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US Navy Gerald R. Ford class Aircraft Carrier - CVN |
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| 11/22 | |
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Development: The current Nimitz-class aircraft carrier which are in US naval service have been part of United States power projection strategy since Nimitz was commissioned in 1975. Displacing about 100,000 tons when fully loaded, a Nimitz-class carrier can steam faster than 30 knots, cruise without resupply for 90 days, and launch aircraft to strike targets hundreds of miles away. The endurance of this class is exemplified by USS Theodore Roosevelt, which spent 159 days underway in support of Operation Enduring Freedom without visiting a port or being refueled. The Nimitz design has accommodated many new technologies over the decades, but it has limited ability to support the most recent technical advances. As a 2005 Rand report said, "The biggest problems facing the Nimitz class are the limited electrical power generation capability and the upgrade-driven increase in ship weight and erosion of the center-of-gravity margin needed to maintain ship stability." With these constraints in mind, the US Navy developed what was initially known as the CVN-21 program, which ultimately evolved into CVN-78, Gerald R. Ford. Improvements were made through developing technologies and more efficient design. Major design changes include a larger flight deck, improvements in weapons and material handling, a new propulsion plant design that requires fewer people to operate and maintain, and a new smaller island that has been pushed aft. Technological advances in electromagnetics have led to the development of an Electromagnetic Aircraft Launch System (EMALS) and an Advanced Arresting Gear (AAG). An integrated warfare system, the Ship Self-Defense System (SSDS), has been developed to allow the ship to more easily take on new missions. The new Dual Band Radar (DBR) combines S-band and X-band radar. Flight deck changes support the requirements for a higher sortie rate, around 160 a day with surges to 270. These advances will allow the in coming Gerald R. Ford class carriers to launch 25% more sorties, generate triple the electrical power, require less time offline, and offer various quality-of-life improvements. Flight deck: Changes to the flight deck are the most visible of the differences between the Nimitz and Gerald R. Ford classes. Several sections have been altered to improve aircraft handling, storage, and flow, all in the service of increasing the sortie rate. Catapult No. 4 on the Nimitz class cannot launch fully loaded aircraft because of a deficiency of wing clearance along the edge of the flight deck. CVN-78 will have no catapult-specific restrictions on launching aircraft, but still retains four catapults, two bow and two waist. The number of aircraft lifts from hangar deck to flight deck level was reduced from four to three. Another major change is that the smaller, redesigned island will be further aft than those of older carriers. This shift creates deck space for a centralized rearming and refueling location, and thereby reduces the number of times that an aircraft will have to be moved after landing before it can be relaunched. Fewer aircraft movements require, in turn, fewer deck hands to accomplish them, reducing the size of the ship's crew and increasing sortie rate. As well, the movement of weapons from storage and assembly to the aircraft on the flight deck has been streamlined and accelerated. Ordnance will be moved to the centralized rearming location via relocated, higher-capacity weapons elevators that use linear motors. The new path that ordnance follows does not cross any areas of aircraft movement, thereby reducing traffic problems in the hangars and on the flight deck. According to Rear Admiral Dennis M. Dwyer, these changes will make it hypothetically possible to rearm the airplanes in "minutes instead of hours". Power generation The new Bechtel A1B reactor for the CVN 21 class is smaller and simpler, requires fewer crew, and is yet far more powerful than the Nimitz-class A4W reactor. Two reactors will be installed on each Ford-class carrier, each one capable of producing 300 MW of electricity, triple the 100 MW of each A4W. The propulsion and power plant of the Nimitz-class carriers was designed in the 1960s, when onboard technologies did not require the same quantity of electrical power that modern technologies do. "New technologies added to the Nimitz-class ships have generated increased demands for electricity; the current base load leaves little margin to meet expanding demands for power." Compared to the Nimitz-class reactor, the CVN 21 reactor has about half as many valves, piping, major pumps, condensers, and generators. The steam-generating system uses fewer than 200 valves and only eight pipe sizes. These improvements lead to simpler construction, reduced maintenance, and lower manpower requirements as well as to a more compact system that requires less space in the ship. The modernization of the plant led to a higher core energy density, lower demands for pumping power, a simpler construction, and the use of modern electronic controls and displays. The new plant requires just one-third the watchstanding requirements and a decrease of required maintenance. A larger power output is a major component to the integrated warfare system. Engineers took extra steps to ensure that integrating unforeseen technological advances onto a Gerald R. Ford-class aircraft carrier would be possible. The Navy expects the Gerald R. Ford class will be part of the fleet for 90 years, until the year 2105, which means that the class must successfully accept new technology over the decades. Electromagnetic Aircraft Launch System: The Nimitz-class aircraft carriers use steam-powered catapults to launch aircraft. Steam catapults were developed in the 1950s and have been exceptionally reliable. For over 50 years, at least one of the four catapults has been able to launch an aircraft 99.5% of the time. However, there are a number of drawbacks. One group of Navy engineers wrote, "The foremost deficiency is that the catapult operates without feedback control. With no feedback, there often occurs large transients in tow force that can damage or reduce the life of the airframe." The steam system is massive, inefficient (4–6%), and hard to control. These control problems mean that Nimitz-class steam-powered catapults can launch heavier aircraft, but not aircraft as light as many UAVs, which is an unacceptable limit for a 21st-century platform. The Electromagnetic Aircraft Launch System (EMALS) is more efficient, smaller, lighter, more powerful, and easier to control. Increased control means that EMALS will be able to launch both heavier and lighter aircraft than the steam catapult. Also, the use of a controlled force will reduce the stress on airframes, resulting in less maintenance and a longer lifetime for the airframe. The power limitations for the Nimitz class make the installation of the recently developed EMALS impossible. In June 2014, the Navy completed EMALS prototype testing of 450 manned aircraft launches involving every Navy fixed-wing carrier-borne aircraft type at Joint Base McGuire-Dix-Lakehurst during two Aircraft Compatibility Testing (ACT) campaigns. ACT Phase 1 concluded in late 2011 following 134 launches (aircraft types comprising the F/A-18E Super Hornet, T-45C Goshawk, C-2A Greyhound, E-2D Advanced Hawkeye, and F-35C Lightning II). On completion of ACT 1, the EMALS demonstrator was reconfigured to be more representative of the actual ship configuration aboard Ford, which will use four catapults sharing several energy storage and power conversion subsystems. ACT Phase 2 began on 25 June 2013 and concluded on 6 April 2014 after a further 310 launches (including launches of the EA-18G Growler and F/A-18C Hornet, as well as another round of testing with aircraft types previously launched during Phase 1). In Phase 2 various carrier situations were simulated, including off-centre launches and planned system faults, to demonstrate that aircraft could meet end-speed and validate launch-critical reliability. EMALS was tested in June 2015. Advanced Arresting Gear landing system: Electromagnetics will also be used in the new Advanced Arresting Gear (AAG) system. The current system relies on hydraulics to slow and stop a landing aircraft. While the hydraulic system is effective, as demonstrated by more than fifty years of implementation, the AAG system offers a number of improvements. The current system is unable to capture UAVs without damaging them due to extreme stresses on the airframe. UAVs do not have the necessary mass to drive the large hydraulic piston used to trap heavier, manned airplanes. By using electromagnetics the energy absorption is controlled by a turbo-electric engine. This makes the trap smoother and reduces shock on airframes. Even though the system will look the same from the flight deck as its predecessor, it will be more flexible, safe, and reliable, and will require less maintenance and manning. Sensors and self-defense systems: Another addition to the Gerald R. Ford class is an integrated Active electronically scanned array search and tracking radar system. The dual-band radar (DBR) was being developed for both the Zumwalt-class guided missile destroyers and the Ford-class aircraft carriers by Raytheon. The island can be kept smaller by replacing six to ten radar antennas with a single six-faced radar. The DBR works by combining the X band AN/SPY-3 multifunction radar with the S band Volume Search Radar (VSR) emitters, distributed into three phased arrays. The S-band radar was later deleted from the Zumwalt class destroyers as a cost saving measure. The three faces dedicated to the X-band radar are responsible for low altitude tracking and radar illumination, while the other three faces dedicated to the S-band are responsible for target search and tracking regardless of weather. "Operating simultaneously over two electromagnetic frequency ranges, the DBR marks the first time this functionality has been achieved using two frequencies coordinated by a single resource manager." This new system has no moving parts, therefore minimizing maintenance and manning requirements for operation. The carrier will be armed with the Raytheon Evolved Sea Sparrow missile (ESSM), which defends against high-speed, highly maneuverable anti-ship missiles. The close-in weapon system is the rolling airframe missile (RAM) from Raytheon and Ramsys GmbH. The AN/SPY-3 consists of three active arrays and the Receiver/Exciter (REX) cabinets abovedecks and the Signal and Data Processor (SDP) subsystem below-decks. The VSR has a similar architecture, with the beamforming and narrowband down-conversion functionality occurring in two additional cabinets per array. A central controller (the resource manager) resides in the Data Processor (DP). The DBR is the first radar system that uses a central controller and two active-array radars operating at different frequencies. The DBR gets its power from the Common Array Power System (CAPS), which comprises Power Conversion Units (PCUs) and Power Distribution Units (PDUs). The DBR is cooled via a closed-loop cooling system called the Common Array Cooling System (CACS). The REX consists of a digital and an analog portion. The digital portion of the REX provides system-level timing and control. The analog portion contains the exciter and the receiver. The exciter is a low-amplitude and phase noise system that uses direct frequency synthesis. The radar’s noise characteristics support the high clutter cancellation requirements required in the broad range of maritime operating environments that DBR will likely encounter. The direct frequency synthesis allows a wide range of pulse repetition frequencies, pulse widths, and modulation schemes to be created. The receiver has high dynamic range to support high clutter levels caused by close returns from range-ambiguous Doppler effect waveforms. The receiver has both narrowband and wideband channels, as well as multichannel capabilities to support monopulse radar processing and sidelobe blanking. The receiver generates digital data and sends the data to the signal processors. The DBR uses IBM commercial off-the-shelf (COTS) supercomputers to provide control and signal processing. DBR is the first radar system to use COTS systems to perform the signal processing. Using COTS systems reduces development costs and increases system reliability and maintainability. The high-performance COTS servers perform signal analysis using radar and digital signal processing techniques, including channel equalization, clutter filtering, Doppler processing, impulse editing, and implementation of a variety of advanced electronic protect algorithms. The IBM supercomputers are installed in cabinets that provide shock and vibration isolation. The DP contains the resource manager, the tracker, and the command and control processor, which processes commands from the combat system. The DBR utilizes a multitier, dual-band tracker, which consists of a local X band tracker, a local S band tracker, and a central tracker. The central tracker merges the local tracker data together and directs the individual-band trackers’ updates. The X band tracker is optimized for low latency to support its mission of providing defense against fast, low-flying missiles, while the VSR tracker is optimized for throughput due to the large-volume search area coverage requirements. The combat system develops doctrine-based response recommendations based on the current tactical situation and sends the recommendations to the DBR. The combat system also has control of which modes the radar will perform. Unlike previous-generation radars, the DBR does not require an operator and has no manned display consoles. The system uses information about the current environment and doctrine from the combat system to make automated decisions, not only reducing reaction times, but also reducing the risks associated with human error. The only human interaction is for maintenance and repair activities. The Enterprise Air Surveillance Radar (EASR) is a new design surveillance radar that is to be installed in the second Gerald R. Ford-class aircraft carrier, John F. Kennedy, in lieu of the Dual Band radar. The America-class amphibious assault ships starting with LHA-8 and the planned LX(R) will also have this radar. The EASR suite’s initial per-unit cost will be about $180 million less than the DBR, for which the estimate is about $500 million. Planned aircraft complement: The Ford class is designed to accommodate the new Joint Strike Fighter carrier variant aircraft (F-35C), but aircraft development and testing delays have affected integration activities on CVN-78. These integration activities include testing the F-35C with CVN-78’s EMALS and advanced arresting gear system and testing the ship’s storage capabilities for the F-35C’s lithium-ion batteries (which provide start-up and back-up power), tires, and wheels. As a result of F-35C developmental delays, the US Navy will not field the aircraft until at least 2017. As a result, the Navy has deferred critical F-35C integration activities, which introduces risk of system incompatibilities and costly retrofits to the ship after it is delivered to the Navy. Construction: Construction began on 11 August 2005, when Northrop Grumman held a ceremonial steel cut for a 15-ton plate that will form part of a side shell unit of the carrier. Construction began on components of CVN-78 in early 2007 and is nearing completion. It is under the final steps of construction at Newport News Shipbuilding, a division of Huntington Ingalls Industries (formerly Northrop Grumman Shipbuilding) in Newport News, Virginia. This is the only shipyard in the United States capable of building nuclear-powered aircraft carriers. In 2005, it was estimated to cost at least $8 billion excluding the $5 billion spent on research and development (though that was not expected to be representative of the cost of future members of the class). A 2009 report said that Ford would cost $14 billion including research and development, and the actual cost of the carrier itself would be $9 billion. The life-cycle cost per operating day of a carrier strike group (including aircraft) was estimated at $6.5 million in 2013 published by the Center for New American Security. A total of three carriers have been authorized for construction, but if the Nimitz-class carriers and Enterprise were to be replaced on a one-for-one basis, eleven carriers would be required over the life of the program. However, the last Nimitz-class aircraft carrier is not scheduled to be decommissioned until 2058. In a speech on 6 April 2009, then Secretary of Defense Robert Gates announced that the program would shift to a five-year building program so as to place it on a "more fiscally sustainable path". Such a measure would result in ten carriers after 2040. First-of-class type design changes As construction of CVN-78 progresses, the shipbuilder is discovering first-of-class type design changes, which it will use to update the model before the follow-on ship construction. To date, several of these design changes have related to EMALS configuration changes, which have required electrical, wiring, and other changes within the ship. Although the Navy reports that these EMALS-related changes are nearing completion, it anticipates additional design changes stemming from remaining advanced arresting gear development and testing. In total, over 1,200 anticipated design changes remain to be completed (out of nearly 19,000 planned changes). According to the Navy, many of these 19,000 changes were programmed into the construction schedule early on - a result of the government’s decision at contract award to introduce improvements during construction to the ship’s warfare systems, which are heavily dependent on evolving commercial technologies. source: wikipedia |
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images (for more images go to the individual ship pages) |
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    USS Gerald R. Ford (CVN 78) - final outfitting - 2016    |
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