZ

Black was given the Langley and the tenders Aroostook and Gannet, as well as planes based aboard battleships and cruisers.

The Blue force was considerably smaller, having only 15 cruiser-based planes and two other aircraft based on the Wyoming. Planes aboard the Wyoming were useless, however, for the battleship was not equipped with a catapult. Grimes records:

The Black War Diary shows that the greatest part of the air activity during Fleet Problem V was centred around the Langley. Scouting flights were conducted each day as the Black Fleet proceeded towards Guadalupe. The largest number of planes used at any one time was ten. The duration of these flights ranged from 30 minutes to two hours.

On the last day before the arrival at Guadalupe, the Langley received a ‘well done’ for the feat of launching ten planes in 13 minutes! None of these flights resulted in contacts.

On March 10, the Langley was ordered to have her planes ready for an 0530 takeoff the next morning. These planes were to make an aerial reconnaissance flight over the anchorage before the Black Fleet entered. This operation never took place, the Problem being terminated at 0508 March 11 by the Chief 0bserver.

Introduction of the Langley to fleet operations was considered a valuable experience. As a result of this problem, the Commander-in-Chief, U.S. Fleet, recommended that the Saratoga and Lexington be completed as quickly as possible. He also urged that steps be taken to ensure the development of planes of greater durability, dependability and radius, and that catapult and recovery gear aboard cruisers and battleships be further improved.

Fleet Problem VI: 1926

Details concerning Fleet Problem VI, conducted in 1926, are unavailable. Pertinent documents on orders, instructions and operation reports are lost. It is known, however, through the Annual Report of the Secretary of the Navy, 1926, that a combined U.S. Fleet participated in a joint Army-Navy minor problem and conducted “strategical and tactical exercises in the vicinity of the Canal Zone until the middle of March 1926.”

Fleet Problem VI was conducted during this period.

Just before Fleet Problem VII got underway in 1927, a joint Army-Navy exercise was conducted, again testing defences of the Panama Canal. USS Langley provided defence against attacks on ships by land-based Army planes and was also used for spotting submarines. This exercise marks the first time an aircraft carrier was used to protect ships of the line. Battleship-based planes were used for spotting during bombardment of the Canal installations.

Canal defences were again found weak, but again, “constructive” planes were used in the attacks. In each of the two attacks on Miraflores Locks, only one plane was launched; it represented the attacking forces. This was not considered an effective test. Grimes noted: “In later problems when carriers were available from which attacks in force could be launched and greater reality could be introduced into manoeuvres, the vital necessity for air defence of the Canal was to become even more apparent.”

Fleet Problem VII: 1927

The seventh Fleet Problem provided more experience in carrier operations. Conducted in the Caribbean in March, Blue Fleet was given the task of escorting a large, slow, overseas convoy and was then to establish a base under enemy opposition. This fleet was then to oppose the Black Naval Force from that base. Black’s mission was to provide search and contact scouting, track submarines, and attack a large convoy accompanied by a strong escort. The Langley was assigned to the Blue Force. Again, the converted collier-made-carrier was to provide protection for ships of the line.

 

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A Vought VE-7 Bluebird fighter traps aboard USS Langley in 1927. This aircraft is interesting because it has an arrestor hook to catch an athwartships wire and tiny hooks between the main wheels to catch longitudinal wires. It also sports a British-designed “hydrovane” immediately forward of the main axle, theoretically resisting the tendency of the aircraft to nose over when ditching, but perhaps having an opposite effect in most sea states. The Bluebird was designed as a two-seat Army trainer, but the single-seat version performed better than many contemporary American fighters.

On the last day of the game, Black conducted a surprise air attack—delivered by 25 land-based aircraft (from Mole St. Nicholas, Haiti)—against the Blue Force. Shortly before this, Langley maintained a protective air patrol over the convoy, but discontinued it hours before the attack was pressed home. Caught unawares, Langley‘s planes were no help.

Even though the problem had officially terminated by the time Black’s aircraft reached Blue’s ships, observers considered the attack successful, though the Commander-in-Chief deplored the clumsy formation of the attacking planes.

One of the most revealing outcomes of this problem was the need to allow aircraft carriers greater latitude in manoeuvring, as dictated by weather and the position of the enemy forces. Commander, Air Squadrons, also felt that he should have complete freedom of action in employing carrier-based aircraft in order to get maximum efficiency in air operations.

Fleet Problems VIII and IX: 1928 and 1929

Fleet Problem VIII, conducted in the Hawaiian-Pacific area in April 1928, provided further experience in aircraft carrier operations and scouting patrols, Langley, Aroostook and Gannet again participated and again air operations were limited to scouting. Bad weather and heavy seas effectively limited air operations, but despite uncooperative weather, Commander-in-Chief, Battle Fleet, noted that a sufficient number of aircraft were launched from the Langley “to show that the use of planes from carriers for all contemplated operations is both practicable and feasible.”

 

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USS Lexington launches a Martin T4M-1 torpedo bomber in 1929.

Of all the Fleet Problems conducted before 1940, the next, Fleet Problem IX, undoubtedly received the most publicity. Conducted in 1929, it saw the introduction of the world’s largest aircraft carriers, the Saratoga and Lexington. The problems entered their third phase. “The experience gained and the conclusions drawn,” says historian Grimes of this problem, “had a marked influence on the development of fleet tactics and strategy in general, and on Naval Aviation in particular.”

The Panama Canal was again chosen for the critical area under hypothetical attack. Previous exercises indicated a major weakness in defence of the Canal, protection from air attack, but this problem was to test the conclusions reached in the past by providing actual aircraft carriers and full strengths of aircraft.

The problem assumed that a war had existed between Blue (the U.S.) and two enemy nations, Black (in the Pacific) and Brown (in the Atlantic). In airpower, Blue was assigned the Lexington, 145 naval aircraft, and the cooperation of the U.S. Army in the Canal Zone and 37 planes based there. Black was given the Saratoga and the Langley. When it became evident that Langley would not complete her overhaul in time for the games, the tender Aroostook was substituted, the single amphibian aboard representing Langley‘s 18 fighters and six scouts, though these aircraft were actually transferred to the Sara. The Brown force proved to be a paper power; neither ships, planes, nor personnel were assigned; other than in initial planning and estimates of the situation by Blue and Black, Brown ceased to be a factor in the game.

Destroy Panama Canal

A detachment from the Blue force, including the Lexington, transited to the Pacific side before Black force could launch a surprise attack. On the same day, the remainder of the Blue force was to have left Hampton Roads for the Canal. It was Black’s intent to destroy the Canal before this second detachment could complete the passage.

Blue’s intelligence indicated that Black would attempt an attack on the Pacific side. Actually, Black planned a surprising two-pronged attack. The “squadron” aboard the Aroostook was to make a long-range flight, far beyond capability of return. Its attack was to be made on the Atlantic side, at the conclusion of which, the “planes” were to land and surrender. Simultaneously, Saratoga, accompanied by Omaha, was to attempt a daring tactic: take a wide, two-day swing to the south and then launch carrier-based planes for the Pacific attack. This latter demonstration was to make a profound impression on naval tacticians.


Surface Attack Group

On the morning of January 25, 1929, two days before the Problem was to end, the main Blue force, including the Lexington, came upon Black’s striking force. Black’s Battleship Division Five was steaming downwind while the carrier was steaming up, preparatory to launching her planes for an air attack. The battleships opened fire and, because of the close range, would surely have sunk the Lexington in actual battle. For this carrier, it was a disastrous ending to her first important activity in the problem.

Umpires ruled the carrier “damaged,” however, for the loss of the carrier at this early stage of the game would have had a profound restriction on Blue’s capability during the coming “interesting” part of the problem. Lexington was instead penalized in speed; she was permitted only 18 knots.

The carrier had already launched some planes. After the attack by the battleships, the carrier, running into rain and reduced visibility, was forced to recover these aircraft under very adverse conditions. Noted the Commander-in-Chief, U.S. Fleet: “Flight deck personnel and flying personnel alike are deserving of great credit for the manner in which squadrons came aboard on this occasion.”

Sara vs DD

The Saratoga, in the meantime, was steaming south. She was detected by an enemy destroyer upon which she opened her eight-inch guns. This had unfortunate results. The destroyer was “sunk,” but in the process, one of Sara’s planes, a T3M (a Martin torpedo bomber), was literally destroyed.

Spotted in the hangar deck just aft of the forward elevator and 68 feet from the muzzle of the gun, the plane suffered 36 crushed ribs and some torn fabric, directly attributable to the blast from the heavy gun. The eight-inchers were destined to be removed from the Saratoga, but not before WW II.

Later that day, the carrier encountered another Blue ship, the Detroit, which continued to track her through the night, supplying the Blue commander with vital information. The Lexington was ordered to give chase, but because of her reduced speed could not close during the night.

At 0525 the next day, the Chief Observer cancelled this penalty.

 

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USS Detroit (CL-8) shadowed Lady Lex overnight in Fleet Problem IX. She was a fast Omaha class cruiser, mounting ten 152 mm and eight 76 mm guns, six torpedo tubes and two aircraft on a pair of catapults. She had a crew of 458 and displaced 7050 tons on a 167.8 x 16.9 x 6.1 metres hull. Detroit could manage a handy 34 knots.

The 26th was an active day for the Saratoga, and not an altogether lucky one. Near five that morning, while about 145 miles from Panama, she launched an initial attack of 70 planes against the Canal. Her aircraft in the air, the good times were over for the Sara.

Navigation errors

Because of navigational discrepancies, the carrier and the Omaha contacted Blue’s Battleship Division Two instead of her own Battleship Division Five. The carrier was under heavy fire at short range from three of the enemy battleships and was scored a “sinking.” Had she escaped this disaster, four torpedoes “fired” from an enemy submarine at 1200 yards would have hurt her heavily and possibly sunk her. At 0656, Sara launched two more squadrons, at the completion of which she had 83 aircraft in the air.

At 0600 the same day, the Aroostook stopped near Jicaron Island and 17 minutes later her single plane—a Sikorsky amphibian, theoretically representing Langley‘s squadrons—took off to bomb Gatun Locks, Gatun Spillway and Coco Solo.

The commander of the Blue force, though, had committed a blunder by not advising either Coco Solo or the Army of the substitution. The Sikorsky went about its mission of bombing the Atlantic side of the Canal, encountering no opposition. When he completed the job, he landed at the Atlantic terminal of the Canal, surrendered to a stunned “enemy” and confessed his accomplishment.

Saratoga‘s problems were not yet over. Shortly after the Chief Observer lifted the speed limitation from the Lexington, Lex launched her aircraft against her sister ship. The Sara-based planes, returning from a successful raid on Miraflores and Pedro Miguel locks and the airfields at Fort Clayton and Albright, were in the process of landing when the Lexington-launched planes arrived on the scene. Sara “went down” for the third time.

Men in the Lexington had little to cheer about, though, on the morning of January 27. Friendly planes of VT-9 (squadron) took off from their moorings at Balboa and stood out to attack the Black carrier and bombarding forces. About 0700 they reached a carrier and started bombing. Later, they learned it was their own ship, the Lexington.

“This error was understandable, in view of the fact that Saratoga and Lexington were operating within 12 miles of each other at that time and it was not possible to distinguish markings, owing to the presence of a large number of men on turret tops. For purposes of identification, each turret top of the Saratoga bore two painted white stripes parallel to the axis of the guns. The turret tops of the Lexington were painted conventional war colour,” observed Commander-in-Chief, U.S. Fleet.

In later years, Saratoga was made more easily recognisable by the painting of a large stripe down the centre of her stack.

Fleet Problem IX marked an outstanding achievement in Naval Aviation.

 

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The Boeing F2B-1 was typical of the early USN carrier-borne fighters, scouts and dive-bombers that flew from USS Lexington and Saratoga in Fleet Problem IX. This aircraft, from the “Tophatters” VB-3 Squadron, was probably based in Saratoga. With a wingspan of 10.3 metres, length 7.1 metres and height 2.4 metres, its Curtiss D-12 radial engine delivered 535 hp, giving it a maximum speed of 138 knots.

It marked the first appearance of modern large carriers with the Fleet in a fleet problem. But the most significant event of this problem, and possibly in any before WW II, was the employment of Saratoga as a separate striking force. Its effect on the future use of carriers was immediate. In the 1930 manoeuvres, a tactical unit, built around the aircraft carrier, appeared in force organization for the first time.

For many historians of naval warfare, Fleet Problem IX marked the introduction of the fast carrier task force. Regardless of its genesis, this tactical weapon was tested and refined during the war games of the Thirties. Addition of the carriers Ranger, Lexington, and Saratoga was to provide more flexibility and realism in future games. A discussion of them, as well as the results of the fleet problems, will be presented in the following chapter describing in detail the evolution of aircraft carriers.


Carrier Evolution VI: War Games II

USN Carrier Evolution VI: The last of the Fleet Problems

Sixth article in a series by Scot MacDonald. Reprinted with permission: Naval Aviation News, September 1962, pp 34-38.

“The culmination of the year’s operations arrives when the carriers with their squadrons participate in the annual cruise of the Fleets. On these cruises, the year’s efforts to perfect the detail of aircraft operations are given the test of simulated major campaigns against possible enemies. Our efforts in the past have been crowned with a certain amount of success, but every success has only indicated new possibilities of the employment of aircraft in fleet operations and has emphasised the vital importance of continuously operating with the Fleet the maximum number of aircraft that can be carried on our surface vessels.” RADM J. M. Reeves, USN, Commander, Aircraft Squadrons, Battle Fleet, 1929.

ADML Joseph Mason (Bull) Reeves (1872-1948) qualified as a naval aviation observer in 1925, as a four-ringed captain at age 53. He was often referred to as “the father of USN naval aviation”. A “show me” pragmatist, he introduced systematic methods that evaluated and refined naval aviation theories. Recalled for WW II service, he served with distinction in a number of important staff duties.

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RADM Reeves

RADM Reeves described the year-long training schedule of naval aviators as the twenties came to an end:

Concurrently with gunnery exercises, the squadrons are embarked on the aircraft carriers and they participate in the monthly exercises with the Fleet. These fleet exercises are arranged to present new and increasingly difficult problems to all arms of the Fleet and to insure the effective coordination of these arms in major fleet operations and engagements.

It is not sufficient for one officer, Commander, Aircraft Squadrons, to be proficient in effectively employing aircraft. This knowledge must be possessed by all flag officers. To this end, aircraft on the various carriers, and the carriers themselves, are assigned from time to time in fleet exercises to the various subdivisions of the Fleet. In part of a problem, the aircraft will cooperate with destroyers; in another part, they operate offensively against destroyers; in another part, they operate with and against submarines; they operate continually with battleships and these battleship planes must continue their activities during the attack of ‘hostile’ aircraft. This employment of aircraft on widely differing missions reacts not only to the vast improvement of the air arm, but also and equally important, it acquaints the officers of command rank with the possibilities and effective means of employing aircraft to further the main mission of the Fleet, the destruction of the enemy.

Fleet Problem IX

Fleet Problem IX, conducted in 1929, created a profound impression on the tacticians of the day. In March and again in April of 1930 two more problems were presented to the Fleet, both conducted in the Caribbean, and both concerned with the versatility of aircraft carriers as naval weapons. They were Fleet Problems X and XI.

Fleet Problem X investigated the manoeuvres necessary to gain a tactical superiority over a force of approximately the same strength and in the use of light forces and aircraft in search operations. Carriers were here defined as a complete tactical unit, operating with cruisers and destroyers as a high-speed striking force.

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The large carriers Saratoga (left) and Lexington were pitted against one another in Fleet Problem IX, with the small carrier Langley (below) assisting Saratoga.

 

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The Blue force, representing the US, was assigned both Saratoga and Langley, while the Black force, a coalition of enemy nations, operated the Lexington. Earliest control of the Caribbean was crucial to solving the problem. At the outset, neither force knew exactly where his opponent was, though Black, through intelligence reports, had enough information available to assume the Blue ships would transit the Panama Canal to the Atlantic side. The ships already had.

Blue’s commander considered the water too rough for the safe operation of seaplanes on the first day of the problem and was reluctant to send his carrier-based planes because he expected to contact the Black carrier force before dark. The Black ships were in a position just north of the island of Haiti.

By dawn next morning, they had moved to the west side of the island. On the second day of the problem, the Blue commander again called off air operations because of bad weather and rough seas. Black, on the other hand, conducted extensive scouting operations while advancing to the west. Haitian-based planes scouted from daylight to dark, while Lexington-based fighters and scouts launched every three hours for a 12-hour period.

Strike

Weather improved on the third day and the Blue commander ordered his carrier planes launched. Still neither side had any idea where the opponent was. This status continued through the fourth day, and it was not until the fifth that contact finally was made. Saratoga was spotted by Lexington aircraft and as a result of the attack that followed, Sara’s flight deck was damaged. Before her planes could be respotted for launching off the usable end of her deck, Sara suffered another and terminal attack. Lexington next turned her attention to the Langley and in two flights of first 15 and then 12 planes successfully placed the converted collier’s flight deck out of commission.

Next, USS Litchfield, one of Saratoga‘s plane guards, was dive-bombed and placed out of action. Blue’s battleships then felt the effects of Lexington‘s planes with the result that the West Virginia suffered the destruction of two anti-aircraft guns; the California lost an observation plane on deck, injury or death to personnel, foretop material damaged, and a 15 per cent reduction in main battery fire; and the New Mexico lost four AA guns as well as an observation plane still on one of the ship’s turrets.

Neither Saratoga nor Langley took part in the main action that followed the destruction of their flight decks.


Sudden complete reversals

At its conclusion, Fleet Problem X demonstrated the suddenness with which an engagement could be completely reversed by the use of air power. Scouting planes and scouting operations were also scored; the planes were found wanting in range and the scout pilots unable to bomb carrier decks when contact was made.

A month later, Fleet Problem XI investigated further the limitations of scouting planes as well as their most effective use. After the game, it was recommended that scouting squadrons be increased to 18 planes and that a more suitable scouting plane be developed. It was felt that better flotation was needed for amphibians and that a greatly increased range for carrier-based scouts, as well as the ability to take off with a short run, were necessary. Among desirable secondary characteristics were small size, folding wings, and high speed, even at the cost of ceiling and armament.

It was also recommended that semipermanent task groups be organised, each consisting of one large aircraft carrier, a division of cruisers, and a division of destroyers. These ships were to be trained as a unit in frequent exercises.

Fleet Problem XII

The 1931 Fleet Problem (XII), conducted in the Pacific-Panama Bay area, had among its tasks exercises in strategic scouting, the employment of carriers and light cruisers, and refuelling at sea.

Primarily, this problem dealt with actions between a fleet strong in aircraft and weak in battleships, and in a reverse situation where the fleet was weak in aircraft. At its conclusion, it was considered that two cruisers and two destroyers were minimum protection for an aircraft carrier in a carrier group. Further, the commander of that group should be stationed in the aircraft carrier, rather than in a cruiser or destroyer, so that he could fully understand the mission of that group and obtain its quickest cooperation. Also, it was pointed out, escorting vessels must maintain the speed and proportionate fuel capacity of the carrier.

At the end of the problem, the three carriers transited the Canal and headed for Cuban waters and more exercises.

Civilian relief

On the last day of March, CAPT Ernest J. King, commanding Lexington, was ordered to assist navy and marine units in relief operations in Nicaragua. An earthquake had destroyed most of the city of Managua. When Lexington launched five aircraft with medical personnel and supplies aboard, in addition to provisions, she inaugurated carrier aircraft relief operations in the US Navy. This was to become a frequent peacetime mission.

 

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Managua suffers widespread severe periodical earthquakes. Typical of the damage is this Managua buildingdestroyed in 1972. The 1931 quake cost 2000 lives.

During Fleet Problem XIII, held in the Pacific-West Coast area in 1932, the vulnerability of submarines to air detection and attack, at that time, was clearly demonstrated. Four out of five submarines of one force, assigned scouting missions, were detected by land and carrier-based planes and “sunk”. COs of these submarines reported their own vulnerability when operating in an aircraft-screened area.

Aircraft carriers assigned to the problem were forced to exercise in widely separated areas of the Pacific. RADM H. E. Yarnell, who commanded the “USA” aircraft during the exercise, noted that in event of actual war in the Pacific, the number of aircraft carriers on hand would be totally inadequate to meet the needs.

Also, the admiral pointed out, this problem was not greatly dissimilar from all other problems conducted in the past, in that when one aircraft carrier was assigned to each of the forces in the war games, each of the forces invariably made the destruction of the other’s carrier the prime tactic. This resulted in both forces losing their carriers early in the game.

It was therefore obvious, he repeated, that the side with the greater number of carriers had a tremendous advantage. He suggested that at least six or eight more aircraft carriers be added to the navy’s inventory. The next problem, XIV, was conducted in the same area the next year, 1933. Its conditions were that “during preparation for escorting an expeditionary force overseas in a campaign, an overseas possession was in danger of a raid, and important industrial, military and mobilisation centres of a long coast line were threatened by carrier raids.”

Surface attack group

The Blue force was to protect the West Coast while Black was ordered to make at least one raid on the San Diego-San Pedro, San Francisco and Puget Sound areas. Black divided its force into three groups. Its Northern Carrier Group was to raid San Francisco and then proceed to Puget Sound to the north. The Southern Carrier Group was to raid San Pedro and then San Francisco, rendezvousing later with Black’s Support Group.

The first four days were uneventful. On the fifth day, a Lexington-based plane of the Northern Group spotted an enemy submarine, causing the carrier to change formation for the approach to the launching point of the raid. Weather worsened, forcing the suspension of flight operations. Early the next morning, as Lexington warmed up her planes, a Blue battleship was sighted at 4500 yards range. As the carrier tried to escape, a second enemy battleship came into view and the Northern Carrier Group was declared out of action, caught unexpectedly between two enemy battleships at close range.

The Southern Carrier Group had better luck. On the seventh day of the problem, Saratoga-based planes successfully launched the attack. Black reported that 12 scouts had attacked the oil refinery with 24 100-lb bombs; five scouts attacked a power house at Long Beach with ten equally powerful bombs, encountering no enemy force and sustaining no losses. The force lost three bombers to the enemy’s two fighters during an 18-bomber attack on an enemy transport, an oil field at El Segundo and docks at Long Beach. Saratoga sustained light damage and the force moved north for the San Francisco raid.

Where’s the CAP?

When she arrived in the San Francisco area, Saratoga launched her planes. Before she completed, aircraft from the cruiser Richmond and the carrier Langley bombed her flight deck. After Sara’s planes returned from the raid, 37 per cent of her flight deck was assessed damaged, 36 planes lost, and her flight deck out of commission for 38 hours. The CV-2 aircraft had succeeded in making a dive bombing attack on Langley, temporarily disabling her flight deck, and attacked Crissy Field, San Francisco docks, San Andreas reservoir, and the dry-dock at Hunter’s Point.

 

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The Omaha class light cruiser Richmond (CL-9) carried two floatplanes between the after funnel and mainmast. The six-inch cruiser displaced 7050 tons, and could make a handy 35 knots.

This exercise underscored the urgent requirement for the development of better planes, particularly carrier bomber and torpedo planes. RADM Yarnell again pleaded for three additional 18,000-ton carriers, which were permitted under existing treaties.

In the period 1933-34, the Fleet conducted a series of 20 tactical exercises. The last three of these comprised Fleet Problem XV, which also proved the last of the war games of the three-carrier period. In his official monograph, Aviation in the Fleet Exercises, 1911-1939, historian LCDR James M. Grimes, USNR, described the war games:

The primary effort of the Commander-in-Chief when drawing them up had been to introduce realism into fleet tactics and to simulate as nearly as possible actual wartime operations. For this reason, the opposing fleets represented actual navies of the period. Carrier operations were extensive throughout the problem.

There were several important results of Fleet Problem XV as regards the development of naval aviation. The most important, perhaps, was the realisation brought out by air operations during the problem, that if the carrier was to be the offensive weapon it was considered to be, carrier-based planes would have to be so armed that they could carry the offensive to the enemy.

It was seen that planes carrying 100-lb. bombs were obsolete and of little use against an enemy force equipped with planes capable of carrying 500-and 1000-lb. bombs. The Commander-in-Chief, in his remarks at the critique held on Fleet Problem XV, stated that at least three-fourths of the carrier-based planes should be so equipped.

 

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USS Ranger (CV-4), launched 25 February 1933, was the first USN carrier to be designed as a carrier from the keel up. She displaced only 17,577 tons on a 234.4 x 33.4 x 6.8 metres (769 x 109 x 22 ft) hull. Her six boilers and two turbines developed 53,500 shp and could drive the ship at 29.25 knots. She had three elevators, no catapult but carried 86 aircraft with 2,148 crew (1941 figures). In this photo Ranger has her bad-weather palisades erected forward and her hinged funnels are in the upright position.

USS Ranger joins

USS Ranger joined the Fleet for the next war game, Fleet Problem XVI, conducted in 1935. Actually, this game consisted of five separate exercises, none of them related, spread over the Pacific from the Aleutians to Midway and Hawaii. Both the Army and Coast Guard participated.

The major air operations took place during the third phase of the problem. Unfortunately, these were marred by a series of plane and personnel casualties that, unfortunate in themselves, also seriously affected later air and sea operation. Although valuable experience was obtained in the mass flight of patrol squadrons, nothing of significance developed in the operation of aircraft carriers.


Panama-Pacific area

Fleet Problem XVII was conducted in the Panama-Pacific area in 1936. The exercises (again five) saw extensive use of patrol planes and the effective use of the automatic pilot, but there was no major contribution to, or effect on, the evolution of carriers, either in design or tactics.

The question of proper employment of aircraft carriers was brought up again in Fleet Problem XVIII of 1937: Should they operate with the main body of a fleet or should they operate at a distance?

Black’s aircraft commander held that a carrier tied down to a slow main body formation was certain to be destroyed. “Once an enemy carrier is within striking distance of our fleet,” he said, “no security remains until it, its squadrons, or both, are destroyed, and our carriers, if with the main body, are at a tremendous initial disadvantage in conducting necessary operations.”

But his force commander took a different view. He felt that carriers should be an integral part of the main body and defended his decision to employ them in such a way, as he did in this problem. He suggested that Ranger, because of her small size, could provide scouting and spotting with less chance of being detected. He hoped that when Yorktown and Enterprise joined the fleet, such an employment of Ranger might be possible.

Fleet problem XIX was the last of the Ranger phase of the war games. It was conducted in 1938 and consisted of Parts II, V, and XI of the Annual Fleet Exercises.

Land-based air success

In the first phase, the outstanding performance was a long-range San Diego-based patrol plane bombing attack which successfully eliminated Lexington as a carrier unit in the game.

 

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The Consolidated P2Y was the forerunner of the highly successful PBY Catalina of WW II fame.

The notable development of the second phase of the war game, Part V, was an attack on Pearl Harbor, launched from Saratoga some 1000 miles off the coast of Oahu. Sara’s recon group flew over the Lahaina area, photographing beaches and reporting the enemy’s strength there.

At the same time, Sara sent an attack group, which bombed Fleet Air Base, Hickam Field, Wheeler Field, Wailupe Radio Station, and returned to the carrier. This tactic was to be employed by the Japanese some three years later, in December 1941.

In phase three (Part XI), the outstanding air operation was an unopposed air attack by Lexington– and Saratoga-based planes launched against Mare Island and Alameda in California.

“Excellent experience was provided in planning and executing a fast carrier task force attack against a shore objective,” says Grimes. “The problem of defending a coastline, or even an isolated portion thereof, against fast enemy raiding forces equipped with large carriers and protected by powerful surface ships was seen to be one difficult of solution.”

Yorktown and Enterprise entered into the 1939 exercises of Fleet Problem XX, which were conducted in the Caribbean area and off the northeast coast of South America. The war games entered their final phase. Neither Langley nor Saratoga participated.

New ASW efficiency

As a result of this game, reports indicated that carrier operations reached a new peak of efficiency; particular credit was given the two new carriers which, despite inexperience, contributed significantly to the success of the problem. These exercises studied employment of planes and carriers in connection with convoy escort, development of coordinating measures between aircraft and destroyers for anti-submarine defence, attack on mobile patrol plane bases, scouting and attack by patrol planes, defence of surface ships against aircraft attack, and trial of various forms of evasion tactics against attacking aircraft and submarines.

 

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USS Arizona (BB-39) carried three catapult-mounted scout aircraft in the 1930s. She was a Pennsylvania-class battleship of 31,400 tons and just one of the many vessels sunk at Pearl Harbour by a Japanese aircraft carrier force, 7 December 1941.

The last war game, XXI, was played in 1940 in the Hawaiian-Pacific area. It consisted of two separate exercises. Historian Grimes describes them:

The first exercise was designed to afford training in making estimates and plans; in scouting and screening; in the coordination of various types of fighting units; in employing standard and fleet dispositions; and finally to train the opposing forces in decisive engagement.

The second major exercise of the problem was designed to afford training in scouting, screening, communications, coordination of types, protection of a convoy, seizure of advanced bases and finally, decisive engagement.

Joint Services cooperation comment

Between the two major parts of the problem were two minor exercises in which air operations played a major part: Fleet Joint Air Exercise 114A and Fleet Exercise 114. Exercise 114A underscored the need for greater cooperation between the army and navy in organising the defence of the Hawaiian area. Exercise 114 compared patrol plane attacks on surface units with use of planes in high altitude tracking. The former proved the planes vulnerable, while the latter met with great success.

Few new difficulties emerged from this war game. Reiterated was the question of latitude given carrier commanders by force commanders. Yorktown‘s commanding officer stated his belief that success could best be achieved when aircraft personnel in carriers operated under a broad directive. The exercise proved again—as it did in Fleet Exercise 114—that low-level horizontal bombing attacks had little chance of success, especially against a ship that was not otherwise engaged.

By 1940, the war games were halted. Although one was planned for the next year, worsening world tensions caused their cessation. Various tactical exercises were held instead.

Naval aviation grew with the war games. The first phase ”the pre-aircraft carrier years” employed “constructive” carriers and merely indicated to the navy the potentials of this new weapon. The Langley phase was an informative one, but this was more an experimental ship than an aircraft carrier.

New tactics refined

The games reached fruition with the addition of the Lexington and Saratoga in Fleet Problem IX. It saw the employment of an aircraft carrier as a separate striking force and introduced a new tactic in the book of naval strategy. The Ranger phase showed the potentials of small aircraft carriers, employed with telling effect in WW II. And the final phase, the addition of Yorktown and Enterprise, increased and refined carrier operations in the critical years prior to WW II.


Carrier Evolution VII: Early Japanese

USN Carrier Evolution VII: Early Japanese carriers

Seventh article in a series by Scot MacDonald. Reprinted with permission: Naval Aviation News, October 1962 pp. 39-42.

“In the last analysis, the success or failure of our entire strategy in the Pacific will be determined by whether or not we succeed in destroying the U.S. Fleet, more particularly, its carrier task forces.” ADML Isoroku Yamamoto, IJN, 1942.

“I think our principal teacher in respect to the necessity of emphasising aircraft carriers was the American Navy. We had no teachers to speak of besides the United States in respect to the aircraft themselves and to the method of their employment … We were doing our utmost all the time to catch up with the United States.” FADM Osami Nagano, IJN, 1945.

By Christmas Eve 1921, the Washington Disarmament Conference had already been going on for a month and a half. Participating were Great Britain, Japan, France, Italy, and the United States. It was on this day that Great Britain refused any limitation on auxiliary vessels, in view of France’s demand for 90,000 tons in submarines. The delegates then began to consider confining the treaty to capital ships and aircraft carriers.

Washington Treaty

The Washington Naval Treaty, signed February 6, 1922, established a tonnage ratio of 5-5-3 for the capital ships of Great Britain, the United States, and Japan, respectively, assigning a smaller tonnage to France and Italy. The same ratio for aircraft carriers was set, with an overall limitation of 135,000 tons each for Great Britain and the U. S., and 81,000 tons for Japan. It also limited any new carrier to 27,000 tons, with a provision that, if total carrier tonnage were not thereby exceeded, nations could build two carriers of not more than 33,000 tons each, or obtain them by converting existing or partially constructed ships which would otherwise be scrapped by the treaty.

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HIJMS Hosho, was the first purpose-built aircraft carrier ever to be commissioned, 27 December 1922, 17 months before HMS Hermes. The temporary island was removed after her initial trials. The 168 x 18 x 6.7 metres hull displaced 10,500 tons at full load. The 30,000 hp engines, powered by geared turbines and 16 boilers, drove the ship at 25 knots. With a crew of 550, she carried 26 aircraft. She served in support of the Battle of Midway, with nine obsolescent B4Y1 torpedo bombers, but was not hit. After WW II, Hosho (photo right in October 1945) repatriated Japanese nationals.

December 27 that year, Japan commissioned its first aircraft carrier, the Hosho (Flying Phoenix). This was a remarkable hoku bokan (literally, mother ship for aircraft). Though the British were the first to operate aircraft onto and off a ship especially designed for that use, their first aircraft carriers were conversions. Hosho was a carrier from the keel, the first of its kind completed in any navy of the world.

Hermes contemporary

Laid down in 1919 at the Asano Shipbuilding Co. of Tsurumi, the ship was fitted out at Yokosuka Navy Yard at a standard displacement of 7470 tons, a speed of 25 knots, with the capability of handling six bombers (plus four reserve), five fighters (in addition to two in reserve) and four reconnaissance planes, a total of 21 aircraft.

Hosho was indeed a strange looking craft. She was all flying deck. Originally, she had an island structure and a tripod mast, but either because of the small width of her flying deck (and its attending hazards) or because some turbulence might have been caused by it, the island was taken off. The carrier sported three funnels on the starboard side. These were of the hinged type, held upright when not in use, and swung outboard to provide additional safety from stack gas. Later, they were placed in a fixed position, bending aft and slightly downward.

Hosho‘s original armament consisted of four 14 cm (five-inch) single mount guns and two 8 cm (three-inch) single mount high angle guns. At the outbreak of WW II, her high angle guns were replaced by four 25 mm twin mount machine guns. Later, the 14 cm guns were removed and 25 mm double or single mount machine guns were added.

 

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The Nakajima A1N Gambet, Navy Type 3 Carrier Fighter, was in Japanese naval service from 1929 to 1935. Developed from the British Gloster Gamecock, its final version, the A1M2, had a 450 hp engine, a top speed of 150 knots and carried two 7.7 mm machines guns. It also had a 200-mile range with two small 30 kg bombs.


Japanese names

Before continuing with Japanese development, an explanation of the naming of their aircraft carriers is in order.

“Transliteration of the names of Japanese aircraft carriers into American equivalents is a pretty risky business,” said Roger Pineau, a frequently published writer on the Japanese Navy after World War II. “It becomes misleading. The names should be treated as such and should not be taken too literally. For instance, when we speak of astronaut Carpenter, we don’t visualize a man walking around with hammer and saw in hand.”

Chris Beilstein, another expert on Japanese aircraft carriers, concurs. “The Shokaku becomes ‘Flying Crane,’ for that is the closest we can translate the original Japanese. The first Japanese CV’s carried names of mountains and provinces. These, in turn, were frequently named after mythological characters. Shokaku, for example, could have been a flying crane in an age-old story, a crane that was named Shokaku. This is very much like our real life Misty, the wild horse. Certainly, to translate ‘Misty’ to literal Japanese would be meaningless to them, or at best, misleading. It would be more accurate to translate it ‘Wild Horse.’ Thus, ‘Misty,’ to the Japanese, would mean ‘Wild Horse,’ just as we would erroneously translate Shokaku as ‘Flying Crane.”

Japanese Naval Aviation dates back to 1912 when the Navy sent officer trainees to the USA, Great Britain, and France. They returned from France with two Farman seaplanes, and from the USA with two Curtiss seaplanes. A beach on the west side of Tokyo Bay, Oppama, was selected as a site for a seadrome in the fall of that year and placed into commission. The first class at Oppama consisted of four officers and 100 men.

The first landing on the Hosho was made by a British civilian, a Mr Jourdan, on February 22, 1923. (In chronological comparison, Eugene Ely landed on a platform on the armoured cruiser USS Pennsylvania January 18, 1911; USS Langley, the USN’s first aircraft carrier, a converted collier, was commissioned March 20, 1922; the first USA aircraft carrier built as such, from the keel, USS Ranger, was not commissioned until June 4, 1934.)

Akagi, a converted battlecruiser in the 1928A naval expansion program, decided upon in 1920, was completed by March 1923. Under the limitations set by the Washington Naval Treaty, Japan turned her attention to the conversion of the battlecruiser (then eight months under construction at the Kure Naval Arsenal). This, in 1928, became Japan’s second aircraft carrier, the Akagi (Red Castle, actually the name of a Japanese mountain). Akagi displaced over 30,000 tons standard when completed, had a speed of 31 knots, and carried 60 aircraft. She was armed with ten eight-inch and 12 4.7-inch guns.

 

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HIJMS Akagi, Japan’s second aircraft carrier, seen here in 1928, was reconstructed in 1935-38 with a full-length flight deck, port-side island and increased aircraft complement, from 60 to 91. She was VADM Nagumo’s Pearl Harbour flagship, before contributing to a highly profitable Indian Ocean raid, dusting up Darwin as she passed by, 19 February 1942, and sinking the carrier HMS Hermes, two RN cruisers and HMAS Vampire off Sri Lanka (Ceylon) in April. Akagi was lost at Midway, 4 June 1942, after one bomb hit and internal AVGAS (aviation gasoline) explosions.

A sister ship, the Amagi (Heavenly Castle), was also scheduled for conversion at that time, but sustained severe damage in the earthquake of 1 September 1923. She was scrapped in July 1924 at Yokosuka. In her place, Japan converted the Kaga (the name of an old Japanese province) to an aircraft carrier. Originally, she was laid down as a 39,000-ton battleship, but was scheduled for the scrap pile as a result of agreed disarmament limitations. Conversion was completed in 1928 and she was commissioned the following year.

 

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Akagi launches a D3A-1 (Val) dive bomber for the 19 February 1942 raid on Darwin.

The 1929 Japanese Year Book states, of Akagi and Kaga: They are the pride of the Japanese Navy, and though slightly inferior to the Saratoga of the USN in respect of speed, the Akagi surpasses the other in point of the range of her high angle guns, of which she carries 12 4.7-inchers. The Hosho … [is] by far smaller than the Akagi, but in the mode of construction [it possesses] special features of [its] own. The completion of the Kaga, only second to the Akagi, is a powerful addition to the Japanese Navy.

Kaga was reported as displacing 26,900 tons standard, but actually displaced over 30,000 tons, had a speed of 27 knots and carried 60 aircraft.

 

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HIJMS Kaga, converted from a battleship hull, is seen here after major reconstruction (lengthened flight deck, completely re-engined, starboard side island) in 1936. She was at Pearl Harbour and contributed to the Darwin raid on 19 February 1942. Kaga missed the Indian Ocean sortie after running aground at Palau, 9 February 1942. She too was lost at Midway, 4 June 1942, after four bomb hits and internal AVGAS explosions.

London Treaty 1930

As the signatories of the Washington Naval Treaty reconvened in London in 1930, Japanese naval officers began to chafe under the ship construction restrictions imposed upon their nation. At that time, the armed forces were unpopular with the liberal government in power. Final decision on the size of the Navy lay in the competence of the civilian government. Most career officers were hostile to the treaty; those officers, who supported the civilian government in the bitter fight that ensued concerning ratification of the 1930 London Treaty, were either forced to resign within the next few years or were placed in unimportant posts. Militarists, ascending in power, referred contemptuously to the ratification as “the May 15th Affair.”

The London Treaty carried forward the general limitations of the earlier Washington agreement and provided for further reductions of naval armament. Under terms applicable to Naval Aviation, the definition of an aircraft carrier was broadened to include ships of any tonnage designed primarily for aircraft operations. It was agreed that installation of a landing-on or flying-off platform on a warship designed and used primarily for other purposes would not make that ship an aircraft carrier. It also stipulated that no capital ship in existence on April 1, 1930 would be fitted with such a platform or deck.

Rapid expansion

The Japanese Navy expanded rapidly after 1930, at such a rate that it became necessary to conscript men. In 1931, a replenishment plan was authorised, permitting the Navy to complete construction of the Ryujo (Galloping Dragon), a small aircraft carrier of about 10,000 tons laid down in 1929. It was completed in 1933, its limited deck free of an obstructive island. Ryujo had a speed of 29 knots, carried 36 aircraft, and was armed with 12 five-inch guns. She was Japan’s fourth aircraft carrier. In June 1934, USS Ranger became the United States Navy’s fourth carrier.

In 1932, naval authorities referred a second naval replenishment plan to the Ministry of Finance for study. This called for a total expenditure of ¥460,000,000 (about $230 million), covering the construction of one aircraft carrier of 8000 tons, other capital and auxiliary ships, and the establishment of eight flying corps on land: all this to be completed by the end of 1936. This aircraft carrier was never built.

In 1934, preliminary disarmament conferences were held in London. Congress had already passed and President Roosevelt authorised an act that popularly became known as the Vinson­Trammell Act. This permitted the USA to construct naval ships to the tonnage limitations prescribed by the previous Washington and London Naval Treaties. Under this authorisation, USS Wasp (CV-7) was laid down in 1936.

Japanese militarists were not eager to continue in the disarmament pacts. Wrote U.S. Ambassador to Japan, Joseph C. Grew, “Japanese attitude toward the coming Naval Conference in 1935 London Treaty is intensely unpopular among the Japanese Naval officers high and low;” and in separate correspondence, “The situation is entirely different from that in 1930 … Under present conditions the Navy alone will have the final say [as to the size of the Imperial Japanese Navy].”


Quantitative parity

It boiled down to this: Japan wanted quantitative as well as qualitative parity in ship power, equal to the United States and Great Britain. The 5-5-3 ratio was no longer acceptable. Neither the USA nor Britain favoured such an increase in Japanese strength. Granted equality in armoured ships, Japan would be the major power in the Pacific, greater than the USA and Great Britain combined when their Fleets were divided geographically. Japan persisted. The Japanese Year Book of 1935 enumerated that country’s “official” reasoning:

1. The progress and development made recently in battleships, aeroplanes, etc., have made it extremely difficult to effectuate defence operations.

2. The remarkable increases in the air forces of the USSR and China, and the revival of the Far Eastern naval forces of the former.

3. The establishment of the naval port of Singapore by Great Britain, and the extension and strengthening of the naval port of Hawaii by the USA have had a great effect on the naval plan of operations in Far Eastern waters.

4. The birth of Manchoukuo [independence of Manchuria, 18 February 1932] has brought forth vast in Far Eastern policies. It has increased the responsibility of the Japanese Empire as the stabilizing power in the Far East.

These were political arguments the world’s two top naval powers could not buy. But Japan was adamant, refused compromise and, on December 29, 1934, gave the required two years’ formal notice that after 31 December 1936, she would no longer be bound by the terms of the Washington and London Naval Treaties. Her act of abrogation unleashed the restraints on international shipbuilding.

 

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HIJMS Soryu, laid down in 1934 and commissioned in December 1937, displaced 19,500 tons on a 222 x 21 x 7.44 metres hull. Her four screws and 152,000 hp engines made her nearly 40 per cent faster than the similar-sized 25-knot HMAS Sydney and Melbourne.

Two more aircraft carriers were laid down in Japanese ways in 1934 and 1936, the Soryu (Blue Dragon) and Hiryu (Flying Dragon). Soryu displaced about 18,000 tons standard, had a speed of 34.5 knots, and handled 63 aircraft. Hiryu was heavier, 18,500 tons standard, and had a speed of 34.3 knots. Officially, both ships were carried on the books at 10,050 tons standard; the true tonnage was not revealed until after WW II. Both ships carried the same number of planes and had the same armament, 12 five-inch guns.

 

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HIJMS Hiryu in 1939.

HIJMS Hiryu, sister ship to Soryu, was laid down in 1936 and commissioned in 1939. Hiryu had a port-side island, like Akagi, which meant that when operating aircraft she would be on the starboard side of a tight multi-carrier formation, with her aircraft flying right-hand circuits. The starboard-side island ships would be deployed in the port column, with their aircraft flying left-hand circuits. Hiryu was also part of the carrier group that bombed Pearl Harbour and Darwin and participated in the Indian Ocean raid. Hiryu was the only operational front line Japanese carrier left in the Battle of Midway after Kaga, Soryu and Akagi were all disabled early on 4 June 1942. In that battle, Hiryu launched two strikes, at 1050 and 1245, that severely damaged USS Yorktown (CV-5, below), leading to that carrier’s total loss. In turn, Hiryu was hit by four bombs from a strike by Yorktown‘s sister-ship Enterprise (CV-6) around 1700, which led to her scuttling early the next morning. At Midway, Hiryu carried a formidable arsenal of 21 A6M Zero fighters, 21 Aichi D3A (Val) dive bombers and 21 Nakajima B5N (Kate) torpedo bombers.

 

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USS Yorktown (CV-5) hit amidships by a torpedo from a Hiryu-launched strike, 4 June 1942.

It was sometime between 1935 and 1937 that naval ship designers configured carriers to provide a surprising technical innovation. Akagi and Kaga underwent major modernisation at this time. The lower flight decks were suppressed, the upper flight decks were extended forward, and the eight-inch gun turrets and mountings were reduced in Akagi from ten to six, while Kaga replaced her 12 x 4.7-inch guns with 16 five-inchers. Kaga‘s unwieldy funnels were also reduced. The modernisation of Kaga, which included new machinery, added about 1½ knots to her speed, giving her 28.3, but Akagi‘s modernization cost her several knots, bringing her down to 28.


Port-side islands

But the startling innovation was the introduction of small islands on the port side of the carriers Akagi and Hiryu. The remaining carriers had islands on the starboard (standard) side—of those that had them at all. Strategists planned to use these carriers in a formation that was unique. The lead carriers in the basic formation were to be the port-islanded Hiryu and Akagi, followed by the Soryu and Kaga. This would supposedly allow for a more compact formation with nonconflicting aircraft traffic patterns. This formation was used in the Battle of Midway.

(Ed. note: This explanation remains valid only if the carriers turned together to a flying course of about 90 degrees port. See the caption to the Hiryu photo above for a better explanation.)

Japan’s next venture into aircraft carrier construction was the Shokuku (Flying Crane) and Zuikaku (Lucky Crane). These carriers were kept fairly well under wraps, insofar as specifications are concerned. They were authorised under the very ambitious Fleet Replenishment Program of 1937, the same program under which the famed super battleships Yamato and Musashi were built.

Shokaku was laid down December 12, 1937 at the Yokosuka Navy Yard, while Zuikaku was started at Kawasaki Dockyard May 25, 1938. Basically, the ships had similar specifications. They displaced 25,675 tons standard, had a designed speed of 34.2 knots, carried 16 five-inch guns in twin mounts, and could carry up to 84 aircraft, although a normal complement was 73. There were no major differences between the ships. Zuikaku, however, was fitted with a bulbous bow, the first Japanese warship so designed. Shokuku was launched June 1, 1939, and completed August 8, 1941; Zuikaku was launched November 27, 1939, and completed September 25, 1941.

Funnel modifications

Completion of both carriers was delayed when the original funnel arrangement was changed in mid-construction by the Aeronautical Headquarters. As designed, the funnels were to appear one on each side of the island bridge, fore and aft on the starboard side. This was changed by placing the two funnels immediately aft of the island.

The Japanese did not give either ship much publicity. Both ships, Zuikaku and Shokaku, were to figure prominently in most sea battles of WW II involving naval air. Their design was based on the best material gathered from experiences in Akagi, Kaga, and the Soryu types. Later Japanese carriers (i.e., multiple ship design classes) were constructed in two groups: the large to be like Taiho (with armoured flight deck) , and the medium to be repeats of the Soryu class. Zuikaku and Shokaku comprised an entire class.

Japan’s next aircraft carrier was a conversion. In 1936 the submarine depot ship Takasaki was under construction. While she was still in the ways, the decision was made to complete the ship as a carrier. Work on this project was not started until January 1940, but was completed in December that year. The carrier was renamed Zuiho (Happy Phoenix). She displaced 11,200 tons standard, sailed at 28 knots, and carried 30 aircraft. She was armed with eight five-inch guns. A sister ship, Shoho (Lucky Phoenix), converted between January 1941 and January 1942, was originally named Tsurugisaki, launched as a submarine depot ship in 1934. Zuiho and Shoho particulars were similar.

Other aircraft carriers were under construction or conversion. At least 15 more would be commissioned during the war years, produced in growing restrictions of limited materials, and, after the Battle of Midway in 1942, in desperation.

Further rapid expansion

In the five-year period preceding 7 December 1941, Japan’s military might grew stronger. In March 1936 the cabinet was dominated by men in uniform and the development of heavy industry was pushed. An extraordinarily ambitious and successful expansion of the Navy was launched in 1937, the same year hostilities broke between Japan and China. That same year, the Panay was sunk. In 1938, the National Mobilization Bill was passed. In September 1940, Germany, Italy and Japan concluded a three-power pact. November 1941, Japanese Prime minister, Gen. Hideki Tojo, stated that British and American influence must be eliminated from the Orient.

 

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The best carrier in the world is useless without capable aircraft. The deadly Nakjima B5N (Kate) was the best of the early WW II torpedo bombers. Its 1115 hp engine gave it a speed of 200 knots and a very respectable 600-mile strike range with an 800 kg torpedo.

The Japanese Navy had been conducting intensive training of its officers and men during this period. Most of the training, including war games, was conducted in out-of-the-way gulfs and in the stormy northern reaches of the Pacific. The men were hardened by the elements and drilled continuously. To avoid antagonizing the Japanese, the U.S. Navy at the same time was instructed to hold all of its fleet problems in the less satisfactory areas west of the International Date Line.

Pearl Harbor

By 1941, Japan was determined to wage war. On November 10, VADM Chuichi Naguma, placed in charge of the initial attack, issued his first operation order on the mission. The Striking Force of Akagi, Kaga, Soryu, Hiryu, Shokaku and Zuikaku, as well as other capital ships, sortied from Kure navy base between 10 and 18 November, rendezvousing on the 22nd in Tankan Bay in the Kuriles.

ADML Yamamoto ordered the force to sortie on 26 November. On 2 December he broadcast a prearranged signal that would launch the attack on Pearl Harbor: “Niitaka Yama Nobore” (Climb Mount Niitaka). Five days later, 7 December, the Japanese Navy launched its surprise attack by aircraft, launched from carriers, at Pearl Harbour and the Philippines. The next day, the United States and Japan were officially at war.


Carrier Evolution VIII: Early CVAs

USN Carrier Evolution VIII: Early Attack Carriers

Eighth article in a series by Scot MacDonald. Reprinted with permission: Naval Aviation News, November 1962, pp 44-48.

“We have hit the Japanese very hard in the Solomon Islands. We have probably broken the backbone of the power of their Fleet. They have still too many aircraft carriers to suit me, but soon we may well sink some more of them … We are going to press our advantages in the Southwest Pacific and I am sure that we are destroying far more Japanese airplanes and sinking far more of their ships than they can build.”— Franklin D. Roosevelt, President of the United States, 1942.

At the outbreak of World War II, the United States had in commission seven aircraft carriers and one escort carrier. USS Langley, the experimental ship officially classed as CV-1, had been converted and assigned to duty as a seaplane tender 15 September 1936.

 

langleyfw

USS Langley (CV-1), converted from the collier Jupiter (AC-3), was the USN’s first aircraft carrier (above). She was converted to a seaplane carrier (AV-3, below) in 1936 but was lost ferrying 32 US Army Air Force P-40 fighters from Fremantle to Tjilatjap, Java. Nine Japanese twin-engine Mitsubishi G4M (Betty) land-based naval aircraft scored five bomb hits, which led to her being abandoned and scuttled on 27 February 1942.

 

langley38fw

After the abrogation by Japan from disarmament treaties, the U.S. took a realistic look at its naval strength. By Act of Congress on 17 May 1938, an increase of 40,000 tons in aircraft carriers was authorised. This permitted the building of USS Hornet (CV-8) and USS Essex (CV-9). On 14 June 1940, another increase in tonnage was authorised. Among the ships built under this program were the Intrepid and the new Yorktown. On 19 July, an additional 200,000 tons for carriers was authorised.

Dollars cannot buy yesterday

ADML H. R. Stark, then Chief of Naval Operations, reported to the Secretary of the Navy:

In June 1940, the Congress granted the Navy an 11 per cent increase in combat strength and, in July, a further increase of approximately 70 per cent. When these ships and aircraft are completed, the U.S. Navy in under-age and over-age ships will include 32 battleships, 18 aircraft carriers, 91 cruisers, 325 destroyers, 185 submarines, and 15,000 airplanes…From 1921 to 1933, the United States tried the experiment of disarmament in fact and by example. This experiment failed. It cost us dearly in relative naval strength—but the greatest loss is TIME. Dollars cannot buy yesterday. Our present Fleet is strong, but it is not strong enough.

Additional tonnage was authorised 23 December 1941 and 9 July 1942.

Essex class

USS Essex (CV-9) was first of a series of early attack aircraft carriers of World War II. CV-9 was to be the prototype of an especially designed 27,000-ton (standard displacement) aircraft carrier, considerably larger than the Enterprise and smaller than the Saratoga. These were to become known as the Essex class carriers, although this classification was dropped in the ’50s.

 

essex1fw

The early Essex class displaced 36,380 tons (fully laden) on an 862 x 108 x 34 feet (263 x33 x 10.4 metres) hull. They had eight boilers, four steam turbines and four shafts that developed 150,000 shp and could drive the ship at 33 knots. Initially, they carried 2600 crew and 90-100 operational aircraft. Armament included four twin five-inch (127 mm) turrets fore and aft of the island and four single five-inch or eight 40 mm guns at the bows and stern on the hangar deck level.

On 9 September 1940, eight more of these carriers were ordered and were to become the Hornet, Franklin Ticonderoga, Randolph, Lexington, Bunker Hill, Wasp and Hancock, CV-12 through -19, respectively. Re-use of the Lexington, Wasp and Hornet names was in line with the Navy’s intent to carry on the traditions of the fighting predecessors: Lexington (CV-2) was lost in the Battle of the Coral Sea in May 1942; Wasp (CV-7) was sunk September that year in the South Pacific while escorting a troop convoy to Guadalcanal; Hornet (CV-8) was lost the following month in the Battle of Santa Cruz Islands.


The name game

It is appropriate to comment here that the ships’ names at commissioning date did not all bear the same name at the date of their programming. Names were changed during construction. Hornet (CV-12) was originally Kearsarge, Ticonderoga (CV-14) was Hancock, Lexington (CV-16) was Cabot, Wasp (CV-18) was Oriskany, and Hancock (CV-19) was originally Ticonderoga. The last two of the 13 originally programmed CV-9 class aircraft carriers, Bennington (CV-20) and Boxer (CV-21), were ordered on 15 December 1941.

In drawing up the preliminary design for USS Essex, particular attention was directed at the size of both her flight and hangar decks. Aircraft design had come a long way from the comparatively light planes used in carriers during the thirties. Flight decks now required more takeoff space for the heavier fighters and bombers being developed. Most of the first-line carriers of the pre-war years were equipped with flush deck catapults, but owing to the speed and size of these ships very little catapulting was done—except for experimental purposes. With the advent of war, airplane weights began to go up as armour and armament got heavier; crew size aboard the planes also increased. It was inevitable, noted the Bureau of Aeronautics (BuAer) toward the war’s end in 1945, that catapult launchings would become more common under these circumstances. Some carrier commanding officers reported that as much as 40 per cent of launchings were effected by the ships’ catapults.

ytownhangarcat

Six of the early Essex class had an athwartships catapult mounted in the hangar. Here, Yorktown (CV-10) launches a Grumman TBM Avenger in May 1943. All the hangar catapults were later removed.

The hangar area design came in for many conferences between Bureaus and much more official correspondence. Not only were the supporting structures to the flight deck to carry the increased weight of the landing and parked aircraft, but they were to have sufficient strength to support the tricing up of spare fuselages and parts (50 per cent of each plane type aboard) under the flight deck and still provide adequate working space for the men using the area below.

Deckhead spares stowage

“At present,” noted the Bureau of Construction and Repair in April 1940, “it appears that a few of the smaller fuselages can be triced up overhead in locations where encroachment on head-room is acceptable, and that the larger fuselages will have to be stowed on deck in the after end of the hangar. The number to be stowed will depend upon the amount of reduction in operating space in the hangar which can be accepted.”

[Ed. note. On 20 June 1940, the Bureau of Construction and Repair consolidated with the Bureau of Engineering to become the Bureau of Ships (BuShips). ]

CAPT Marc A. Mitscher, then Assistant Chief, BuAer, answered: “The question of spare airplanes is now under reconsideration in correspondence with the Fleet and the results decided upon will have a bearing in the case of CV-9.”

Deck-edge lift

A startling innovation in CV-9 was a port side deck-edge elevator in addition to two inboard elevators. Earlier, BuAer experimented with a ramp arrangement between the hangar and flight decks, up which aircraft were hauled by crane. This proved too slow. Bureau of Ships (BuShips) and the Chief Engineer of A.B.C. Elevator Co. designed the engine for the side elevator. Essentially, it was a standard elevator, 60 by 34 feet (18.3 x 10.4 metres) in platform surface, which travelled vertically on the port side of the ship. CAPT Donald B. Duncan, Essex’s first commanding officer was enthusiastic. After the first four months of operation after commissioning, he wrote to BuAer:

The elevator has functioned most satisfactorily in all respects and it is desired to point out some of the operational advantages realised with this type of elevator.

Since there is no large hole in the flight deck when the elevator is in the ‘down’ position, it is easier to continue normal operations on deck, irrespective of the position of the elevator. The elevator increases the effective deck space when it is in the ‘up’ position by providing additional parking room outside the normal contours of the flight deck, and increases the effective area on the hangar deck by the absence of elevator pits.

The elevator performed well, its machinery less complex than the two inboard elevators and required about 20 per cent fewer man-hours of maintenance. CAPT Duncan recommended that consideration be given using two deck-edge elevators, one on each side. BuAer, in forwarding the recommendation to BuShips, offered another advantage for consideration: a conventional elevator suffering a casualty while in the “down” position “would leave a large hole in the flight deck while the deck-edge type would cause only minor and non-critical loss of flight deck area.”

BuShips, obviously pleased with the operational performance of the new elevator—the first of its kind—reluctantly turned down the recommendation, however. The Bureau noted that the addition of a starboard deck-edge elevator would not permit an Essex class aircraft carrier to transit the Panama Canal. Any other location for a second such elevator would involve structural and arrangement changes too extensive to be considered.

ytownbowlndgfw

Another redundant feature of some early Essex class ships was the bow arrestor gear, to emergency land on aircraft in the event of flight deck damage aft. Here, Yorktown (CV-10) makes 20 knots astern to recover an aircraft across her bow.

Keel laid 28 April 1941

On 28 April 1941, keel for the USS Essex was laid at Newport News Shipbuilding and Dry Dock Co. On 2 October, the following year, her prospective commanding officer filed his first weekly progress-and-readiness report to the Chief of Naval Operations (CNO). He noted that there was marked speed-up of work on the ship during the preceding month and estimated that the ship would probably be delivered on 1 February 1942: “There are certain items that have been authorised for installation on the CV-9-19 class carrier, but will not be accomplished on this vessel prior to delivery.”

Late authorisation

RADM Walter S. Anderson, president of the dock trials and inspection team of CV-9 on 23 December 1942, noted a few of these discrepancies in his report:

Due to late authorisation of a number of changes arising out of recent war experiences, the volume of uncompleted hull work was greater than normal … The Board regrets that the catapults for this vessel were not delivered in time for installation, as military value of the vessel would be much improved thereby … Only the starboard flight deck track was installed … This class of carriers is designed to include cruising turbines as part of the main drive turbine installation. However, due to production difficulties and as a result of efforts to expedite delivery, cruising turbines were omitted. Space and connections for their future installation are provided and this can be accomplished with very little alteration …

Commissioned 31 December 1942

Nevertheless, the Board was pleased and impressed with progress on construction of the Essex. RADM Anderson recommended acceptance of the ship:

“On 31 December 1942, only slightly over 20 months will have elapsed since keel-laying, which is, in the opinion of the Board, a record worthy of commendation.

This indicates a high degree of cooperation between the Supervisor of Shipbuilding, the Newport News Shipbuilding and Dry Dock Co., and representatives of the officers and men of the ship’s company.”

On the last day of 1942, USS Essex was commissioned.

 

essexkamifw

The Essex class were tough. Here USS Essex absorbs a heavily-laden kamikaze strike 25 November 1944. The ship resumed restricted flight operations within 30 minutes and repairs were completed in time for the carrier to resume unrestricted operations three weeks later.


Essex sea trials

CAPT Duncan was proud of his new command, but not so impressed as to ignore certain discrepancies that still existed. The ventilation system, for instance, was less than satisfactory. BuShips sent representatives to the ship to assist in correcting discrepancies, during sea trials March 1 in the North Atlantic and, a month and a half later, when the ship was again at Norfolk and still had complaints.

As other CV-9 carriers were launched, the complaints continued to be registered. BuShips investigated the ventilation system as installed in USS Intrepid (CV-11) and outlined corrective measures in future carriers of the class.

Requested to comment on the adequacy and operation of the trash burner installed in the Essex, CAPT Duncan started off quietly enough. “It is most unsatisfactory,” he said. Then he warmed to his subject:

It is doubtful if it could be worse. It is in the very centre of the office spaces. There is no satisfactory place for collection of trash waiting its turn to be burned. All of it has to be carried through the passageways in the vicinity of the departmental offices. The heat from the trash burner when it is operating (which is not often because it is usually broken down) is such as to make the surrounding spaces almost untenable.

The design of the trash burner is poor. Its construction is worse. The ship had not been in commission a month before it practically fell apart. The brick work fell down, the door fell off and it suffered other casualties too numerous to mention. It has taken constant attention from the Engineer’s force to keep it operating at all and the heat generated in the compartment in which it is located is such that it is physically impossible for men to stay in it for continuous operation.

The trash burner problem was taken in hand and redesigned.

Production line

Lexington was commissioned on 17 February 1943, followed by Yorktown on 15 April, Bunker Hill on 25 May, Intrepid on 16 August, Wasp on 24 November, and Hornet on 29 November that year. In 1944, Franklin was commissioned on 31 January, Hancock on 15 April, Ticonderoga on 8 May, Bennington on 6 August, and Randolph on 9 October. The last of the programmed 13 CV-9s, Boxer, was commissioned on 16 April 1945.

The lighting system installed in the Lexington came under the scrutiny of BuShips. Generally, it was considered inadequate “in intensity and quality” in many passageways and compartments, in addition to the running, signal, and anchor lights. A survey of the system produced the following action on the outside lights: the ahead masthead light was relocated to the forward edge of the foretruck (frame 92), the ahead range light was moved forward and shielded from illuminating the deck below, the astern masthead light was moved higher, so as not to interfere with gunnery, and the astern range light was removed.

Nineteen more

Nineteen more Essex class ships were ordered or scheduled, starting with ten of them on 7 August 1942. They were Bon Homme Richard (CV 31) Kearsarge (CV-33), Oriskanay (CV-34), Reprisal (CV-35), Antietam (CV-36), Princeton (CV-37), Shangri La (CV-38), Lake Champlain (CV-39), Tarawa (CV-40), and Crown Point (CV-32)—later renamed Leyte. The last three ordered were Valley Forge (CV-45), Iwo Jima (CV-46), and Philippine Sea (CV-47). The keels were laid for Reprisal and Iwo Jima 1 July 1944 and 29 January 1945, but both were cancelled on 11 August 1945. Six additional 27,000-tonners, CVs 50 through 55, were cancelled on 27 March 1945.

 

essex1951korea

The Essex class were versatile. USS Essex was the first carrier in the world to operate jet aircraft in combat. Shorn of her five-inch turrets, the straight-deck Essex recovers McDonnell F2H Banshees off Korea in 1951.

In recap, after WW II erupted and until its successful conclusion by Allied forces, the U.S. Navy ordered 32 aircraft carriers of the CV-9 class, of which the keels of 25 were laid down. A total of 17 were actually commissioned during the war years. The total number of CV-9s commissioned—including those commissioned after the war—was 24.

Class characteristics

Several characteristics marked the Essex class carriers upon their introduction to the Fleet. The pyramidal island structure, for instance, rose cleanly from the starboard side, topped by a short stack and a light tripod mast. The port elevator was also a distinguishing feature, along with the two inboard elevators. Ticonderoga, Randolph, Hancock, Bennington and Boxer, as well as hull numbers from CV-31 on, had rounded bows extending beyond the flight deck. Overall lengths varied within this class; they were either 872 or 888 feet long (266 or 271 metres). It is interesting to note that they had a uniform water line length of 820 feet (250 metres). All were armed with 12 five-inch .38 calibre (127 mm) dual purpose guns, but some had 17 quadruple 40 mm anti-aircraft mounts while others had 18. A few also had 20 mm AA armament. Generally, there were accommodations aboard each for 360 officers and 3088 enlisted men.

More SHP

Except for CV-2 and CV-3, Lexington and Saratoga, the power plants were increased over other aircraft carriers in the Fleet. The machinery was “entirely modern in design and arranged so as to gain the maximum resistance to derangement and battle damage. There are eight control superheat boilers arranged in four fire rooms. Steam lines are such that the boilers in each fire room can be connected to one main machinery unit so that the plant can be operated as four separate units.” They had four screws.

These carriers had better protecting armour than their predecessors (again excepting Lex and Sara), better facilities for handling ammunition, safer and greater fuelling capacity, and more effective damage control equipment.

The tactical employment of U.S. carriers changed as the war progressed. In early operations, through 1942, the doctrine was to operate singly or in pairs, joining together for the offence and separating when on the defence—the theory being that a separation of carriers under attack not only provided a protective screen for each, but also dispersed the targets and divided the enemy’s attack. Combat experience in those early operations did not bear out the theory and new proposals for tactical deployment were the subject of much discussion. As the new Essex and Independence class carriers became available, these new ideas were put to the test.


Independence class

The Independence class carriers—light carriers, designated CVLs— were products of an effort to increase this country’s seagoing air strength in the early days of the war. Nine keels to light cruisers of the Cleveland class were laid down at the New York Shipbuilding Corp. yard at Camden, N.J. They were to have been the Amsterdam (CL-59), Tallahasee (CL-61), New Haven (CL-76), Huntington (CL-77), Dayton (CL-78), Fargo (CL-85), Wilmington (CL-79), Buffalo (CL-99), and the Newark (CL-100). They eventually became the Independence, Princeton, Belleau Wood, Cowpens, Monterey, Langley, Cabot, Bataan, and San Jacinto, CVLs 22 through 30, respectively.

Naming and designating these last four sometimes went through a rigorous and confusing metamorphosis. Neither Cabot nor Bataan encountered any difficulty. The names and designations were reached in June and July 1943 without attending problems, but Fargo was named Crown Point (CV-27) when the decision was reached to convert her to an aircraft carrier.Then, on 15 July 1943, her name was changed to USS Langley and she was given the designation CVL. (Actually, all these cruiser-to-carrier conversions were originally designated CVs when the decision to convert was made; all were redesignated CVLs on the same day.)

The Newark (CL-100) had a rougher time of it. On 2 June 1942, she was changed to CV-30; on 23 June, her name was changed to Reprisal, which she kept for a little over six months. On 6 January 1943, her name was again changed, to San Jacinto.

Light carrier design

The light carriers displaced 11,000 tons standard. In design, the bridge was box-like in appearance, with a small crane forward. They had four stacks, paired off in twos, on the starboard side, aft of the island. These stacks angled out from the hangar deck and rose vertically above the flight deck level.

As the Essex and Independence class carriers joined the Fleet in increasing numbers, it was possible to operate several carriers together, on a continuing basis, forming a carrier task group. Tactics changed. Experience taught the wisdom of combined strength. Under attack, the combined anti-aircraft fire of the task group carriers and their screen provided a more effective umbrella of protection against marauding enemy aircraft than was possible when the carriers separated. When two or more of these task groups supported each other, they constituted a fast carrier task force.

Multi-carrier group

The first attempt to operate a multi-carrier group occurred on 31 August 1943, during a raid on the Japanese-held island of Marcus. Task Force 15, which conducted the raid, consisted of Yorktown (CV-10), Essex (CV-9) and Independence (CVL-22), the cruisers Nashville and Mobile, the battleship Indiana, and ten destroyers. Aircraft were launched from the carriers at a point approximately 130 miles north of the island.

 

essex1967

The Essex class was durable. By 1967 USS Essex had an angled deck, mirror, twin catapults and enclosed bow.

On 5-6 October 1943, RADM Alfred E. Montgomery led Task Force 14 on a second raid on Wake Island. The task force comprised two task groups, operating a total of six aircraft carriers—Essex, Yorktown (CV-10), Lexington (CV-16), Independence, Belleau Wood, and Cowpens—seven cruisers and 24 DDs, the largest carrier task force yet assembled.

In the course of the two-day strikes, ship handling techniques for a multi-carrier force, devised by RADM Frederick C. Sherman’s staff, were tested under combat conditions. ADML Chester W. Nimitz, then Commander in Chief, Pacific Fleet, dispatched his congratulations to the task force. His words were prophetic. Lessons learned from operating the carriers as a single group of six, as two groups of three, and three groups of two provided the basis for many tactics that later characterised carrier task force operations. With the evolution of the fast carrier task force and its successful employment in future operations, the rising sun of the east began slowly to sink in the west.


Carrier Evolution IX: Escort CVEs

USN Carrier Evolution IX: Escort Carriers

Ninth article in a series by Scot MacDonald. Reprinted with permission: Naval Aviation News, December 1962 pp 49-53.

“The story of the escort aircraft carriers is like a story with a surprise ending. When the United States began to build them, there was a definite purpose in view—fighting off submarines and escorting convoys. But as the war progressed, the small carrier demonstrated surprising versatility. It became a great deal more than its name implies. From a purely defensive measure, the escort carrier emerged as an offensive weapon.”—FADM Chester W. Nimitz, USN, CinCPacFlt/CinCPOA, 1945.

Toward the end of World War I, Great Britain experimented in converting light cruisers to aircraft carriers—notably in HMS Cavendish, of 32 knots and about 10,000 tons displacement. But with the signing of the Armistice, the project was abandoned. Despite this, it was a subject of interest in the following years.

Vindictive
Where it all began: HMS
Vindictive (ex-Cavendish) was laid down as a Hawkins class cruiser and converted to an aircraft carrier, carrying 12 aircraft, in June 1918. The flight decks were removed and the ship reconfigured back to a cruiser in 1924.

Cruiser conversion considered in 1925

In 1925, the General Board seriously considered the conversion of cruiser hulls to aircraft carriers. Although treaty limitations restricted the building up of carrier strength, there was sufficient uncommitted construction tonnage to permit the building of more carriers than the U.S. Fleet had. Could this uncommitted tonnage be best employed in building small carriers? The Board’s answer can best be summed up in this excerpt from its report:

Incomplete studies of the subject by the Bureau of Construction and Repair and the meagre information available concerning the performance of airplanes from carriers of approximately 10,000 tons displacement does not justify building them at this time.

1927 analysis

But the subject of “light” carriers was of recurrent interest to the U.S. Fleet. In May 1927, LCDR Bruce G. Leighton prepared a paper in which he analysed the problem. He titled it: Light aircraft carriers: A study of their possible uses in so-called “cruiser operations,” comparison with light cruisers as fleet units.

Though the title may have been cumbersome, the document was impressive. He forecast every fundamental combat requirement of the latter-day CVLs and CVEs, including the bombing of capital ships, support of fleet operations, anti-submarine work, scouting and reconnaissance, and the reduction of enemy shore bases. He concluded that “all things considered, it might well be considered as a worthy substitute for the light cruiser, or even distinctly preferable to the cruiser.”

John S. McCain Sr

For the next dozen years, the subject interjected itself spasmodically and unsuccessfully into Navy thinking. But in March 1939, CAPT (later ADML) John S. McCain Sr, then commanding the Ranger, wrote to the Secretary of the Navy advocating the building of at least eight “pocket-size” carriers of cruiser speed. These were not meant to replace the CVs, but to supplement them, giving force commanders much more flexibility in the use of ship-based aircraft at sea, without jeopardising the much more costly heavy carriers. RADM (later FADM) Ernest J. King, in his endorsement to the letter, was not at all enthusiastic about this scheme. He suggested that existing aircraft carriers carry the maximum number of planes permissible as a better solution than the construction of smaller carriers.

The matter was not entirely dropped, however, for the Bureau of Construction and Repair was considering and even drawing plans for the conversion of 20- or 21-knot passenger ships, creating experimental carriers with short flight decks. By November 1940, the Chief of Naval Operations brought these considerations to an abrupt halt, basing his decision on a letter from SecNav to the Chairman of the U.S. Maritime Commission. SecNav wrote:

The characteristics of aircraft have changed, placing more exacting demands upon the carrier. These demands are such that a converted merchant vessel will no longer make as satisfactory an aircraft carrier as was the case when the plans for those vessels were being drawn.

Presidential influence

In commenting on the beginning of escort carriers, historian LEUT William G. Land, USNR in Functional development of the small carrier (CVE) says, “The escort carrier was forced upon the Navy by the President.”

Indeed, President Franklin D. Roosevelt did actively enter the “light” carrier controversy. Great Britain had been at war with Germany since September 1939. Since that time and before the U.S. entered the war, large numbers of U.S.-built military aircraft were sold to the British. The U.S. had need for an aircraft-carrying ship to speed delivery. By mid-February 1941, RADM W. F. Halsey (later FADM) had written to Commander-in-Chief , U.S. Fleet:

A previously stated expectation, that the Navy would be called upon to provide transport for Army aircraft, has now materialised in the current diversion of Enterprise and Lexington to transport 80 pursuit planes from the West Coast to Hawaii. To continue with primary reliance on aircraft carriers for such work, as is our present necessity, seriously endangers the availability of air-offensive power in the Fleet.

ADML Husband E. Kimmel, in endorsing this letter from his Commander Aircraft Battle Force to the Chief of Naval Operations, fully concurred and pointed out that on five separate occasions in the past he had himself urged such action.

Helicopter carrier?

Earlier, on 21 October 1940, CNO had received a memorandum from the President’s Naval Aide advising him that President Roosevelt proposed the Navy acquire a merchant ship and convert it to an aircraft carrier, accommodating eight to twelve helicopters (not yet operated by the Navy) or aircraft capable of landing or taking off in a small space. The purpose of this type carrier was to “provide quick conversions for carrying small planes which could hover ahead of convoys, detect submarines and drop smoke bombs to indicate their locations to an attacking surface escort craft.”

Tracker
HMS Tracker, an escort carrier with 816 Squadron Swordfish embarked.

CNO decided on the last day of 1940 that the Chairman of the Maritime Commission would be consulted to determine the availability of ships for this purpose. On January 2nd, it was found that two Danish ships might permit conversion, but later investigation proved this would not be possible.


Standardisation

The results of this January 2 conference determined that the two ships (one was to be sold to Great Britain ) selected:

Should be of the same or very similar design in order that the plans made for one could be applicable to both; that the airplanes should be further investigated to determine the type and availability; that an armament of four AA pom-poms and one five-inch surface gun should be such as to insure stability at all stages of loading.

These converted merchant ships were to fill the need later expressed by (then) ADML Halsey, the transport of aircraft, as well as to provide protection to Allied convoys.
On 6 January 1941, ADML Harold R. Stark, CNO , convened a conference in his Washington office to discuss merchant-conversion. The autogyro type aircraft was considered of dubious usefulness because of its inability to carry any load other than smoke bombs; an aircraft, to meet the purpose designed, must have some offensive characteristics. An abbreviated deck was ruled out. The converted ship should be diesel-driven in order to eliminate smokestacks. The decision was made to obtain from the Maritime Commission, if possible, C-3 cargo ships.

Two diesel C-3s

On the following day, CNO was informed that two diesel-driven C-3 type ships, the Mormacmail and the Mormacland, would be suitable for conversion and were available. He was told by President Roosevelt that any plan that would take more than about three months to complete conversion would be unacceptable. This, in effect, placed pressure on the project. The idea of substituting “blimps” for autogyros or heavier-than-air craft was flirted with but, by January 15, was “out of the picture.” The Mormacmail was acquired on 6 March 1941. On June 2—just within the three-month limitation set by the President—she emerged from conversion and was placed in commission as the aircraft escort vessel USS Long Island (AVG-1), commanded by CMDR Donald B. Duncan who, on 31 December 1942, was to become the first commanding officer of USS Essex.

C3 Cargo version

Attacker

The American Maritime Commission’s C-3 type hull was versatile. It lent itself to superstructures ranging from sleek cargo-passenger ships (top) to aircraft carriers, such as the Bogue class HMS Attacker where steel trusswork supported a lightweight wooden flight deck. Early vessels had an aircraft lift and small hangar aft with a single catapult forward. Later versions might have an extended hangar, two lifts, two catapults and even a rudimentary island. The extended hangar presented some problems in that the hangar deck followed the natural sheer of the C-3 main deck, making aircraft easy to stow but requiring a difficult up-hill push to range. These CVEs accommodated 16 to 28 aircraft in a hull that displaced about 14,400 tons and measured 491 x 105 x 26 ft (150 x 32 x 7.9 metres). Early ships had four seven-cylinder diesel engines but later versions had a steam turbine that delivered about 8,500 SHP to a single screw, good for 16 to 18 knots. WW II crew size varied from 408 in the USN to 646 in the RN.

Early plans for the conversion called for the installation of a 305-foot (93 metres) flight deck on the Mormacmail, but the Bureau of Aeronautics required at least 350 feet (106.6 metres) to safely land SOC Seagulls aboard. Upon commissioning, Long Island had a deck length of 362 feet (110.6 metres). She had one elevator, handled 16 planes, had a trial run speed of 17.6 knots and berthed 190 officers and 780 men.

The Mormacland, acquired at the same time, was similarly converted and was turned over to the British as HMS Archer (BAVG-1) when it was completed the following November. Experience with the BAVG and the two British conversions led the British to believe that the diesel-driven ships were too slow for their purpose as special escort vessels—although they were no slower than the later Bogue carriers.

(Ed. note: The British also found some early diesel propulsion units seriously unreliable. For instance, despite major dockyard repairs in 1943, the diesel-driven HMS Archer was reduced to stores and maintenance duties after completing only two missions.)

Training and trials ship

Long Island was used primarily as a training ship during the remaining peacetime months of 1941. She was subjected to tests and experiments—much the way USS Langley had been in her early days—to obtain data needed for the construction of later escort carriers. As a result of the Navy’s experiences with this ship, other CVEs were outfitted with two elevators instead of one, the flight decks were lengthened, and the anti-aircraft power was increased.

On 26 December 1941, SecNav approved the conversion of 24 merchant hulls for the 1942 shipbuilding program and, in March, ordered the conversion of cruiser hulls, which became the CVLs. LCDR Leighton’s 1927 paper was proving its farsightedness.

Naval aviation historian Henry Dater traced the next developments in a paper published in Military Affairs:

There were only 20 C-3 hulls available for conversion, ten of which were earmarked for the Royal Navy and ten for the United States .  
The new ships were improved by the substitution of a steam turbine power plant for the diesel engines employed in the Long Island and Charger (the latter was redesignated CVE-30 and replaced CVE-1 as a training ship when the Long Island was pressed into service, ferrying planes and pilots at the outbreak of war), and by the addition of a slightly larger flight deck (436 x 79 feet; 133 x 24 metres), a small island, and a considerably larger hangar space.
They were referred to either as the CVE-6 class, from the numerical designation of HMS Battler, or as the Bogue class, from the first ship to operate with the U.S. Navy.
The remaining four CVEs authorised for the 1942 program were converted from Cimarron class fast fleet oilers and were known as the Sangamon (CVE-26) class. These were considerably larger, having a flight deck of 503 feet by 85 feet (153 x 26 metres), and were able to accommodate two small squadrons of aircraft. Because of their size, work was rushed on them during the summer of 1942 so that they would be available for the North African invasion in the autumn.

Easy pickings

Before the U.S. entered the war, German U-boats hovered near British coastal ports and picked off merchant ships with ease. Land-based RAF planes drove the German submarines further out to sea. To make matters more difficult for the enemy, convoys sailed closer together, opening up larger areas of the North Atlantic for the German subs to search. The Germans solved this problem by developing the “wolf pack” technique of operating in groups, then concentrating for the kill when convoys were sighted.

Henry Dater wrote:

It was this technique which created the British desire for aircraft escort vessels in late 1940 and 1941. With the entry of the United States into the conflict the Germans found easy pickings off the American coast, but it was only a matter of time until land-based air on this side of the Atlantic drove them out to sea once more. There, in mid-ocean, was a vast area in which the convoys did not have the assistance of aircraft. By early 1943 it became evident that the decisive campaign was to be fought in that area.

CVEs
Not highly regarded for their steady deck properties, The CVEs were allotted the “will roll on damp grass” category by pilots.

Escort procedures

The air officer of the Bogue described escort procedures during March and April 1943:

The ship was stationed inside the convoy for this work. The convoys were in columns of five ships each with about 700 yards between columns.
They left a double space in the middle in the centre of which they placed the Bogue. The other escorts were placed around the convoy in a half circle. The idea was, if possible, to use our catapults and to stay in our centre position when launching our planes so there wouldn’t be any wide separation. As it happened, we had westerly winds on the east-bound convoy so we had to turn around to launch planes and to take them aboard. Consequently, the separation was fairly large due to the fact that it was what is called a high speed convoy, “nine knots!”

Hunter-killer tactics

Though this tactic met with considerable success at first, it was primarily defensive. A new technique was found more effective. A small task group took up a position where it could throw its support to either of two convoys in a general area. Escort carrier-based aircraft scouted ahead, searching out German U-boats before the submarines could make contact. This permitted the carriers to be released from the difficult manoeuvre necessary in the central slot of the convoy. Out of this technique emerged the successful hunter-killer tactic that eventually freed Allied shipping in the North Atlantic.

 


The Sangamon class escort carriers, built as fleet oilers under the Merchant Marine Act of 1936, were completed in 1939, but in the 1942 shipbuilding program were slated for reconfiguration as aircraft carriers. Only four hulls were on hand. “Had more oiler hulls been available,” wrote LEUT Land, “they would have become the prototype of the small carrier for the ensuing year’s program. But the overwhelming need for fleet oilers—to make possible our logistic advance—prevented this type of hull from being again used for carriers, until 1944.”

Sangamon oiler

Sangamon CVE

SangamonKami
Launched as the
Esso Trenton on 4 November 1939 and purchased by the USN 22 October 1940, USS Sangamon (AO-28) served initially as a tanker (top). One of the largest USN escort carriers, she was the lead in a four-ship class and completed her conversion (ACV-26, later CVE-26) on 20 August 1942 (middle). Sangamon was damaged by a kamikaze in a night attack, 4 May 1945 (bottom). With all bridge communications and all aircraft but one destroyed, that aircraft became her only means of radio communication with the fleet. Sangamon returned to Norfolk for repairs that were halted by Japan’s surrender.

Sangamon dimensions

The Sangamons had an over-all length of 553 feet (168.6 metres), a speed of 18.3 knots, a trial displacement of 23,235 tons, and carried 120 officers and 960 men. They were armed with two five-inch, 38 calibre guns, two quad and ten twin 40mm AA mounts. They were equipped with two hydraulic catapults forward.

Historian Land wrote:

With the CVs, except Ranger, being employed in the Pacific, planning for the North African landings depended on the completion of the AO conversions of Suwannee, Sangamon, Chenango and Santee. For this reason, Suwannee had to cut down on its pre-commissioning period, fitting out and shakedown in order to be substituted in the final plans for the much smaller Charger, the ex-BAVG that had been doing regular duty as qualification carrier in Chesapeake Bay. Santee, likewise, was barely completed in its essentials and had had hardly any exercise with its air group before its first combat operation was to begin.

CAPT William D. Sample, commanding Santee, wrote of the hectic early days aboard:

Santee left Norfolk Navy Yard 13 September 1942 with yard workmen still on board and her decks piled high with stores. During that first month, Santee returned to the yard twice and was never free of the yard workmen. The completion of the ship continued while the fitting out and shake-down were proceeding together. At the end of the month, the air group had operated aboard only a day and a half and guns had been fired only for structural tests…The Navy Yard had done an almost impossible task in getting the ship out in time for the pending operations but, in so doing, only the essentials had been completed, and it was then necessary for the ship to install, adjust, calibrate and repair until the ship could use her battery and equipment…The service experience necessary to test many of the questionable features of the ship’s design was soon obtained in a wintry gale encountered en route to Bermuda. The two forward boats were carried away, the new upper decks proved to be sieves and the repair work of the ship’s force got underway in earnest.

Chenango
The first of a pair of USAAF P-40 Warhawks catapults from USS
Chenango to explore Port Lyautey runway serviceability in support of the Casablanca landings. The P-40s had no hook and once airborne were forced to land somewhere solid, other than the aircraft carrier from which they launched. The Port Lyautey airfield had been very effectively bombed by USN aircraft and both aircraft crashed while attempting to land between the bomb craters. Despite futile efforts to stop them, 85 more Chenango P-40s arrived overhead some 45 minutes later. Of these, 20 were destroyed attempting to land.

Aircraft ferry

The carrier Chenango was used, in the North African operation that followed, as a ferry carrier for Army P-40s on the outward trip, as a fuel supply ship while moored at Casablanca, and as a fleet escort, with a borrowed air group furnishing air cover, on the return trip. Her sister ships, however, launched TBF-1 Avengers, SBD-3 Dauntless and F4F-4 Wildcat aircraft in support of landing operations for the capture of Casablanca and Port Lyautey. They were units of Task Force 34.

As part of the Northern Attack Group, Sangamon and Chenango assisted troops landing at Mehedia, not far from Port Lyautey (now Kenitra). Ranger and Suwanee provided air cover for the Centre Attack Group at Fedhala, northeast of Casablanca. Santee was the only carrier assigned to the Southern Attack Group, providing combat air patrol and anti-submarine patrol for the landing force at Safi —the only port in Morocco, other than Casablanca, that would permit the landing of 28-ton General Sherman tanks. It was for the capture of Casablanca that these tanks were needed.
Between 8-11 November 1942, Suwanee launched 255 combat sorties; Santee, 144, and Sangamon, 183.

Neutralise airfield citadel

During Sangamon ’s participation in the Northern Attack Group operation, her planes were called upon to neutralise a kasbah or citadel that guarded the Port Lyautey airdrome. Several SBDs delivered bombs on target. “The garrison then,” wrote Samuel Eliot Morison, “came out with their hands up and our infantry walked in.” By November 15, Sangamon’s part in the invasion of North Africa was completed and she sailed for Hampton Roads.

Planes in the Suwanee joined those based in the Ranger in bombing missions during the Battle of Casablanca. The Suwanee, like the Santee at Safi, encountered light winds. Many landings were made aboard with only 22-knot winds across the deck.

Despite the greenness of the crews in escort carriers, generally, they gave a good account of themselves, according to CinCLant:

The CVEs proved to be a valuable addition to the Fleet. They can handle a potent air group and, while their speed is insufficient, they can operate under most weather conditions and are very useful ships.

Their missions in the invasion of North Africa completed, Sangamon, Chenango, and Suwanee were dispatched to the Pacific. By the end of 1942, U.S. carrier strength in the Pacific had been reduced to the Enterprise and the Saratoga.

 


Mass production

In the meantime, President Roosevelt announced a need for more escort carriers. Shipbuilder Henry J. Kaiser had impressed the President with the merits of a plan which would permit the mass production of escort carriers, under a program to be supervised by the Maritime Commission.

Casablanca class

 

There were more Casablanca (aka Kaiser) class aircraft carriers built (and lost in action) than any other class of carrier in WW II: Liscombe Bay (CVE-56) was torpedoed by the Japanese submarine I-175 on 24 November 1943, Gambier Bay (CVE-73) was sunk by IJN Centre Force gunfire in the Battle of Samar on 25 October 1944, St Lo (ex-Midway) (CVE-63) was struck by a kamikaze in the Battle of Samar on 25 October 1944, Ommaney Bay (CVE-79) on 4 January 1944 was hit by a kamikaze in the Sulu Sea and Bismarck Sea (CVE-95) took two kamikaze hits off Iwo Jima on 21 February 1945. The Casablanca class had two five-cylinder reciprocating engines, four boilers and two shafts.

The first of these, USS Casablanca (CVE-55), was commissioned 8 July 1943, and gave its name to the class—CVE-55 through CVE-104. They were also referred to as Kaiser class escort carriers. The Kaiser yard completed its 50-ship program on 8 July 1944. This was an impressive achievement in a wartime production program.

Dimensions

The Casablanca class had an overall length of 512 feet, 3 inches (156.1 metres), a speed of 19.3 knots, a trial displacement of 9570 tons, and carried 110 officers and 750 men. They had one five-inch (127 mm), 38 calibre gun and eight twin 40 mm AA mounts. The aircraft complement consisted of 12 Grumman Avenger TBMs and 16 Grumman (General Motors-built) Wildcat FM-2s; on the flight deck was a single hydraulic catapult, forward. Final details were worked out for a new class escort carrier during the trials of the Sangamon and Santee and during the planning for the 1944 building program. These ships were the first Navy-designed escort carriers for which hull and propeller model tests were carried out at the David W.Taylor Basin. The design was formally approved by CNO on 10 December 1942 and the contract was let on 23 January 1943.

The first of these carriers was the Commencement Bay (CVE-105) from which the class got its name. It had an overall length of 557 feet (169.8 metres), a speed of 19 knots, and a trial displacement of 23,100 tons. Few of these ships saw action in the war—the Commencement Bay was commissioned in November 1944. Only nine others were commissioned before V-J Day the following August. They incorporated all lessons learned since the Long Island was commissioned.

As the escort carriers gained experience, they earned the respect of the Fleet by proving themselves versatile in anti-submarine warfare. The Sangamon class first demonstrated combat capability in the support of the North African invasion. The first major carrier-supported amphibious landing in the Pacific was the capture of the Gilberts and Marshalls. Eight escort carriers participated, two of the Bogue class, three of the Sangamon class, and three of the Casablanca class. The changing status of these vessels is reflected in their redesignation. Originally identified as aircraft escort vessels (AVGs), they were redesignated on 20 August 1942, as auxiliary aircraft carriers (ACVs, and finally, on 15 July 1943, a directive changed the escort carrier symbol to CVE, reclassifying them as combatant ships.

Effectiveness

At the end of the North African invasion, CAPT (later VADM) Calvin T. Durgin evaluated the effectiveness of the escort carriers when he presented his report:

Due to their low speed, lack of protection and light armament, it is considered hazardous to employ a CVE group in operation where there is likely to be an effective enemy opposition. Such a group can, however, be used to advantage, and is capable of inflicting substantial damage to the enemy in assault where the enemy air and sea opposition is negligible or when it is being contained by other superior forces. When this situation exists, the CVE is well equipped to provide all support until landing strips are established ashore, and it can be effectively employed for bombardment spotting, combat air patrols over beaches and surface forces, for all forms of air reconnaissance missions and for bombing, rocket and strafing attacks.

His experience with escort carriers was to stand him in good stead. On 13 December 1944, the functional type command, Escort Carrier Force, Pacific, was created; RADM Durgin was placed in command.

The establishment of this force was made possible by the increasing number of carriers—notably of escort design—made available to the Fleet. Experience at Palau and Morotai and the difficulties encountered later at Leyte all pointed to the need for better planning in advance of operations if the CVEs were to perform efficiently their enlarged responsibilities. RADM Durgin’s command held administrative control over all escort carriers operating in the Pacific, except those assigned to training and transport duty.

On 15 December 1944, the escort carriers provided direct support for landings on Mindoro, and in the assault area on the next two days. Between 3-22 January 1945, 17 escort carriers covered the approach of the Luzon Attack Force against serious enemy air opposition from kamikaze pilots. This force of ships, Task Group 77.4, conducted preliminary strikes in the assault area, covered the landings in Lingayen Gulf , and supported the inland advance of troops ashore. In 1945 the CVEs saw a great deal of action. On the last three days of January, six escort carriers under RADM Sample (as CAPT, first C.O. of Santee) provided air cover and support for landings by Army troops at San Antonio near Subic Bay, and at two other nearby Philippine beaches.

Iwo Jima

In February, RADM Durgin directed his carriers in the battle for the capture of Iwo Jima. In March, the Okinawa campaign began, the last, and, for naval forces, the most violent major amphibious campaign of World War II. As Task Group 52.1, RADM Durgin, with an original strength of 18 escort carriers, conducted pre-assault strikes and supported the occupation of Kerama Retto, joined in the pre-assault strikes on Okinawa, and, from a fairly restricted operating area south-east of the island, supported the landings and flew daily close support for operations ashore until the island was secure on June 21.

The U.S. suffered few losses to the enemy in these ships. Five carriers of the Casablanca class were lost in the Pacific; one Bogue class was torpedoed in the Atlantic. During the war years, 76 CVEs of various classes were commissioned, in addition to the Long Island, commissioned months earlier. Seven more Commencement Bay class were commissioned during the post-war years. During the war, four sister ships to Long Island were transferred to the British, as were 34 additional escort carriers of the Bogue class. Four were sunk; at the end of the war, the rest were returned to the U.S. from Lend-Lease and were either sold or placed in the reserve fleet.

ASW victories

Through fulfilling a basic need of transporting large numbers of assembled aircraft to various theatres of war, the quickly conceived and executed escort carrier developed into an anti-submarine warfare weapon that defeated the German U-boat threat in the North Atlantic. They provided combat capability in the support of fleet operations in both the Atlantic and the Pacific. In short, they displayed a versatility, proved under the pressures and urgencies of a war that engulfed the world.

Rendova

Rendova was a Commencement Bay class CVE, and one of HMAS Sydney’s “oppo” carriers in Korea. Seen here with Marine F4U Corsairs on deck, 6 May 1952, the two carriers destroyed bridges and stopped all daylight transport movement in their allotted operational area.

 


Carrier Evolution X: Battle CVAs

USN Carrier Evolution X: The battle carriers

Tenth article in a series by Scot MacDonald. Reprinted with permission: Naval Aviation News, January 1963, pp 54-56.

The life of the Midway also demonstrates the progress of our Navy; the accommodation of our ships to aircraft of high performance; the use of missiles; exploitation of electronics; the capability to employ a whole family of weapons unheard of when her keel was first laid. No other navy, no other service of any country, has a single military unit as powerful, as versatile and as mobile as this great ship.—VADM George W. Anderson, Jr., Chief of Staff, U.S. Pacific Command, 1957.

Like the CVEs, the CVBs (now CVs or CVNs) were a direct product of World War II needs and experience, though their missions were different. The former were to be most effective in providing close support of troop landings. The latter was designed to pit against the enemy the most potent aircraft carrier the world had yet seen.

Tough, rugged

The CVBs were to provide a solution to the problem of designing a tough rugged ship that would have good aircraft operating features as well as every possible characteristic that would enable it to both give and take punishment. Our early war losses were caused by our failure to adequately control damage sustained. It was obvious that we needed a much sturdier aircraft carrier than we operated in the early years of the war, one with an armoured flight deck and improved compartmentation. The resulting design gave us a new breed of ship, battlecruiser fast, battleship rugged, and with more aircraft operating capacity than anything we had known.

USS Midway

USS Midway (CVB-41) was the first of six planned carriers of a new design. Construction began during World War II. Toward the end of hostilities, three of the new carriers were cancelled. Upon delivery, the Midways were the mightiest aircraft carriers in the world.

Faster, heavier aircraft

At the same time, aircraft designers were producing larger, heavier types to be operated off seagoing carriers. These higher performance planes, heftier, faster, would place great demands on the flight decks of the proposed CVBs. The planes would require greater room, and these considerations added to the overall weight of the constructed carrier.

On 9 July 1942, Congress authorised their construction. Already, the toll on both U.S. and Japanese carriers had been heavy. In January that year, Saratoga was damaged by submarine torpedo and forced to a yard for repairs. In the Battle of the Coral Sea in May, the light carrier Shoho was sunk by U.S. carrier-based planes which, the next day, also damaged the Shokaku. In this battle, the Yorktown was damaged; the Lexington, ravaged by uncontrollable fires, sank. During the decisive Battle of Midway, the Imperial Japanese Navy lost the Akagi, the Kaga, the Hiryu, and the Soryu. Yorktown, already damaged at Coral Sea, was hit again at Midway and on 7 June was sunk.

Midway: Turning point

Midway was a significant victory for the Allied forces. While proving a turning point in the war, it again conclusively demonstrated the warfare potential and, in fact, superiority of carrier aviation. To commemorate the occasion, the escort carrier CVE-63 was named USS Midway, but on 15 September 1944, her name was changed to USS St. Lo, relinquishing her name to the first of a new class aircraft carrier then being built, USS Midway (CVB-41).

This battle carrier was laid down on 27 October 1943. A sister ship, CVB-42, was laid down as USS Coral Sea on 1 December 1943, but upon the death of the President, was renamed USS Franklin D. Roosevelt. The third large aircraft carrier built, CVB-43, became USS Coral Sea. Contracts for the new carriers were signed 7 August 1942, and by 18 September, plans for them were well under way. On that date, the Chief of the Bureau of Ships wrote to the Commander in Chief, U. S. Fleet, to the Vice Chief of Naval Operations and to several Bureau chiefs, discussing the proposed contract design:

It will be noted that the island is shown offset from the side of the flight deck to the maximum extent permitted by clearance for passage of the Panama Canal. This location of the island has the obvious advantage that a straight fore and aft flight deck runway for airplanes is interfered with to the least possible extent. It gives a flight deck width in way of the island of 107 feet (32.6 metres).


Panama Canal transit

This was one of the last times the Panama Canal was a limiting factor in the construction of aircraft carriers. The “Canal block” was broken when it was later decided to construct a carrier not to go through it.

Concerning the island structure, BuShips continued:

Extensive wind tunnel model tests of the CV-9 class island with a large number of modifications involving various degrees of streamlining and attempts to reduce smoke nuisance on the flight deck caused by stack gases have been performed. These studies showed clearly that the details of island contour were of negligible importance in effect upon air-flow patterns as compared with the bulk of the ship and of the island itself. In view of these conclusions, attempts to streamline the various essential protuberances on the island and of the island itself were discarded in the case of the CV-9 class and, therefore, have not been incorporated in the present plans.

Island structure debate

The island structure was the subject of considerable correspondence in the months and years following. There was an obvious effort by most bureaus to keep the island as small as possible. In this there was general agreement. Comment and discussion became extensive when locations of specific spaces in the island were brought up, as well as uses to which they would be put. Occasionally, proposed requirements threatened to bloat the island structure, but as alternate locations were found, it was possible to keep it to a reasonable size. In October 1942, for instance, the Chief of the Bureau of Aeronautics, RADM John S. McCain, noted:

Location in the island of the following space, the functions of which do not necessarily require island space is noted: Pilot balloon room, two squadron lockers, Repair I, flight deck crew, flight deck control, flight deck equipment, and one unassigned space … This bureau considers that effort should be continued to reduce island size.

Hangar deck catapult

The original proposals called for the installation of two flush deck type catapults capable of launching VT type aircraft and one double action type in the hangar, capable of launching fully loaded VSB type aircraft. But by October 1942, the General Board considered the complications involved in the installation of a hangar catapult and decided against it. Within the year, the decision was reached to eliminate hangar catapults from Essex class carriers, then either under construction or planned.

Hangar fires resulting from combat damage offered particular danger in both Japanese and U. S. aircraft carriers during the early days of the war. In designing the CVB-41 class carriers this danger was considerably lessened by the introduction of four bulkheads in the hangar, dividing it into three spaces connected by sliding doors.

Underwater subdivision of compartments and spaces was given considerable attention, in event of torpedo or mine hit, and was described as “excellent.” To provide additional protection, the flight deck was armoured with 3½ inches (8.9 cm) of solid steel, and the deck side belt armour at the waterline tapered from 7½ inches (19 cm) to three (7.6 cm).

The long, hard slog

In 1943, the wave of war in the Pacific turned against the Japanese as Allied forces made a concerted offensive, capturing Rendova Island in July. The Japanese-held airfield at Munda in New Georgia Island was taken by the Allies, who invaded Bougainville in October and landed on the Gilberts in November.

That same year, U. S. shipyards launched and the Navy commissioned another 15 CVs and 24 CVEs.

In early 1944, the Marshalls were taken. On the first day of this operation, complete control of the air was obtained and maintained by carrier-based aircraft. The Marianas were invaded in June and Guam recaptured in August. Leyte was occupied in October-November, the opening blows struck by Task Force 38 under VADM Marc Mitscher. American shipyards, mass production well organised, launched seven more CVs and 33 more CVEs.

Okinawa

From 18 March to 21 June 1945, the Okinawa campaign raged. The desperate Japanese had already turned to the Kamikaze strikes and now introduced the Baka bomb, seriously damaging the carrier Franklin. Between May and August, carrier-based aircraft were launched against the Japanese home islands, destroying or immobilising the remnants of the Japanese Navy.

On 2 September, the formal terms of surrender were signed and World War II was over. Eight days later, on 10 September, USS Midway was commissioned, the first of the CVBs, CAPT Joseph F. Bolger commanding. In the following month, on 27 October 1945, USS Franklin D. Roosevelt (CVB-42) was commissioned. Construction on USS Coral Sea (CVB-43) was delayed, the ship finally being commissioned on 1 October 1947. Three additional CVBs, the 44, 56 and 57, were cancelled.

Midway V2aMidwayV2bMidwayV2c

USS Midway, on 6 September 1947, conducted Operation Sandy, the first launch of a heavy ballistic rocket (a captured German V2) from a moving platform. The liquid-fuelled rocket travelled only a small distance before blowing up, with most of the debris landing six miles or so from the launch point. The USN opted for solid-fuelled rockets after this experience.

Midway was a giant among aircraft carriers. She had an overall length of 968 feet (295 metres), an extreme beam of 136 feet (41.5 metres) at the flight deck, and had a standard displacement of 45,000 tons. Midway had a trial speed of 33 knots, four propellers and a shaft horsepower of 212,000.

She was armed with 18 five-inch (127 mm)/54 calibre single double-purpose guns, and 21 quad 40mm A.A. mounts. Like the Essex class carriers, CVB-41 had a deck-edge elevator in addition to her forward and aft elevators. She accommodated 379 officers and 3725 enlisted.

 


Subtle differences

These general characteristics held true for her sister ships. But there were subtle differences, especially in the case of the Coral Sea. Comments in correspondence during construction of the Midway indicated that a large number of minor modifications, learned in the construction of the CV-9 class carriers, the Midway herself, and from wartime experiences, would be incorporated in the final design of CV-43.

Midway had her shakedown in November 1945. Her aircraft aboard consisted of 57 F4U-4 Corsairs, 59 SB2C-4E Helldivers and four F6F Hellcats, totalling 120 aircraft, 17 fewer than her full complement of 137.

The carrier’s nucleus crew came from a Carrier Aircraft Service Unit (CASU) under ComAirLant. Plane handlers were sent to Great Lakes where they boarded the training ships Sable and Wolverine for an approximate six-week period, during which they learned basic carrier work.

Handler training

The February Naval Aviation News of 1946 described their later training:

The men then proceeded to a CASU, where they awaited shakedown of a carrier other than their own. Their own still was building. Most of the Midway’s original crew leaders shook down on the USS Antietam and the USS Charger. On this shakedown, embryo plane handlers stood battle stations, observed the regular crew at work and finally assisted. They were supervised by a training officer from Com-AirLant who expedited their progress.

Following this shakedown, the Midway’s nucleus crew returned to a CASU near where the ship was building. Here they were groomed in taxiing, spotting and parking aircraft. The work [was] accomplished on a runway painted to simulate a flight deck. Also, they familiarised themselves with the aircraft they would be using.

MidwayP2Va

Courtesy of RATOG, USS Midway launches a nuclear-bomb-capable P2V Neptune (wingspan 101 feet, 30.8 metres) in 1949 (above). Sister ship USS Franklin D. Roosevelt, with the bridge about to go IFR, replicates the feat in 1951 (below).

FDR-P2V

Midway conducted her shakedown in the Caribbean, devoting 51 out of 57 days to air and gunnery operations, simulating all types of wartime conditions. Exercises included fuelling escort ships at sea, damage control drills and problems, A.A. tracking and firing at towed spars and drones, emergency lube-oil drills for engineers, arming planes, gassing, and use of inert gas.

Battle exercises

Air operations involved all types of flying and battle exercises, climaxing the tour with a two-day strike against the Caribbean island of Culebra—a well-pummelled three-mile tract of land used by U. S. warships for shakedown training at that time.

USS Franklin D. Roosevelt also conducted her shakedown training in the Caribbean, under command of CAPT Apollo Soucek. After post-shakedown alterations in New York, she was shifted to Norfolk, where she became flagship of ADML Marc Mitscher during the first large-scale training operations since the end of World War II. These manoeuvres of the Eighth Fleet took place in the western Atlantic between 19 April and 27 May 1946.

In the following year, during Caribbean manoeuvres, Sikorsky H03S helicopters were operated. Noted Naval Aviation News in June 1947:

It was not the first time a helicopter had operated off a carrier deck. Four (of them) were with the Byrd Antarctic expedition…But the helicopter really proved its worth as a utility and rescue plane off the FDR, a showing which may have an effect on fleet operations of the future.

FDR employment

Activity of the FDR in the early post-war years was typical of that of her sister ships. After an extended yard period between March 1947 and July 1948, she completed refresher training in the Caribbean before leaving for her second tour in the Mediterranean. At this time, the “Berlin blockade” was formed and the presence of CVB-42 in that area provided a “show of strength.” This was her mission for the next five years, as the Berlin blockade was followed by crises in eastern Mediterranean countries and armed aggression in Korea.

Midway 1974
USS
Midway, a hard-working carrier in November 1974, became a hard-working museum that opened in June 2004, close to downtown San Diego. In its first year, Midway Museum attracted 879,281 visitors.

In October 1952, the CVBs were re-designated attack aircraft carriers (CVAs). In 1953 the fleet modernisation program was authorised. First aircraft carrier to undergo rework was the FDR. The ships were equipped with steam catapults, hurricane bows, and the angled-deck design of Project 110.


Carrier Evolution XI: Japanese WW II

USN Carrier Evolution XI: The Japanese carriers in WW II

Eleventh article in a series by Scot MacDonald. Reprinted with permission: Naval Aviation News, April 1963.

Japan is beaten, and carrier supremacy defeated her. Carrier supremacy destroyed her army and navy air forces. Carrier supremacy destroyed her fleet. Carrier supremacy gave us bases adjacent to her home islands … Carrier supremacy demolished the island air bases and eliminated the air force that was using them. Carrier supremacy made the island naval bases untenable for such shipping as escaped our submarines. Carrier supremacy permitted us to give close, tactical air support to the troops who stormed the island fortresses: VADM Marc A. Mitscher, USN, quoted in Naval Aviation News, October 1945.

 

shinano

HIJMS Shinano  was unknown to Allied intelligence until well after she was sunk by USS Archer-Fish (later Archerfish), in Japan’s home waters. Laid down as a Yamato class super-battleship, Shinano  was completed as an aircraft carrier following Japan’s disastrous losses in the Battle of Midway. Displacing 72,000 tons at full load, Shinano was the biggest carrier ever constructed until USS Forrestal  (80,000 tons, full load, commissioned 1955.) Shinano, launched 5 October 1944 and commissioned six weeks later, measured 266.1 x 36.3 x 10.8 metres (872.7 x 131 x 35.4 feet). Four screws and geared steam turbines fed by 12 boilers gave the ship 27 knots. Armament included 16 x 127 mm (five-inch), 145 x 25 mm guns and 330 x 130 mm rocket launchers. On her maiden voyage, from Yokosuka to Kure for outfitting, 28 November 1944, Archer-Fish scored four hits from six torpedoes fired at 0318. The carrier had sunk by 1100.
(No clear photographs of the carrier are known to exist. Sketch by LCDR Shizuo Fukui, 1950.)

When Japan struck Pearl Harbor on December 7, 1941, she had the strongest aircraft carrier force in the Pacific. This supremacy lasted until June 1942, when the Battle of Midway was fought and won by the USN. Thereafter, the bokubokan (mother ship for aircraft), though an effective and dangerous fighter, was an everweakening force; ships sunk by USN planes and submarines were not replaced in sufficient numbers and strength. The study of the Japanese maritime wartime construction is a study of desperation in the face of an inevitable defeat.

archerfish

USS Archer-Fish SS-311, Shinano’s nemesis, was a Balao class submarine and measured 95 x 8.3 x 5.1 metres (311.75 x 27.25 x 16.8 feet) and displaced 1526/2391 tons surfaced/submerged. Her engines delivered a total of 5400/2740 shp surfaced/submerged, which gave her 20.5/8.75 knots respectively. Complement was 80 and armament included ten 533 mm (21 inch) torpedo tubes. Standing down from B-29 lifeguard duties off Tokyo on 28 November 1944, Archer-Fish spotted the carrier. Initially credited with sinking a heavy cruiser, this was changed to a 28,000-ton carrier. It was only after the war that the submarine was credited with sinking the largest warship ever destroyed by a single submarine.

At the outbreak of war, Japan had six fine bokubokan, the carriers Akagi,  Kaga,  Soryu, Hiryu, Shokaku and  Zuikaku , in addition to three lighter carriers, the  Zuiho, Hosho and  Ryujo . The keels were already laid for others and some conversions were being made. At that time, the USN had only seven carriers, widely dispersed. At the Battle of Midway, Japan lost  Kaga ,  Akagi ,  Hiryu and  Soryu , and never fully recovered from this decisive defeat.

First wartime construction

Japan’s first wartime-constructed carrier was the Taiho (Big Lucky Bird, aka Great Phoenix), authorised as a 29,300-ton ship under the 1939 estimates. Built at Kawasaki Dockyard, she was laid down in July 1941, launched in April 1943, and delivered in March 1944. She had a good cruising range of 10,000 miles at 18 knots, but could reach 33 knots with ease. Kawasaki claims that she was the most heavily protected flattop in the world at the time of her delivery. And well she might have been; her armour was impressive.

Taiho had 95 mm (3¾ inches) of plating on the flight deck between her two elevators, covering a distance of some 150 metres (492 feet). The platforms on these elevators were 51 mm (two inches) thick and weighed 100 tons. Such weight required a low centre of gravity for the ship, resulting in a very short distance between the waterline and the flight deck, the same height as that of the Hiryu, a carrier some 12,000 tons lighter.

taiho

HIJMS Taiho was another short-lived Japanese giant aircraft carrier that succumbed to an American submarine. Displacing 37,270 tons and capable of 33 knots from four shafts driven by 160,000 shp, her dimensions were 260.6 x 30 x 9.6 metres (855 x 98.5 x 31.5 feet). Commissioned 7 March 1944, Taiho was torpedoed by USS Albacore SS-218 in the early stages of the Battle of the Philippine Sea, 19 June 1944. A single torpedo jammed the forward elevator in a partly down position and fractured AVGAS lines. Some reports claim a quick repair scheme, constructing a wooden deck over the jammed lift, allowed restricted flight operations 30 minutes later. All reports agree that poor damage control led to massive internal AVGAS explosions about five hours afterwards that sent her to the bottom.

In designing and constructing this carrier, the slanting low smokestacks of her predecessors were abandoned and she returned to the “stack in island” type, the stack emerging high on the island and inclining outwards at 26 degrees.

Taiho was an excellent carrier, but she had a short life: three months. On  19 June 1944, during the Battle of the Philippine Sea, she was hit by a torpedo from the submarine Albacore, damaging gasoline pipes and jamming her forward elevator in the partly down position. Though her speed and manoeuvrability were not seriously affected, she did lose the ability to launch aircraft until the elevator well was shored up. AVGAS fumes spread through the ship. In a few hours she exploded and sank.

 

albacoress218

USS Albacore SS-218, a Gato class submarine, sank HIJMS Taiho, the flagship of a force steaming to interdict the Saipan landings. Ordered to move 100 miles south from his pre-briefed patrol position, Albacore‘s captain raised his periscope to find himself in the midst of a main carrier group, 19 June 1944. Allowing one carrier to pass, he selected Taiho  as a target but his Torpedo Data Computer malfunctioned. He fired all six bow tubes as the carrier was launching a strike. One Japanese pilot (Sakio Komatsu) saw the danger and deliberately dived onto one torpedo, exploding it, but another torpedo from the same spread found its mark. Albacore  was lost, 7 November 1944, after setting off a Japanese mine off the north-east coast of Hokaido.

Five modifications of the Taiho class were ordered in the 1942 program, but none was laid down, owing to shortages and crowded shipyards.

Unryu class

The Unryu (Cloudy Dragon) class was next to enter the scene. This ship was constructed under the 1941 estimates. Seven sister ships were ordered in the 1942 program. Two were never named and never laid down.

Unryu was a modification of the  Soryu , the plans simplified for quicker construction. She displaced 17,150 tons standard. Sister ships  Katsuragi and Aso were slightly heavier, displacing 17,400 tons, while  Ikoma Kasagi and  Amagi were heavier yet, 18,300 tons. They had a speed of 34 knots, except for  Katsuragi and  Aso which, because of shortages, were equipped with destroyer-type engines and could only reach a relatively slow 32 knots.

Not one of these ships took an important part in any engagement. Both  Unryu and  Amagi were completed in August 1944 and were used for transport duty. Exactly 105 days after her commissioning, Unryu was sunk by a torpedo from the submarine  Redfish. Amagi suffered two attacks from USN carrier-based aircraft while the ship was at Kure. The second attack, on 24 July 24, 1945, capsized her. Katsuragi also came under attack by US carrier planes four days later, also at Kure. She suffered minor damage because she was protected by camouflage. After the war, she was used for repatriation and was scrapped in 1947.


Material shortages

Neither Aso, Kasagi nor Ikoma was completed by the end of the war. Aso was launched 1 November 1944,  Ikoma on 17 October, and  Kasagi two days later. They were 60 to 80 per cent complete when work on them was halted because of material shortages. Aso was used as a target ship for kamikaze training attacks and did not survive this abuse.  Ikoma was moored at Shodo Jima where she sustained bomb damage toward the end of the war. She and Kasagi were scrapped. Seven more Unryu class ships were added to the 1942 program, but they never got beyond the paper work.

The Japanese wartime carrier construction program, though ambitious, was not at all successful. What few successes they did enjoy were short-lived. Since the pressure was on—especially after the Battle of Midway—it was natural that they would turn to quick conversions. In this area, too, the results were discouraging. The submarine depot ships  Taigei, Tsurugisaki, and Takasaki were the first to be converted. They became the  Ryuho, Shoho and Zuiho. HIJMS Ryuho, one of only four Japanese carriers to survive WW II was converted from a 10,500 tons submarine depot ship, like Zuiho and Shoho.

ryuhog

Commissioned in 1943, Ryuho displaced 16,150 tons (full load) from a 215.8 x 19.6 x 66 metres (707.5 x 64.25 x 21.75 feet) hull. The four boilers and two shafts delivered 52,000 shp, giving maximum speed of 26.5 knots. With a complement of 875, the ship carried 30 aircraft and eight 127 mm (five inch) guns. Employed chiefly as an aircrew training carrier, Ryuho was called up to help repel the American invasion of Saipan. She emerged virtually unscathed, but like the other Japanese carriers in that action, she lost most of her aircraft and aircrew in the “Marianas Turkey Shoot”.

Ryuho’s structure was weak when she entered the yard for conversion. While being strengthened and given carrier characteristics, she was hit by several bombs from one of the B-25 bombers led by Jimmy Doolittle and launched from the USS  Hornet . This, of course, delayed completion. When conversion was completed, she displaced over 15,000 tons standard. She had a speed of 26.5 knots, was armed with eight 127 mm (five inch) guns, and accommodated 30 aircraft.  Ryuho saw much action, participating in the battles of the Philippine Sea and Leyte Gulf in 1944. In March 1945, she was moored at Kure, bombed by carrier-based USN aircraft and gutted by fires.

Shoho and Zuiho both displaced over 13,000 tons standard upon completion of conversion.  Zuiho was completed in December 1940, while  Shoho was completed nearly two years later. Both had a speed of 28 knots, were armed with eight 127 mm (five inch) guns, and accommodated 30 aircraft.

Coral Sea

Shoho’s first battle was her last: she was sunk by carrier-based aircraft of the Lexington and Yorktown on 7 May 1942, during the Battle of the Coral Sea. Zuiho was not much luckier. Her contributions to the Battle of Midway and the Aleutians campaign were negligible. At the Battle for Leyte Gulf, she was sunk by carrier-based aircraft.

The conversions of the Ise and Hyuga from battleships proved to be one of the most puzzling experiments undertaken by the Japanese after the Battle of Midway. Their aft turrets were removed and abbreviated flight decks were installed. A large hangar, an elevator, and two catapults were added, permitting the ships to launch all their aircraft in 20 minutes.

 

ise

HIJMS Ise  (above) and Hyuga (below) were WW I-era battleships of 38,700 tons with 12 x 356 mm (14 inch) guns in six twin turrets. After Midway, they were converted into hybrid aircraft carriers with a hangar and two catapults. Their designated wheeled dive bombers, Asahi D4Y1 Model 11 Suisei (Judy) never arrived, but the ships operated a few seaplanes.

 

hyuga

The planes scheduled for these ships were sent to Formosa (now Taiwan) before the ships were completed. The conversions were employed in the Battle of Leyte Gulf. By this time, Japan had run out of aircraft to supply them, and the ships were used solely in their capacity as battleships. They were later sunk, in July 1945, by USN carrier-based planes.

Another conversion, that of the Ibuki from an improved Mogami class cruiser, also had a rough time of it. She was authorised under the 1941 program but shortly after her launching in May 1943, work on her was halted for six months while authorities haggled with the possibility of reconverting her into a fast oil tanker—much needed by the Japanese navy. The decision made, work renewed, this time at a furious pace. Four of her eight boilers were pulled out and this space used for the storage of fuel oil. A hangar and two elevators were installed, and a bridge was placed on her starboard side. She was capable of 29 knots and could carry 27 aircraft. But work stopped again, this time when the construction of small submarines took priority in the shipyards. She was never finished; at the end of the war the  Ibuki was scrapped.

The most ambitious conversion and the most disappointing career was that of the Yamato class battleship  Shinano. Laid down as a battleship but not completed when hostilities broke, the possibility of converting her to a carrier was entertained. This possibility became a necessity after the Battle of Midway. Survivors of this battle pointed out serious deficiencies in carrier construction and designers at the Naval Technical Bureau listened well. Heavier armoured flight decks were needed to protect them from dive-bombing attacks. Fuel and ammunition stowage spaces needed redesign.

“Hotel ship”

Originally, plans for the conversion of the Shinano called for her to act as a “hotel ship,” supporting land- or other carrier-based planes; she was not to carry aircraft of her own. This plan was changed and by September 1942 the new design was completed and construction began. Shinano, basically, was to be a CVB. Heavy emphasis was placed on armour. Large bulges below the waterline were to minimise torpedo damage. At the waterline, a 203 mm (eight-inch) thick belt of armour was retained. Another 102 mm (four-inch) thick armoured deck had already been installed before conversion started and this deck became the hangar deck.

Rolling metal curtains opened up the forward two-thirds of this deck for night operations and rough seas. The remaining third was closed completely when the curtain was rolled into place. Her flight deck and elevators were designed to withstand 454 kg (1000 pounds) bombs. With this weight,  Shinano displaced 68,000 tons during her trials at sea.

redfishss395

USS Redfish SS-395 helped to put the carrier Junyo out of the war and sank the carrier Unryu. Allied carrier-borne aircraft, along with submarines, defeated Japan’s Pacific Ocean primary war machine: the aircraft carrier.

The Battle of Midway also called attention to the ship’s ventilation system. All ducts were protected with 38 mm (1½ inch) armour. Wood was eliminated from the ship wherever possible. A fire-resistant paint was introduced, and a foam fire-extinguishing system was installed. The carrier was launched on 5 October 1944 and commissioned 19 November. On the 28th, yard workers still aboard and crewed by green hands, she got underway for Kure where the air complement was to board.

Carrier aviation rout

It was at this point that USS  Archer-Fish picked her out on radar while surfaced. The submarine chased the zig-zagging force and waited until the carrier and her three-destroyer escort crossed her line of fire. At 0315  Archer-Fish fired six torpedoes; four hit the carrier. Slowly, she flooded and listed. At 1018 28 November, all hands were ordered to abandon ship. A few minutes later,  Shinano capsized and sank—with half her crew still aboard.

For many in the Japanese Navy, the powerful  Shinano was the last hope. With her sinking, Japanese carrier aviation died, never to operate again.