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.
Development:
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.
Design:
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.
Armaments:
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
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Modifications:
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.
Modifications:
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.
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SCB-27 / SCB-125 modified vessels:
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