CVN 21 / CVN-X / CVX - Design
The Navy has adopted an evolutionary design approach for future carriers, beginning with the CVN 77 as a transition ship and retains the Nimitz-class hull form largely unchanged through at least CVNX 2.
Innovations for the next-generation aircraft carrier include an enhanced flight deck with increased sortie rates, improved weapons movement, a redesigned island, a new nuclear power plant, allowance for future technologies and reduced manning. Other features of the CVNX being proposed by ONR include real-time damage detection and dynamic magazine protection.
CVNX-1 will feature a new design nuclear propulsion plant leveraging three generations of submarine reactor technology. The requirement for a new nuclear propulsion system reflects a need for a reduction in manning, maintenance, acquisition, and life cycle costs. This new powerplant will enable CVNX-1 to meet the large-scale electrical demands predicted for 21st century shipboard technology. A new electrical generation distribution system will also be a critical feature of the CVNX design. This feature will result in immediate warfighting enhancements in several areas:
- Survivability. A redundant grid electrical system will enhance damage control features. Electrical auxiliary systems will require reduced maintenance and allow the ship to utilize all generated electric power more effectively than the current design, where the carrier cannot always efficiently access all power available.
- Availability. Reduced maintenance and greater reliability will enable CVNX-1 to have a greater availability in reduced shipyard periods.
- Flexibility. The advanced electrical features of this new powerplant will allow for the rapid reconfiguration of CVNX-1 to utilize advanced technologies, as they become available.
The tentative goals with CVNX-1 will also include a further reduction in operating costs and manpower requirements from CVN-77.
CVNX-2 will be the culmination of the evolutionary carrier design program started with CVN-76. Key features of CVNX-2 will include an electromagnetic aircraft launching system that will have reduced manpower and maintenance as well as lower wind over deck requirements for aircraft launch and recovery. This system will also extend aircraft life, as peak loads on the airframe will be reduced. This design utilizes technology similar to that used by European rail systems to propel ‘bullet’ trains. The benefits will be freeing the catapults from dependence on ship-generated steam, as well as an increase in available energy and a major reduction in both weight and volume. Consideration had been given to an internal combustion catapult that would utilize a combination of JP-5 and an oxidizer to propel the launch assist mechanism. A drawback to this system was the separate storage and piping systems required for the oxidizer, as well as the drain on JP-5 resources. CVNX-2 will be designed with modular architecture and systems that are reconfigurable to provide operational flexibility. CVNX-2 will have an advanced armor system to improve her combat survivability. Commercial systems will be adapted for use in ship operations, habitability, mooring, and maneuvering. An advanced weapons information management system will automate the process of weapons inventory control, weapons movement, and weapons deployment from the magazine to the aircraft. The long-term goals with CVNX-2 envision additional reductions in total operating costs and manpower requirements.
The Navy remains committed to a 21st century aircraft carrier utilizing advanced technological applications. The goal is to create a sea based tactical air platform that not only retains the warfighting relevance of the NIMITZ class, but also is designed with architecture for change. This approach will allow the Navy to take advantage of maturing technologies that not only enhance warfighting capabilities but also provide opportunities to reduce life cycle costs. While this new ship will be the most advanced sea-based aviation platform ever deployed by the Navy, it will be an evolutionary progression of the current NIMITZ design. CVNX will have stealthier features than current carriers but will not be a completely stealth design. The stealth wave piercer design seen in speculative drawings is definitely not the shape of things to come.
The Department of Defense and the Navy stated on 19 December 2002 that they had decided to rename the CVNX program CVN-21 and that the first ship would have 80 percent of the kinds of new capability that was anticipated by the time the Navy would have reached the CVNX-2. This includes crew reductions, new flight decks, and a new nuclear reactor power plant, which will provide upwards of three times the electrical output of the current power plant. This would open up the opportunity to begin experimenting with the kinds of weapons systems that heretofore were not possible with the kind of electrical power available.
The design of CVN-21 is different than CVNX-1 in that there are changes in the deck spacing and arrangement which was to be a part of CVNX-2. Interior spaces are to be redesigned. Changes as a result of the power plant and some other improvements in the internal spacing with in the ship will result in a reduction in manpower levels. Crew reductions are expected to be roughly eight hundred fewer people -- other than the air wing. Based on these design changes the Navy and the DoD consider CVN-21 to be transformational.
According to studies conducted by the Newport News Shipbuilding Carrier Innovation Center, one possibility evaluated would have been to remove elevator number one (on the starboard side, near the bow catapults) and simply make it part of the flight deck. Elevators two and three would be widened and strengthened to handle up to three aircraft. This would vastly improve aircraft operating efficiency. According to Rear Admiral Alfred G. Harms, Commander, Carrier Group Three, the number one elevator is…"rarely used. Particularly at night because of the safety considerations." This improved flight deck layout would increase air operations safety as well as the ship’s sortie rate.
There's also been a recognition that electromagnetic rail guns are not ready for deployment with a ship in FY '07. They are still in the state of being developed so that they are not as test articles but as deployable systems. And so the notion that the Navy would back-fit into this first hole or into its next iteration those capabilities as they come on line is very much a part of current thinking, and it has to do with the interior space that is freed up and volume in a ship that otherwise wouldn't have been available.
Starting in the mid-1990s, the Navy focused on the development of high-strength low-alloy steel (HSLA-65, -80, and -100) for ship construction in the thickness range of 5/16-inch. to 1-5/8 inch. HSLA-65 and HSLA-100 steels are being considered for immediate application as the primary structure in the DD (X), CVN 77, and CVNX 1 for weight reduction and fabrication cost savings. More recently, Division metallurgists have collaborated with researchers from Japan in a cooperative program to develop structurally acceptable methods to use “under-matched” strength weldments for use with high-strength steel alloys (yield strength greater than 150 ksi). This technology has the potential to significantly reduce the costs of high-strength steel in ship construction.
The Navy believe that the new carriers can shed a few pounds if this steel is used in the carrier hulls. Preliminary calculations indicated that if it was used in hull plate, it could provide equal or greater service life than the traditional high-strength steel, but be thinner, and therefore weigh less. The same would be true for the hull's interior supporting structures.
HSLA-65 is stronger and tougher than conventional steel, and has proven itself in commercial bridges, pipelines and other ship above-deck structures. Rigorous certification testing of this new steel is underway.
On 10 July 2003 it was announced that the U.S. Navy had awarded Northrop Grumman Corporation a contract to support the future aircraft carrier program, CVN 21. Northrop Grumman's Newport News sector is the prime contractor for the award.
The $107.6 million contract allows the company to continue pre-system development and design efforts for CVN 21. Work performed under the contract includes research and design development efforts as well as pre-system development and design in support of ship construction with delivery planned for 2014. This contract is a modification to a previous contract, bringing the total value of the contract to $303.5 million.
According to the DOT&E, the technical risk for this program is moderate. The Navy is conducting a comprehensive early operational assessment in FY04 intended to identify additional risk factors in ten major areas of the ship. By using the proven Nimitz hull form the Navy reduced technical risk in Phase I of the ships development. The Navy plans to use Multi-Function Radar and Volume Search Radar for CVN-21 and these are being developed as part of the new DD(X) destroyer program. The greatest risk will probably be in the IWS, most of which is in Phase II of the CVN 21 program. Safe and adequate operational testing of the IWS providing self-defense against anti-ship cruise missiles will require testing with a selfdefense test ship.
The program has a competitive test and evaluation program set up for EMALS. A successful EMALS program should significantly reduce the complexity, space, and manpower consumed by legacy steam and hydraulic systems. It could also help increase the life expectancy of carrier aircraft due to a much smoother launch sequence.
The LFT&E program, as planned by the Navy and DOT&E, will be a comprehensive evaluation based on CVN survivability studies, battle damage lessons learned, flight deck accident lessons learned, relevant weapons effects tests, probability of kill versus probability of hit studies, damage scenario-based engineering analyses of specific hits, vulnerability assessment reports, a total ship survivability trial, a ship shock trial, and extensive surrogate testing.
