The Navy's Nimitz class nuclear powered aircraft carriers provide sustainable, independent forward presence and conventional deterrence in peacetime; operate as the cornerstone of joint/allied maritime expeditionary forces in times of crisis; operate and support aircraft attacks on enemies; and protect friendly forces and engage in sustained independent operations in war. Carriers support and operate aircraft that engage in attack on airborne, afloat, and ashore targets that threaten free use of the sea and engage in sustained operations in support of other forces.
They are the largest warships in the world, are powered by two nuclear reactors, and carry 85 aircraft. The crew consists of a ship's company of 3,200 and an air wing of 2,480.
The advantages of nuclear propulsion in combat effectiveness are substantial. The ability of a carrier to operate continuously at maximum speed results in reduced time to arrive in theater and in increased time on station. Additionally, once there, the carrier is ready to fight immediately, since no ship refueling is needed before commencing operations. Air crews can continue to train while the ship is in transit. The only refueling the carrier requires is for the air wing (weekly in most cases).
Fossil fuel propulsion is also an option. However the impact on the combat availability of the carrier is considerable. The ship's ability to maintain maximum speed for sustained periods is sharply reduced. Refueling for fossil fuel-powered carriers must take place three times in transit between the U.S. West Coast and combat stations in Southwest Asia. While in theater, refueling is typically needed every two days.
The power density required for a fossil fueled aircraft carrier dictates the use of gas turbines. These require extensive intake and exhaust ducting. The exhaust can impair deck operations under some conditions.
In the FY1967 budget, Secretary of Defense McNamara reversed course from the conventionally powered CVA-67 John F. Kennedy, and requested three nuclear carriers to be built over the next 5 years. The program the Johnson administration presented to Congress for 1967 called for the nuclear carrier (the Nimitz, CVAN 68) and two oil-fired destroyers but no nuclear frigates.
Harold Brown to briefed the Joint Committee, and referred to the decision to proceed with conventional power on USS John F. Kennedy (as CVA-67 would now be called) by saying, “let’s face it, Bob made a mistake.” It was not until late August that McNamara, in response to a memorandum from Charlie Hitch, approved nuclear propulsion for the carriers scheduled to begin construction in 1967, 1969, and 1971. But the Kennedy would remain a conventionally-powered carrier, largely due to the timing of the decision more than anything else.
McNamara changed his mind in part due to an analysis completed at the Center for Naval Analyses by economist Patrick Parker showing that the costs of a nuclear carrier over its lifetime were less than originally thought. Part of the disparity in cost estimates stemmed from McNamara’s systems analysis office assuming that a larger nuclear-powered aircraft carrier would carry an extra squadron of planes, which over the 25 years of operations added $308 million to the cost. This was fully two-thirds of the cost differential between a conventional and nuclear-powered carrier. Since the Navy did not intend to put more planes (at least it stated so at the time) on the carrier, these costs were not accurate.
Costs were also reduced by using the new two-reactor cores that were expected to last 13 years, or four times as long as the cores originally installed in Enterprise. The Navy had used systems analysis in essence to beat McNamara at his own game. The Navy could now show in reasonable detail and with sufficient sophistication in analysis that the nuclear-powered carrier not only was more effective, but also roughly equal in cost over its lifetime compared to conventional carriers.
The demonstrated superiority of nuclear propulsion for aircraft carriers included the fact that the ship could accelerate and decelerate quickly, enabling the rapid maneuvers necessary when the ship was launching and landing different types of aircraft. The quick response to orders changing speed made possible the rapid return to the base course so that at the end of a given time, the ship would be farther along toward its intended objective than an oil-fired carrier. Other advantages were the absence of stack gases, which disturbed the air and corroded equipment, high sustained speed, and long endurance so that the ship would arrive and remain in an operation area unlimited by the supply of ship's fuel.
Aircraft carriers form the centerpiece of US Naval global forward presence, deterrence, crisis response, and warfighting. In addition to their power-projection role, they serve as joint command platforms in the worldwide command-and-control network. The carrier air wing can destroy enemy aircraft, ships, submarines, and land targets, or lay mines hundreds of miles from the ship. Aircraft are used to conduct strikes, support land battles, protect the battle group or other friendly shipping, implement a sea or air blockade. The air wing provides a visible presence to demonstrate American power and resolve in a crisis. The ship normally operates as the centerpiece of a carrier battle group commanded by a flag officer embarked in the carrier and consisting of four to six other ships, including guided missile cruisers, destroyers, frigates, replenishment ships and submarines.
USS Theodore Roosevelt (CVN 71) departed Newport News Shipbuilding (NYSE: NNS) on July 2, 1998 after a year-long period of maintenance and overhaul work. The ship returned to its homeport in Norfolk, Va. Work performed on Roosevelt included the replacement of all four ship propellers, blasting and painting of the hull, major renovations of onboard storage tanks and miscellaneous systems upgrades.
The USS Abraham Lincoln (CVN 72) joined the fleet in 1990 as, concurrently, USS Coral Sea (CV 43) was decommissioned. USS Abraham Lincoln underwent a one-year comprehensive overhaul and a change of homeport from Alameida, Calif. to Everett, Wash. since its last major deployment in 1995. On 11 June 1998 USS Abraham Lincoln (CVN-72) departed Naval Station Everett to the Arabian Gulf and back over a six-month period, the ship's fourth major Western Pacific deployment.
CVN 73, 74 and 75 were authorized to replace conventionally powered carriers as they retired in the 1990s. The Congress authorized full funding in 1988 for CVN 74 and 75. These ships are modified repeats of CVN 73. The keel of USS Harry S Truman (CVN 75) was laid 29 November 1993 and the ship was christened at Newport News on 07 September 1996. Harry S Truman completed acceptance sea trials on 24 June 1998, was delivered to the US Navy a few days later. The ship was commissioned and put into active service on 25 July 1998 at the Norfolk Naval Base in Norfolk, VA. At that time, the Navy's oldest active commissioned ship, Independence (CV 62), transitioned to the inactive fleet.
The 1993 decision to close Naval Air Station Alameda, Ca. made it necessary to develop the facilities and infrastructure to accommodate one NIMITZ-class aircraft carrier in San Diego. The USS John C. Stennis (CVN 74) arrived in San Diego in 1998. This was in addition to the two conventionally-powered aircraft carriers, USS Kitty Hawk (CV 63) and USS Constellation (CV 64), presently homeported there. The nuclear-powered NIMITZ-class aircraft carrier is a much larger and deeper draft ship than its steam-driven predecessors. Thus, the dredging of the berthing areas, turning basin and the access channel adjacent to NAS North Island was necessary.
|Join the GlobalSecurity.org mailing list|