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Essex class Aircraft Carrier - CVA / CV


essex class aircraft carrier us navy cva cvs 02x   


CV/CVA/CVS 9 USS Essex (1942-69)
CV/CVA/CVS 10 USS Yorktown (1943-70)
CV/CVA/CVS 11 USS Intrepid (1943-74)
CV/CVA/CVS 12 USS Hornet (1943-70)
CV/CVA/CVS 13 USS Franklin (1944-47)
CV/CVA/CVS/CVT 16 USS Lexington (1943-91)
CV/CVA/CVS 17 USS Bunker Hill (1943-47)
CV/CVA/CVS 18 USS Wasp (1943-72)
CV/CVA/CVS 20 USS Bennington (1944-70)
CV/CVA 31 USS Bon Homme Richard (1944-71)
Ticonderoga subclass (long hulled Essex class)
CV/CVA/CVS 14 USS Ticonderoga (1944-73)
CV/CVA/CVS 15 USS Randolph (1944-69)
CV/CVA 19 USS Hancock (1944-76)
CV/CVA/CVS 21 USS Boxer (1945-69)
CV/CVA/CVS 32 USS Leyte (1946-59)
CV/CVA/CVS 33 USS Kearsarge (1946-70)
CV/CVA 34 USS Oriskany (1950-76)
CV 35 USS Reprisal (cancelled)
CV/CVA/CVS 36 USS Antietam (1945-63)
CV/CVA/CVS 37 USS Princeton (1945-70)
CV/CVA/CVS 38 USS Shangri-La (1944-71)
CV/CVA/CVS 39 USS Lake Champlain (1945-66)
CV/CVA/CVS 40 USS Tarawa (1945-60)
CV/CVA/CVS 45 USS Valley Forge (1946-70)
CV 46 USS Iwo Jima (cancelled)
CV/CVA/CVS 47 USS Philippine Sea (1946-58)
design: 34000 tons (full load) / actual: 36960 tons / after modification: up to 47120 tons

265,8 meters (872 feet) short units / 270,7 m (888 ft) long units
Beam: 45 meters (147.5 ft) - max. / 28,3 meters (93 ft) - waterline
Draft: 8,4 meters (27.5 ft) full load
Speed: 32,5 knots (60 km/h)
4 x Westinghouse geared steam turbines
8 x Babcock & Wilcox boilers

4 shafts / 4 propellers
Range: 20000 NM (37000 km) at 15 knots (28 km/h)

Complement: 2630
12 x 5-inch (127mm)/38-caliber guns (4x2 / 4x1)
32-72 x Bofors 40mm AA guns (8-18x4)
55-76 x Oerlikon 20mm AA guns

full flight deck with island and hangar deck
for up to 100 aircraft

1 x SK air-search radar
1 x SC air-search radar
2 x SG surface-search radar
1 x SM fighter-direction radar (later units)
2 x Mk 4 fire-control radar (earlier units)
2 x Mk 12 fire-control radar (later units)
2 x Mk 22 height-finding radar (later units)
10-17 x Mk 51 AA directors



The Essex class was a class of aircraft carriers of the United States Navy that constituted the 20th century's most numerous class of capital ships. The class consisted of 24 vessels, which came in both "short-hull" and "long-hull" versions. Thirty-two ships were originally ordered; however as World War II wound down, six were canceled before construction, and two were canceled after construction had begun. No Essex-class ships were lost to enemy action, despite several vessels sustaining very heavy damage. The Essex-class carriers were the backbone of the U.S. Navy's combat strength during World War II from mid-1943 on, and, along with the addition of the three Midway class carriers just after the war, continued to be the heart of U.S. Naval strength until the supercarriers began to come into the fleet in numbers during the 1960s and 1970s.

The preceding Yorktown-class aircraft carriers and the designers' list of trade-offs and limitations forced by arms control treaty obligations shaped the formative basis from which the Essex class was developed - a design formulation sparked into being when the Japanese and Italians repudiated the limitations proposed in the 1936 revision of the Washington Naval Treaty of 1922 (as updated in October 1930 in the London Naval Treaty) - in effect providing a free pass for all five signatories to resume the interrupted naval arms race of the 1920s in early 1937.

At the time of the repudiations, both Italy and Japan had colonial ambitions, intending or were already conducting military conquests. With the demise of the treaty limitations and the growing tensions in Europe, naval planners were free to apply both the lessons they had learned operating carriers for fifteen years and those of operating the Yorktown-class carriers to the newer design.

Designed to carry a larger air group, and unencumbered by the latest in a succession of pre-war naval treaty limits, Essex was over sixty feet longer, nearly ten feet wider in beam, and more than a third heavier. A longer, wider flight deck and a deck-edge elevator (which had proven successful in the one-of-a-kind USS Wasp (CV-7)) facilitated more efficient aviation operations, enhancing the ship's offensive and defensive air power.

Machinery arrangement and armor protection was greatly improved from previous designs. These features, plus the provision of more anti-aircraft guns, gave the ships much enhanced survivability. In fact, during the war, none of the Essex-class carriers were lost and two, USS Franklin (CV-13) and USS Bunker Hill (CV-17), came home under their own power even after receiving extremely heavy damage and were successfully repaired. Some ships in the class would serve until well after the end of the Vietnam War as the class was retired by newer build classes.

Debates raged, and continue to this day, regarding the effect of strength deck location. British designers' comments tended to disparage the use of hangar deck armor, but some historians, such as D.K. Brown in Nelson to Vanguard, see the American arrangement to have been superior. In the late 1930s, locating the strength deck at hangar deck level in the proposed Essex-class ships reduced the weight located high in the ship, resulting in smaller supporting structures and more aircraft capacity for the desired displacement. Subsequently, the larger size of the first supercarriers necessitated a deeper hull and shifted the center of gravity and center of stability lower, enabling moving the strength deck to the flight deck thus freeing US Naval design architects to move the armor higher and remain within compliance of US Navy stability specifications without imperiling seaworthiness. One of the design studies prepared for the Essex project, "Design 9G", included an armored flight deck but reduced aircraft capacity, and displaced 27,200 tons, or about 1,200 tons more than "Design 9F", which formed the basis of the actual Essex design; 9G became the ancestor of the 45,000-ton Midway class.

After the abrogation of disarmament treaties by Japan in 1936, the U.S. took a realistic look at its naval strength. With the Naval Expansion Act of Congress passed on 17 May 1938, an increase of 40,000 tons in aircraft carriers was authorized. This permitted the building of Hornet and Essex, which became the lead ship of her class.

CV-9 was to be the prototype of the 27,000-ton (standard displacement) aircraft carrier, considerably larger than Enterprise, yet smaller than Saratoga (a battlecruiser converted to a carrier). The Navy ordered the first three of the new design, CV-9, CV-10 and CV-11, from Newport News Shipbuilding & Drydock on 3 July 1940. These were to become known as Essex-class carriers. Under the terms of the Two-Ocean Navy Act, ten more of these carriers were programmed. Eight were ordered on 9 September, CV-12 through −15 from Newport News, and CV-16 through −19 from Bethlehem Steel's Fore River Shipyard; the last two, CV-20 and CV-21, were ordered eight days after Pearl Harbor from the Brooklyn Navy Yard and Newport News respectively.

After the US declaration of war, Congress appropriated funds for nineteen more Essexes. Ten were ordered in August 1942 (CV-31 and 33-35 from Brooklyn, CV-32 from Newport News, CV-36 and -37 from the Philadelphia Navy Yard, CV-38 through -40 from the Norfolk Navy Yard) and three more in June 1943 (CV-45 from Philadelphia, -46 from Newport News and -47 from Fore River). Ironically, only two of these were completed in time to see active World War II service. Six ships ordered in 1944 (CV-50 through -55) were canceled before construction was begun.

The first eight hulls were originally assigned names from historic Navy ships (Essex, Bon Homme Richard, Intrepid, Kearsarge, Franklin, Hancock, Randolph, Cabot). Lexington was originally laid down as Cabot, but was renamed during construction after the original USS Lexington (CV-2) was lost in the Battle of the Coral Sea in May 1942. Yorktown, originally to be named Bon Homme Richard, was renamed after the original USS Yorktown (CV-5) was lost at the Battle of Midway on 7 June 1942. Wasp's name was changed from Oriskany after the original USS Wasp (CV-7) was sunk in September 1942 in the South Pacific near Guadalcanal, and Hornet's name was changed from Kearsarge after the original USS Hornet (CV-8) was lost in October 1942 in the Battle of Santa Cruz Islands. The erstwhile Valley Forge was renamed Princeton after the USS Princeton (CVL-23) was sunk in the Battle of Leyte Gulf in October 1944. The names of the Ticonderoga and the Hancock were swapped while they were under construction: the John Hancock life insurance company had offered to conduct a bond drive to raise money for the Hancock if that name was used for the carrier under construction in the company’s home state of Massachusetts.

At the conclusion of the war, the six ships ordered but never laid down (CV-50 through 55) were canceled. Of the nine still unfinished six were completed and two (Reprisal and Iwo Jima) scrapped; Oriskany was taken in hand for modification to an improved design, completing in 1950. In summary, during World War II and until its conclusion, the US Navy ordered 32 aircraft carriers of the Essex class, including the Ticonderoga subgroup, of which 26 were laid down and 24 actually commissioned.

In drawing up the preliminary design for Essex, particular attention was directed at the size of both the 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. 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.

The pride of the carrier, known as the "Sunday Punch", was the offensive power of 36 fighters, 36 dive bombers and 18 torpedo planes. The F6F Hellcat would be the standard fighter, the SB2C-1 Helldiver the standard scout aircraft and dive-bomber, and the TBF Avenger was designed as a torpedo plane but often used in other attack roles. Later in the war some Essexes, such as Bunker Hill, also included F4U Corsairs in fighter-bomber squadrons (VBFs), the precursor to modern fighter-attack squadrons (VFAs). In the last year of the Pacific War, all of the carrier-based combat aircraft could mount several 5-inch High Velocity Aircraft Rockets (HVARs), which greatly improved their effectiveness against ground targets.

The defensive plan was to use radio and radar in a combined effort to concentrate anti-aircraft fire.

The design boasted twelve 5 inches (127 mm)/38 caliber gun turrets (4 twin mounts located near the island on the starboard side and 4 single open mounts located on the port side forward and port side aft), seventeen quadruple 40mm Bofors 40 mm anti-aircraft guns and 65 single 20 mm Oerlikon close-in defense guns. With a range of ten miles and a rate of fire of fifteen rounds per minute, the 5-inch guns fired the deadly VT shells. The VT shells, known as proximity fuzed-shells, would detonate when they came within 70 feet (21 m) of an enemy aircraft. The 5-inch guns could also aim into the water, creating waterspouts which could bring down low flying aircraft such as torpedo planes. The Bofors 40 mm guns were a significant improvement over the 1.1 in/75 caliber guns mounted in the earlier Lexington and Yorktown classes.

The Essex class also made use of advanced technological and communications equipment. All units were commissioned with SK air-search and SC and SG surface-search radars. Several of the class received SM fighter-direction radar. Two Mark 37 fire control directors fitted with FD Mark 4 tracking radar for the 5"/38 battery were installed; the Mk4 proved inadequate at distinguishing low-level intruders from surface clutter and was quickly replaced with the improved Mark 12/Mark 22 combination. 40mm AA batteries were controlled by Mark 51 optical directors with integrated gyro gun-sight lead-angle calculators. A Plan Position Indicator (PPI) display was used to keep track of ships and enabled a multi-carrier force to maintain a high-speed formation at night or in foul weather. The new navigational tool known as the Dead Reckoning Tracer was also implemented for navigation and tracking of surface ships. Identification Friend or Foe (IFF) was used to identify hostile ships and aircraft, especially at night or in adverse weather. The four-channel Very High Frequency (VHF) radio permitted channel variation in an effort to prevent enemy interception of transmissions. It also allowed for simultaneous radio contact with other ships and planes in the task force.

The "long-hull" Essexes:
Beginning in March 1943, one visually very significant change was authorized for ships then in the early stages of construction. This involved lengthening the bow above the waterline into a "clipper" form. The increased rake and flare provided deck space for two quadruple 40mm mounts; these units also had the flight deck slightly shortened forward to provide better arcs of fire. Of the Essex-class ships laid down after 1942, only Bon Homme Richard followed the original "short bow" design. The later ships have been variously referred to as the "long-bow units", the "long-hull group", or the "Ticonderoga class". However, the U.S. Navy never maintained any institutional distinction between the long-hull and short-hull members of the Essex class, and postwar refits and upgrades were applied to both groups equally. Less immediately visible aspects of the March 1943 design modification included safer ventilation and aviation-fuel systems, moving the Combat Information Center below the armored deck, the addition of a second flight-deck catapult, the elimination of the hangar deck catapult, and a third Mk 37 fire-control director; some of these changes were also made to short-bow ships nearing completion or as they returned to the yards.

Modifications were made throughout the Essex building program. The number of 20mm and 40mm anti-aircraft guns was greatly increased, new and improved radars were added, the original hangar deck catapult was removed, the ventilation system was substantially revised, details of protection were altered, and hundreds of other large and small changes were executed. In the meantime, earlier ships were continually modified as they returned to the yard for repair and overhaul. For example, Intrepid, one of the first to be commissioned, by the end of the war had received two H-4B flight deck catapults on place of her original single H-4A; three quad 40mm mounts below the island to starboard, three more on the port side and one additional on both the starboard quarter and the stern; 21 additional 20mm mounts; SM fighter-control radar; FD Mk 4 radar replaced with Mk 12/22; and an enlarged flag bridge. In fact, to the skilled observer, no two ships of the class looked exactly the same.

Post-war rebuilds:
The large numbers of new ships, coupled with their larger Midway-class contemporaries, sustained the Navy's air power through the rest of the 1940s, the Korean War era, and beyond. While the spacious hangars accommodated the introduction of jets, various modifications significantly improved the capability of fifteen of the ships to handle the jets’ increased weight and speed. These modifications included jet-blast deflectors (JBDs); mirror and then Fresnel-lens landing light systems (a British innovation); greater aviation fuel capacity; stronger decks, elevators, and catapults; and ultimately an angled flight deck.

Five of the long-hulls were laid up in 1946-47, along with all of the short-hulls. Eight of the last nine completed stayed on active duty to form, with three Midways, the backbone of the post-war Navy's combat strength. Though the Truman administration's defense economies sent three of the active Essexes into "mothballs" in 1949, these soon came back into commission after the Korean War began. Ultimately, nine short-hulls and all thirteen long-hulls had active Cold War service.

Oriskany, which had been left unfinished at the end of the war, was completed to an improved design between August 1948 and September 1950, with a much stronger (straight) flight deck and a reconfigured island. Eight earlier ships were thoroughly rebuilt to the Oriskany design under the SCB-27A program in the early 1950s. Six more of the earlier ships were rebuilt to an improved 27C design as the last stage of the SCB-27 program; these ships received steam catapults instead of the less powerful hydraulic units. The otherwise unmodified Antietam received an experimental 10.5 degree angled deck in 1952. An angled flight deck and enclosed hurricane bow became the distinctive features of the SCB-125 program, which was undertaken concurrently with the last three 27C conversions and later applied to all 27A and 27C ships except Lake Champlain. Shangri-La became the first operational United States angled deck aircraft carrier in 1955. Oriskany, the first of the modernized ships but the last angled-deck conversion, received a unique SCB-125A refit which upgraded her to 27C standard, and included steam catapults and an aluminum flight deck.

Korean War and subsequent Cold War needs ensured twenty-two of the twenty-four ships had extensive post–World War II service (Bunker Hill and Franklin had suffered heavy damage and were never recommissioned). All initially carried attack air groups; however by 1955 seven unconverted Essexes were operating under the anti-submarine warfare carrier (CVS) designation established in August 1953. As the Forrestal-class "supercarriers" entered the fleet, the eight 27A conversions were designated CVS to replace the original unconverted ships; the latter began to leave active service in the late 1950s. Two 27C conversions were designated CVS in 1962 (although CVS-11 Intrepid would operate as an attack carrier off Vietnam) and two more in 1969. The seven angle-deck 27As and one 27C received specialized CVS modifications including bow-mounted SQS-23 sonar under the SCB-144 program in the early 1960s. The updated units remained active until age and the growing number of supercarriers made them obsolete, from the late 1960s into the middle 1970s. However, one of the very first of the type, Lexington, served until 1991 as a training ship.

Of the unmodernized Essexes, Boxer, Princeton, and Valley Forge were redesignated Landing Platform Helicopter (LPH) amphibious assault ships for the Marine Corps, and remained in commission with their original straight decks until about 1970. The remainder decommissioned in the late 1950s and early 1960s and were promptly reclassified as aircraft transports (AVT), reflecting their very limited ability to operate modern aircraft safely. An unmodernised Essex was offered to the Royal Australian Navy in 1960 as a replacement for HMAS Melbourne but the offer was declined due to the expense of modifications required to make it operationally compatible with the RAN's primarily British-designed fleet. All were scrapped, most in the 1970s.

Evolution of the air wing:
For a typical attack carrier (CVA) configuration in 1956–57 aboard Bennington, the air wing consisted of one squadron each of the following: FJ3 Furies, F2H Banshees, F9F Cougars, AD-6, AD-5N, and AD-5W Skyraiders, AJ2 Savages, and F9F-8P photo Cougars.

By the mid-to-late 1960s, the attack air wing had evolved. Oriskany deployed with two squadrons of F-8J Crusaders, three squadrons of A-4E Skyhawks, E-1 Tracers, EKA-3B Skywarriors, and RF-8G photo Crusaders. In 1970, the three A-4 squadrons were replaced by two squadrons of A-7A Corsair IIs. The F-4 Phantom II and A-6 Intruder were considered too heavy to operate from the Essex-class.

Tasked and fitted out as an ASW carrier (CVS), the air wing of an Essex such as Bennington in the 1960s consisted of two squadrons of S2F Trackers and one squadron of SH-34 Seabat ASW helicopters (replaced in 1964 by SH-3A Sea Kings). Airborne early warning was first provided by modified EA-1Es; these were upgraded in 1965 to E-1Bs. A small detachment of A-4B's or A-4C's (4 aircraft) were also embarked to provide daylight fighter protection for the ASW aircraft.

Landing Platform Helicopter converted ships such as the USS Boxer never had an angled landing deck installed and flew only helicopters such as the UH-34 Seahorse and CH-46 Sea Knight. Four converted Essex class ships served alongside the purpose built Iwo Jima-class amphibious assault ships providing floating helicopter bases for US Marines. The LPHs were sometimes also used as aircraft ferries for all branches of the U.S. armed forces. The AV-8A arrived into Marine Corps inventory too late to see regular fixed wing operations return to these ships. It was possible to launch and recover small aircraft like the OV-10 Bronco without need of catapult or arresting wires, but this was very rarely permitted on these straight-deck ships for safety reasons and to avoid interruption of helicopter operations.

Military contributions:
One author called the Essex class "the most significant class of warships in American naval history", citing the large number produced and "their role in making the aircraft carrier the backbone of the U.S. Navy."

Essex-class ships played a central role in the Pacific theater of World War II from 1943 through the end of the war, beginning with raids in the central Pacific and the invasion of Tarawa in the Gilbert Islands. The ships successfully performed a number of missions, included air superiority, attacking the Japanese fleet, supporting landings, fleet protection, bombing the Japanese home islands, and transporting aircraft and troops. Along the way, the carriers survived bombs, torpedoes, kamikazes, and typhoons without one ship being sunk.

Eleven of the Essex carriers participated in the Korean War. These ships played a major role throughout the entire war. Missions included attacks on all types of ground targets, air superiority, and antisubmarine patrols.

Thirteen of the 24 carriers originally built participated in the Vietnam War, including the prelude and follow-up. However, their inability to support the latest aircraft constrained some of those ships to specialized roles as helicopter carriers or antisubmarine platforms. The ships still performing an attack mission generally carried older aircraft types than the supercarriers. Yet, the Essex class still made significant contributions to all aspects of the U.S. war effort. In one notable event, during the Gulf of Tonkin Incident, aircraft from the Ticonderoga fired at North Vietnamese torpedo boats that had attacked a U.S. destroyer.

The carriers also contributed between the wars, projecting U.S. power around the world and performing antisubmarine patrols. When the Cold War heated up, the Essex carriers were often involved, including Quemoy and the Matsu Islands, the Bay of Pigs Invasion, and the Cuban Missile Crisis. Also, from 1957 through 1991 an Essex-class ship served as the Navy's training carrier - the Antietam from 1957 through 1962 and the Lexington for the remainder of the time.


Hull numbers 22-30 in the aircraft carrier sequence were assigned to the Independence-class light carriers (CVL); hull numbers 41-44 were assigned to the large carriers (CVB) of the Midway class.

Reprisal, laid down in July 1944 at the New York Navy Yard and launched in 1945, had her construction cancelled due to an accident on 12 August 1945 when the ship was about half complete. She was scrapped incomplete after tests. Iwo Jima (CV-46) was laid down at Newport News Shipbuilding yards in January 1945 but cancelled in August 1945 and broken up on the slipway.

Six fiscal-year 1945 ships, none of which received names, were assigned to Fore River (CV-50), Brooklyn Navy Yard (CV-51 and CV-52), Philadelphia Navy Yard (CV-53) and Norfolk Navy Yard (CV-54 and CV-55). Their construction was canceled in March 1945.

Oriskany (CV-34) was ordered and laid down as an Essex-class vessel, was completed in 1950 to the much modified SCB-27 design, and from commissioning until her reconstruction 1957-59 was listed as the lead ship of the separate Oriskany class.

Later class assignments:
Successive rebuildings and changing roles meant that the original unitary Essex class became divided by the Navy into several classes, which went through many shifts and re-namings. According to the United States Naval Vessel Register the final class assignments were:

CVS-10 Yorktown class (SCB-27A): Essex, Yorktown, Hornet, Randolph, Wasp, Bennington, Kearsarge, Lake Champlain
CVS-11 Intrepid class (SCB-27C + SCB-144): Intrepid
CVA-19 Hancock class (SCB-27C): Ticonderoga, Hancock, Bon Homme Richard, Oriskany, Shangri-La
AVT-8 Franklin class (unreconstructed ships): Franklin, Bunker Hill, Leyte, Antietam, Tarawa, Philippine Sea
AVT-16 Lexington class (training carrier): Lexington
LPH-4 Boxer class (helicopter assault conversions): Boxer, Princeton, Valley Forge

source: wikipedia


SCB-27 (SCB-27A, SCB-27C) programme:

... was the United States Navy designation for a series of upgrades to the Essex class aircraft carriers (both the short-hull and long-hull (Ticonderoga) versions), conducted between 1947 and 1955. These upgrades were intended to allow the World War II-era carriers to operate jet aircraft.

Officially, Ship Characteristics Board Program 27 proper referred to the completion of USS Oriskany (CV-34), left unfinished at war's end, to a heavily revised design; reconstructions of earlier ships were programs SCB-27A and 27C. The SCB-27 modernization was very extensive, requiring some two years for each carrier. To handle the much heavier, faster aircraft of the early jet-era, the flight deck structure was significantly reinforced, able to support aircraft weighing up to 52,000 pounds (23,587 kg), namely the North American AJ Savage. Stronger and larger elevators, much more powerful catapults, and new Mk 5 arresting gear were installed. The original four twin 5"/38 gun mounts were removed, clearing the flight deck of guns. The new five-inch gun battery consisted of eight weapons, two on each quarter beside the flight deck. Twin 3"/50 gun mounts replaced the 40mm guns, offering much greater effectiveness through the use of proximity fuzed ammunition. The reconstruction eliminated the difference between "short-hull" and "long-hull" ships; all now had similar clipper bows.

The island was completely redesigned, made taller, but shorter in overall length with the removal of its gun mounts. In addition, the boiler uptakes were rebuilt and angled aft to accommodate a single radar and communications mast atop the island. To better protect aircrews, ready rooms were moved from the gallery deck to below the armored hangar deck, with a large escalator on the starboard side amidships to move flight crews up to the flight deck. Internally, aviation fuel capacity was increased to 300,000 US gallons (1,135,624 L) (a 50% increase) and its pumping capacity enhanced to 50 US gallons (189.3 L) per minute. Fire fighting capabilities were enhanced through the addition of two emergency fire and splinter bulkheads to the hangar deck, a fog/foam firefighting system, improved water curtains and a cupronickel fire main. Also improved were electrical generating power, and weapons stowage and handling facilities. All this added considerable weight: displacement increased by some twenty percent. The armor belt was removed and blisters were fitted to the hull sides to compensate, widening waterline beam by eight to ten feet. The ships also sat lower in the water, and maximum speed was slightly reduced, to 31 knots.

Modification sub-types:
The two sub-types of SCB-27 modifications were primarily a result of changes in catapult technology in the early-1950s. SCB-27A vessels utilized a pair of H 8 slotted-tube hydraulic catapults, while the later SCB-27C vessels were fitted with a pair of C 11 steam catapults, a British innovation (in fact the first four installed, on USS Hancock and USS Ticonderoga, were British-built). To accommodate the catapult machinery, the SCB-27C vessels were slightly heavier (43,060 vice 40,600 tons) and after bulging wider abeam (103 vice 101 feet) than their SCB-27A sisters. Additionally, the SBC-27C carriers were equipped with jet blast deflectors, deck cooling, fuel blending facilities, emergency recovery barrier and storage and handling for nuclear weapons, which was not included in all of the SCB-27A carriers. Under SCB-27C the No. 3 (after) elevator was moved to the starboard deck edge; this elevator was located further aft on the first three SCB-27C ships than it was on the ships which received it concomitantly with an angled flight deck under the SCB-125 program.

The greater capacity of steam catapults meant that the 27C ships were able to serve as attack carriers through the Vietnam era while their hydraulic-equipped 27A sisters were relegated to antisubmarine duties.

Program history:
USS Oriskany (CV-34), laid up incomplete at the conclusion of World War II, served as the prototype and was re-ordered to the SCB-27 standard. All of the SCB-27 modernized Essex carriers, save USS Lake Champlain (CV-39), were further modified under the SCB-125 modernization program.

Characteristics after SCB-27 modification:
Displacement: 40600 tons (full load)
Length: 274 meters
Beam: 46,3 meters
Draft: 9,04 meters
8 x single 5”/38 caliber guns (127mm)
14 x twin 3”/50 caliber guns (76mm)

SCB-125 (SCB-125A) programme:
... was the United States Navy designation for a series of upgrades to the Essex class of aircraft carriers conducted between 1954 and 1959. These upgrades included the addition of an angled flight deck and other enhancements aimed at improving flight operations and seakeeping.

Principal alterations:
The SCB-125 modifications included
Angled flight deck
Enclosed hurricane bow
Mirror landing system
Mark 7 arresting gear
Primary Flight Control moved to aft end of island
Air conditioning
No 1 (forward) elevator lengthened (SCB-27C ships only)
No 3 (aft) elevator moved from centerline to starboard deck edge (on SCB-27A ships; had been part of SCB-27C refits)

Program history:
The SCB-125 upgrade program was first applied to the final three Essex-class carriers to undergo the SCB-27C modernization while they were still in the midst of their original refit. Ultimately every SCB-27 ship would undergo the SCB-125 modification with the exception of USS Lake Champlain (CV-39).

Despite the drastic alteration of the carriers' appearance, the SCB-125 refit involved relatively little modification of the ships' existing structure compared to SCB-27, and took around six to nine months as against the approximately two years of the earlier program. The original SCB-27A vessels, which were fitted with a pair of H 8 hydraulic catapults, were not upgraded with the C 11 steam catapults fitted to their SCB-27C sister ships due to machinery space limitations. The SBC-27As also did not receive the enlarged No. 1 (forward) elevator installed in the 27C ships as part of SBC-125.

The first three 27C ships (Hancock, Intrepid and Ticonderoga) had had their No 3 elevators moved from the centerline to the starboard deck edge, in a position relatively far aft. The next three (Shangri-La, Lexington and Bon Homme Richard), which underwent 27C and 125 concurrently, had the elevator relocated to a deck-edge position farther forward, and this location was used for the 27A ships as they in turn underwent SCB-125.

USS Oriskany (CV-34), the prototype for the SCB-27 conversion, was the final Essex to undergo SCB-125 conversion and as such, received further enhancements. As a result of the addition of aluminum flight-deck cladding, Mk 7-1 arresting gear and more-powerful C 11-1 steam catapults to the standard SCB-125 modifications, Oriskany alone was referred to as a SCB-125A vessel. These changes also made Oriskany the sole SCB-27A vessel to receive steam catapults.

Characteristics after SCB-125 modification:
Displacement: 41200 tons (full load)
Length: 270 meters
Beam: 60 meters
Draft: 9,17 meters
7 x single 5”/38 caliber guns (127mm)
4 x twin 3”/50 caliber guns (76mm)

SCB-144 modification:
The seven angle-deck 27As and one 27C received specialized CVS modifications under the SCB-144 program in the early 1960s. SCB-144 was part of the Navy Fleet Rehabilitation and Modernization (FRAM) II program intended to improve the ASW capability of the SCB-27A CVS carriers.
- installation of the SQS-23 bow-mounted sonar dome
- installation of a stem hawsepipe and bow anchor
- modifications to the Combat Information Center

Ships modified: Essex, Yorktown, Intrepid, Hornet, Randolph, Wasp, Bennington, Kearsarge.
SCB-27 / SCB-125 modified vessels:
essex class aircraft carrier us navy scb-27 scb-125 modification rebuilding
  essex class aircraft carrier us navy scb-27 scb-125 modifications 04



essex class aircraft carrier us navy cva cvs 05 drawing



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