By REAR-ADMIRAL E. L. COCHRANE, USN, Chief of the Bureau of Ships
By first punching the foe off balance and now smashing his last holds on the ocean, our aircraft carriers have proved modern speeders of Victory. Here “Buships” chief details how we’ve come from a mere seven to more than a hundred of these sky-sweepers.
December 7, 1941, the United States had on hand seven full-sized carriers, the Lexington, Saratoga, Ranger, Yorktown, Enterprise, Wasp, and the Hornet, also the small escort carrier, Long Island. Of these the Lexington, Yorktown, Wasp, and Hornet have since been lost. For every one of those veterans lost, however, there has been built and are now at sea, nearly 30 replacements (including the escort carriers transferred to our allies).
In the two and a half years since Pearl Harbor, the number of carriers on hand (excluding the 38 transferred by lendlease to the British) has been increased to 90. totaling more than 1,400,000 tons. During this same period the combatant vessels of our Navy in all categories have more than tripled — going from 345 vessels, totaling 1,382,755 tons, to 1071 units, totaling 3,434,762 tons.
With the outbreak of war and following the heavy carrier losses in 1942. the desperate need for carrier strength in the Pacific and the growing demands for fighter transports pushed six vessels of the aircraft carrier program into top priority. With first call on the nation’s scarce materials and components, the inauguration of shift work, and the seven-day week, actual completions surpassed even the most optimistic forecasts.
Carriers thus got off to a good start and remained at the top of the pyramid until May 1942 when the joint Chiefs of Staff gave an over-riding priority of landing craft for the North African invasion. Even when the first landing craft program expanded into another, the carriers continued to have the nod over the great bulk of larger naval vessel construction.
The completion of the Essex only 17 mo. after keel laying, and the comparable building periods for the new Yorktown and Intrepid as compared with initial estimates of three to four years, bespeak the effectiveness of the wartime efforts to accelerate shipbuilding when backed by this position of priority. The pushing up of the destroyer-escort program to top priority in the fall of 1942 to meet the growing submarine menace had little effect on the carrier program because by that time the large proportion of the necessary materials had been procured.
The big push on carriers came largely in 1942, but the full results did not show up until the late spring of 1943. Fortunately the preliminary designs and the contract plans for the Essex-class carriers had been started in 1939 following the Naval Expansion Act of May 17. 1938, which authorized the expansion of the U. S. naval aircraft carrier tonnage from 135,000 to 175,000 tons. Although this was not implemented by contractual authority and appropritions for the construction of one large carrier until the regular Navy Appropriation Act of 1941 was approved on June 11, 1940, those charged with the Navy’s shipbuilding had already gone earnestly to work.
Innumerable studies were made, tests were run on proposed carrier designs, models were towed, and details were refined and improved. Because of this advance work the Bureau of Ships had contract plans prepared and was ready when the 11 and 70 percent expansion programs followed in June and July, 1940, closely after the “go ahead” had been given for the first of this class. Before the actual contract was let for the Essex to be built at Newport News Shipbuilding & Dry Dock Co., it was decided to increase the contract to three vessels.
It is fortunate for the Navy’s program that the general board of the Navy had considered and approved the preliminary plans prepared by the Bureau of Ships for use in the event that it was decided to convert any of the Cleveland- class light cruisers into aircraft carriers. There leas difference of opinion in the Navy on this scheme. Adm. H. E. Stark, USN, then chief of Naval Operations, was one of the farsighted exponents of this type which is now proving very valuable. With the plans provided by the Bureau of Ships, the New York Shipbuilding Co., was able to convert and complete what would have been a cruiser into a carrier by Jan. 1st, 1943, less than a year after the company received the contract plans for the conversion.
Before the end of 1943, all of this class were completed by New York Ship and had been commissioned as aircraft carriers some 20 mo. before the last vessel had been scheduled for completion as a light cruiser. The speed of this performance was due in part to over-riding priorities for materials established for the first two vessels, but in the main to the enthusiasm and energy with which the shipbuilders did their work.
CVE Program
The long building periods experienced in completing pre-Essex large aircraft carriers, coupled with the growing needs of our allies for aircraft transports and for other purposes led the Navy early in 1941 to experiment with the installation of a flight deck on one of the rapidly multiplying C-3 type Maritime Commission ships and their quick conversion into the now famous “baby flat-tops.” The shortage in merchant tonnage at this time, however, prohibited any large scale conversion program until the actual outbreak of war.
In addition to the pre-Pearl Harbor conversion of the C-3 SS. Mormacmail to the USS Long Island, the Navy by the outbreak of the war, had completed one conversion for the British and had in progress the conversion of five more fighter transports. By incorporating items developed for the regular Navy carriers and making use of equipment such as catapults and arresting gear, which had been ordered in anticipation of the needs of the large carriers but which they would not require for some months, the early conversions were pushed ahead to completion in record time.
Demands for the baby carriers for escort and other duty, as well as the vastly growing needs for more aircraft transport capacity, brought Henry Kaiser into the carrier picture in May 1942. A special class of airplane transports, which are in fact complete escort carriers, since known as Kaiser Carriers, was designed from the keel up.
This was a Maritime Commission construction project with the Navy acting as consultant on purely naval matters. Naval material, such as catapults, arresting gear, armament, etc., was furnished by the Navy. The 50th CVE was accepted by the Navy on July 8, 1944.
Design Procedure
In peacetime the Bureau of Ships submits, for the approval of the General Board, preliminary designs or “spring styles” of the types of naval ships being considered for the building program. In wartime the initiative generally comes from the needs of the Fleet. The chief of Naval Operations, with the approval of the Secretary of the Navy, may direct the Bureau of Ships to construct certain vessels and may establish their required characteristics if there are no approved characteristics which satisfy the need.
Operations may, for example, direct that the vessel carry a stipulated number of planes, have a large enough deck and vessel speed sufficient to fly-off and fly-on a certain type of aircraft. The Bureau of Ships prepares preliminary drawings incorporating the general characteristics, checks them for stability, etc., and presents them to operations and the general board, members of which consider them and indicate any further changes they consider necessary.
The design people then make the indicated changes, develop the design in consultation with the other Bureaus, build and tow a model, study the structural stresses, and work up a set of contract plans. These plans will be cleared again with the Office of the chief of Naval Operations and — for a carrier — with the Bureaus of Aeronautics and Ordnance. This procedure is repeated until a satisfactory design is evolved. Thus, in effect, the operational forces submit a broad outline of the job the vessel must do and rely on the technical Bureaus (here the Bureau of Ships, the Bureau of Aeronautics, and the Bureau of Ordnance) to fill the bill.
Problems of Carrier Design
Carrier design and construction must not only meet the exacting requirements involved in all combatant ship construction, but they must incorporate the essentials demanded by Navy’s flying arm and carry the approval of the Bureau of Aeronautics on the features that affect the vessel’s effectiveness as a mobile airfield. The carrier must have as large a deck as possible at a height above the water that will insure dryness. It must be fast enough for planes to fly off and on during the maximum proportion of the time, and it must have the required mobility to effect surprise attacks and successful withdrawals after the attack.
Another construction problem is to find space not only for the ships’ officers and crew, which are as numerous on an Essex-class carrier as on a North Carolina class battleship, but in addition to make room for the additional aviation personnel and their planes and equipment, the requirements for navigational and ship control, gunnery control, and flight operations control has made the island or control structure above the flight deck a masterpiece of compactness.
The piping and wiring problem is complicated by the need for distribution of high octane gasoline and the constant fire hazard which this involves. Not only is there danger of fire from enemy action, but operational accidents on the part of the carrier’s own planes or crew are a constant source of danger. The wiring is a special problem since carriers have large high speed elevators and complicated flight deck lighting and recognition arrangements in addition to all the usual wiring required by naval vessels.
In solving some of the problems involved in building ships for a many-ocean Navy, the width of the Panama Canal must be considered. In placing the antiaircraft guns, it is desirable to have them as far outboard and as high as possible to give them the widest possible firing arc and still keep them below the level of the flight deck and within a breadth over-all which will permit passage through the Canal’s locks if the carrier must be moved from one ocean to the other
The underwater form of the carrier is not unlike that of any fast combatant ship. The great weight of the flight deck so high above the keel and the unbalanced superstructure or island on the starboard side, however, create new problems of ballasting and stability. This same increase of topside weight requires every ingenuity to be brought into play in working out substitutions of lighter metals, plastics, etc., for the heavy shipbuilding materials usually employed in the ship’s structure and various fittings
Improvements Increase Efficiency
Many improvements have been made and more are being made to increase the effectiveness of the carriers as fighting machines. Constant studies are being carried on, and action reports are being utilized, to increase the effectiveness of the ships and to reduce the hazards involved in bringing their maximum power to bear on the enemy.
There have been great improvements in plane handling equipment, including portable tractor-driven cranes, jeeps, and tractors for handling the planes in the hanger and on the flight deck. The installation of deck-edge elevators has accelerated the handling of planes and provides additional facilities for lifting planes and ammunition. Separate high speed elevators and lifts are provided for bombs and ammunition.
The new carriers operate with high temperature and high pressure steam in the main machinery similar to that developed in the later destroyers and subsequently used in nearly all of the Navy’s modern combatant ships.
Splinter protection, compartmentation, and light armor give the maximum protection that weight limits permit.
Air-conditioning is provided in ready rooms and certain control spaces, also in the ultra-modern sick bay and dental office.
The shops for aircraft upkeep, maintenance, and repairs are extraordinarily complete and have all the modern tools to provide complete repairs for its aircraft and electronic equipment.
The number of plans required to construct a carrier is a good index of the complexity of its design. An Essex-class carrier requires several dozens of preliminary design plans, over a hundred contract plans and many thousands of shipyard working plans, as compared to only about 8,000 plans for an Iowa-class battleship, or about half as many foor a light cruiser. This total does not take into account the thousands of plans used by the manufacturers who supply the components and innumerable items of equipment.
Construction
The vessels built as aircraft carriers from the keel up present much the same problem in construction, up to the main deck, as do any other combatant vessels. They are built on similar ways and require the same sort of cranes, fabrication equipment and machine tools. When it comes to erecting the flight deck and outfitting, there are some additional special facilities needed, but these do not interfere with the subsequent use of the basic facilities for work on other types of vessels.
At Newport News Shipbuilding & Drydock Co., the Essex (CV-9)—first of the new approximately-27,000-ton class of carriers—was laid on the way previously vacated by the USS Hornet (CV-8). Although the new carrier was more than 7,000 tons larger and 46 ft. longer than the Hornet, the ways were amply large to accommodate its construction. At the same yard, the new Yorktown went down on a way vacated by the Indiana, a 35,000ton battleship of the South Dakota class.
In 1940 the Navy awarded facility contracts for the construction of two building dry docks to Newport News to be used for the construction or repair of the largest size naval vessels. Immediately on the availability of these dry docks, two Essex-class carriers were laid down in them.
Bethlehem-Fore River had only one large shipway in service — the one on which the Lexington was built — when the company got its original award for carrier construction. The first carrier was laid down on the Lexington shipways and others were briefly delayed until two new ways, then under construction, were sufficiently far advanced to be used. The remainder of the group were built on the original way as soon as the first carrier was launched.
Had there been no manpower shortage, no shortage of materials, components, propelling machinery, and other essentials, the availability of additional building ways might have stepped up the program. Actually the completions have been just about geared to the availability of steel, turbines, gears, and the many other items where production has had to be drastically expanded.
In general, a good balance has been maintained, and in only very few instances has there been a bottleneck which has seriously slowed down the completion date. Some problems were encountered in the procurement of critical raw materials. necessitating changes in Navy specifications.
Heavier metals were substituted for aluminum wherever possible in order to release the latter material for the airplane program, and the amount of copper and nickel alloy was reduced to the absolute minimum to meet the demands for their use in the manufacture of other munitions. Actually the carrier program encountered fewer cases of delays resulting from material shortages than other programs, owing to the high priority which the carrier program enjoyed. This resulted in more favorable delivery of turbines, valves, ball bearings, pumps, electrical equipment controls, radio, etc. Delays were encountered, however, in the production of certain engine parts.
Impossible Was Achieved
In spite of all the problems, shortages, and construction difficulties encountered, the aircraft carrier program has been accomplished in a period of time which many experts had viewed as an impossibility. Within a period of 2 1/2 yr. the Bureau has added to the four remaining prewar carriers a total of nearly 100 carriers of all types. As stated in reports issued by the Secretary of the Navy and the Commander-in-Chief, US. Fleet, these are:
| Description | Designation | No. Completed to July 1, 1944 |
|---|---|---|
| Essex-class | CV9 | 10 |
| Converted Cruisers | CVL | 9 |
| Converted C-3’s | CVE | 51 * |
| Converted tankers | CVE | 4 |
| Kaiser-built | CVE | 50 |
* Includes 38 transferred to the United Kingdom
This growth has been only one part of the overall growth of the Navy during this period. From a total of 4,084 vessels of all types, totaling 2,693,943 tons when war was declared, the shipbuilders of the United States, working closely with the Bureau of Ships, have designed, constructed and put into service new vessels in a never ending succession, until today we have “on hand” 5,948 naval vessels totaling 8,530,701 tons, a great many more units and more Hum three times the tonnage on hand on Dec. 7, 1941.
Varied Carrier Types
The aircraft carriers of the United States fleet are classified into six basic groups, as follows:
CVB (Aircraft Carriers, Large). The new 45,000-ton supercarrier will have a long flight deck which will enable it to serve as a floating base for the coming bigger and heavier planes. It has also been designed to have enough speed to insure its being able to fly its planes off and on under virtually any wind conditions.
CV (Aircraft Carriers). The Essex-class carriers are approximately 800 ft. long, displace over 27,000 tons, carry more than 80 aircraft, and make over 30 knots. They are armed with 5-in. anti-aircraft guns and bristle with 40-mm. quads of Chicago Pianos. The propelling machinery in one of these vessels is powerful enough to provide all the power required by a small city. In addition to the ten Essex-class carriers reported completed and at sea, there are more units of this type still in the process of construction.
CVL (Aircraft Carriers, Light). Independence-class carriers. These are converted from the 10,000-ton Cleveland-class cruisers. They have a flight deck over 600 ft long, carry a good complement of planes and have high enough speed to enable them to fly their planes off when the smaller CVE’s are forced to use the catapult. The rapid conversion into carriers of several of these ships, which were already under construction as cruisers, was one of the great production achievements in the early part of the war.
CVE (Aircraft Carriers, Escort). The escort carriers are of three classes :
- CVE’s built from C-3 merchant hulls. These are about 500 ft. long, carry approximately 20 planes and make the speed needed for planes to fly off and on in normal wind conditions. More than 50 of these have been completed, including 38 transferred to the British.
- CVE’s converted from Cimarron-class oilers. These carriers are slightly longer and faster than the C-3 conversions and can carry extra fuel for their own use and that of the accompanying destroyers and destroyer escorts. Four have been completed and more are in production at the Todd-Pacific Tacoma Yard.
- CVE’s built by the Kaiser Vancouver Yard. These were ordered as airplane transports and are about the same length as C-3’s, but have somewhat finer lines, are 1,500 tons lighter and are rated at a somewhat higher speed.
Aviation Week, October 1, 1944