SC - 21 ( United States ) SC - 21 ( Surface Combatant for the 21st century ) was a program started in 1994 to design land attack ships for the United States Navy . A wide variety of designs were examined , including an arsenal ship with 500 cruise missiles , but eventually a " tumblehome " design of around 16 , 000 tons with two long - range guns and 128 missile tubes was selected as the DD - 21 , the Destroyer for the 21st century . However the program was cancelled in November 2001 , with a cheaper version of the DD - 21 emerging as the DD ( X ) or Zumwalt class destroyer . It was envisaged that the DD - 21 hull would be used for a future air defense cruiser ( CG - 21 ) , which evolved into the CG ( X ) program . Background . The origins of SC - 21 lie in the realization by Admiral Joseph Metcalf III that new technologies such as vertical launch missiles permitted a complete rethink of warship design . He established a steering group , Group Mike , to study the possibilities . Group Mike sponsored two studies in 1987 , the Ship Operational Characteristics Study ( SOCS ) and the Surface Combatant Force Requirement Study ( SCFRS ) . SOCS sought to identify the operational characteristics required of an escort ship , and SCFRS estimated how many such ships were required by the fleet . Since it was expected at that time that the Navy would be fighting prolonged campaigns in the Norwegian Sea , SOCS put an emphasis on ships ' continuing ability to fight after an initial Soviet attack . This in turn called for larger , more survivable escort ships than had historically been the norm , around 12 , 000 tons , and for networking sensors and weapons together so that they could be used by the task force as a whole even if an individual ship had their radar disabled . Survivability also called for the bridge and Combat Information Center to be combined and " buried " in the heart of the ship , and for the ship to use electric drive to distribute the engineering around the ship , which would also give more room for weapons and the scope for railguns and laser weapons in future . SCFRS suggested that the Navy should not replace the " Perry " class frigate for convoy escort duties , but concentrate on building front - line combatants that could be assigned to less demanding convoy duties in their later years . Both studies reported in 1989 , and almost immediately were rendered obsolete by the ending of the Cold War . The Navy suddenly faced the disappearance of its greatest threat , and the prospect of budget cuts as part of the peace dividend . Interest waned in big new designs like the SOCS ship ; the Destroyer Variant ( DDV ) program of December 1991 was intended as a stopgap , the final development of the " Burke " class destroyer . In 1992 the CNO ordered a 21st - century Destroyer ( DD - 21 ) Technology Study . This led to a new program called Surface Combatant for the 21st century ( SC - 21 ) , intended as a family of ships with a range of capabilities that would not necessarily fit old designations of " destroyers " and " cruisers " . Meanwhile strategy papers such as " FORWARD . . . FROM THE SEA " were redefining the Navy ' s priorities towards littoral warfare and the support of amphibious assaults inland . It seemed , then , that land attack would be the most important mission for the new ships . Naval fire support role . Since the retirement of the Iowa - class battleships , there had been a Congress - mandated requirement relating to the Navy ' s capability for Naval Fire Support ( NFS ) . The U . S . Marine Corps and the U . S . Navy maintained that destroyers would be adequate in this role , 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 calibres . US battleships were re - activated three times after WWII specifically for NFS , and their 16 inch gunfire was used in every major engagement of the U . S . from WWII to the Gulf War . " Iowa " and " Wisconsin " were finally struck from the Naval Vessel Register in 2006 , having been kept on in part to fill a naval fire support role . Program approved . The SC - 21 Mission Need Statement was approved by the Joint Requirements Oversight Council between September – October 1994 . The Defense Acquisition Board approved the project on 13 January 1995 , allowing the program to proceed to Cost & Operational Effectiveness Analysis ( COEA ) . Concept designs . The SC - 21 COEA had an unusually wide remit , and studied a variety of designs from 2 , 500 tons to 40 , 000 tons . There were three main " concepts " . Concept 1 looked at possible upgrades to existing vessels , Concept 2 looked at variations of existing designs , and Concept 3 was for new ships : Option 3B1 was closest to what became the " Zumwalt " class , with a pair of 64 - cell VLS fore and aft and two standard 5 " guns on a conventional flared hull of around 9 , 400 tonnes . A bigger hull would be required to enclose everything in a stealthy shape , and to accommodate the much bigger AGS gun system . Arsenal ship . In a separate study in 1993 , two French students had been assigned the design of a Large Capacity Missile Ship , a 20 , 000 - tonner with 500 VLS cells filled with land - attack missiles . This design was inspired by a RAND paper in that year , which suggested a land invasion could be halted by destroying 20 % of its vehicles with precision munitions . This would take several days with aircraft , but a surface ship with large numbers of land - attack missiles could achieve the same effect almost instantly . This design was apparently included in the SC - 21 assessment as an afterthought - it was not included in the original list of concepts . Two designs were considered , both with 512 VLS cells - Option 3A6 was a minimal version of 13 , 400 tons with no self - defense capability , Option 3A5 was a 30 , 000 ton " goal ship " with many more survivability features . The latter Maritime Fire Support Ship became the basis of the Arsenal Ship championed by CNO Jeremy Boorda . In fact he was so enthusiastic that the rest of the SC - 21 program was suspended in favor of development of the Arsenal Ship . The Navy set up a joint venture with DARPA on March 18 , 1996 . The Arsenal Ship would be acquired as a prototype under DARPA ' s Other Transaction Authority under Section 845 of the National Defense Authorization Act for FY 1994 ( Public Law 103 - 160 ) , which allowed them to bypass much of the bureaucracy involved with defense procurement , enabling a prototype to be built by the end of 2000 . The requirement was for a network - capable ship with around 500 VLS and less than 50 personnel , for a cost of less than $ 520 m for the lead ship . A further five ships would be acquired at a later date . In July 1996 , five consortia were awarded $ 1 m to come up with some concepts . Three received follow - on contracts in January 1997 , but the Navy had lost enthusiasm for the project with Boorda ' s suicide in May 1996 , and in April 1997 the Arsenal Ship was redesignated as the Maritime Fire Support Demonstrator ( MFSD ) , which would be a technology demonstrator for a revitalised SC - 21 program . As a result , Congress cut funding to the project and it was finally canceled in October 1997 . The Arsenal Ship concept was revived in 2002 by converting four " Ohio " - class submarines into SSGN s carrying 154 VLS tubes . DD - 21 . In 1997 , plans for the Littoral Combatant ( 3B1 ) were revived under the SC - 21 banner . It was initially renamed the Power Projection Ship , and then DD - 21 , Destroyer for the 21st century . Influenced by the Arsenal Ship , it would have a stealthy hull with a significant land attack capability . At first the plan was to install a twin - barreled Vertical Gun for Advanced Ships ( VGAS ) , developed from experiments on advanced projectiles for the " Iowa " battleships , but this was dropped in favour of a conventional 5 " gun and two 64 - cell VLS . It would also feature a revolutionary cross - layer active sonar . An Operational Requirements Document was signed in November 1997 , and an Advanced Development Memorandum on 11 December . A Program Executive Office was established on 25 February 1998 . As with the " Burke " class , the construction of the DD - 21 ships would be split between Bath Iron Works and Ingalls to preserve the industrial base . However there would be a competition between the two yards to design DD - 21 and to be the full - service contractor for the class , which would mean the winning team receiving 85 % of the total program costs of around $ 70 billion . BIW partnered with Lockheed Martin as the combat system designer and integrator , forming the " Blue " team ; Ingalls partnered Raytheon in the " Gold " team . The new design was compared to the current " Burke " hull and possible developments of it , and it was decided to go ahead with a new hull to be called DD - 21 ( or DD 21 ) , the 21st century Land Attack Destroyer . The new hull was judged to have more potential for stealth and reductions in manning than the " Burke " s . This was important , as one aim of the program was to reduce manning and operational costs by 70 % , while providing scope for a follow - on cruiser class . On 4 July 2000 it was announced that the lead ship of the class would be named after Admiral Elmo Zumwalt , who had died earlier that year . The name would be inherited by subsequent versions of the design , culminating in USS " Zumwalt " . The ship ' s delivery schedule was delayed by a year following the decision in January 2000 to use electric drive in the ship . But by early 2000 a " tumblehome " design had emerged that resembles that of the eventual " Zumwalt " class , albeit with differences in the weapons carried . Sources disagree on the displacement of the DD - 21 , and indeed it probably varied during the design process , but around 16 , 000 tons seems most likely . As of July 2001 , 32 DD - 21s were planned , with construction planned to start in FY05 . Many of the weapons planned for the DD - 21 were to be trialled in existing ships , increasing the land attack capability of the existing fleet in FY05 before the delivery of DD - 21 in FY10 . Rocket - boosted Extended Range Guided Munitions ( ERGM ) for existing 5 " / 62 guns would have a range of , while the long - range Block IV Tactical Tomahawk missile could be fired from existing Mk 41 vertical launching system s . It was also planned to turn old Standard Missile SAMs into Land Attack Standard Missiles ( LASM ) with range . Initially it was planned to use the Vertical Gun for Advanced Ships ( VGAS ) , but this was abandoned in favor of a more conventional Advanced Gun System fore and aft , each with a separate magazine of 600 - 750 rounds . The guns would fire a 155 mm version of the ERGM which would double the payload and increase the range to . Together the two guns would give the ship a rate of fire of 24 rounds / minute , giving them the throw weight of two 6 - gun 155 mm artillery batteries . Precision munitions make gunfire three times more effective than unguided shells , hence the DD - 21 was said to have the destructive power of six batteries . The Navy ' s goal was to have 256 VLS cells on the DD - 21 , but the final number may have been 128 - some sketches show missiles being launched from fore and aft but the aft launchers appear to have been replaced by a second gun system and / or a helicopter pad . As well as LASM and Tactical Tomahawk , the DD - 21 would receive the Advanced Land Attack Missile ( ALAM ) , a new missile with a variety of warheads and a design range of up to . CG - 21 . A 21st century air defense cruiser ( CG - 21 ) was announced in January 2000 to replace the 27 Ticonderoga class cruiser s . Procurement was to begin after the end of the DD - 21 program , perhaps around 2015 . Development work had not started before the program was terminated in November 2001 ; CG - 21 was replaced by the CG ( X ) program , which was subsequently cancelled in 2010 . Cancellation . The winner of the competition to design the DD - 21 was due to be announced in March 2001 , but the decision was put back twice as the new Bush administration reviewed defense spending . On March 1 it was announced that the decision would be made in May , and on May 31 it was announced that the Navy would wait for the results of the Quadrennial Defense Review , and a future shipbuilding review . After the House Appropriations Committee proposed a reduction in the DD - 21 allocation in the FY2002 budget in late October 2001 , on 1 November the Navy announced a less ambitious Future Surface Combatant program ( FSC ) . Polmar claims that DD - 21 was terminated primarily for political reasons as the program was closely identified with the Clinton administration , whereas Work views it as the culmination of a debate within the Navy about whether they should use in the littoral zone large capable ships like the DD - 21 or more numerous smaller ships like the " Streetfighter " concept . It did not help that the original plan called for the fifth ship to cost $ 750 m in FY96 dollars , but in the fourth quarter of 1999 alone the program cost went up from $ 3 . 2bn to $ 5 . 2bn . Streetfighter evolved into the Littoral Combat Ship ; under FSC the DD - 21 became the DD ( X ) which would become the Zumwalt class destroyer , whilst the preliminary plans for CG - 21 would be folded into the CG ( X ) ballistic missile defense cruiser . The hull of the " Zumwalt " class is similar to that of the DD - 21 , but the new design displaces 14 , 564 tons and unlike the DD - 21 , the deckhouse is flush to the sides of the hull . The central " block " of VLS cells is replaced by a peripheral VLS of 80 cells , which allows both guns to be located forward of the deckhouse . This in turn allows the stern to be given over to helicopter facilities but means that the automated magazine can only contain 750 rounds , supplemented by an auxiliary store .