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美采用新方法建第二艘福特级航母。
送交者: SDUSA 2014年08月06日08:05:50 于 [军事天地] 发送悄悄话

Future Carrier to Feature More Prebuilt Parts

by KRIS OSBORN on AUGUST 6, 2014

CVN 79

The Navy and Newport News Shipbuilding are working on new shipbuilding methods and making early progress with initial construction of the second, next-generation Ford-class aircraft carrier slated to enter service in March 2023 — the John F. Kennedy, or CVN 79.

The construction strategy for the Kennedy, which is thus far only 6 percent built, is using a handful of techniques intended to lower costs and call upon lessons learned from the building of the first Ford-class carrier in recent years, the USS Gerald R. Ford. The Ford was christened in November, is now undergoing additional testing and slated to enter service in 2016.

The Navy was criticized by lawmakers and government watchdog groups during the construction of the Ford for its rising costs. As of last year, construction costs for the ship were estimated at $12.8 billion, several billion dollars above previous figures.

Navy officials point out that at least $3 billion of the Ford’s costs are due to what’s described as non-recurring engineering costs for a first-in-class ship such as this. Nevertheless, they say the service is making progress with efforts to lower costs for the Kennedy.

“Through lessons learned and an intense, focused effort to improve the way carriers are built, we are confident in substantial cost reduction on CVN 79,” Rear Adm. Thomas Moore, program executive officer for carriers, told Military.com in a written statement.

Newport News Shipbuilding, which is a subsidiary of Huntington Ingalls Industries Inc., is now assembling the lower portions of the Kennedy under a construction preparation contract with the Navy.

The construction preparation contract affords the shipbuilder an opportunity to gather and purchase materials and parts for the ship while beginning initial assembly. Of the 1,128 total structural units that comprise the Kennedy, 654 of them are covered under the construction preparation contract, said Mike Shawcross, vice president of Kennedy carrier construction.

More than 230 structural units have already been completed on items such as pipe assemblies, cabling, shafts, rudders and struts, he said.
Newport News Shipbuilding is able to buy larger quantities of parts earlier in the construction process with the Kennedy because, unlike the circumstance during the building of the Ford, the Kennedy’s ship design is already completed, Shawcross explained.

In addition, one of the construction techniques for the Kennedy includes assembling compartments and parts of the ship before moving them to the dock, he said. Production lines have been started for groups of ship units that are similar, he said.

Construction begins with the bottom of the ship and works up with inner-bottoms and side shells before moving to box units, Shawcross explained. The bottom third of the ship gets built first.

As for the design, the Kennedy will be largely similar to the design of the Ford, with a few minor alterations. The aircraft elevators on the Kennedy will use electric motors instead of a hydraulic system to lower costs, Shawcross added.

Also, some of the design methods have changed such as efforts to fabricate or forge some parts of the ship instead of casting them because it makes the process less expensive, he said.

USS John F Kennedy CVN 79 People Working

The Kennedy will replace the USS Nimitz, which is due to retire by 2027; the Ford-class carriers are slated to replace the existing Nimitz-class carriers on a one-to-one basis in an incremental fashion over the next half century or so.

“We are moving towards a construction contract being awarded this year and anticipate that the Christening ceremony will take place in September of 2020, with a scheduled delivery to the fleet in March 2023,” Kennedy program manager Capt. Doug Oglesby said in a written statement.

Built with a host of new technologies to improve operational performance and efficiency over the existing Nimitz-class carriers, the Ford-class ships are engineered with slightly larger deck space to allow for a greater sortie rate, more computer automation to reduce the need for manpower and an electromagnetic catapult to propel jets off the deck an into the sky over the ocean.

The new electromagnetic catapult system and new advanced arresting gear are designed for smoother, safer and more efficient take-offs and landings compared to the steam catapults now used on today’s carriers.
Also, the Ford-class carriers are being built with three times the electrical power generating capacity compared to Nimitz-class carriers, Moore said.

The USS Ford will have four 26-megawatt generators bringing a total of 104 megawatts to the ship. This helps support the ship’s developing systems such as its Electro-Magnetic Aircraft Launch System, or EMALS, and provides power for future systems such as lasers, and rail-guns.

The ships are engineered with a redesigned island, slightly larger deck space and new weapons elevators in order to achieve a 33-percent increase in sortie-generation rate. The new platforms are built to launch more aircraft and more seamlessly support a high-op tempo, Navy officials said.

The new weapons elevators allow for a much more efficient path to move and re-arm weapons systems for aircraft. The elevators can take weapons directly from their magazines to just below the flight deck, therefore greatly improving the sortie-generation rate by making it easier and faster to re-arm planes.



Read more: http://defensetech.org/2014/08/06/future-carrier-to-feature-more-prebuilt-parts/#ixzz39cmzBVcU 
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