USS Zumwalt undergoing sea trials.
|Builders:||Bath Iron Works|
|Operators:||United States Navy|
|Preceded by:||Arleigh Burke class|
|In commission:||15 October 2016|
|Type:||guided missile destroyer|
|Displacement:||14,564 long tons (14,798 t)|
|Length:||600 ft (180 m)|
|Beam:||80.7 ft (24.6 m)|
|Draft:||27.6 ft (8.4 m)|
|Speed:||In excess of 30 kn (56 km/h; 35 mph)|
|AN/SPY-3 Multi-Function Radar (MFR) (X band active electronically scanned array)|
|Aviation facilities:||Flight deck and enclosed hangar for up to two medium-lift helicopters|
The Zumwalt-class destroyer is a class of United States Navy guided missile destroyers designed as multi-mission stealth ships with a focus on land attack. The class emerged from the previous DD-21 vessel program, previously known as the "DD(X)". The class is multi-role and designed for surface warfare, anti-aircraft warfare, and naval gunfire support. They take the place of battleships in filling the former congressional mandate for naval fire support, though the requirement was reduced to allow them to fill this role. The vessels' appearance has been compared to that of the historic ironclad warship.
The class has a low radar cross-section; an integrated power system that can send electricity to the electric drive motors or weapons, the Total Ship Computing Environment Infrastructure (TSCEI), automated fire-fighting systems, automated piping rupture isolation  or free-electron lasers. The class is designed to require a smaller crew and be less expensive to operate than comparable warships. It has a wave-piercing tumblehome hull form whose sides slope inward above the waterline, which has been stated to reduce the radar cross-section (RCS) by returning much less energy than a conventional flare hull form. 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..."
The lead ship is named Zumwalt 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 $3.96 billion (excluding R&D costs) – well-exceeding the per-unit cost of a nuclear-powered Virginia-class submarine ($2.688 billion). The dramatic per-unit cost increases eventually triggered a Nunn-McCurdy Amendment breach and cancellation of further production. In April 2016, the total program cost was $22.5 billion with an average cost of $7.5 billion per ship.
- 1 History
- 2 Names and hull numbers
- 3 Design elements
- 4 Controversy
- 5 See also
- 6 Footnotes
- 7 References
- 8 External links
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.[full citation needed] 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 Arleigh Burke-class destroyers, and no longer needs 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 now makes more sense to build at least eight more Burkes, 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 Zumwalts. 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.
In late 2005, the program entered the detailed design and integration phase, for which Raytheon is the Mission Systems Integrator. Both Northrop Grumman Ship Systems and General Dynamics Bath Iron Works share dual-lead for the hull, mechanical, and electrical detailed design. BAE Systems Inc. has 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. are involved to some extent in this project, which is 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 Zumwalt (DDG-1000), and Northrop Grumman Shipbuilding was awarded a contract for the construction of Michael Monsoor (DDG-1001), 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:
- October 2008: DDG-1000 starts construction at Bath Iron Works
- September 2009: DDG-1001 starts construction at Bath Iron Works.
- April 2012: DDG-1002 starts construction at Bath Iron Works
- April 2013: DDG-1000 initial delivery
- May 2014: DDG-1001 delivery
- March 2015: Initial operating capability
- Fiscal 2018: DDG-1002 delivery
The Navy plans for Zumwalt to reach initial operating capability (IOC) in 2016. The second ship, Michael Monsoor, is to reach IOC in 2018, and the third ship, Lyndon B. Johnson (DDG-1002), is to reach IOC in 2021.
Names and hull numbers
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 will be DDG-1000, which abandons the guided missile destroyer sequence used by the Arleigh Burke-class destroyers (DDG-51–), and continues the previous "gun destroyer" sequence from the last of the Spruance class, Hayler (DD-997).
Ships in class
|Ship||Hull Number||Laid down||Launched||Commissioned||Status|
|Zumwalt||DDG-1000||17 November 2011||28 October 2013||15 October 2016||Active|
|Michael Monsoor||DDG-1001||23 May 2013||21 June 2016||Fitting out|
|Lyndon B. Johnson||DDG-1002||30 January 2017||Under construction|
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.
Despite being 40% larger than an Arleigh Burke-class destroyer, the radar cross-section 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 Los Angeles-class submarines. 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).
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.
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 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." The tumblehome has not been featured in any USN concept design since the Zumwalt class.
Advanced Gun System
There has been research on extending the range of naval gunfire for many years. Canadian engineer Gerald Bull and Naval Ordnance Station Indian Head tested an 11-inch (279 mm) sub-caliber saboted long-range round in a stretched 16-inch (406 mm)/45 caliber Mark 6 battleship gun in 1967. The Advanced Gun Weapon System Technology Program (AGWSTP) evaluated a similar projectile with longer range in the 1980s. After the battleships were decommissioned in 1992, the AGWSTP became a 5-inch (130 mm) gun with an intended range of 180 kilometers (110 mi), which then led to the Vertical Gun for Advanced Ships (VGAS). The original DD-21 was designed around this "vertical gun", but the project ran into serious technology/cost problems and was radically scaled back to a more conventional 6.1-inch (155 mm) Advanced Gun System (AGS). One advantage of this move was that the gun was no longer restricted to guided munitions.
The Advanced Gun System is a 155 mm naval gun, two of which would be installed in each ship. This system consists of an advanced 155 mm gun and the Long Range Land Attack Projectile (LRLAP). This projectile is a rocket with a warhead fired from the AGS gun; the warhead weighs 11 kg / 24 lb and has a circular error of probability of 50 meters. This weapon system will have a range of 83 nautical miles (154 km);[Note 1] the fully automated storage system will have 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. The combined firepower from a pair of turrets gives each Zumwalt-class destroyer firepower equivalent to 12 conventional M198 field guns. This initial strike firepower is possible by using a Multiple Rounds Simultaneous Impact (MRSI) firing tactic and does not equal the sustained firepower. To provide sufficient stability to fire these guns, the Zumwalts will use ballast tanks to lower themselves into the water. 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. Other projectiles are being researched as substitutes, 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 due to the installed Rolls-Royce turbine generators being capable of producing 78 megawatts (105,000 hp), enough to power the electromagnetic weapon.
Peripheral Vertical Launch System
The Peripheral Vertical Launch System (PVLS) is an attempt to reclaim the prized center space of the hull while increasing the safety of the ship from the loss of the entire missile battery and the loss of the ship in the case of a magazine explosion. The system scatters pods of VLS around the outer shell of the ship having a thin steel outer shell and a thick inner shell. The design of the PVLS would direct the force of the explosion outward rather than ripping the ship in half. Additionally, this design reduces the loss of missile capacity to the pod being hit.
Aircraft and boat features
Two spots will be available on a large aviation deck with a hangar capable of housing two full size SH-60 helicopters. Boat handling is to be dealt within a stern mounted boat hangar with ramp. The boat hangar's stern location meets high sea state requirements for boat operations.
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.
The Dual Band Radar in its entirety (SPY-3 & SPY-4) is to be installed only on the Gerald R. Ford-class aircraft carrier Gerald R. Ford. 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, 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.
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 14 feet (4.3 m), the AMDR for the Flight III ships is to be less sensitive than the 22 ft variant that had been planned for CG(X).
A study to place the AMDR on a DDG-1000 hull was done with the 22-foot (6.7 m) 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:
... that developing a BMD capability "from scratch" for TSCE was not considered viable enough by the study team to warrant further analysis, particularly because of the investment already made in the Aegis program. The navy concluded that developing IAMD software and hardware specifically for TSCE would be more expensive and present higher risk. Ultimately, the navy determined that Aegis was its preferred combat system option. Navy officials stated that Aegis had proven some BMD capability and was widely used across the fleet, and that the navy wanted to leverage the investments it had made over the years in this combat system, especially in its current development of a version that provides a new, limited IAMD capability.
Because the DBR provides Interrupted Continuous Wave Illumination instead of the Continuous-wave radar used on the other DDGs, the Zumwalt class requires modified versions of the ESSM and the SM-IIIA missiles and cannot use the other kinds of Aegis missiles.
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.
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.
- Hull-mounted mid-frequency sonar (AN/SQS-60)
- Hull-mounted high-frequency sonar (AN/SQS-61)
- Multi-function towed array sonar and handling system (AN/SQR-20)
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 DDX proposed to use a permanent-magnet motor (PMM) within the hull. 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 is considered to be another technology leap and is 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 will have 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 Integrated Power System (IPS) is, in some ways, similar to the old turbo-electric drive, the addition of PMMs and integration of all electrical power systems gives ten times the power available on current destroyers. It also 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.
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.
The Total Ship Computing Environment Infrastructure (TSCEI) is based on General Electric Fanuc Embedded Systems' PPC7A and PPC7D single-board computers 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.
Lawmakers and others have questioned whether the Zumwalt-class costs too much and whether it provides the capabilities the U.S. military needs. In 2005 the Congressional Budget Office estimated the acquisition cost of a DD(X) at $3.8–4.0bn in 2007 dollars, $1.1bn 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 the following: "The committee understands there is no prospect of being able to design and build the two lead ships for the $6.6 billion budgeted. The committee is concerned that the navy is attempting to insert too much capability into a single platform. As a result, the DD(X) is now expected to displace more than 14,000 tons and by the navy's estimate, cost almost $3.3 billion each. Originally, the navy proposed building 32 next-generation destroyers, reduced that to 24, then to 7, and finally to 3, in order to make the program affordable. In such small numbers, the committee struggles to see how the original requirements for the next generation destroyer, for example providing naval surface fire support, can be met."
Prompted by the November 22, 2016, break-down of Zumwalt in the Panama Canal with both propellers seized, Mike Fredenburg analyzed the program for the National Review and 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." After detailing problems relating to the skyrocketing costs, lack of accountability, unrealistic goals, a flawed concept of operations, the perils of designing a warship around stealth, as well as the failure of the Advanced Gun System, Fredenburg concludes:
The Zumwalt is an unmitigated disaster. Clearly it is not a good fit as a frontline warship. With its guns neutered, its role as a primary anti-submarine-warfare asset in question, its anti-air-warfare capabilities inferior to those of our current workhorse, the Arleigh Burke-class destroyers, and its stealth not nearly as advantageous as advertised, the Zumwalt seems to be a ship without a mission.
The following specific concerns have been raised about the design:
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 22-foot (6.7 m) radar system has been canceled with the CG(X) and it has been determined that a 14-foot (4.3 m) 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 Burkes. However, costs for the Flight III Burkes 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 Burkes and the Zumwalts and if they were both upgraded to the same combat system then the only limitation of the Zumwalts in this role would be their limited missile magazines.[verification needed]
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 Ticonderoga-class cruisers and Burke-class Flight IIa destroyers. Procurement of a BMD specific version of the Zumwalt-class destroyer is also being 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 ships' immediate role is littoral dominance and land attack, Raytheon contends that they could become BMD-capable with few modifications.
The original DD-21 design, displacing around 16,000 tons, would have accommodated between 117 and 128 VLS cells. However, the final DDG-1000 design was considerably smaller than that of the DD21, resulting in room for only 80 VLS cells. The Zumwalt uses Mk.57 VLS cells which are larger than the Mk.41 cells found on most American destroyers. Given the vessel's expected role, the Zumwalt-class destroyers will likely carry many more Tomahawk missiles than either the Ticonderoga- or Arleigh Burke-class ships.
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, although the ESSM has a range (27 nautical miles (50 km; 31 mi)) exceeding that of the earlier Naval Tartar anti-aircraft missile (17.5-nautical-mile (32.4 km; 20.1 mi) RIM-24C).
Vice Admiral Barry McCullough On 31 July 2008 (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. It is not clear if the Standard Missile capability will be integrated into the Zumwalt-class destroyer or not.
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) VLS 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.
In summary, the committee is concerned that the navy has foregone the long range fire support capability of the battleship, has given little cause for optimism with regard to meeting near-term developmental objectives, and appears unrealistic in planning to support expeditionary warfare in the mid-term. The committee views the navy's strategy for providing naval surface fire support as 'high risk', and will continue to monitor progress accordingly.
A controversial point of the DD(X) destroyer(s) is their planned naval surface fire support (NSFS) role. The original DD21 and the Arsenal Ship had more serious NSFS capabilities, which would meet a Congress-mandated requirement related to the Iowa-class battleships. The requirement was eventually relaxed, the battleships stricken from the registry, and the navy left with small tonnage ships for NSFS or alternative methods such as air support. The official position of the U.S. Marine Corps and the U.S. Navy is that the Zumwalt-class destroyer(s) will be adequate as naval surface gunfire support ships, although there are dissenters.
While smaller caliber guns (and missiles) have been used for centuries in naval fire support, very large guns have special capabilities beyond that of mid-range calibers. US battleships were re-activated three times after World War II specifically for naval fire support, and their 16-inch (410 mm) gunfire was used in every major engagement of the U.S. from World War II through Operation Desert Storm in January/February 1991. The Zumwalt class will have two 6.1-inch (150 mm) guns with limited ammunition. The ships will fire a specially designed "guided" artillery shell some 63 nautical miles (117 km; 72 mi) inland.
In March 2006, Iowa and Wisconsin were stricken from the Naval Vessel Register, having been kept on in part to fill a naval fire support role. However, Congress was "deeply concerned" over the loss of naval surface gunfire support they could provide and noted that "navy efforts to improve upon, much less replace, this capability have been highly problematic", The U.S. House of Representatives asked that the battleships be kept in a state of readiness should they ever be needed again and directed the navy to increase the number of Arleigh Burke-class destroyers that are currently being modernized. The modernization includes extending the range of the 5-inch guns on the Flight 1 ships with Extended Range Guided Munitions (ERGMs) that would enable the ships to fire projectiles about 40 nautical miles (74 km; 46 mi) inland; However the ERGM was canceled after it failed the firing tests in February 2008. The Navy is studying future options for naval fire support; Alliant Techsystems’ ballistic trajectory extended range munition may be one possibility.
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 decision to not use a tumblehome hull in the CG(X) cruiser, before the program was canceled, may suggest that there were concerns regarding Zumwalt's seakeeping. However, in a 1/4 scale test of the hull design, named Sea Jet, the tumblehome hull proved seaworthy.
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, a propulsion concept with the goals of providing increased propulsive efficiency, reduced acoustic signature, and improved maneuverability over previous destroyer-class combatants.
In 2005, a Critical Design Review (CDR) of the DDG-1000 led to the selection of the Mk 110 57 mm (2.2 in) 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 9 nmi (17 km; 10 mi). 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 30 mm (1.2 in) 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 2.17 nmi (4.02 km; 2.50 mi).
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 76 mm (3 in) 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.[verification needed]
- The AGS "can fire rocket-powered, computer-guided shells that can destroy targets 63 miles (101 km) away,... three times farther than ordinary destroyer guns can fire."
- "GAO-15-342SP DEFENSE ACQUISITIONS Assessments of Selected Weapon Programs" (PDF). US Government Accountability Office. March 2015. p. 73. Retrieved 15 July 2015.
- "Navy Requires $450 Million More to Complete Zumwalt-Class Due to Shipyard Performance". usni.org, 6 April 2016.
- Bubala, Mary (16 October 2016). "Historic And Cutting Edge USS Zumwalt Commissioned In Baltimore". WJZ-TV. Retrieved 16 October 2016.
- Kasper, Joakim (20 September 2015). "About the Zumwalt Destroyer". AeroWeb. Retrieved 25 October 2015.
- GAO-05-752R Progress of the DD(X) Destroyer Program. U.S. Government Accountability Office. 14 June 2005.
- CRS RL32109 Navy DDG-51 and DDG-1000 Destroyer Programs: Background and Issues for Congress[permanent dead link]. CRS, 14 June 2010.
- "MK 57 Vertical Launch System Archived 24 September 2012 at the Wayback Machine.". Raytheon
- Navy Swaps Out Anti-Swarm Boat Guns on DDG-1000s – News.USNI.org, 5 August 2014
- Section 1011 of the National Defense Authorization Act for Fiscal Year 1996 (Public Law 104-106; 110 Stat. 421)
- "New Zumwalt-Class Destroyer Is Not Your Father's Tin Can". Los Angeles Times. 5 July 2000.
- John Pike. "Navy Approves Raytheon's Zumwalt Total Ship Computing Environment Infrastructure".
- Sanchez, Lucia (January–March 2007). "Electromagnetic Railgun – A "Navy After Next" Game Changer". CHIPS – the Department of the Navy Information Technology Magazine. Retrieved 13 July 2013.
- "Boeing: Raygun dreadnoughts will rule the oceans by 2019". The Register. 17 April 2009. Retrieved 18 April 2009.
- NDAA 2007 pp. 69–70.
- "Cutting-edge Navy warship being built in Maine". Fox News. 12 April 2012. Retrieved 12 April 2012.
- The US Navy's budget request for two Virginias in financial year 2016 (FY2016) is US$5,376.9 million, including $2,030.4m of advance funding from previous years.
- "Root Cause Analyses of Nunn-McCurdy Breaches -- Zumwalt-Class Destroyer, Joint Strike Fighter, Longbow Apache, and Wideband Global Satellite," Rand Corporation (2011); see Vol. 1, Ch. 3 via http://www.rand.org/pubs/monographs/MG1171z1.html
- Taylor, Andrew (26 September 2006). "House OKs $70B for Iraq, Afghanistan". The Washington Post. Associated Press.
- 109th Congress :Department of Defense Appropriations Act, 2007. (109–289) US Government Printing Office. 29 September 2006.
- "Navy: No Need to Add DDG 1000s After All". Navy Times. Gannett Government Media. 31 July 2008. Retrieved 25 January 2016.
- Smith, R. Jeffrey; Nakashima, Ellen (8 March 2009). "Pentagon's Unwanted Projects in Earmarks". Washington Post. pp. A01.
- Cavas, Christopher P (26 September 2008). "Roughead pushes for littoral combat ship". Navy Times.
- Ewing, Philip (19 August 2008). Lawmaker: Third DDG 1000 Far From Done Deal. Defense News.
- Scully, Megan (24 September 2008). "Negotiators agree to buy more F-22s, Zumwalt destroyers". Congress Daily.
- Cavas, Christopher P. (2 February 2009), "New Destroyer Emerges in US Plans", Defense News, p. 1
- Bennett, John T.; Osborn, Kris (6 April 2009). "Gates Reveals DoD Program Overhaul". Defense News.
- Drew, Christopher (18 April 2009). "General Dynamics To Build New Destroyer". New York Times.
- Pike, John. "CG(X) Next Generation Cruiser". globalsecurity.org. Retrieved 2012-12-15.
- O'Rourke, Ronald (10 March 2016). "Navy DDG-51 and DDG-1000 Destroyer Programs: Background and Issues for Congress" (PDF). Congressional Research Service.
- "U.S. Navy Awards Northrop Grumman $90 Million Long-Lead Material Contract for DDG 1000". Northrop Grumman Corporation. 13 November 2007.
- "Navy Awards Contracts for Zumwalt Class Destroyers" (Press release). Navy News Service. 14 February 2008.
- "BIW News February 2009" (PDF). General Dynamics Bath Iron Works. 1 March 2009.
- "Keel Laid for First DDG 1000 Destroyer". NavSea. NOV17-01. Archived from the original on 2014-10-29.
- Tarantola, Andrew (29 October 2013). "America's Newest and Deadliest Destroyer Has Finally Set Sail". Gizmodo.com. Retrieved 12 April 2016.
- "GAO-08-804, Defense Acquisitions: Cost to Deliver Zumwalt-Class Destroyers Likely to Exceed Budget". Government Accountability Office. 31 July 2008.
- "First Zumwalt-Class Destroyer to Join U.S. Navy Fleet by late 2014". navyrecognition.com. 25 November 2013.
- "Raytheon awarded $75 million for DDG 1000 Zumwalt class Destroyer program". navyrecognition.com. 18 December 2013.
- "U.S. Navy Christened USS Zumwalt (DDG 1000), New Class of Destroyer". navyrecognition.com. 13 April 2014.
- "Future Zumwalt class Destroyer USS Michael Monsoor (DDG 1001) Deckhouse Successfully Integrated". navyrecognition.com. 17 November 2014.
- "General Dynamics Bath Iron Works Awarded $212 Million for DDG 1002 Deckhouse, Hangar and Launch-System Modules". navyrecognition.com. 6 August 2013.
- Osborn, Kris (14 January 2014). "DDG 1000 Preps for Heavy Weather Trials". DoDBuzz.com.
- Clayton, Cindy (30 October 2008). "Navy to name newest destroyer after SEAL who died in Iraq". The Virginian-Pilot. Retrieved 22 April 2010.
- "Navy Names Zumwalt Class Destroyer USS Lyndon B. Johnson". Office of the Assistant Secretary of Defense (Public Affairs), United States Department of Defense. 16 April 2012. Archived from the original on 15 May 2012. Retrieved 2012-04-16.
- "GAO Assessments of Major Weapon Programs." Government Accountability Office
- Patterson, Thom; Lendon, Brad (14 June 2014). "Navy's stealth destroyer designed for the video gamer generation". CNN. Retrieved 29 October 2014.
- "Zumwalt Class Destroyer Integrated Composite Deckhouse & Apertures (IDHA)". Raytheon Company. 22 March 2007.
- Cavas, Christopher P (12 September 2008). "Will DDG 1000 Produce Any Ships at All?". Defense News.[dead link]
- Fabey, Michael (25 January 2013). "U.S. Navy Seeks Alternate Deckhouse For DDG-1002". Aerospace Daily & Defense Report.
- Schneider, David (31 July 2013). "The Electric Warship". IEEE Spectrum. IEEE. Retrieved 1 August 2013.
- Tarantola, Andrew. "Stealth on the Navy's newest destroyers might be too good". engadget.com. Retrieved 11 April 2016.
- Forczyk. p. 18, 76
- Forczyk p. 32, 76
- "DDG-1000 Zumwalt / DD(X) Multi-Mission Surface Combatant". globalSecurity.org. 1 September 2008.
- "Wave Piercing Tumblehome Hull". Raytheon Company. 22 March 2007.
- Van Dam, L. Bruce (4 June 1999). Does the Past Have a Place in the Future? The Utility of Battleships into the Twenty-First Century (PDF). Fort Leavenworth, Kansas: US Army Command and General Staff College., citing a letter from Major Tracy Ralphs to Senator John Warner on 25 February 1999.
- "Advanced Gun System (AGS)". BAE Systems. 2008.
- "Zumwalt-Class Destroyer Critical Technologies". Raytheon.
- "Next-Gen Naval Gunfire Support: The USA's AGS & LRLAP". Defense Industry Daily. 23 February 2014.
- Ewing, Philip (16 April 2012). "SAS12: Approach of the Gray Elephant". DoD Buzz.
- Cavas, Christopher P. (2016-11-06). "New Warship's Big Guns Have No Bullets". DefenseNews.
- Navy Planning on Not Buying More LRLAP Rounds for Zumwalt Class - News.USNI.org, 7 November 2016
- Sharp, David. "Admiral: Shipbuilders won't install railgun on new Navy destroyers". militarytimes.com. Retrieved 8 November 2016.
- Dent, Steven (15 February 2016). "The Navy wants to deploy railguns on its latest destroyer". engadget.com. AOL.
- "Zumwalt Class Destroyer Peripheral Vertical Launch System (PVLS) Advanced VLS". Raytheon Company. 22 March 2007. Archived from the original on 7 January 2009.
- "Navy Switches from Composite to Steel". Defense News. 11 June 2014. Retrieved 2014-06-15.
- "The US Navy's Dual Band Radars". Defenseindustrydaily.com. 11 August 2010. Retrieved 2011-12-27.
- "Archived copy" (PDF). Archived from the original (PDF) on 12 December 2014. Retrieved 28 October 2014.
- "Navy Programs: Ship Self-Defense" (PDF). Director of Operational Test and Evaluation.
- O'Neil, William D. (August 2007). "The Cooperative Engagement Capability (CEC): Transforming Naval Anti-air Warfare" (PDF). Center for Technology and National Security Policy, National Defense University. Retrieved 29 October 2014.
- "Navy C4ISR and Unmanned Systems". Sea Power 2016 Almanac. Navy League of the U.S. January 2016. p. 91.
- O'Rourke, Ronald (18 October 2012). "Navy DDG-51 and DDG-1000 Destroyer Programs: Background and Issues for Congress" (PDF). Congressional Research Service. p. 23. Retrieved 2014-06-15.
- Fabey, Mike (29 November 2016). "The U.S. Navy's New Super Stealth Destroyer Is Getting Ready for Combat". nationalinterest.org. The National Interest. Retrieved 29 November 2016.
- McCullough, Vice Adm. Barry; Stiller, Allison (31 July 2008). Statement on Surface Combatant Requirements and Acquisition Strategy (PDF). House Armed Services Committee.
- "Zumwalt Undersea Warfare Combat System Receives Official Navy Nomenclature". Raytheon. 9 December 2008.
- "Dead Aim, Or Dead End? The USA's DDG-1000 Zumwalt Class Program". Defense Industry Daily. 21 September 2008. (subscription required (. ))
- "Zumwalt Class Destroyer Autonomic Fire Suppression System (AFSS)". Raytheon Company. 22 March 2007.
- "GE Fanuc Embedded Systems Selected By Raytheon For Zumwalt Class Destroyer Program". GE Fanuc Intelligent Platforms. 25 July 2007.
- "GE Fanuc Embedded Systems Selected By Raytheon For Zumwalt Class Destroyer Program". Lynuxworks. 25 July 2007.
- Gallagher, Sean (18 October 2013). "The Navy's newest warship is powered by Linux". arstechnica.com. Retrieved 18 October 2013.
- Kamath, Maya (6 February 2015). "Linux used to build US Navy's most powerful destroyer yet". techworm.net.
- "Navy Approves Raytheon's Zumwalt Total Ship Computing Environment Infrastructure". Raytheon. 30 October 2007.
- Gilmore, J. Michael (19 July 2005). Statement on The Navy's DD(X) Destroyer Program before the Subcommittee on Projection Forces. US House of Representatives.
- FREDENBURG, MIKE. "How the Navy's Zumwalt-Class Destroyers Ran Aground". NationalReview.com. Retrieved 19 December 2016.
- "John Young – Assistant Secretary of the US Navy For Research, Development And Acquisition". Jane's Defence Weekly. 12 January 2005. Archived from the original on 19 February 2009.
- "Aegis Ballistic Missile Defense". U.S. Department of Defense Missile Defense Agency. 7 March 2011. Retrieved 2012-12-15.
- Military Power of the People's Republic of China 2008 (PDF). Office of the Secretary of Defense. p. 2 (p12 of PDF).
- Cavas, Christopher P (4 August 2008). "Missile Threat Helped Drive DDG Cut". DefenseNews.
- "LYONS: Naval shipbuilders sinking". Washington Times. 22 February 2009.
- O'Rourke, Ronald (10 June 2010). "Navy CG(X) Cruiser Program: Background for Congress" (PDF). Congressional Research Service.
- "CRS RL33745 Navy Aegis Ballistic Missile Defense (BMD) Program: Background and Issues for Congress 8 April 2010". Opencrs.com. Retrieved 2014-06-15.
- Fabey, Michael (10 June 2011). "Potential DDG-51 Flight III Growth Alarms". Aviation Week.[dead link]
- Cavas, Christopher P. (4 June 2010). "Axing DDG 1000 Radar May Save Cash, Enable BMD". Defense News.
- Cavas, Christopher P. (10 October 2013). "Raytheon Wins Key US Navy Radar Competition". Defense News. Retrieved 2014-06-15.
- "The US Navy's Dual Band Radars". Defense Industry Daily. 2013-10-01. Retrieved 2014-06-15.
- "DD-21 Zumwalt". globalsecurity.org. 27 April 2005.
- "DDG 1000 Flight I Design". Northrop Grumman Ship Systems. 2007. Archived from the original on 15 September 2007.
- "DDG1000_ASNE_Program_Overview_04.17.13" (PDF). Retrieved 2014-06-15.
- "National Defense Authorization Act of 2007" (PDF). p. 194. Archived from the original (PDF) on 23 September 2008. Retrieved 7 November 2008.
- Novak, Robert (6 December 2005). "Losing the Battleships". CNN.
- AR 600-8-27 p. 26 paragraph 9–14
- NDAA 2007 p. 193
- NDAA 2007 p. 68
- NDAA 2007 pp. 67–68, 193
- "MK 45 5-inch / 54-caliber (lightweight) gun". Federation of American Scientists. 26 November 1999.
- Matthews, William (25 March 2008). "Navy ends ERGM funding". Navy Times.
- Will DDG-1000 Destroyers Be Unstable?. Defense Industry Daily. 12 April 2007., quoting Cavas, Christopher P (2 April 2007). "Is New U.S. Destroyer Unstable?". DefenseNews.
- Pike, John. "Sea Jet Advanced Electric Ship Demonstrator (AESD)". globalsecurity.org. Retrieved 2014-06-15.
- Cavas, Christopher P. (12 October 2014). "Experts Question US Navy's Decision To Swap Out DDG 1000's Secondary Gun". Defense News.
|Wikimedia Commons has media related to Zumwalt class destroyer.|
- Raytheon's official DDG 1000 Program web page
- Zumwalt class Destroyer on Navy Recognition site
- Advanced Gun System set to be installed on the DD(X) destroyers
- Concept of employment for naval surface fire support (near term capability)
- Eaglen, Mackenzie (7 October 2008). "Changing Course on Navy Shipbuilding: Questions Congress Should Ask Before Funding". The Heritage Foundation.