Essex Class Aircraft Carrier - Design

Design

In drawing up the preliminary design for 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 1930s. Flight decks now required more takeoff space for the heavier aircraft 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 armor and armament got heavier; aircrew complements also increased. By the war's end in 1945, catapult launches would become more common under these circumstances, with some carrier commanding officers reporting up to 40% of launches by catapult.

The hangar area design came in for many design conferences between the naval bureaus. Not only were the supporting structures to the flight deck required to carry the increased weight of landing and parked aircraft, but they were to have sufficient strength to support the storing of spare fuselages and parts (50% of each plane type aboard) under the flight deck and still provide adequate working space for the men using the area below.

One innovation in Essex was a portside deck-edge elevator in addition to two inboard elevators. The deck-edge elevator was adopted in the design after it proved successful on the Wasp. Experiments had also been made with hauling aircraft by crane up a ramp between the hangar and flight decks, but this method proved too slow. The Navy's Bureau of Ships and the Chief Engineer of A.B.C. Elevator Co. designed the engine for the side elevator. It was a standard elevator, 60 by 34 ft (18 by 10 m) in platform surface, which traveled vertically on the port side of the ship. The design was a huge success; it greatly improved flight deck operations.

There would be no large hole in the flight deck when the elevator was in the "down" position, a critical factor if the elevator ever became inoperable during combat operations. Its new position made it easier to continue normal operations on deck, irrespective of the position of the elevator. The elevator also increased the effective deck space when it was in the "up" position by providing additional parking room outside the normal contours of the flight deck, and increased the effective area on the hangar deck by the absence of elevator pits. In addition, its machinery was less complex than the two inboard elevators, requiring about 20% fewer man-hours of maintenance.

Ongoing improvements to the class were made, particularly with regards to the ventilation system, lighting systems, and the trash burner design and implementation.

These carriers had better armor protection than their predecessors, better facilities for handling ammunition, safer and greater fueling capacity, and more effective damage control equipment. Yet, these ships were also designed to limit weight and the complexity of construction, for instance incorporating extensive use of flat and straight metal pieces, and of Special Treatment Steel (STS), a nickel-chrome steel alloy that provided the same protective qualities as Class B armor plate, but which was fully structural rather than deadweight.

The original design for the class assumed a complement of 215 officers and 2,171 enlisted men. However, by the end of World War II, most crews were 50% larger than that.

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 offense and separating when on the defense—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, tactics changed. Experience taught the wisdom of combined strength. Under attack, the combined anti-aircraft fire of a task group's 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. 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 characterized carrier task force operations, with the evolution of the fast carrier task force and its successful employment in future operations.