This first nuclear-powered carrier for the US navy was commissioned in November 1961 as the USS Enterprise (CVAN-65), with the letter ‘N’ within the letter suffix designation code representing the fact that it was nuclear-powered. It was originally envisioned that the USS Enterprise would be the lead in a class of six ships.
The idea for a nuclear-powered carrier had been under
consideration by the US navy since early 1949. By 1952 Secretary of the Navy
Dan A. Kimball said that he hoped the next carrier would be nuclear-powered.
The Atomic Energy Commission and the Department of Defense (DOD) jointly
announced in 1954 plans ‘for the development of nuclear propulsion for large
naval vessels’.
With nuclear-powered carriers, onboard reactors heat
pressurized water and turn it into high-pressure steam. This high-pressure
steam is then employed to power a ship’s main propulsion turbine engines, which
are mechanical, turbine generators, and auxiliary machinery. It also provides
the steam required by the ship’s catapults.
Unlike conventionally-powered carriers that must refuel
every few thousand miles, nuclear-powered carriers have the ability to steam at
high speed for up to a million miles. However, like conventionally-powered
carriers, nuclear-powered carriers must still be replenished constantly with
aviation fuel and ordnance for their aircraft plus food and other supplies for
their crews.
As nuclear reactors produce a great deal of radiation, the
areas of a ship in which they are located must be heavily shielded to protect
the engineering crew. The level of training required among the engineering crew
of nuclear-powered carriers is much higher than that of their
conventionally-powered counterparts. Since nuclear reactors do not produce the
exhaust gases of ships powered by fuel oil-fired boilers, nuclear-powered ships
do not require stacks, which does free up a certain amount of room on a
carrier’s island.
The First Nuclear-Powered US Navy Carrier
In 1956 Congress authorized the construction of the first
nuclear-powered carrier. On 4 February 1958, at the same time the keel of the
new ship was being laid down, Secretary of the Navy William B. Franke announced
that it would be assigned the proud name Enterprise to perpetuate the famous
Second World War Yorktown-class carrier USS Enterprise (CV-6) and its five
naval predecessors.
This first nuclear-powered carrier for the US navy was
commissioned in November 1961 as the USS Enterprise (CVAN-65), with the letter
‘N’ within the letter suffix designation code representing the fact that it was
nuclear-powered. It was originally envisioned that the USS Enterprise would be
the lead in a class of six ships.
The first commander of the USS Enterprise was Captain (later
Vice Admiral) Vincent de Poix. In early 1962 he described some of the abilities
of his new ship:
There are four rudders, one almost directly astern of
each propeller. This provides excellent maneuverability at all speeds as well
as tactical diameters in turns which compares with much smaller ships …
Her ability to launch a strike on the enemy from one
position, recover, and launch another 24 hours later from an unpredictable
position more than 800 miles away from her previous strike position will
constantly be a factor in causing the enemy to utilize protective forces that
could be deployed elsewhere.
If a show of force is required, Enterprise can be on distant
station in a shorter period of time than any other ship in the fleet.
Ship Description
At the time it was built, the USS Enterprise was the largest
ship ever constructed with a length of 1,123 feet and a full load displacement
of 89,600 tons. The general shape and dimensions of the ship were based on the
design of the Kitty Hawk-class carriers. The Enterprise typically carried 100
planes.
Like the previous Kitty Hawk class, the USS Enterprise had
four steam-powered catapults and four deck-edge elevators. Its most distinctive
external feature was the box-like design of the upper portion of its island,
which had large flat-panel phased-array antennas mounted instead of the more
conventional rotating radar antennas. The original radar design arrangement on
the Enterprise was eventually removed and replaced by more conventional
rotating radars.
During its many decades of service, the USS Enterprise went
through a number of modernization programmes. In 1975 the US navy redesignated
the letter suffix code for the ship from CVAN to CVN, when it received its own
inventory of ASW aircraft.
Due to the cost of building the Enterprise, the US navy
decided not to build any additional examples of the ship. It was inactivated in
December 2012 because of the high cost of refuelling the eight nuclear reactors
on board the ship. However, it will not be formally decommissioned until it is
completely defuelled, which will take until 2015 or longer.
A comparison of Capital warships of the Twentieth Century.
Nimitz-Class Carriers
Despite some early problems with the USS Enterprise, mainly
centred on its phased-array radar system, the Secretary of Defense and Congress
were generally very pleased with its operational performance. This resulted in
Congress authorizing the construction of a new, more affordable class of
nuclear-powered carriers, designated the Nimitz class. They would be based
around the design of the Kitty Hawk-class carriers, which in turn had been
based on the cancelled USS United States (CVA-58).
The first ship in the Nimitz class was the USS Nimitz
(CVAN-68) that was laid down in June 1968 but not commissioned until May 1975.
This long gestation period pushed back the planned commissioning date of the
follow-on Nimitz-class carriers, resulting in a dramatic increase in their
cost. President Jimmy Carter responded to this additional expense by boldly
suggesting that the US navy cancel the Nimitz class and build a class of
smaller and more affordable carriers. As might be expected, the majority of the
US navy’s senior leadership reacted very badly to the president’s view on what
was best for the service and with its Congressional supporters overcame his
objections. Congress would go on to authorize funding for the construction of
additional Nimitz-class carriers.
Some within the US navy and the preceding President Gerald
Ford administration had also believed that smaller non-nuclear-powered carriers
might be a solution to the high cost of nuclear-powered vessels and had done
various studies on the matter beginning in the 1970s. However, none ever came to
fruition. These proposed smaller, non-nuclear-powered carriers went by
different names: Sea Control Ship (SCS), mid-size carrier (CVV) and the VSTOL
Support Ship (VSS), the acronym ‘VSTOL’ standing for Vertical/Short Take-Off
and Landing.
Additional Nimitz-Class Carriers Authorized
The USS Nimitz was followed by the USS Dwight D. Eisenhower
(CVAN-69). In June 1975 both ships were reclassified with the letter suffix
designation code CVN as they had their own dedicated ASW aircraft, making them
multi-mission carriers.
The following eight Nimitz-class carriers were assigned the
letter suffix designation code CVN from their commissioning date: USS Carl
Vinson (CVN-70), USS Theodore Roosevelt (CVN-71), USS Abraham Lincoln (CVN-72),
USS George Washington (CVN-73), USS John C. Stennis (CVN-74), USS Harry S.
Truman (CVN-75), USS Ronald Reagan (CVN-76) and USS George H.W. Bush (CVN-77).
The last was commissioned in January 2009, thirty-four years after the first in
its class. All ten Nimitz-class carriers continue in service to this day and
remain the tip of the spear in America’s military projection around the globe.
Class Description
Nimitz-class carriers are twenty-four storeys high and
require more than 900 miles of cable and wiring, 60,000 tons of structural steel
and almost a million pounds of aluminium. The four bronze propellers that push
them through the seas are 21 feet across and weigh 66,220 pounds each. There
are nearly 30,000 light fixtures and 2,000 phones aboard a Nimitz-class
carrier. A distillation plant produces 400,000 gallons of fresh water daily for
each ship and its crew. That is enough for 2,000 suburban homes every day. The
kitchens on board the ships prepare 18,150 meals per day.
The Nimitz-class carriers have an overall length of 1,094
feet with a full load displacement of almost 100,000 tons in the last units
constructed. They can carry up to ninety planes in an emergency, with a typical
number today being around fifty-six planes.
As with the previous Kitty Hawk class, the Nimitz-class
carriers have four steam-powered catapults and four deck-edge elevators. Unlike
the USS Enterprise (CVAN-65) that had eight A2W nuclear reactors, the
Nimitz-class ships have only two of the latest-generation A4W nuclear reactors,
the extra space being employed for many other purposes such as storage of
aviation fuel and ordnance.
The Merits of Nuclear-Powered Carriers
The US navy preference for nuclear-powered carriers over
their conventionally-powered equivalents was addressed in an August 1998
Government Accounting Office (GAO) report entitled ‘U.S. Navy Aircraft
Carriers: Cost Effectiveness of Conventionally and Nuclear-Powered Carriers’.
The following extract partly summarizes the GAO’s conclusions:
Each type of carrier offers certain advantages. For
example, conventionally powered carriers spend less time in maintenance, and as
a result, they can provide more forward presence coverage. By the same token,
nuclear carriers can store larger quantities of aviation fuel and munitions
and, as a result, are less dependent on at-sea replenishment. There was little
difference in the operational effectiveness of nuclear and conventional
carriers in the Persian Gulf War …
Pictured still in dry dock during its launching
ceremony is the unfinished USS Gerald R. Ford (CVN-78). It is the first ship in
the brand-new Gerald R. Ford class of supercarriers. It has a new bulbous lower
bow section seen here that improves hull efficiency by adding buoyancy to the
forward end of the ship. Total cost of the ship when completed is expected to
be $14 billion. She was commissioned in 2017.
The second ship in the new Ford class of carriers will
be the USS John F. Kennedy (CVN-79), seen here in model form. Construction of the
vessel began in February 2011 and it is expected to be completed by 2020. The
island on the Ford class of supercarriers will have only a single large
foremast projecting out of the roof rather than the two separate masts seen on
Nimitz-class carriers
Nimitz-Class Replacement Carrier
With the extremely long lead-in time between the
authorization of a modern carrier and its commissioning, the US navy began
thinking about the replacement for the Nimitz-class carriers as far back as the
early 1990s. The first ship in this new proposed class of carriers would be a
prototype referred to as the CVX.
In 1998 a US navy spokesman stated that the CVX prototype
would be designed with a ‘clean sheet of paper’, suggesting that it would not
be an evolutionary improvement over the previous Nimitz-class carriers but a
revolutionary improvement with a dramatic rise in operational capabilities.
Also implied was the fact that the CVX might not be nuclear-powered and would
be more affordable and less costly to operate than the preceding Nimitz class.
Despite the 1998 pronouncement by the US navy on what they
visualized for the CVX prototype, the funding necessary for the implementation
of the revolutionary ship never materialized. Instead, in 2001 the new
Secretary of Defense, Donald Rumsfeld, proposed that a prototype carrier be
built as an evolutionary improvement over the previous Nimitz-class carriers
and be labelled as CVX-1. It would be followed into production by the building
of a more revolutionary improved Nimitz-class carrier designated the CVX-2.
The US navy then decided to merge the concept of the CVX-1
and CVX-2 into a single ship initially referred to as the CVN-21, with the
numbers in the designation code representing the twenty-first century. Building
of the new carrier, named the Gerald R. Ford and given the designation code
CVN-78, began in 2007 with a commissioning date of 2017. As indicated by the
ship’s letter suffix designation code, the Gerald R. Ford is nuclear-powered.
The intended replacement for the ‘legacy’ McDonnell
Douglas F/A-18 Hornet, and to complement the Boeing F/A-18 Super Hornet on the
Nimitz and Ford class of carriers, is the Lockheed Martin F-35C multi-mission
aircraft seen here. The single-engine, single-seat F-35C is a variant of the
standard F-35, originally known as the Joint Strike Fighter (JSF), and has
stealth features. It first entered service with the US navy in 2013 and may
represent the last generation of manned carrier aircraft employed by the service.
On the horizon for use on the Nimitz and Ford class of
carriers are unmanned combat aerial vehicles, the possible future of carrier
aviation. Pictured on the flight deck of a Nimitz-class carrier is a tailless
Northrop Grumman demonstration drone, designated the X-47B. It was successfully
launched and recovered from Nimitz-class supercarriers in 2013. It has a wing
span of 62 feet and two weapon bays, plus stealth features.
Carrier Description
The PCU (Pre-Commissioning Unit) Gerald R. Ford is 1,106
feet long and when commissioned it is estimated that it will have a full load
displacement of over 100,000 tons. It will carry approximately seventy-five
aircraft that will be launched by four catapults. Aircraft will be moved
between the flight deck and hangar deck by three deck-edge elevators instead of
the four on the previous Nimitz-class carriers.
The island on the Gerald R. Ford is smaller and located further
aft than seen on the previous Nimitz-class carriers. To increase the number of
missions (sorties) that the ship’s aircraft can perform and at the same time
reduce the number of personnel needed, a great deal of automation was
incorporated into the carrier’s final design.
From the Naval Sea System Command comes this passage
describing the reasons why the new Ford class of carriers will be more
cost-effective than the previous Nimitz class:
Each ship in the new class will save more than $4 billion
in total ownership costs during its 50-year service life, compared to the
Nimitz-class. The CVN 78 is designed to operate effectively with nearly 700
fewer crew members than a CVN 68-class ship. Improvements in the ship design
will allow the embarked air wing to operate with approximately 400 fewer
personnel. New technologies and ship design features are expected to reduce
watch standing and maintenance workload for the crew … The Gerald R. Ford class
is designed to maximize the striking power of the embarked carrier air wing.
The ship’s systems and configuration are optimized to maximize the sortie
generation rate (SGR) of attached strike aircraft, resulting in a 33 per cent
increase in SGR over the Nimitz class. The ship’s configuration and electrical
generating plant are designed to accommodate new systems, including direct
energy weapons, during its 50-year service life.
The Gerald R. Ford will be fitted with an Electromagnetic
Aircraft Launch System (EMALS) when commissioned, in place of the steam-powered
catapults currently employed on the Nimitz-class carriers. The advantages
provided by installing the EMALS on the Gerald R. Ford, according to the US
navy, are numerous. These include a reduction in size and weight, plus
requiring less maintenance and therefore fewer personnel to operate. According
to the programme manager for the EMALS, it will be able:
to launch today’s current air wing as well as all future
carrier aircraft platforms in the U.S. Navy’s inventory through 2030 with
reduced wind-over-the-deck requirements when compared to steam catapults, and
additional capability for aircraft growth during the 50-year life of a carrier.
To supplement the EMALS on the Gerald R. Ford it will also
be fitted with the new Advanced Arresting Gear (AAG). This employs an electric
motor-based system in place of the existing hydraulic arresting gear system. It
has been stated by the US navy that the AAG will be much more reliable than the
existing arresting gear system. It is planned to eventually upgrade the
Nimitz-class carriers with the AAG.
The last two Nimitz-class carriers, the USS Ronald Reagan
and USS George H.W. Bush were fitted with a new Advanced Recovery Control (ARC)
system which is digitally controlled. This was in contrast to the previous Mk.
7 mechanically-controlled arresting gear system fitted to the first eight
Nimitz-class carriers commissioned.
Two other carriers in what is now referred to as the Gerald
R. Ford or Ford class have also been authorized: the John F. Kennedy (CVN-79)
and the Enterprise (CVN-80). Construction on the John F. Kennedy began in 2011,
with construction of the Enterprise scheduled to begin in 2018. Current plans
call for eventually building seven more Ford-class carriers to replace the ten
existing Nimitz-class carriers on a one-for-one basis. It is anticipated that
the last Nimitz-class carrier will be decommissioned in 2058.
