Zumwalt-class destroyer

The "Zumwalt"-class destroyer is a class of three United States Navy guided missile destroyers designed as multi-mission stealth ships with a focus on land attack. It is a multi-role class that was designed for secondary roles of surface warfare and anti-aircraft warfare and originally designed with a primary role of naval gunfire support. The class design emerged from the DD-21 "land attack destroyer" program as "DD(X)" and was intended to take the role of battleships in meeting a congressional mandate for naval fire support. The ship is designed around its two Advanced Gun Systems, their turrets and magazines, and unique Long Range Land Attack Projectile (LRLAP) ammunition. LRLAP procurement was cancelled, rendering the guns unusable, so the Navy re-purposed the ships for surface warfare.
These ships are classed as destroyers, but they are much larger than any other active destroyer or cruiser in the US Navy. The vessels' distinctive appearance results from the design requirement for a low radar cross-section (RCS). The "Zumwalt" class has a wave-piercing tumblehome hull form whose sides slope inward above the waterline, which dramatically reduces RCS by returning much less energy than a conventional flare hull form. The appearance has been compared to that of the historic USS "Monitor" and her famous antagonist CSS "Virginia".
The class has an integrated electric propulsion (IEP) system that can send electricity from its turbo-generators to the electric drive motors or weapons, the Total Ship Computing Environment Infrastructure (TSCEI), automated fire-fighting systems, and automated piping rupture isolation. The class is designed to require a smaller crew and to be less expensive to operate than comparable warships.
The lead ship is named for Admiral Elmo Zumwalt and carries the hull number DDG-1000. Originally, 32 ships were planned, with $9.6 billion research and development costs spread across the class. As costs overran estimates, the quantity was reduced to 24, then to 7, and finally to 3, significantly increasing the cost per ship to $4.24 billion ($7.5 billion including R&D costs) and well exceeding the per-unit cost of a nuclear-powered ($2.688 billion). In April 2016, the total program cost was $22.5 billion. The dramatic per-unit cost increases eventually triggered a Nunn–McCurdy Amendment breach and cancellation of further production, so the Navy reverted to building more "Arleigh Burke" destroyers.
History.
Background and funding.
Many of the features were developed under the DD-21 program ("21st Century Destroyer"), which was originally designed around the Vertical Gun for Advanced Ships (VGAS). In 2001, Congress cut the DD-21 program by half as part of the SC21 program; to save it, the acquisition program was renamed as DD(X) and heavily reworked.
Originally, the Navy had hoped to build 32 destroyers. That number was reduced to 24, then to 7, due to the high cost of new and experimental technologies. On 23 November 2005, the Defense Acquisition Board approved a plan for simultaneous construction of the first two ships at Northrop Grumman's Ingalls yard in Pascagoula, Mississippi and General Dynamics' Bath Iron Works in Bath, Maine. However, at that date, funding had yet to be authorized by Congress.
In late December 2005, the House and Senate agreed to continue funding the program. The U.S. House of Representatives allotted the Navy only enough money to begin construction on one destroyer, as a "technology demonstrator". The initial funding allocation was included in the National Defense Authorization Act of 2007. However, this was increased to two ships by the 2007 appropriations bill approved in September 2006, which allotted US$2.568 billion to the DDG-1000 program.
On 31 July 2008, U.S. Navy acquisition officials told Congress that the service needed to purchase more s, and no longer needed the next-generation DDG-1000 class, Only the two approved destroyers would be built. The Navy said the world threat picture had changed in such a way that it made more sense to build at least eight more "Burke"s, rather than DDG-1000s. The Navy concluded from fifteen classified intelligence reports that the DDG-1000s would be vulnerable to forms of missile attacks. Many Congressional subcommittee members questioned that the Navy completed such a sweeping re-evaluation of the world threat picture in just a few weeks, after spending some 13 years and $10 billion on the development of the surface ship program known as DD-21, then DD(X), and finally DDG-1000. Subsequently, Chief of Naval Operations Gary Roughead cited the need to provide area air defense and specific new threats such as ballistic missiles and the possession of anti-ship missiles by groups such as Hezbollah. The mooted structural problems have not been discussed in public. Navy Secretary Donald Winter said on 4 September that "Making certain that we have – I'll just say, a destroyer – in the '09 budget is more important than whether that’s a DDG 1000 or a DDG 51".
On 19 August 2008, Secretary Winter was reported as saying that a third "Zumwalt" would be built at Bath Iron Works, citing concerns about maintaining shipbuilding capacity. House Defense Appropriations Subcommittee Chairman John Murtha said on 23 September 2008 that he had agreed to partial funding of the third DDG-1000 in the 2009 Defense authorization bill.
A 26 January 2009 memo from John Young, the US Department of Defense's (DoD) top acquisition official, stated that the per ship price for the "Zumwalt"-class destroyers had reached $5.964 billion, 81 percent over the Navy's original estimate used in proposing the program, resulting in a breach of the Nunn–McCurdy Amendment, requiring the Navy to re-certify and re-justify the program to Congress or to cancel its production.
On 6 April 2009, Defense Secretary Robert Gates announced that DoD's proposed 2010 budget will end the DDG-1000 program at a maximum of three ships. Also in April, the Pentagon awarded a fixed-price contract with General Dynamics to build the three destroyers, replacing a cost-plus-fee contract that had been awarded to Northrop Grumman. At that time, the first DDG-1000 destroyer was expected to cost $3.5 billion, the second approximately $2.5 billion, and the third even less.
What had once been seen as the backbone of the Navy's future surface fleet with a planned production run of 32, has since been replaced by destroyer production reverting to the "Arleigh Burke" class after ordering three "Zumwalt"s. In April 2016, the U.S. Naval Institute stated the total cost of the three "Zumwalt" ships is about $22.5 billion with research and development costs, which is an average of $7.5 billion per ship.
Construction.
In late 2005, the program entered the detailed design and integration phase, for which Raytheon was the Mission Systems Integrator. Both Northrop Grumman Ship Systems and General Dynamics Bath Iron Works shared dual-lead for the hull, mechanical, and electrical detailed design. BAE Systems Inc. had the advanced gun system and the MK57 VLS. Almost every major defense contractor (including Lockheed Martin, Northrop Grumman Sperry Marine, L-3 Communications) and subcontractors from nearly every state in the U.S. were involved to some extent in this project, which was the largest single line item in the Navy's budget. During the previous contract, development and testing of 11 Engineering Development Models (EDMs) took place: Advanced Gun System, Autonomic Fire Suppression System, Dual Band Radar [X-band and L-band], Infrared, Integrated Deckhouse & Apertures, Integrated Power System, Integrated Undersea Warfare, Peripheral Vertical Launch System, Total Ship Computing Environment Infrastructure (TSCEI), Tumblehome Hull Form. The decision in September 2006 to fund two ships meant that one could be built by the Bath Iron Works in Maine and one by Northrop Grumman's Ingalls Shipbuilding in Mississippi.
Northrop Grumman was awarded a $90M contract modification for materials and production planning on 13 November 2007. On 14 February 2008, Bath Iron Works was awarded a contract for the construction of , and Northrop Grumman Shipbuilding was awarded a contract for the construction of , at a cost of $1.4 billion each.
On 11 February 2009, full-rate production officially began on the first "Zumwalt"-class destroyer. Construction on the second ship of the class, "Michael Monsoor", began in March 2010. The keel for the first "Zumwalt"-class destroyer was laid on 17 November 2011. This first vessel was launched from the shipyard at Bath, Maine on 29 October 2013.
The construction timetable in July 2008 was:
The Navy planned for "Zumwalt" to reach initial operating capability (IOC) in 2016. The second ship, "Michael Monsoor", was commissioned in 2019, and the third ship, , was to have reached IOC in 2021.
Ships in class.
In April 2006, the Navy announced plans to name the first ship of the class "Zumwalt" after former Chief of Naval Operations Admiral Elmo R. "Bud" Zumwalt Jr. The vessel's hull number would be DDG-1000, which abandoned the guided missile destroyer sequence used by the s (DDG-51–), and continued the previous "gun destroyer" sequence from the last of the , .
DDG-1001 would be named for Master-at-Arms 2nd Class Michael A. Monsoor, the second Navy SEAL to receive the Medal of Honor in the Global War on Terror, the navy announced on 29 October 2008.
On 16 April 2012, Secretary of the Navy Ray Mabus announced that DDG-1002 would be named for former naval officer and U.S. President, Lyndon B. Johnson.
The Navy chose to use an unusual two-part commissioning scheme for the ships. The initial commissioning was done prior to weapons systems integration, and the ships were placed in the status of "in commission, special", before sailing to San Diego for weapons installation and final acceptance. The first two ships used this approach, while the last one will use the more traditional approach with formal commissioning after final acceptance.
Design.
As of January 2009, the Government Accountability Office (GAO) found that four out of 12 of the critical technologies in the ship's design were fully mature. Six of the critical technologies were "approaching maturity", but five of those would not be fully mature until after installation.
Stealth.
Despite being 40% larger than an "Arleigh Burke"-class destroyer, the radar cross-section (RCS) is more akin to that of a fishing boat, according to a spokesman for Naval Sea Systems Command. The tumblehome hull and composite deckhouse reduce radar return. Overall, the destroyer's angular build makes it "50 times harder to spot on radar than an ordinary destroyer."
The acoustic signature is comparable to that of the s. Water sleeting along the sides, along with passive cool air induction in the mack, reduces infrared signature.
The composite deckhouse encloses much of the sensors and electronics. In 2008, "Defense News" reported there had been problems sealing the composite construction panels of this area; Northrop Grumman denied this.
The U.S. Navy solicited bids for a lower cost steel deckhouse as an option for DDG-1002, the last "Zumwalt" destroyer, in January 2013. On 2 August 2013, the US Navy announced it was awarding a $212 million contract to General Dynamics Bath Iron Works to build a steel deckhouse for destroyer "Lyndon B. Johnson" (DDG-1002). The U.S. Naval Institute stated "the original design of the ship would have had a much smaller RCS, but cost considerations prompted the Navy over the last several years to make the trades in increasing RCS to save money..."
To improve detection in non-combat situations by other vessels, such as traversing busy shipping channels or operating in inclement weather, the Navy is testing adding onboard reflectors to improve the design's radar visibility.
The usefulness of the stealth features has been questioned. The class's role was to provide Naval Surface Fire Support, which requires the ship to be in typically crowded near-shore waters, where such large and distinctive ships can be tracked visually, and any surface ship becomes non-stealthy when it begins firing guns or missiles.
Tumblehome wave piercing hull.
The "Zumwalt"-class destroyer reintroduces the tumblehome hull form, a hull form not seen to this extent since the Russo-Japanese War in 1905. It was originally put forth in modern steel battleship designs by the French shipyard Forges et Chantiers de la Méditerranée in La Seyne, Toulon. French naval architects believed that tumblehome, in which the beam of the vessel narrowed from the waterline to the upper deck, would create better freeboard, greater seaworthiness, and, as Russian battleships were to find, would be ideal for navigating through narrow constraints (e.g. canals). On the downside, the tumblehome battleships leaked – partly due to their riveted construction – and could be unstable, especially when turning at high speed. The tumblehome has been reintroduced in the 21st century to reduce the radar return of the hull. The inverted bow is designed to cut through waves rather than ride over them. The stability of this hull form in high sea states has caused debate among naval architects, with some charging that "with the waves coming at you from behind, when a ship pitches down, it can lose transverse stability as the stern comes out of the water—and basically roll over."
Advanced Gun System.
The Advanced Gun System is a 155 mm naval gun, two of which are installed in each ship. This system consists of an advanced 155 mm gun and its Long Range Land Attack Projectile (LRLAP). This projectile is a rocket with a warhead fired from the AGS gun; the warhead has an 11 kg / 24 lb bursting charge and has a circular error probable of 50 meters. This weapon system has a range of . The fully automated storage system has room for up to 750 rounds. The barrel is water-cooled to prevent overheating and allows a rate of fire of 10 rounds per minute per gun. Using a Multiple Rounds Simultaneous Impact (MRSI) firing tactic the combined firepower from a pair of turrets gives each "Zumwalt"-class destroyer initial strike firepower equivalent to 12 conventional M198 field guns. The "Zumwalt"s use ballast tanks to lower themselves into the water for a reduced profile in combat. In November 2016, the Navy moved to cancel procurement of the LRLAP, citing per-shell cost increases to $800,000–$1 million resulting from trimming of total ship numbers of the class. The Navy is monitoring research on alternative munitions, but since the AGS was tailor-made to use the LRLAP, modifications will be needed to accept different shells, which is unlikely to happen by the time the first "Zumwalt" vessel enters operational service in 2018, leaving it unable to fulfill the naval gunfire support role it was designed for.
"Lyndon B. Johnson", the last "Zumwalt", is being considered for the installation of a railgun in place of one of the 155 mm naval guns after the ship is built. This is feasible because the installed Rolls-Royce turbine generators are capable of producing , enough for the electrically powered weapon.
In March 2021, the Navy solicited information from industry on how to reconfigure the "Zumwalt"-class ships to host hypersonic missiles. Since they would be too large to fit in the VLS tubes, it has been suggested that the two AGS, having no use since the cancellation of its ammunition, could be replaced with three-pack advanced payload modules to fulfill a conventional prompt strike deterrence role.
Peripheral Vertical Launch System.
The Peripheral Vertical Launch System (PVLS) is an attempt to avoid intrusion into the prized center space of the hull while reducing the risk of loss of the entire missile battery or of the ship in a magazine explosion. The system consists of pods of VLS cells distributed around the outer shell of the ship, with a thin steel outer shell and a thick inner shell. The design of the PVLS directs the force of any explosion outward rather than into the ship. Additionally, this design reduces the loss of missile capacity to the affected pod only.
Aircraft and boat features.
Two spots are available on a large aviation deck with a hangar capable of housing two full size SH-60 helicopters. Boats are handled within a stern mounted boat hangar with ramp. The boat hangar's stern location meets high sea state requirements for boat operations.
Radar.
Originally, the AN/SPY-3 active electronically scanned array primarily X band radar was to be married with Lockheed Martin's AN/SPY-4 S band volume search radar. Raytheon's X-band, active-array SPY-3 Multi-Function Radar (MFR) offers superior medium to high altitude performance over other radar bands, and its pencil beams give it an excellent ability to focus in on targets. SPY-3 will be the primary radar used for missile engagements. A 2005 report by Congress' investigative arm, the Government Accountability Office (GAO), questioned that the technology leap for the Dual Band Radar would be too much.
On 2 June 2010, Pentagon acquisition chief Ashton Carter announced that they will be removing the SPY-4 S-band Volume Search Radar from the DDG-1000's dual-band radar to reduce costs as part of the Nunn–McCurdy certification process. Due to the SPY-4 removal, the SPY-3 radar is to have software modifications so as to perform a volume search functionality. Shipboard operators will be able to optimize the SPY-3 for either horizon search or volume search. While optimized for volume search, the horizon search capability is limited. The DDG-1000 is still expected to perform local area air defense. This system is thought to provide high detection and excellent anti-jamming capabilities, particularly when used in conjunction with the Cooperative Engagement Capability (CEC). It is, however, not reported if the CEC system will be installed on the "Zumwalt"-class destroyers upon commissioning, but it is scheduled for eventual incorporation in the ship type.
In that the Zumwalt class has no AN/SPG-62 fire-control radars that are used for terminal guidance for Standard and Evolved Sea-Sparrow Missiles (ESSMs) anti-aircraft engagements, the SPY-3 will generate Interrupted Continuous Wave Illumination (ICWI) rather than the Continuous Wave Illumination of the AN/SPG-62 fire-control radars. Significant software modifications are required to support the ICWI, transmit and receive link messages to the missiles. Standard Missile (SM)-2 IIIA and the ESSM slated for Zumwalt class require modified missile receivers, transmitters, encoders, decoders and a redesigned digital signal processor to work with the ship's system. These modified missiles will not be able to be used on Aegis class ships.
The SPY 3 had to be reprogrammed to do the volume search that the SPY-4 was supposed to have performed. With the duties of volume and surface search and terminal illumination there is concern that a large scale missile attack could overwhelm a radar's resource management capacity. In such a case the radar may be unable to properly manage incoming threats or guide offensive missiles.
The Dual Band Radar in its entirety (SPY-3 & SPY-4) is to be installed only on the . With the development of the AMDR (Air and Missile Defense Radar), it seems unlikely the DBR is to be installed on any other platforms, as it is on the DDG-1000 class, or in total, as it is on "Gerald R. Ford". 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, , in lieu of the Dual Band radar. The s starting with LHA-8 and the planned s will also have this radar.
AMDR (Air and Missile Defense Radar) was originally proposed to be installed in the hull of DDG-1000 type under the CG(X) program. However, due to cost growth, the CG(X) program was canceled. The AMDR has continued in fully funded development for installation on the DDG-51 Flight III ships. However, a smaller than optimally planned aperture of , the AMDR for the Flight III ships is to be less sensitive than the variant that had been planned for CG(X).
A study to place the AMDR on a DDG-1000 hull was done with the aperture primarily for Ballistic Missile Defense (BMD) purposes. In that the DDG-1000 does not have an Aegis combat system, as does the DDG-51 class ships, but rather the Total Ship Computing Environment Infrastructure (TSCEI), the Radar/Hull Study stated:
Common Display System.
The ship's Common Display System is nicknamed "keds": Sailors operate keds via trackballs and specialized button panels, with the option to the interface by using touchscreens. The technology array allows sailors to monitor multiple weapons systems or sensors, saving manpower, and allowing it to be steered from the ops center.
Sonar.
A dual-band sonar controlled by a highly automated computer system will be used to detect mines and submarines. It is claimed that it is superior to the "Burke"s sonar in littoral ASW, but less effective in blue water/deep sea areas.
Although "Zumwalt" ships have an integrated suite of undersea sensors and a multi-function towed array, they are not equipped with onboard torpedo tubes, so they rely on their helicopters or ASROC missiles to destroy submarines that the sonar picks up.
Propulsion and power system.
The "Zumwalts" use an Integrated Power System (IPS), which is a modern version of a turbo-electric drive system. The IPS is a dual system, with each half consisting of a gas turbine prime mover directly coupled to an electrical generator, which in turn provides power for an electric motor that drives a propeller shaft. The system is "integrated" because the turbo-generators provide electrical power for all ship systems, not just the drive motors. The system provides much more available electrical power than is available in other types of ship.
The DDX proposed to use permanent-magnet motors (PMMs) within the hull, an approach that was abandoned in favor of a more conventional induction motor. An alternate twin pod arrangement was rejected as the ramifications of pod drives would require too much development and validation cost to the vessel. The PMM was considered to be another technology leap and was the cause of some concern (along with the radar system) from Congress. As part of the design phase, Northrop Grumman had the world's largest permanent magnet motor, designed and fabricated by DRS Technologies. This proposal was dropped when the PMM motor failed to demonstrate that it was ready to be installed in time.
"Zumwalt" has Converteam's Advanced Induction Motors (AIM), rather than DRS Technologies' Permanent Magnet-Synchronous Motors (PMM).
The exact choice of engine systems remains somewhat controversial at this point. The concept was originally for an integrated power system (IPS) based on in-hull permanent magnet synchronous motors (PMMs), with Advanced Induction Motors (AIM) as a possible backup solution. The design was shifted to the AIM system in February 2005 in order to meet scheduled milestones; PMM technical issues were subsequently fixed, but the program has moved on. The downside is that AIM technology has a heavier motor, requires more space, requires a "separate controller" to be developed to meet noise requirements, and produces one-third the amount of voltage. On the other hand, these very differences will force time and cost penalties from design and construction changes if the program wishes to "design AIM out" …
The system reduces the ship's thermal and sound signature. The IPS has added to weight growth in the "Zumwalt"-class destroyer as noted by the GAO.
Electric power is provided by two Rolls-Royce MT30 gas turbines (35.4 MW ea.) driving Curtiss-Wright electric generators.
The second ship of the class, "Michael Monsoor", will require a new gas turbine after she experienced problems during sea trials resulting in damaged turbine blades.
Automation and fire protection.
Automation reduces crew size on these ships: the "Zumwalt"-class destroyer's minimum complement is 130, less than half of needed by "similar warships". Smaller crews reduce a major component of operating costs. Ammunition, food, and other stores are all mounted in containers able to be struck below to magazine/storage areas by an automated cargo handling system.
Water spray or mist systems are proposed for deployment in the "Zumwalt"-class destroyer, but the electronic spaces remain problematic to the designers. Halon/Nitrogen dump systems are preferred but do not work when space has been compromised by a hull breach. The GAO has noted this system as a potential problem yet to be addressed.
Computer network.
The Total Ship Computing Environment Infrastructure (TSCEI) is based on General Electric Fanuc Embedded Systems' PPC7A and PPC7D single-board computers<ref name="TSCEI/GEFanuc"></ref> running LynuxWorks' LynxOS RTOS. These are contained in 16 shock, vibration, and electromagnetic protected Electronic Modular Enclosures. "Zumwalt" carries 16 pre-assembled IBM blade servers. The network allows a seamless integration of all on-board systems, e.g. sensor fusion, easing operation and mission planning.
Criticism.
Lawmakers and others questioned whether the "Zumwalt"-class costs too much and whether it provides the capabilities that the military needs. In 2005, the Congressional Budget Office estimated the acquisition cost of a DD(X) at $3.8 billion to $4 billion in 2007 dollars, $1.1 billion more than the navy's estimate. The National Defense Authorization Act For the Fiscal Year 2007 (Report of the Committee on Armed Services House of Representatives on H.R. 5122 Together With Additional And Dissenting Views) stated:
Mike Fredenburg analyzed the program for National Review after "Zumwalt" broke down in the Panama Canal in November 2016, and he concluded that the ship's problems "are emblematic of a defense procurement system that is rapidly losing its ability to meet our national security needs." Fredenburg went on to detail problems relating to the skyrocketing costs, lack of accountability, unrealistic goals, a flawed concept of operations, the perils of designing a warship around stealth, and the failure of the Advanced Gun System. He concludes:
Ballistic missile/air defense capability.
In January 2005, John Young, Assistant Secretary of the Navy for Research, Development, and Acquisition, was so confident of the DD(X)'s improved air defense over the "Burke" class that between its new radar and ability to fire SM-1, SM-2, and SM-6, "I don't see as much urgency for [moving to] CG(X)" – a dedicated air defense cruiser.
On 31 July 2008, Vice Admiral Barry McCullough (Deputy Chief of Naval Operations for Integration of Resources and Capabilities) and Allison Stiller (Deputy Assistant Secretary of the Navy for Ship Programs) stated that "the DDG 1000 cannot perform area air defense; specifically, it cannot successfully employ the Standard Missile-2 (SM-2), SM-3 or SM-6 and is incapable of conducting Ballistic Missile Defense." Dan Smith, president of Raytheon's Integrated Defense Systems division, has countered that the radar and combat system are essentially the same as other SM-2-capable ships, "I can’t answer the question as to why the Navy is now asserting … that "Zumwalt" is not equipped with an SM-2 capability". The lack of anti-ballistic missile capability may represent a lack of compatibility with SM-2/SM-3. The "Arleigh Burke"-class ships have BMD systems with their Lockheed-Martin AEGIS tracking and targeting software, unlike the DDG-1000's Raytheon TSCE-I targeting and tracking software, which does not, as it is not yet complete, so while the DDG-1000, with its TSCE-I combat system, does have the SM-2/SM-3 missile system installed, it does not yet have the BMD/IAMD upgrade planned for the derived CG(X). The Aegis system, on the other hand was used in the Aegis Ballistic Missile Defense System. Since the Aegis system has been the navy's chief combat system for the past 30 years when the navy started a BMD program, the combat system it was tested on was the Aegis combat system. So while the DDG-51 platform and the DDG-1000 platform are both SM-2/SM-3 capable, as a legacy of the Aegis Ballistic Missile Defense System only the DDG-51 with the Aegis combat system is BMD capable, although the DDG-1000's TSCE-I combat system had both BMD and IAMD upgrades planned. And in view of recent intelligence that China is developing targetable anti-ship ballistic missiles based on the DF-21, this could be a fatal flaw.
On 22 February 2009 James "Ace" Lyons, the former commander in chief of the U.S. Pacific Fleet, stated that the DDG-1000's technology was essential to a future "boost phase anti-ballistic missile intercept capability".
In 2010, the Congressional Research Service reported that the DDG-1000 cannot currently be used for BMD because the BMD role was deferred to the DDG-1000 derived CG(X) program (the DDG's had the strike role, the CG had the BMD role, but they shared both the SM3 missile, and the TSCE-I), the proposed radar of the CG(X) was much larger (22') and used much more energy and cooling capacity than the DDG-1000's. Since then, the radar system has been canceled with the CG(X) and it has been determined that a radar could be used either on DDG-51 or on DDG-1000, though it would not have the performance the navy predicts would be needed "to address the most challenging threats". Were the CG(X)'s BMD requirement adopted by the DDG-1000, the DDG-1000 would have to get the TSCE-I upgrade slated for the CG(X) to support that mission.
The study that showed a cost benefit to building Flight III "Arleigh Burke"-class destroyer with enhanced radars instead of adding BMD to the "Zumwalt"-class destroyers assumed very limited changes from the Flight II to the Flight III "Burke"s. However, costs for the Flight III "Burke"s have increased rapidly "as the possible requirements and expectations continue to grow." While the Flight III design and costs have been studied by the navy, there is very little reliable data available on what the cost would be to modify a DDG-1000–class ship to provide a BMD capability. However, if the Air Missile Defense Radar is adopted in common on both the Flight III "Burke"s and the "Zumwalt"s and if they were both upgraded to the same combat system then the only limitation of the "Zumwalt"s in this role would be their limited missile magazines.
With the awarding of the development contract to the next generation Air and Missile Defense S-Band Radar to Raytheon, deliberation to put in place this radar on the "Zumwalt"-class destroyer is no longer being actively discussed.
It is possible for the "Zumwalt"-class destroyers to get the more limited BMD hardware and software modifications that would allow them using their existing SPY-3 radar and Cooperative Engagement Capability to utilize the SM-3 missile and have a BMD capability similar to the BMD-capable s and "Burke"-class Flight IIa destroyers. Procurement of a BMD specific version of the "Zumwalt"-class destroyer was also proposed.
"Zumwalt" PLAS cells can launch the SM-2 Standard missile, but the ships have no requirement for ballistic missile defense. The tubes are long and wide enough to incorporate future interceptors, and although the ship was designed primarily for littoral dominance and land attack, Raytheon contended that they could become BMD-capable with few modifications.
Missile capacity.
The original DD-21 design would have accommodated between 117 and 128 Vertical launching system cells. However, the final DDG-1000 design provides only 80 cells. "Zumwalt" uses MK.57 cells which are larger than the Mk.41 cells found on most American destroyers.
Each VLS cell can be quad packed with RIM-162 Evolved Sea Sparrow Missiles (ESSM). This gives a maximum theoretical load of 320 ESSM missiles. The ESSM is considered a point defense weapon not generally used for fleet area defense.
The "Zumwalt"-class destroyer is not an Aegis system. It uses instead the class-unique Total Ship Computing Environment Infrastructure (TSCEI) integrated mission system. The peripheral vertical launch system (PVLS) is capable of accommodating all Standard missile types. It has not been publicly stated if the TSCE will be modified to support the Standard missile or the ballistic missile defense mission.
Naval fire support role.
The design concept for the "Zumwalt" class developed from the "Land Attack Destroyer (DD 21)" development effort. A primary goal for DD 21 was to provide sea-based fire support for on-shore troops, as part of the force mix that would replace the retiring s as mandated by Congress. There was considerable skepticism that the "Zumwalt" class could succeed in this role.
The "Zumwalt" class was intended to provide naval surface fire support (NSFS) using the AGS and additional land attack using Tomahawk missiles from its PVLS launchers. As deployed, the "Zumwalt" class cannot provide NSFS, since there are only 90 rounds of ammunition available that are compatible with the AGS. The "Zumwalt" class was re-purposed as surface attack vessels and are no longer intended for use as land attack destroyers.
Tumblehome design stability.
The stability of the DDG-1000 hull design in heavy seas has been a matter of controversy. In April 2007, naval architect Ken Brower said, "As a ship pitches and heaves at sea, if you have tumblehome instead of a flare, you have no righting energy to make the ship come back up. On the DDG 1000, with the waves coming at you from behind, when a ship pitches down, it can lose transverse stability as the stern comes out of the water – and basically, roll over." The Navy decided not to use a tumblehome hull in the CG(X) cruiser before the program was canceled, which may suggest that there were concerns regarding "Zumwalt"s sea-keeping abilities. However, the tumblehome hull proved seaworthy in a 1/4-scale test of the hull design named "Sea Jet".
The Advanced Electric Ship Demonstrator (AESD) "Sea Jet" funded by the Office of Naval Research (ONR) is a 133-foot (40-meter) vessel located at the Naval Surface Warfare Center Carderock Division, Acoustic Research Detachment in Bayview, Idaho. "Sea Jet" was operated on Lake Pend Oreille, where it was used for test and demonstration of various technologies. Among the first technologies tested was an underwater discharge waterjet from Rolls-Royce Naval Marine, Inc. called AWJ-21.
While underway during the spring of 2019, USS "Zumwalt" sailed through a storm causing sea state six conditions off the coast of Alaska. The test indicated that the "Zumwalt" class possesses greater stability compared to typical hull forms. During an interview, Captain Andrew Carlson, the commanding officer of USS "Zumwalt" at the time, related "All told I'd rather be on that ship than any other ship I've been on." According to Captain Carlson, during the storm, he summoned his executive officer from his cabin to inform him of the sea state six conditions. Based on the rolls he had been experiencing in his cabin, the executive officer thought that at most they were at sea state three, where wave height only reaches a maximum of . A combination of the "Zumwalt" class's hull form, rudder stop locations and propeller size contribute to its improved seakeeping.
Secondary guns.
In 2005, a Critical Design Review (CDR) of the DDG-1000 led to the selection of the Mk 110 cannon to defend the destroyer against swarming attacks by small fast boats; the Mk 110 has a rate of fire of 220 rpm and a range of . From then to 2010, various analysis efforts were conducted to assess potential cost-saving alternatives. Following a 2012 assessment using the latest gun and munition effectiveness information, it was concluded that the Mk 46 Gun System was more effective than the Mk 110 with increased capability, reduced weight, and significant cost avoidance. The Mk 46 has a rate of fire of 200 rpm and a range of .
Naval experts have questioned the decision to replace the close-in swarm defense guns of the "Zumwalt"-class destroyers with ones of decreased size and range. The 57 mm can engage targets at two to three miles, while the 30 mm can only start to engage at around one mile, inside the range of a rocket-propelled grenade fired from a small boat. However, the DDG-1000 program manager said that the 57 mm round's lethality was "significantly over-modeled" and "not as effective as modeled" in live test-firing, and "nowhere near meeting the requirements"; he admitted that the results were not what he expected to see. When the Naval Weapons Laboratory re-evaluated the Mk 46, it met or exceeded requirements and performed equal to or better than the 57 mm in multiple areas, even coming just ahead of the naval cannon. A 30 mm gun mount also weighs less, around 2 tons compared to 12–14 tons for the 57 mm, but the navy is adamant that weight had nothing to do with the decision.