Lexington class aircraft carrier

This article is about the two members of the class converted to aircraft carriers. For the original battlecruiser class, see Lexington class battlecruiser.

USS Lexington before World War II
Class overview
Name:	Lexington class
Builders:	Fore River Shipyard New York Shipbuilding Corporation
Operators:	United States Navy
Preceded by:	USS Langley (CV-1)
Succeeded by:	USS Ranger (CV-4)
Cost:	about $45,000,000
Built:	1920–27
In service:	1927–46
In commission:	1927–45
Planned:	2
Completed:	2
Lost:	1
Retired:	1
General characteristics (as built)
Type:	Aircraft carrier
Displacement:	36,000 long tons (37,000 t) (standard) 47,700 long tons (48,500 t) (deep load)
Length:	888 ft (270.7 m)
Beam:	107 ft 6 in (32.8 m)
Draft:	32 ft 6 in (9.9 m) (deep load)
Installed power:	180,000 shp (130,000 kW)
Propulsion:	4 shafts, 4 sets turbo-electric drive 16 water-tube boilers
Speed:	33.25 knots (61.58 km/h; 38.26 mph)
Range:	12,000 nmi (22,000 km; 14,000 mi) at 14 kn (26 km/h; 16 mph)
Complement:	2,122 (including aviation personnel)
Armament:	4 × 2 - 8-inch (203 mm) guns 12 × 1 - 5-inch (127 mm) anti-aircraft guns
Armor:	Belt: 5–7 in (127–178 mm) Deck: .75–2 in (19–51 mm) Gun turrets: .75 in (19 mm) Bulkheads: 5–7 in (127–178 mm)
Aircraft carried:	91
Aviation facilities:	1 Aircraft catapult

The Lexington class aircraft carriers were the first operational aircraft carriers in the United States Navy. (USS Langley was a strictly developmental ship.) There were two ships in the class: USS Lexington (CV-2) and USS Saratoga (CV-3).

The Lexington-class carriers were constructed on hulls originally laid down as battlecruisers after World War I. But under the Washington Naval Treaty of 1922, all U.S. battleship and battlecruiser construction was cancelled. However, the Treaty allowed two of the unfinished ships to be converted to carriers.

They proved extremely successful as carriers, supporting wide-scale operations. Experience with the Lexington class convinced the Navy of the value of large carriers. The Lexington class carriers were the largest aircraft carriers in the fleet until the Midway-class carriers were completed. The class served in World War II, seeing action in many battles. Though Lexington was lost in the first carrier battle (Coral Sea), Saratoga served to the end of the war.

Development

The Lexington-class were originally designed as battlecruisers, with heavy guns, high speed, and moderate armor protection. The Navy laid down six ships of the class from 1916 to 1919. When the battlecruisers were cancelled under the Washington Naval Treaty, two of the unfinished ships were designated for completion as carriers.

Description

General description

Their official displacement on commissioning was 33,000 long tons (34,000 t) (in accordance with the Washington Treaty). In reality both ships were well in excess of that and displaced 36,000 long tons (37,000 t) at standard load. At full load (with fuel, ammunition, aircraft, gasoline, and stores) they displaced 47,700 long tons (48,500 t).

Aside from their great size, their most innovative feature was the "hurricane bow," a configuration of carriers where the bow was sealed up to the flight deck; this turned out to be the most useful of the three possible configurations for a carrier's bow (the other two being an additional flying-off deck and an antiaircraft battery).

Design

The Lexington-class aircraft carriers set the pattern for future American carrier designs of very large and long ships with topside flight decks, starboard-side islands, and a high-volume hangar decks. The tall funnel directed smoke well away from the flight deck and avoided smoke-fouling problems common with other early carriers.

These ships were given a 866.17-by-105.9-foot (264.0 by 32.3 m) teak flight deck. Their hangar had a clear height of 20 feet (6.1 m) and encompassed 33,528 square feet (3,114.9 m²). It was the largest enclosed space afloat, civilian or military, when built. The hangar was 424 feet (129.2 m) long and its width varied from 68 to 74 feet (20.7 to 22.6 m), constrained by the bulky funnel uptakes and boat compartments. The height of the hangar was not exceeded on an American aircraft carrier until the Forrestal class ships appeared in the mid-1950s. Aircraft repair shops, 108-foot (32.9 m) long, were aft of the hangar and below them was a storage space for disassembled aircraft, 128 feet (39.0 m) long. The hangar was divided by a single fire curtain just forward of the aft aircraft elevator.

The carriers were fitted with two hydraulically powered elevators on their centerline. The forward elevator was 30-by-60-foot (9.1 × 18.3 m) and had a capacity of 16,000 pounds (7,257.5 kg). A 20-by-26-foot (6.1 by 7.9 m) section of the flight deck adjoining the rear edge of the elevator could split down the centerline to lift aircraft otherwise too long. Carrying 12,000 pounds (5,400 kg), it moved at a speed of 2 feet per second (0.61 m/s). The aft elevator measured 30-by-36-foot (9.1 by 11.0 m) and could only lift 6,000 pounds (2,721.6 kg). Munitions were delivered from the magazines by two hydraulically powered bomb lifts and one torpedo lift. A folding crane with a capacity of 10 long tons (10 t) was positioned on the flight deck forward of the gun turrets. Aviation gasoline was stored in eight compartments of the torpedo protection system and their capacity has been quoted as either 132,264 US gallons (500,670 l; 110,133 imp gal) or 163,000 US gallons (620,000 l; 136,000 imp gal). A flywheel-powered aircraft catapult, 155 feet (47.2 m) long, was fitted at the bow; it could launch a 10,000-pound (4,536 kg) aircraft at a speed of 48 knots (89 km/h; 55 mph). It was removed in 1934 as unnecessary.

Propulsion

Turbo-electric propulsion had been selected for the battlecruisers and was retained when they were converted into aircraft carriers because American companies struggled to produce the very large geared turbines necessary for such big ships. "It was efficient, rugged and always reliable. But it was also heavy, intricate, and not easy to maintain and keep tuned up." The machinery also required special ventilation measures to dissipate heat and to keep out any salt air.

Each propeller was 14 feet 9 inches (4.50 m) in diameter and each of the four propeller shafts was powered by two 22,500-shaft-horsepower (16,800 kW) electric motors acting in tandem. These motors were about five times the size of any earlier electric motor. Four General Electric turbo generators powered each propeller shaft and each was rated at 35,200 kilowatts (47,200 hp), 5000 volts and 4620 amps of direct current (DC). Each of the four AC alternators produced 40,000 KVA. Sixteen water-tube boilers, each in their own individual compartment, provided steam for the generators at a working pressure of 295 psi (2,034 kPa; 21 kgf/cm²) and a temperature of 460 °F (238 °C). Two other advantages of the turbo-electric drive were that the substitution of flexible electric cables for bulky steam-lines meant that the motors could be mounted further to the rear of the ship, which reduced both vibration and weight by shortening the propeller shafts and that the ship could go astern at full power simply by reversing the electrical polarity of the motors. The turbo-electric machinery of the Lexington-class ships was designed to produce a total of 180,000 shaft horsepower (130,000 kW) and propel the ships at 33.25 knots (61.58 km/h; 38.26 mph), but each ship reached over 202,000 shp (151,000 kW) and 34.5 knots (63.9 km/h; 39.7 mph) during sea trials in 1928. Six 750-kilowatt (1,010 hp) DC turbo generators were installed in the upper levels of the two main turbine compartments.

The ships carried a maximum of 6,688 long tons (6,795 t) of fuel oil, but only 5,400 long tons (5,500 t) of that was usable as the rest had to be retained as ballast in the port fuel tanks to offset the weight of the island and main guns. They demonstrated a range of 9,910 nautical miles (18,350 km; 11,400 mi) at a speed of 10.7 knots (19.8 km/h; 12.3 mph) with 4,540 long tons (4,610 t) of oil.

Armament

Lexington firing her 8" guns, 1928.

The Navy's Bureau of Construction and Repair was not then convinced that aircraft could be an effective and sufficient armament for a warship. Thus the design as carriers included a substantial gun battery of eight 8-inch 55 caliber guns in four twin gun turrets. These turrets were mounted above the flight deck on the starboard side, two before the bridge, and two behind the funnel. The guns in theory could fire to both sides, but it is probable that if they were fired to port (across the deck) the blast would have damaged the flight deck. The guns could be depressed to –5° and elevated to +41°; they were loaded at an angle of +9°. They fired 260-pound (118 kg) projectiles at a muzzle velocity of 2,800 ft/s (850 m/s); this provided a maximum range of 31,860 yd (29,133 m) at maximum elevation. A 20-foot (6.1 m) rangefinder was fitted on top of the pilothouse to provide fire control for these guns.

Their anti-aircraft armament consisted of twelve 25-caliber 5-inch guns which were mounted on single mounts, six on each side of the ship. They had a maximum elevation of 85°. They fired 53.85-pound (24.43 kg) projectiles at a muzzle velocity of 2,110 ft/s (640 m/s). Their maximum range against surface targets was 17,700 yd (16,200 m) at 30° elevation and they had an anti-aircraft ceiling of 27,400 yd (25,100 m) at 85° elevation.

The experience of the "Fleet Problem" exercises of the 1930s showed that planes were sufficient and the guns were unnecessary. The guns were removed from both ships just after Pearl Harbor. (The removed guns were used as shore-defense guns in Hawaii.) The 8-inch gun turrets were to be replaced with dual 5" DP gun turrets (the standard mounting on U.S. battleships and cruisers). On Saratoga, which had been damaged and was under repair for several months, this was done, but Lexington was rushed back into action with quad 1.1" mounts. Lexington was sunk before receiving her intended 5" guns.

Armor

The waterline belt of the Lexington-class ships tapered 7–5 inches (178–127 mm) in thickness from top to bottom and angled 11° outwards at the top. This angle increased the armor's relative thickness to horizontal, close-range fire, albeit at the cost of reducing its relative height which increased the chance of plunging shellfire going over or under it. It covered the middle 530 feet (161.5 m) of the ships. Forward, the belt ended in a bulkhead that also tapered from seven to five inches in thickness. Aft, it terminated at a seven-inch bulkhead. This belt had a height of 9 feet 4 inches (2.8 m). The third deck over the ships' machinery and magazine was armored with two layers of Special treatment steel (STS) totaling 2 inches (51 mm) in thickness. The steering gear, however, was protected by two layers of STS that totaled 3 inches (76 mm) on the flat and 4.5 inches (114 mm) on the slope.

The gun turrets were protected only against splinters with .75 inches (19 mm) of armor. The conning tower was 2–2.25 inches (51–57 mm) of STS, and it had a communications tube with two-inch sides ran from the conning tower down to the lower conning position on the third deck. The torpedo defense system of the Lexington-class ships consisted of three to six medium steel protective bulkheads that ranged from .375 to .75 inch (10 to 19 mm) in thickness. The spaces between them could be left empty or used as fuel tanks to absorb the detonation of a torpedo's warhead.

World War II service

Lexington and Saratoga were both attached to the Pacific Fleet when the war broke out.

Lexington participated in several raids on Japanese bases, but was sunk in May 1942 at the Battle of Coral Sea.

Saratoga served in several battles in 1942 through 1944, and was twice torpedoed by Japanese submarines, but on each occasion reached port under her own power. In September 1944, she was relegated to training duties, but she returned to combat duty in 1945. She was disabled by Japanese bombers in February 1945, and in June returned to training duties and to transporting returning troops to the U.S.

With the development of jet aircraft after the war, Saratoga became obsolete. Her hangar was large enough for jets, but her elevators were too small. In July 1946, she was used as a target for atomic bomb tests in Operation Crossroads, and sank at Bikini Atoll.

References

• Anderson, Richard M.; Baker, Arthur D. III (1977). "CV-2 Lex and CV-3 Sara". Warship International (Toledo, OH: International Naval Research Organization) XIV (4): 291–328. ISSN 0043-0374. 
• Campbell, John (1985). Naval Weapons of World War II. Annapolis, MD: Naval Institute Press. ISBN 0-87021-459-4. 
• Friedman, Norman (1983). U. S. Aircraft Carriers: An Illustrated Design History. Annapolis, Maryland: Naval Institute Press. ISBN 1-55750-250-1. 
• Hone, Trent (2011). "High-Speed Throughbreds: The US Navy's Lexington class Battlecruiser Designs". In Jordan, John. Warship 2011. London: Conway. pp. 8–31. ISBN 978-1-84486-133-0. 
• Stern, Robert C. (1993). The Lexington Class Carriers. Annapolis, Maryland: Naval Institute Press. ISBN 1-55750-503-9. 

External links

• War Service Fuel Consumption of U.S. Naval Surface Vessels FTP 218
• DANFS page on Lexington
• DANFS page on Saratoga