USS Ranger (CV-4) was an interwar United States Navy aircraft carrier, the only ship of its class. As a Treaty ship, Ranger was the first U.S. vessel to be designed and built from the keel up as a carrier. She was relatively small, just long and under , closer in size and displacement to the first US carrier——than later ships. An island superstructure was not included in the original design, but was added after completion.
Deemed too slow for use with the Pacific Fleet's carrier task forces against Japan, she spent most of World War II in the Atlantic Ocean, where the German fleet, the Kriegsmarine, was a weaker opponent. Ranger saw combat in that theater and provided air support for Operation Torch. In October 1943, she fought in Operation Leader, air attacks on German shipping off Norway. She was sold for scrap in 1947.
Design and development
Work began in 1925 on the design of a fourth aircraft carrier for the US Navy, as a follow-on to the small , converted from a collier, and the large and , which were in the process of being converted from incomplete battlecruisers. Carrier number four was the Navy's first opportunity to design a ship built as an aircraft carrier. Preliminary design work occurred before extensive operation of the preceding three. Having limited experience to draw on, key characteristics of the design were derived from wargaming experience at the U.S. Naval War College. During design and construction many alterations would occur as a result of increasing experience with Langley, Lexington, and Saratoga.
The major limitation constraining any design was the Washington Naval Treaty of 1922. After Lexington and Saratoga, there were remaining for construction of aircraft carriers. This resulted in modeling for three 23,000 long ton carriers, four 17,250 ton carriers, and five 13,800 ton carriers. Of the three sizes, the smaller 13,800 was selected because the five hulls would have the largest aggregate aircraft capacity. Wargames had indicated that severe attrition to airframes and hulls would occur in any war. The college's solution was to maximize the number of aircraft and hulls allowable under the treaty.
Initially, Ranger was designed as a flush-decker, like Langley, with nothing extending above the flight deck. Keeping the flightdeck clear of obstacles complicated the arrangement of machinery. The smoke from her six boilers was vented up six small stacks, with three on each side of the aft hangar. The stacks were hinged and were rotated to a position parallel with the hangar deck during flight operations. The unusual stack arrangement is a carry-over from her flush-deck design. When an island was added midway through construction, rebuilding the uptakes into the island was rejected as too costly.
Concerns about smoke dispersion impacted propulsion design. Size of the plant influenced both the placement of the boilers and the amount of smoke generated. A moderate 53,000shp power plant could be placed further aft than a 100,000shp plant without affecting trim. The further aft the boilers were placed the further aft the stacks could be too, dispersing smoke over less of the deck. The smaller plant also produced less gasses than a 100,000shp plant. Due to space limits, the carrier was equipped with geared turbines.
Nearly her entire upper deck was devoted to the hangar. The large height and open girders of the flight deck structure allowed for stowage of spare fuselages. The hangar deck was semi-open and had large roll-up metal curtain doors which could be closed in bad weather. The open hangar was adopted to allow the installation of two catapults on the hangar deck for the launching of observation aircraft. The catapults were dropped to save cost. Ranger also incorporated a gallery deck between the flight deck and hangar deck.
The flight deck was a light superstructure sheathed in wood. Designed as a weight-saving measure, the light wood deck was found to be easily repairable. Three elevators were provided to move aircraft between the flight deck and hangar deck. Outriggers at the edge of the flight deck provided extra stowage for aircraft on deck. The carrier operated 76 aircraft as constructed; equal to Lexington with half the displacement.
The carrier was one of the first U.S. Navy ships mounted with light automatic weapons to defend against dive-bombing attacks, and was initially armed with forty .50 cal machine guns. Complementing the machine guns were eight dual-purpose 5-inch (127 mm)/25 caliber guns controlled by two Mark 33 directors. The machine guns were arrayed along the gallery and the 5-inch guns arrayed with one at each corner of the gallery, two at the bow, and two on the fantail.