Fórum Defesa Brasil

CVN convencional em serviço e por isso colocado no Japão.

Rui Elias Maltez escreveu:Foi um lapsus linguae do nosso gurú.

Mas afinal de contas, o Kitty Hawk já não é nada novo.

Por quanto tempo mais navegará?

Pode ser especulativo, mas acho a pergunta pertinente.

Nesse caso, serão no futuro os 10 Nimitz mais os 2 CVN 21?

JLRC escreveu:Rui, o previsto é o CV 63 Kitty Hawk, ser substituído pelo CVN 77 George W. Bush, que está em construção, em 2008, com 52 anos.

Charlie Golf escreveu:

JLRC escreveu:Rui, o previsto é o CV 63 Kitty Hawk, ser substituído pelo CVN 77 George W. Bush, que está em construção, em 2008, com 52 anos.

Caro amigo, o nome do porta-aviões será George H. Bush (nome completo George Herbert Walker Bush III), o pai mafioso mas que ainda assim politicamente se encontra a anos-luz daquela besta bestial do seu filho, o actual inquilino da Casa Branca, George W. Bush (George Walker "O Ranger ou Carniceiro" do Texas" Bush*).


*Alcunhado de Carniceiro do Texas porque durante o mandato de Governador daquele Estado norte-americano - 1995-2000 - nunca acedeu a qualquer pedido de clemência por parte de condenados à pena de morte, tendo obtido a "fabulosa" marca de 152 execuções, facto que o tornaria assim no Governador que mais execuções ordenou na história moderna dos Estados Unidos.

Charlie Golf escreveu:

JLRC escreveu:Rui, o previsto é o CV 63 Kitty Hawk, ser substituído pelo CVN 77 George W. Bush, que está em construção, em 2008, com 52 anos.

Caro amigo, o nome do porta-aviões CVN-77 será George H. W. Bush (nome completo George Herbert Walker Bush III), o pai mafioso mas que ainda assim politicamente se encontra a anos-luz daquela besta bestial do seu filho, o actual inquilino da Casa Branca, George W. Bush (George Walker "O Ranger ou Carniceiro do Texas" Bush*).


*Alcunhado de Carniceiro do Texas porque durante o mandato de Governador daquele Estado norte-americano - 1995-2000 - nunca acedeu a qualquer pedido de clemência por parte de condenados à pena de morte, tendo obtido a "fabulosa" marca de 152 execuções, facto que o tornaria assim no Governador que mais execuções ordenou na história moderna dos Estados Unidos.

Creating a new ship class isn't cheap. According to NAVSEA, the cost of the initial design work to create the CVN-21 ship class and develop its new technologies is projected at $5.6 billion. Building the as-yet unnamed CVN 78 will cost an estimated $8.1 billion, and advance construction is beginning in 2005. This allows shipbuilders to test the design-build strategy before overall construction begins in 2007. CVN 78 will be the first true CVN-21 Class ship, though the transitional Nimitz Class CVN 77 George H. W. Bush will incorporate some elements like upgraded navigation and communications systems, improved air defense armament and ECM, a new fuel system for aircraft fuel, et. al. The target date for CVN 78 commissioning is 2014, whereupon it will replace America's first nuclear-powered aircraft carrier - the 50+ year old USS Enterprise (CVN 65). CVN 78 is also expected to serve for 50 years, from 2014-2064.


CVN-21 Enhancements

DID has a post covering our investigation into the CVN-21's exact build cost, and the future operating cost savings expected as a result of its design innovations. Readers looking for detailed breakdowns should look there. Essentially, CVN-21 carriers are expected to generate savings in two major ways. One is through an array of design and automation changes to various areas of the ship that reduce the required number of sailors aboard. The other is through reduction in the number of major maintenance overhauls required. NAVSEA expects these changes to save $5 billion per ship over the ships' projected 50-year lifetime. Meanwhile, measures are being taken aimed at improving the carriers' effectiveness and survivability.

Some of these changes include:

EMALS Components

An electromagnetic aircraft launching system (EMALS) will replace the steam-powered system used on current ships. The current steam catapults are large, heavy, and operate without feedback control. They impart large loads to the airframe via sudden shock, and are difficult and time consuming to maintain. Additionally, the trend towards heavier, faster aircraft will soon result in energy requirements that exceed the capacity of steam catapults.

EMALS offers a 30% increase in launch energy potential, as well as substantial improvements via reduced weight, smaller volume, and more flexibility; plus increased controllability, availability, reliability, and efficiency. Self-diagnostics can be embedded in it, simplifying maintenance. The other thing that simplifies maintenance is the removal of the 614 kg of steam required for each aircraft launch, plus hydraulics and oils, water for braking, and associated pumps, motors, and control systems.

Because an EMALS-based system will take up far less space, it also provides design flexibility. EMALS launchers can be moved far more easily, downsized and incorporated into a ramp to provide additional launchers for short take-off aircraft, etc.

Finally, its steadier acceleration reduces launch strains on naval aircraft, which helps extend their airframe life. That isn't calculated as part of cost savings for the ship, but it definitely adds up over time.

A redesigned nuclear reactor is expected to supply 25% more power for propulsion, but require only 50% the maintenance costs and a 50% reduction in sailors required to operate it. Removing the steam catapults in favour of EMALS is synergistic, reducing work on the maintenance-heavy steam conduits and allowing the steam from the nuclear reactor to do other things - like make electricity. The CVN-21 Class is expected to have three times the electricity generating capacity of the Nimitz Class.

If our personal experiences with power hungry electronics over the last 20 years are anything to go by, they may need it.

Advanced arresting gear. The Naval Air Systems Command, headquartered at Patuxent River Naval Air Station, is working on an improved system for trapping aircraft as they land and hook the arresting cables. This electrical-hydraulic combination will be designed to be able to handle emerging platforms, such as the F/A-18E/F Super Hornet and F-35C Joint Strike Fighter, which are heavier and able to return to the ship with more unexpended munitions than their predecessors.

Rear Adm. Dwyer has estimated that these changes will enable the size of the CVN-21 ships' crews to be reduced from about 3,000 to 2,500 and possibly as low as 2,100. Note that some 2,500 personnel are also carried in the air wing, and will not be subject to reductions from any of the methods described here.


The CVN-21 class will also feature effectiveness improvements.

Electronic upgradeability. CVN 21 will also employ an integrated warfare system that allows its electronics to slot into a single, open-architecture, scalable weapons system, based on commercial, off-the-shelf technologies. Dwyer noted that the US Navy would like everything to "plug and play." While technology never works quite that way, the process can be made easier - and doing so would improve long-term performance. As Rear Adm. Dwyer pointed out:

"Right now, the way we build aircraft carriers is to buy all the electronic equipment up front, then take seven years to build a ship and deliver it with obsolete electronics. It's kind of crazy now that you think about it. We don't want to do that any more... What we'd like to do is put the electronic equipment in separately from the actual shipbuilding process."

Along similar lines, CVN-21 will feature a so-called smart deck, equipped with redundant and flexible fiber-optic cable that is easier to move and repair than hard copper wiring. It can be blown through the ship for installation - and more easily reeled out for replacement. Its capacity is also easier to upgrade, by clipping on terminating devices that allow for richer exploitation of different electromagnetic bandwidths of light.


CVN-21 Concept

(click for alternate view)A NASCAR flight deck philosophy. The "island" tower on the flight deck is being redesigned, reduced, and moved. As Rear Adm. Dwyer noted: "The people who actually handle aircraft said, 'The island's in the wrong place. It makes the aircraft all jam up. Why don't you move it?'" So the island has shifted 100 feet aft, and the carrier's elevators, deck et. al. are being shifted to a racetrack-like pattern of operations, complete with "pit stop" parking et. al.

It is this system that accounts for the expected improvements in operational flights per day - a key measure of the carrier's ability to both project power and defend itself.

Survivability also received attention. While the bridge and flight deck operations will remain on the island, the carrier's command and decision centers are being moved from the island, to the smart deck, down lower in the ship where they're both safer and less in the way of the aircraft. Meanwhile, the fuel tanks and bomb/ missile/ ammunition magazines are getting more armor, and the hull is being reinforced.

The jump from CVN 68 USS Nimitz to CVN 78 of the CVN-21 Class is much shorter than the journey from CV 1 USS Langley. Aircraft carriers are something of a mature technology, and CVN-21's refinements are more about marginal improvements to effectiveness, cost-efficiency, and future upgradeability than any revolution in carrier design.

The target date for CVN 78 commissioning is 2014, whereupon it will replace America's first nuclear-powered aircraft carrier - the 50+ year old USS Enterprise (CVN 65). CVN 78 is also expected to serve for 50 years, from 2014-2064.

Posted 11/17/06 15:44Print this story Northrop Gets U.S. Navy Carrier Contracts

By CHRISTOHER P. CAVAS


Northrop Grumman’s Newport News, Va., shipyard received two U.S. Navy contracts to start work on a new aircraft carrier and keep an older one running.
On Nov. 15, the company received the first of a planned three annual contracts totaling $24.6 million to begin planning, study and development work for CVN 79, the yet-to-be-named second carrier of the CVN 21 program. The contract is the first to be awarded for the ship, which Northrop is scheduled to begin building in 2012 and deliver in 2019.
On Nov. 16, the first of three yearly contracts to cover advanced planning for the refueling overhaul of the nuclear-powered carrier Theodore Roosevelt was awarded. The value of the planning work is $558 million, according to Northrop. The ship is planned to enter Newport News in 2009 for its first and only scheduled refueling.
Northrop already is working on the refueling overhaul for the carrier Carl Vinson.

Charlie Golf escreveu:A propósito do CVN-21, não sei se já teriam visto estas imagens. Parece um Nimitz class versão 3.0.

Creating a new ship class isn't cheap. According to NAVSEA, the cost of the initial design work to create the CVN-21 ship class and develop its new technologies is projected at $5.6 billion. Building the as-yet unnamed CVN 78 will cost an estimated $8.1 billion, and advance construction is beginning in 2005. This allows shipbuilders to test the design-build strategy before overall construction begins in 2007. CVN 78 will be the first true CVN-21 Class ship, though the transitional Nimitz Class CVN 77 George H. W. Bush will incorporate some elements like upgraded navigation and communications systems, improved air defense armament and ECM, a new fuel system for aircraft fuel, et. al. The target date for CVN 78 commissioning is 2014, whereupon it will replace America's first nuclear-powered aircraft carrier - the 50+ year old USS Enterprise (CVN 65). CVN 78 is also expected to serve for 50 years, from 2014-2064.


CVN-21 Enhancements

DID has a post covering our investigation into the CVN-21's exact build cost, and the future operating cost savings expected as a result of its design innovations. Readers looking for detailed breakdowns should look there. Essentially, CVN-21 carriers are expected to generate savings in two major ways. One is through an array of design and automation changes to various areas of the ship that reduce the required number of sailors aboard. The other is through reduction in the number of major maintenance overhauls required. NAVSEA expects these changes to save $5 billion per ship over the ships' projected 50-year lifetime. Meanwhile, measures are being taken aimed at improving the carriers' effectiveness and survivability.

Some of these changes include:

EMALS Components

An electromagnetic aircraft launching system (EMALS) will replace the steam-powered system used on current ships. The current steam catapults are large, heavy, and operate without feedback control. They impart large loads to the airframe via sudden shock, and are difficult and time consuming to maintain. Additionally, the trend towards heavier, faster aircraft will soon result in energy requirements that exceed the capacity of steam catapults.

EMALS offers a 30% increase in launch energy potential, as well as substantial improvements via reduced weight, smaller volume, and more flexibility; plus increased controllability, availability, reliability, and efficiency. Self-diagnostics can be embedded in it, simplifying maintenance. The other thing that simplifies maintenance is the removal of the 614 kg of steam required for each aircraft launch, plus hydraulics and oils, water for braking, and associated pumps, motors, and control systems.

Because an EMALS-based system will take up far less space, it also provides design flexibility. EMALS launchers can be moved far more easily, downsized and incorporated into a ramp to provide additional launchers for short take-off aircraft, etc.

Finally, its steadier acceleration reduces launch strains on naval aircraft, which helps extend their airframe life. That isn't calculated as part of cost savings for the ship, but it definitely adds up over time.

A redesigned nuclear reactor is expected to supply 25% more power for propulsion, but require only 50% the maintenance costs and a 50% reduction in sailors required to operate it. Removing the steam catapults in favour of EMALS is synergistic, reducing work on the maintenance-heavy steam conduits and allowing the steam from the nuclear reactor to do other things - like make electricity. The CVN-21 Class is expected to have three times the electricity generating capacity of the Nimitz Class.

If our personal experiences with power hungry electronics over the last 20 years are anything to go by, they may need it.

Advanced arresting gear. The Naval Air Systems Command, headquartered at Patuxent River Naval Air Station, is working on an improved system for trapping aircraft as they land and hook the arresting cables. This electrical-hydraulic combination will be designed to be able to handle emerging platforms, such as the F/A-18E/F Super Hornet and F-35C Joint Strike Fighter, which are heavier and able to return to the ship with more unexpended munitions than their predecessors.

Rear Adm. Dwyer has estimated that these changes will enable the size of the CVN-21 ships' crews to be reduced from about 3,000 to 2,500 and possibly as low as 2,100. Note that some 2,500 personnel are also carried in the air wing, and will not be subject to reductions from any of the methods described here.


The CVN-21 class will also feature effectiveness improvements.

Electronic upgradeability. CVN 21 will also employ an integrated warfare system that allows its electronics to slot into a single, open-architecture, scalable weapons system, based on commercial, off-the-shelf technologies. Dwyer noted that the US Navy would like everything to "plug and play." While technology never works quite that way, the process can be made easier - and doing so would improve long-term performance. As Rear Adm. Dwyer pointed out:

"Right now, the way we build aircraft carriers is to buy all the electronic equipment up front, then take seven years to build a ship and deliver it with obsolete electronics. It's kind of crazy now that you think about it. We don't want to do that any more... What we'd like to do is put the electronic equipment in separately from the actual shipbuilding process."

Along similar lines, CVN-21 will feature a so-called smart deck, equipped with redundant and flexible fiber-optic cable that is easier to move and repair than hard copper wiring. It can be blown through the ship for installation - and more easily reeled out for replacement. Its capacity is also easier to upgrade, by clipping on terminating devices that allow for richer exploitation of different electromagnetic bandwidths of light.


CVN-21 Concept

(click for alternate view)A NASCAR flight deck philosophy. The "island" tower on the flight deck is being redesigned, reduced, and moved. As Rear Adm. Dwyer noted: "The people who actually handle aircraft said, 'The island's in the wrong place. It makes the aircraft all jam up. Why don't you move it?'" So the island has shifted 100 feet aft, and the carrier's elevators, deck et. al. are being shifted to a racetrack-like pattern of operations, complete with "pit stop" parking et. al.

It is this system that accounts for the expected improvements in operational flights per day - a key measure of the carrier's ability to both project power and defend itself.

Survivability also received attention. While the bridge and flight deck operations will remain on the island, the carrier's command and decision centers are being moved from the island, to the smart deck, down lower in the ship where they're both safer and less in the way of the aircraft. Meanwhile, the fuel tanks and bomb/ missile/ ammunition magazines are getting more armor, and the hull is being reinforced.

The jump from CVN 68 USS Nimitz to CVN 78 of the CVN-21 Class is much shorter than the journey from CV 1 USS Langley. Aircraft carriers are something of a mature technology, and CVN-21's refinements are more about marginal improvements to effectiveness, cost-efficiency, and future upgradeability than any revolution in carrier design.

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