View source for MBT-70

{{Short description|American-West German main battle tank}}
{{Infobox weapon
| name               = MBT-70
| image              = File:Kampfpanzer 70 (DPM).jpg
| image_size         = 300
| caption            = MBT-70 (KpfPz-70)
| origin             = United States<br /> [[West Germany]]
| service            = 
| type               = [[Main battle tank]]
| is_vehicle         = yes
| used_by            = 
| wars               = 
| designer           = 
| manufacturer       = 
| unit_cost          = 
| number             = 14 (prototypes and pilots)
| variants           = 
| weight             = {{convert|50.4|t}}<ref name="PzMuseumMunster">{{cite sign|title=MBT (MBT 70) "prototype"|type=Sign in the Panzermuseum Munster|url=https://commons.wikimedia.org/wiki/File:Panzermuseum_Munster_2010_0729.JPG|access-date=2010-11-19|via=Wikimedia Commons}}</ref>
| length             = {{convert|9.1|m|ftin}}
| width              = {{convert|3.51|m|ftin}}
| height             = {{convert|1.99|to|2.59|m|ftin|abbr=on}}
| primary_armament   = 152&nbsp;mm XM150E5
| secondary_armament = [[Rheinmetall Rh 202|20&nbsp;mm Rh-202 autocannon]]{{sfn|Hunnicutt|1990|p=133}}<br /> 7.62&nbsp;mm [[M73 machine gun|M73]] or [[MG 3 machine gun|MG 3]] machine gun (coaxial){{sfn|Hunnicutt|1990|p=133}}
| armour             = [[Spaced armour]] <br /> Two layers spaced with 127mm, the inner a softer steel that also served as a spall liner (46mm), and the outer of harder cold-rolled steel (34mm){{Citation needed|date=November 2023}}.
| engine_power       = {{convert|1470|hp}} (MBT-70) <br /> {{convert|1500|hp}} (KPz-70)
| transmission       = Renk HSWL354/2
| fuel_capacity      = 1,300 litres (343 gallons)
| pw_ratio           = 29.2 hp/t (MBT-70) <br /> 29.8 hp/t (KPz-70)
| speed              = {{convert|68.7|km/h|mph|abbr=on}}
| suspension         = Hydropneumatic
| clearance          = 
| vehicle_range      = 644 km (400 miles)
| crew               = 3
}}

The '''MBT-70''' (German: {{lang|de|'''KPz 70'''}} or {{lang|de|'''KpfPz 70'''}}) was an American–[[West German]] cancelled joint project to develop a new [[main battle tank]] during the 1960s.

The MBT-70 was developed by the United States and West Germany in the context of the [[Cold War]], intended to counter the new generation of tanks developed by the [[Soviet Union]] for the [[Warsaw Pact]]. The new tank was to be equipped with a number of advanced features such as newly developed "kneeling" [[hydropneumatic suspension]] and housing the entire crew in the large [[gun turret|turret]], and was armed with a 152mm XM150 gun/launcher, which could use both conventional ammunition and the [[Shillelagh missile|MGM-51 Shillelagh missile]] for long range combat.<ref name="DerSpiegel">{{cite news |url=http://www.spiegel.de/spiegel/print/d-45464941.html |title=Licht vom Mond |access-date=2010-11-08 |work=[[Der Spiegel]] |date=2 November 1969 |language=de |archive-url=https://web.archive.org/web/20121022112816/http://www.spiegel.de/spiegel/print/d-45464941.html |archive-date=2012-10-22 |url-status=live}}</ref>

The program faced significant challenges from the start, including poor communication and coordination between the American and West German teams working on the project. The [[U.S. Army]] and the German [[Bundeswehr]] had different requirements which were not aligned and were not resolved before the project was too far advanced to be changed.

By the late 1960s, the development of the MBT-70 was well over budget, leading West Germany to withdraw from the project in 1969. The United States continued development of the MBT-70 (spun off as the XM803) until 1971 when the program was finally cancelled, with funds and technology from the MBT-70 project redirected to the development of the [[M1 Abrams]]. West Germany independently developed the [[Leopard 2]] as its new main battle tank.

==History==

=== Background ===

The joint German–US main battle tank program was the brainchild of [[US Secretary of Defense]] [[Robert McNamara]]. After serving in the [[United States Army Air Forces|US Army Air Forces]] during World War II, McNamara became a [[Whiz Kids (Ford)|"Whiz Kid"]] at [[Ford Motor Company]], where he later rose to become president. McNamara's interest in German engineering had been shown during his tenure as head of Ford. He had shepherded development of the abortive [[Ford Taunus P4|Ford Cardinal]] – a cancelled project involving the redevelopment for US and other international markets of a compact family car designed by engineers in both the US and Germany. This, it was hoped, would result in a new, competitive product for international markets, with reduced development costs.<ref name="King"/>{{Page range too broad|date=November 2023}}

As Defense Secretary, McNamara began to apply his methods of industrial management to military production. At the time, [[NATO]] member states fielded many different weapons systems and these generally lacked common ammunition, fuel and parts; few weapons were developed jointly, including tanks. While West Germany used American [[M48 Patton]]s, it had historically excelled in engineering armored fighting vehicles and was known to be proceeding with plans to design, develop and build its own tanks. McNamara regarded Germany as an increasingly important member of NATO and believed that joint development would yield superior weapons that could also be used by other NATO members,<ref name="King"/> as well as allies outside NATO.

In 1961, McNamara approached German Minister of Defence [[Franz Josef Strauss]] about beginning a collaborative main battle tank program. Strauss wrote off McNamara's idea and suggested that the U.S. should buy the [[Leopard 1]]. Germany, which was readying production of its indigenous Leopard 1 tank, had little interest in starting another main battle tank project. Strauss did however agree to a common component program. McNamara continued to press for Germany's cooperation in a common tank program, succeeding the next year in brokering a tentative agreement with the Germans.{{sfn|McNaugher|1981|p=4-5}}

The US [[Armor Branch]] had long been pressing the Pentagon to fast-track new main battle tank designs. Consequently, McNamara's seven-year timeline to production was opposed by senior armor officers, who believed an all-new MBT was more urgently needed. Others questioned McNamara's high regard for German engineering, arguing that Germany's collective abilities in tank design and engineering had dwindled and not kept pace with innovations since the end of World War II. Within US armored circles, it was believed that there would be a net [[technology transfer]] towards Germany and there was a common belief that the UK would make a better partner. However, McNamara's choice of Germany was also due to the country's excellent economic position, following its successful post-war rebuilding: the so-called "[[Wirtschaftswunder|economic miracle]]". Hence Germany was better positioned to financially commit to a project of this scale.<ref name="King"/>

In order to develop a tank that would meet the requirements of both armies, in August 1963, Germany and the United States signed a [[memorandum of understanding]] that specified certain desired characteristics and organized a Joint Engineering Agency and a Joint Design Team with equal representation from both countries. Despite these measures, conflicts between the differing engineering practices of each country would plague the MBT-70 project throughout its development.{{sfn|Hunnicutt|1990|p=117}}

=== Development of the MBT-70 ===
In 1963, General [[Welborn G. Dolvin]], a former tank commander, was chosen to lead the US team as project manager. Three contractors—[[Chrysler Defense]], [[General Motors]] and a joint venture of Ford and [[FMC Corporation|FMC]]—entered contention to become the contractor on the American side. Dolvin chose GM, anticipating the company would bring more fresh ideas to the table than longtime incumbent tank producer Chrysler. For the Germans, the German Development Corporation was formed as a joint venture of several German firms.<ref name="King" />

For the first phase of development, GM engineers would work alongside German engineers in [[Augsburg]]. For this part, Americans would manage Germans. For the second phase, the arrangement would be reversed: Germans would take over management at GM's factories in Detroit.<ref name="King" />

There were disputes over almost every part of the design: the gun, the engine, and the use of both [[Metric system|metric]] and [[Society of Automotive Engineers|SAE]] units in the separately manufactured components of the tank. This last dispute was, by far, the most contentious. The disagreement rose to McNamara and German Defense Minister [[Kai-Uwe von Hassel]], who were also unable to settle on a common measurement system. An agreement was made for both sides to use their own preferred measurements on parts they designed. The Americans conceded that metric be used on all fastening points.<ref name="King" /> This was settled by an agreement to use a common metric standard in all interface connections. The resulting complexity contributed to delays in the development schedule, and an inflated project budget.{{sfn|Hunnicutt|1990|p=117}} Another national difference was [[Multiview orthographic projection|different methods of projection]]. In production, confusion over which projection method was being used could result in fabrication errors such as holes placed in the wrong side.<ref name="King" />

The Americans were taken aback by the German's approach to [[intellectual property]]. The German firms jealously guarded their trade secrets from the Americans and pushed aggressively for the use of their products in the final product. This cultural confusion stemmed from differences in the procurement system of both countries. In the US, the Pentagon footed the expenses for most research and development. In return, the government kept complete ownership of the product of the research.<ref name="King"/> German firms conducted research and development under government contracts like in the US,{{sfn|McNaugher|1981|p=13-14}} but retained all the rights to their design. There was thus a great incentive for German firms to solicit orders for their designs.<ref name="King"/>

Dolvin stepped down in October 1966 to assume command of an armored division. The program was considered to be at least moderately successful when Major General Edwin H. Burba took over the project.<ref name="King"/>

Nevertheless, many problems with the tank's political future arose in the US. When a design was finalized in 1965, US program costs were estimated at $138 million. With a production decision looming in 1968, this rose to $303 million. The following year critics came up with a different estimate of more than half a billion by accounting for other additional costs.<ref name="King"/>

Programmatic complexity and growing costs contributed to Germany's disillusionment with the joint project. Germany was concerned about the design differences that were emerging between the two teams. Germany regarded the unconventional American engine as unproven and believed the American gun/launcher as a design that would add costs and complexity to the design while offering only marginal gains in accuracy at ranges beyond 2000 meters (while being worse at ordinary ranges). The use of non-metric fasteners, insisted upon by the Americans, was also believed by Germany to have been an unnecessary compromise.<ref name="500 Germany" /> In 1965, Germany reduced its financial commitment to the program, claiming it was unable to pay for its half of the expenses.{{sfn|McNaugher|1981|p=23-24}} By 1969, Germany had reduced its involvement with the project, which was becoming a political embarrassment within the Bundeswehr. Germany reduced its Detroit office presence to a mere skeleton crew. Germany sought to reduce the size of its KPz-70 purchase, originally 500 tanks, if not cancel it altogether.<ref name="500 Germany" >{{cite book |editor1-last=Pretty |editor1-first=R. T. |editor2-last=Archer |editor2-first=D. H. R. |title=Jane's Weapon Systems 1969–1970 |publisher=B. P. C. Publishing |location=London |year=1969 |isbn=0-354-00516-2 |pages=191–192, 211–212 |edition=1st |chapter=Land Platforms |url=https://archive.org/details/janesweaponsyste0000unse_m9k0}}</ref>

Many Americans both inside and outside the project, including General [[Creighton Abrams]], hoped for an amicable end to German involvement in the program. Burba was succeeded by Brigadier General Bernard R. Luczak in mid-1968. Luczak agreed that the German partnership was not working out. Luczak found support from Deputy Secretary [[David Packard]], who brokered an agreement to end the tank partnership in January 1970.<ref name="King"/>

===Concurrent developments===
By 1965 the German [[Leopard 1]] and the US [[M60 tank|M60]] were the newest main battle tanks in their respective country's service. They were armed with the [[M68 (tank gun)|M68]] 105&nbsp;mm rifled gun (developed from the [[Royal Ordnance L7|British 105mm L7]]) and designed to counter Soviet [[T-54/55]] tanks, which they successfully did, according to Israeli combat experience. But it became very clear that due to the same experience the next generation of [[Soviet Union|Soviet]] tanks would have increased firepower and protection, and both designs would be placed at a disadvantage by the new [[smoothbore]] gun in the [[T-62]]. An upgrade project for the Leopard was planned,<ref name="DerSpiegel" /> but it appeared this model would not be enough of an advance to be worthwhile.

==Design==
[[File:MBT-70 interior arrangement.jpg|thumb|left|upright=1.3|Interior arrangement. Gunner's station in right foreground, commander's station to his rear, driver's rotating capsule partially obscured in left side of turret]]

Many features of the MBT-70 were ahead of their time. The vehicle used an advanced [[hydropneumatic]] [[suspension (vehicle)|suspension]] system that allowed for fast cross-country speeds even though it was to weigh {{convert|45|t|ST}}. The suspension could be raised or lowered on command by the driver, down to put the bottom of the tank just over {{convert|4|in}} from the ground, or up to {{convert|28|in}} for cross-country running.<ref name=mbt70atfprado>{{cite web|url=http://www.fprado.com/armorsite/mbt_70.htm|title=MBT-70 at armorsite|access-date=24 October 2010|archive-url=https://web.archive.org/web/20100926144600/http://www.fprado.com/armorsite/mbt_70.htm|archive-date=26 September 2010|url-status=live|df=dmy-all}}</ref><ref name=MBT-70atglobalsecurity/>

The MBT-70 was designed with a low silhouette, unlike the M60, one of the tallest tanks ever built. The MBT-70 ended up very low, just over {{convert|6|ft}} from the floor to the turret-roof. This left no room in the hull for the driver, who had to be moved into the turret. He was located in a [[cupola]] which was geared to rotate so that he was always looking in the same direction even if the turret turned. He could also spin the cupola around, so the tank could be driven backwards at full speed.<ref name="DerSpiegel" />

The US version was to mount the newly developed Continental AVCR air-cooled V-12 diesel of {{convert|1470|hp}}. German versions originally used a similar [[Daimler-Benz]] model, but later moved to an [[MTU Friedrichshafen|MTU]] design of {{convert|1500|hp}}. The MTU unit could be easily swapped out of the tank, along with the drive train, in 15 minutes. Both versions could reach {{convert|43|mph}} on their engines, compared to {{convert|31.06|mph}} for the T-62.

===Armament===
[[Image:MBT-70 Shillelagh rocket firing.JPG|thumb|right|MBT-70 prototype test firing an MGM-51 missile]]

The MBT-70's main armament was a stabilized '''XM150''' 152&nbsp;mm gun/launcher, a longer-barreled and improved variant of the XM-81 gun/launcher used in the light [[M551 Sheridan]] and the [[M60 Patton#M60A2|M60A2 "Starship"]].<ref name=MBT-70atglobalsecurity>{{cite web|url=http://www.globalsecurity.org/military/systems/ground/mbt-70.htm|title=MBT-70 at globalsecurity.org|access-date=8 November 2010|archive-url=https://web.archive.org/web/20100823045247/http://www.globalsecurity.org/military/systems/ground/mbt-70.htm|archive-date=23 August 2010|url-status=live|df=dmy-all}}</ref> This gun/launcher could fire conventional 152&nbsp;mm rounds like [[Explosive material|High Explosive]], [[anti-personnel]], M409A1 [[High explosive anti-tank warhead|High Explosive Anti-Tank]] (HEAT) and the XM578E1 [[Armor-piercing fin-stabilized discarding sabot]] (APFSDS) rounds, [[Beehive anti-personnel round|Beehive anti-personnel]] rounds, but also the [[Shillelagh missile|MGM-51 Shillelagh missile]], a 152&nbsp;mm guided missile, which had a combat range of some {{convert|3000|m}}.<ref name="DerSpiegel" />{{sfn|Hunnicutt|1990|p=130}}

In the 1960s the effective combat range of the 105&nbsp;mm [[Royal Ordnance L7|L7 tank gun]] was considered to be about {{convert|1800|m}}. The XM578 APFSDS round was made of a newly developed tungsten alloy, which was 97.5 percent tungsten. This new alloy had a density of 18.5 g·cm³, which was a big improvement compared to the older [[tungsten-carbide]] APDS and APFSDS rounds.<ref>{{cite web |url=http://www.globalsecurity.org/military/systems/munitions/m578.htm |title=XM578 152mm, APFSDS |access-date=2010-11-11 |publisher=GlobalSecurity.org |archive-url=https://web.archive.org/web/20100326164634/http://www.globalsecurity.org/military/systems/munitions/m578.htm |archive-date=2010-03-26 |url-status=live}}</ref> Another new feature of the ammunition was that the tank rounds were "caseless"; i.e., they had combustible cases.<ref name="DerSpiegel" />

[[Image:MBT-70 turret.JPG|thumb|Turret weapon layout, autocannon in stowed position, barrel pointing backwards]]
[[Image:MBT-70 secondary cannon 1.JPG|thumb|upright|The 20&nbsp;mm autocannon deployed]]
The MBT-70 was equipped with a [[laser rangefinder]] and a 26-round [[auto-loader]] in the turret bustle.{{sfn|Hunnicutt|1990|p=130}} Although the auto-loader was supposed to be capable of loading both missiles and combustible-case tank rounds,{{sfn|Hunnicutt|1990|p=130}} the German [[Rheinmetall]] autoloader was prone to deforming the ammunition's fragile combustible cases.<ref name="500 Germany" /> The Americans substituted the German autoloader with a General Motors design,{{sfn|Hunnicutt|1990|p=130}} which increased the ammunition capacity to 48 rounds.{{sfn|Hunnicutt|1990|p=299}} Italy had also contributed to the XM-150 as the automatic loading system was built by [[OTO Melara]] (now [[Leonardo S.p.A.|Leonardo]]). This proposed automatic loading system had a vertical rotating magazine equipped with 16 containers, for 5 types of ammunition, which allowed a firing speed of 12 rounds per minute.{{Citation needed|date=November 2023}} 

46 152&nbsp;mm rounds could be carried on the models with Rheinmetall autoloaders. The MBT-70 with the GM autoloader could carry 48 rounds,{{sfn|Hunnicutt|1990|p=299}} and the XM803 could carry 50 rounds.{{sfn|Hunnicutt|1990|p=300}} The MBT-70 with the Rheinmetall loader carried 26 rounds in the autoloader. Twenty more rounds were carried in two compartments including eight rounds stowed on the rear hull bulkhead and twelve behind the driver's capsule.{{sfn|Hunnicutt|1990|p=131}}

The Germans were planning to use the MBT-70 in combination with the ''Keiler'', a tank equipped with a [[Rheinmetall]] 120&nbsp;mm [[smoothbore]] gun.<ref name="DerSpiegel" /> Therefore, a suggestion was made to base a version of the Keiler on the MBT-70 chassis; this version was nicknamed ''Eber'', but only a wooden mock-up was made. According to the German plans, the MBT-70 would destroy enemies at long ranges, while the ''Keiler'' would have an effective combat range of up to {{convert|2000|m}}.<ref name="DerSpiegel" />

The secondary armament of the MBT-70 consisted of a remote-controlled 20&nbsp;mm [[Rheinmetall Mk 20 Rh-202|Rh 202]] [[autocannon]] (with storage for 750 or 660 rounds) for use against aircraft and light armored vehicles.{{sfn|Hunnicutt|1990|p=134, 299}}<ref name="PzMuseumMunster" /> The gun could be retracted into a container behind the driver's rotating cupola for protection as well as to reduce overall height, and was operated remotely by the commander.<ref name="PzMuseumMunster" /> Furthermore, a 7.62&nbsp;mm was mounted co-axially alongside the main gun for close defense. The US prototypes were fitted with the [[M73 machine gun]],{{sfn|Hunnicutt|1990|p=134}} while the German version utilized the [[MG 3 machine gun]].{{cn|date=June 2024}}

The ammunition load of the MBT-70 prototype seen in the [[German Tank Museum|''Deutsches Panzermuseum'']] consists of 42 tank rounds, 6 [[Shillelagh missile]]s, 660 [[20 mm caliber|20×139 mm]] cannon rounds and 2,700 [[7.62×51mm NATO]] machine gun rounds.<ref name="PzMuseumMunster" />

===Protection===
The frontal area of both the hull and turret was protected by [[Spaced armour|spaced armor]] and provision was made for the installation of a [[polyethylene]] radiation shielding to achieve an attenuation ratio of 20:1 against [[neutron radiation]].

The outer layer was made of High Performance Armour developed in the United States and incorporated in the mid-1960s in the design of the MBT-70.<ref>{{Cite book|title=Technology of Tanks (Vols 1-2)|last=Ogorkiewicz|first=Richard M.|publisher=Janes Information Group|year=1991|isbn=978-0710605955|location=London|pages=361}}</ref> The High Performance Armour contained 9% of [[nickel]] and 4% of [[cobalt]] and was produced by [[vacuum arc remelting]]. It was heat treated to 500 BHN, like the other types of high hardness armor, but it was produced from the start in the form of plates 40&nbsp;mm thick.
The frontal arc of the MBT-70 was protected against 105&nbsp;mm [[Armour-piercing fin-stabilized discarding sabot|APDS]] ammunition fired from 800 m distance.<ref>{{Cite book|title=Weapon Systems the Leopard 1 and Leopard 2. Kampfpanzer Leopard and its various models|last=Spielberger|first=Walter J.|publisher=Motorbuch Verlag|year=1995|isbn=978-3613016552}}</ref>
	
Two watertight armored transverse bulkheads separated the crew in the center from the multi-ply rubber fuel tank in the front compartment and the engine compartment in the rear.

To save weight, aluminum was used for the engine compartment floor and for access doors on the engine deck.
The MBT-70 was protected against [[electromagnetic pulse]]s and [[NBC (weapon)|nuclear, biological and chemical weapons]] as well.

[[File:MBT-70 final sketch.JPG|thumb|350px|Sketch showing spaced frontal armor, low profile and seating arrangement of crew]]
The tank's low silhouette, which could be lowered from {{convert|2.59|m}} to only {{convert|1.99|m}}, was also a large advantage. Compared to the M60 tank, the MBT-70 had a lower profile. With the hydropneumatic suspension lowered it was also smaller than the Leopard 1, which gave the MBT-70 a better [[hull down]] position.{{Citation needed|date=February 2013}}

The MBT-70 was equipped with eight XM176 [[smoke grenade|smoke]] [[grenade discharger]]s, each discharger barrel contained two smoke grenades; one [[AN-M8 smoke grenade|AN-M8 HC]] and one [[M34 grenade|M34 WP]].{{sfn|Hunnicutt|1990|p=134}} Actuated from the commander's station, these launchers provided close-in protection and concealment for the vehicle. The KPz-70 was equipped with 16 in four rows of 4.

===Mobility===
;American variant
The American variant was powered by a [[Continental Motors Company|Continental Motors]] AVCR-1100 diesel engine, {{convert|1,475|bhp|abbr=on}}. This was paired to a German [[Renk]] electro-hydraulic [[transmission (mechanical device)|transmission]].<ref name="500 Germany" /> The top speed was {{convert|68|km/h}} and the range was {{convert|645|km}}. The top reverse speed was the same as its top forward speed.<ref name="500 Germany" />

In 1969, the American team decided to eventually replace the diesel engine with an Avco-[[Lycoming Engines|Lycoming]] [[AGT-1500]] [[gas turbine]] engine on the production model.{{sfn|Else|2008|p=67-68}}

;West German variant
The [[Mercedes-Benz Group|Daimler-Benz]]/[[MTU Friedrichshafen|MTU]] MB 873 Ka-500 four-stroke diesel engine on the German variant was heavier and larger than the American [[Continental Motors Company|Continental Motors]] engine. The choice of this engine required some changes to the [[chassis]]. The engine was paired with a [[Renk]] HSWL 354/2 hydraulically operated gearbox with four gears and two reverse. The top speed was {{convert|72|km}} and the range was {{convert|580|km}}.<ref>{{cite book |last1=Spielberger |first1=Walter J. |title=Waffensysteme Leopard 1 und Leopard 2 |date=2003 |publisher=Motorbuch-Verlag |isbn=3-613-01655-9 |pages=370–399}}</ref>

==Testing==
[[File:MBT-70 Aberdeen Speed Test.JPG|thumb|Pilot #2 at Aberdeen Proving Ground undergoing trials]]
A prototype series started in 1965, with two [[mild steel]] hull and six "complete" hulls of both the US and German versions, for a total of 14 hulls. The lower hull and drivetrain were tested in 1966, and full trials began in 1968.

The tank proved to have better mobility than the M60: it was considerably faster, both in all-out speed and, more importantly, with about three times the acceleration. All of this led to a reduction in the time the tank was exposed to fire, in testing it was 1/3 less likely to be seen while maneuvering than the M60, and it could run a {{convert|10|km|mi|abbr=on}} obstacle course in 30% less time.{{citation needed|date=June 2024}}

A year behind schedule, the U.S. and Germany debuted their MBT-70s publicly in October 1967. An American prototype was displayed outside the [[Association of the United States Army]] in Washington.<ref name="American Debut">{{cite news |last1=Beecher |first1=William |title=U.S.-German Tank, Called Deadliest Armored Vehicle, Is on Display Today |url=https://timesmachine.nytimes.com/timesmachine/1967/10/09/82607180.pdf |access-date=8 August 2018 |work=The New York Times |date=9 October 1967}}</ref> The German demonstration in Augsburg ended prematurely: smoke poured out of the tank after the turret's hydraulics malfunctioned. Observers were nonetheless impressed and German officials said the tank was on track to replace all M48 Pattons of the Bundeswehr by 1972.<ref>{{cite news |last1=Philip |first1=Shabecoff |title=Bonn Shows U.S.-German Tank; Turret Malfunction Mars Test |url=https://timesmachine.nytimes.com/timesmachine/1967/10/10/83635285.pdf |access-date=8 August 2018 |work=The New York Times |date=9 October 1967}}</ref>

===Problems===
An unanticipated problem was that the drivers complained of disorientation when the turret was rotated, contrary to the predictions of the designers who felt the location of the cupola near the center of rotation would eliminate this effect. The XM150 gun/launcher had serious problems. The similar but smaller XM81 gun/launcher mounted on the [[M551 Sheridan]] proved to be just as troublesome. There were also several problems with the ammunition. The caseless design made conventional tank rounds too vulnerable to water. Wet rounds expanded so they would not fit into the barrel anymore or left hard residues after being fired.<ref name="DerSpiegel" />

The auto-loader was capable of handling the Shillelagh missile without problems, but the combustible cases of the tank rounds could be deformed by it.<ref name="DerSpiegel" /> As is often a problem with caseless ammunition, the ammunition also had a tendency to "cook-off", or fire prematurely, due to heat build-up in the barrel from previously fired rounds. The attempted solution, to only carry a single round with the balance in missiles, also proved unacceptable. Deployment of the 20mm anti-aircraft cannon also proved difficult and the weapon itself was overcomplicated and nearly impossible to use effectively.{{citation needed|date=November 2010}}

Another problem of the MBT-70 was the increasing weight. While at the beginning of the project, a weight of some {{convert|46.3|t}} was projected, it increased to {{convert|54|t}} during development, which forced the designers to redesign some elements, so that finally a weight of {{convert|50.3|t}} was reached, still higher than required.<ref name="DerSpiegel" /> This meant that the MBT-70 would require its own armored recovery vehicles and bridge-launching systems.{{cn|date=June 2024}} Germany became concerned with the excessive weight of the tank. One solution proposed removing radiation hardening from the turret, but this called into question the wisdom of the driver-in-turret configuration, which was intended to protect the crew in the event of a [[Nuclear explosion|nuclear blast]].{{sfn|Hunnicutt|2015|p=142}} 

Commentators on the MBT-70 typically assert that though it was innovative in many respects, the project was ruined by the use of too many untried and unproven technologies. Senator [[J. William Fulbright|James W. Fulbright]] quipped that to drive an MBT-70, a [[master's degree]] from a technical institute would be required.<ref name="DerSpiegel" />

==Cancellation==
By 1969 the MBT-70 cost five times what was projected,<ref name="DerSpiegel"/><ref name=mbt70atfprado/><ref name=MBT-70atglobalsecurity/> at $1 million a unit. Originally the planned costs of the MBT-70 project were as low as $80 million (or 292.8 million [[Deutsche Mark|DM]]), but in 1969 the project had already cost $303 million (nearly 1.1 billion DM).<ref name="DerSpiegel"/> West Germany's part alone of this was about $130 million (475.8 million DM), which in itself was more than the original planned total costs of the project.<ref name="DerSpiegel"/>

Frustrated with the lack of resolution to the tank's technical problems and excessive weight, Germany announced in April 1969 that it would cut back on its purchase of the MBT-70 and begin development of a new tank.{{sfn|McNaugher|1981|p=25}}

A July 1969 House Armed Services subcommittee report on the troubled M551 Sheridan asked that funding for the MBT-70 be withheld pending a comprehensive review of the program.<ref name="sheridan problems">{{cite news |title=Sheridan Tank under Fire in Subcommittee |url=https://www.newspapers.com/image/198271440/?terms=%22mbt-70%22%20sheridan&match=1 |access-date=13 November 2021 |work=Statesman Journal |agency=AP |date=10 July 1969}}</ref> In August 1969, Senator [[Thomas Eagleton]] was granted a request that the [[Government Accounting Office]] undertake an audit of the program.<ref name="GAO Audit">{{cite news |last1=Weaver Jr. |first1=Warren |title=Tank Fund Halted for a Cost Study |url=https://www.nytimes.com/1969/08/09/archives/tank-fund-halted-for-a-cost-study-senate-balks-the-pentagon-pending.html |access-date=26 August 2018 |work=The New York Times |date=9 August 1969 |archive-url=https://web.archive.org/web/20180826113509/https://www.nytimes.com/1969/08/09/archives/tank-fund-halted-for-a-cost-study-senate-balks-the-pentagon-pending.html |archive-date=26 August 2018 |url-status=live |df=dmy-all }}</ref>

The GAO recommended the tank development program proceed on an austere basis. Acting on this recommendation, Deputy Secretary of Defense [[David Packard]] agreed to withhold $25 million earmarked for the production of six prototypes while the DoD completed a review of the project.<ref>{{cite news |title=Controversial Tank Project suspended by Defense Department |url=https://www.newspapers.com/image/25727596/?terms=gao%20%22battle%20tank%22&match=1 |access-date=13 November 2021 |work=Tucson Daily Citizen |agency=UPI |date=9 September 1969}}</ref> Packard was ultimately persuaded by Army leaders that the American MBT-70 project was technically sound. The Army agreed that development would be better off without German cooperation.<ref name="packard convinced">{{cite news |last1=Hoffman |first1=Fred S. |title=Pentagon Plans Cheaper Tank |url=https://www.newspapers.com/image/60603749/?terms=%22new%20main%20battle%20tank%22&match=1 |access-date=13 November 2021 |work=The Bridgeport Post |date=19 January 1970}}</ref> In January 1970, the Department of Defense ended its tank partnership with Germany and committed to forging ahead with its own design.<ref name="Bonn and Washington split">{{cite news |last1=Beecher |first1=William |title=U.S. and Bonn End 7-Year Joint Effort to Build a Tank |url=https://www.nytimes.com/1970/01/21/archives/us-and-bonn-end-7year-joint-effort-to-build-a-tank.html |access-date=26 August 2018 |work=The New York Times |date=21 January 1970 |archive-url=https://web.archive.org/web/20180826113505/https://www.nytimes.com/1970/01/21/archives/us-and-bonn-end-7year-joint-effort-to-build-a-tank.html |archive-date=26 August 2018 |url-status=live |df=dmy-all }}</ref>

The U.S. spent $305.4 million on the MBT-70 and XM803 programs, while Germany spent $100 million.{{sfn|McNaugher|1981|p=20}}

Germany subsequently started the development of the "Keiler" tank on its own. Later this program would lead to the [[Leopard 2]].<ref>{{cite web|url=http://www.historyofwar.org/articles/weapons_leopard2.html|title=Leopard II at history of war|access-date=24 October 2010|archive-url=https://web.archive.org/web/20101009215500/http://www.historyofwar.org/articles/weapons_leopard2.html|archive-date=9 October 2010|url-status=live|df=dmy-all}}</ref>

==XM803==
[[File:XM803 U.S. Army Armor & Cavalry Collection.jpg|thumb|XM803 at the [[U.S. Army Armor & Cavalry Collection]]. Note the two return rollers, versus three on the MBT-70.]]
Work began on converting the existing MBT-70 design into a low-cost "austere" alternative that would use only American-made components, resulting in the visually similar XM803 prototype. Congress hoped to drive down the per-unit cost to $500,000–$600,000, saving $200,000 per tank versus the MBT-70.<ref name="Bonn and Washington split"/>

The largest cost savings came from a switch to a less expensive steel armor plating. An American-made engine also reduced costs. The design was slightly heavier and slower.<ref name="slower, heavier">{{cite news |last1=Prina |first1=L. Edgar |title=New 'Austere' Army Tank Nearly Ready |url=https://www.newspapers.com/image/735262527/?terms=xm803&match=1 |access-date=12 November 2021 |work=The News Tribune |date=4 August 1970}}</ref> General Motors received a $16.5 million contract to develop the tank in July 1971.<ref>{{cite news |title=Michigan Business in Brief |url=https://www.newspapers.com/image/99029191/?terms=xm803&match=1 |access-date=12 November 2021 |work=The Detroit Free Press |date=30 July 1971}}</ref> Systems were simplified or eliminated altogether to save costs.{{sfn|Kelly|1989|pp=40}} The XM150E5 gun-launcher was replaced with an XM150E6, which included a closed breech scavenging system.{{sfn|Hunnicutt|2015|p=151}} A 24-round General Motors autoloader was installed. Ammunition capacity was increased to 50 rounds.{{sfn|Hunnicutt|2015|p=152}} The commander's 20&nbsp;mm cannon was replaced by a [[.50 caliber]] [[M85 machine gun]].{{sfn|Hunnicutt|2015|p=183}} The driver's escape hatch was deleted and his television, as well as those of all the other crew, were eliminated.{{sfn|Hunnicutt|2015|p=147}} The Continental AVCR-1100-3B engine was derated to {{convert|1250|hp}} at 2600 rpm and paired to a General
Motors XHM-1500-2B transmission.{{sfn|Hunnicutt|2015|p=154-155}} A simplified National Water Lift hydropneumatic suspension was installed. Side skirts were installed, which allowed some armor to be removed from the hull.{{sfn|Hunnicutt|2015|p=156}} Meanwhile, the U.S. Army studied installing a [[gas-turbine]] [[Avco-Lycoming AGT1500|AGT-1500]] generating {{convert|1500|hp}} (this was the engine that would come to power the [[M1 Abrams]]).{{sfn|Hunnicutt|2015|p=154}}

Only one of the two pilot vehicles authorized for construction was completed.{{sfn|Hunnicutt|2015|p=158}} In addition, a surrogate vehicle based on the components of MBT-70 {{failed verification span|text= pilot #4,|date=June 2024}} the M60 and the [[M88 armored recovery vehicle]], was constructed.<ref>{{cite AV media | people = Sofilein | date = 5 January 2020 | title = Meet the 'Pigg'! MBT70/XM803 Hybrid tank at NACM Ft Benning | type =video | url =https://www.youtube.com/watch?v=DElj7GfwtlI | access-date =27 June 2024}}
</ref>

These changes were ultimately insufficient to allay concerns about the tank's cost.{{sfn|Hunnicutt|2015|p=158}} In September 1971, an amendment by Senator [[Thomas Eagleton]] was defeated that would cut $35.3 million in funding for XM803 prototype production.<ref>{{cite news |title=Pullout Deadline Voted by Senate |url=https://www.nytimes.com/1971/10/01/archives/pullout-deadline-voted-by-senate-2d-such-plan-by-mansfield-is.html |access-date=12 November 2021 |work=The New York Times |date=1 October 1971}}</ref><ref>{{cite news |title=U.S. Withdrawal Deadline Again Approved by Senate |url=https://www.newspapers.com/image/68803844/?terms=%22xm803%22&match=1 |access-date=12 November 2021 |work=Kingsport News |agency=UPI |date=1 October 1971}}</ref> but in December 1971, Congress canceled the tank in the defense appropriation bill.<ref name="xm803 terminated">{{cite news |title=U.S. Germany Abandon 'Dream Tank' |url=https://www.newspapers.com/image/7447436/?terms=xm803&match=1 |access-date=12 November 2021 |work=Lubbock Avalanche-Journal |agency=UPI |date=16 December 1971}}</ref> The bill appropriated $20 million for cancelation costs and $20 million for the development of a new tank program.<ref>{{cite news |last1=Turner |first1=Bob |title=Congress Kills Tank Program |url=https://www.newspapers.com/image/332215721/?terms=xm803&match=1 |access-date=12 November 2021 |work=The Tampa Tribune |date=20 December 1971}}</ref> This became the XM1 design project, which led to the production-model [[M1 Abrams]] tank.

== Comparative table ==
{| class="wikitable" style="text-align:center;"
|-
!
! style="width:18em;" | MBT-70 {{sfn|Hunnicutt|1990|p=299}}
! style="width:18em;" | Kpz-70 
! style="width:18em;" | XM803{{sfn|Hunnicutt|1990|p=300}}
|-
! Country
| United States
| West Germany
| United States
|-
! Number of prototypes
| 7
| 7
| 1
|-
! Weight, combat loaded
|{{convert|51700|kg|lb|abbr=on|disp=br()}}
|{{convert|50400|kg|lb|abbr=on|disp=br()}}
|{{convert|51700|kg|lb|abbr=on|disp=br()}}
|-
! Engine
| Continental AVCR-1100-3A
| Daimler-Benz/MTU MB-873 Ka-500 
| Continental AVCR-1100-3B
|-
! Displacement
| 22.2 L 
| 39.8 L 
| 22.2 L 
|-
! Net horsepower
| {{convert|1475|hp|abbr=on}} at 2800 rpm
| {{convert|1500|hp|abbr=on}} at 2600 rpm
| {{convert|1250|hp|abbr=on}} at 2600 rpm
|-
! Net torque
| {{convert|3728|N.m|lbft|-1|abbr=on}} at  2200 rpm
| {{convert|4300|N.m|lbft|-1|abbr=on}} at  1950 rpm
| unknown
|-
! Transmission
| colspan="2"| Renk HSWL 354/2
| General Motors XHM-1500-2B
|-
! Top speed
| {{convert|64.37|kph|mph|abbr=on}}
| {{convert|68|kph|mph|abbr=on}}<ref>{{cite book |last1=Spielberger |first1=Walter J. |title=Waffensysteme Leopard 1 und Leopard 2 |date=2003 |publisher=Motorbuch-Verlag |isbn=3-613-01655-9 |page=375|language=de}}</ref>
| {{convert|64.37|kph|mph|abbr=on}}
|-
! Range
| {{convert|643.7|km|mi|abbr=on|disp=br()}}
| {{convert|580|km|mi|abbr=on|disp=br()}}
| {{convert|643.7|km|mi|abbr=on|disp=br()}}
|-
! Suspension
| National Water Lift Model 812 
(twin cylinder)
| Frieseke & Höpfner Hydrop-Feder
| National Water Lift 
(single cylinder)
|-
! Tracks
|colspan="2"|Diehl 170 double pin tracks
| unknown
|-
! Tracks width 
|colspan="2"|{{convert|635|mm|in|1|abbr=on}}
| {{convert|622|mm|in|1|abbr=on}}
|-
! Main armament
|colspan="2"|XM150E5 152&nbsp;mm gun/launcher
| XM150E6 152&nbsp;mm gun/launcher
|-
! Autoloader
| Rh or GM 
| Rheinmetall<br>(24 rounds)
| General Motors <br>(26 rounds)
|-
! Rate of fire
| 6 rounds/min<br> (on the move, shells and missiles) 
| 10 rounds/min<br> (stopped, shells only)
| 8  rounds/min,<br> (shells only)<ref>{{cite book |title=Operator's instruction manual for Tank, Combat, Full-Tracked, 152 mm Gun/Launcher XM-803 (Pilot Vehicle No. 7) |date=June 1972 |publisher=Detroit Diesel Allison |page=552}}</ref>
|-
! 152&nbsp;mm ammunition carried
| 48
| 46
| 50
|-
! Secondary weapon
|colspan="2"|Rh-202 autocannon retractable into a capsule
| M85 heavy machine gun mounted on top of the commander's stabilized day/night
|-
! Coaxial machine gun
| General Electric M73 
| Rheinmetall MG3A1 
| General Electric M73 
|-
|}

==Legacy==
[[File:MBT-70_U.S._Army_Armor_&_Cavalry_Collection.jpg|thumb|right|MBT-70 with suspension lowered at the [[U.S. Army Armor & Cavalry Collection]]]]
In a post-mortem report of his four years on the project, American program manager Brig. Gen. Bernard Luczak attributed the high cost of the tank to the difficulties of managing a joint program. Luczak claimed [[General Motors]] charged a premium for its defense contract work, which it considered insignificant compared to its burgeoning automotive business.<ref name="King">{{cite book |last1=Kelly |first1=Orr |title=King of the Killing Zone |url=https://archive.org/details/kingofkillingzon00kell |date=1989 |publisher=W. W. Norton & Company, Inc |isbn=0-425-12304-9 |location=New York, New York |pages=13–43 |language=English |chapter=In the Footsteps of the Dinosaur}}</ref>

In the 1989 book ''King of the Killing Zone'' author Orr Kelly called the end of the MBT-70 program, "one of the most fortunate occurrences to befall the U.S. Army."<ref name="King"/>

== Variants ==
[[File:VT 1-1 b.jpg|thumb|right|[[VT tank|VT 1-1]] at the Bundeswehr Technical Center for Weapons and Ammunition]]
*'''XM742 Recovery Vehicle''' – A proposed [[armored recovery vehicle]].{{sfn|Hunnicutt|1990|p=268}}
*'''XM743''' – A proposed [[armored vehicle-launched bridge]] layer carrying the 60-ton capacity XM744 double-folding bridge.{{sfn|Hunnicutt|1990|p=264}}
*'''XM745 Combat Engineer Vehicle''' – A proposed [[military engineering vehicle]] with four-man crew, 165&nbsp;mm (alternatively 152&nbsp;mm) demolition gun and a 25&nbsp;mm autocannon.{{sfn|Hunnicutt|1990|p=257}}
*[[VT tank|VT 1-1]], a tank based on a shortened ''KPz'' 70 chassis.<ref name="MBT-70">{{cite book |editor1-last=Foss |editor1-first=Christopher F. |editor1-link=Christopher F. Foss |title=Jane's Armour and Artillery 1982–83 |publisher=Jane's Publishing Company |location=London |year=1982 |isbn=0-7106-0747-4 |page=14 |edition=3rd |chapter= |url=https://archive.org/details/janesarmourartil0000unse_p4o1}}</ref>

==Surviving vehicles==

Altogether 14 prototypes and test beds were built, two made of mild steel. Some of them have survived in museums and can still be visited today.

===American prototypes===
* One prototype is located in the [[Anniston Army Depot]] in [[Anniston, Alabama]].
* Another prototype, as well as a prototype of the XM803, is located in the Armor Museum Restoration Yard at [[Fort Benning]], Georgia.
* A mild steel prototype in bad condition could be seen in the Military Museum of Southern New England in [[Danbury, Connecticut]] until October 2019. Following the closure of the museum, it was sold for scrap metal. Only the turret remains.

===German prototypes===
* One prototype is located in the [[German Tank Museum|Deutsches Panzermuseum Munster]]
* Another is located in the [[wmde:Wehrtechnische Studiensammlung Koblenz|Wehrtechnische Studiensammlung Koblenz]]

<gallery mode=packed>
File:Aberdeen proving grounds 037.JPG|MBT-70 at Aberdeen Proving Ground
File:MBT70Koblenz.JPG|Kampfpanzer 70 at Koblenz
File:MBT-70 Danbury, CT.jpg|MBT-70 pilot #2 at Danbury, Connecticut
File:XM803 surrogate at the Armor and Cavalry Collection.jpg|XM803 surrogate at the [[Armor and Cavalry Collection]], Fort Benning, Georgia, made from the MBT-70 and M60 parts.
</gallery>

==See also==

* {{lwc|VT tank}}
* {{lwc|MBT-80}}
* {{lwc|Leopard 2}}
* {{lwc|M1 Abrams}}
* {{lwc|Main Ground Combat System}} to be produced in 2035.

{{clear}}

==References==
;Notes
{{Reflist}}

;Bibliography
* {{cite thesis |last1=Else |first1=Daniel H., III. |title=Bias in Weapon Development |type=Dissertation |date=31 January 2008 |pages=67–68 |url=https://www.proquest.com/docview/304642379 |access-date=24 June 2024|id={{ProQuest|304642379}} }}
* {{cite book |last1=Hunnicutt |first1=Richard Pearce |title=Abrams - A History of the American Main Battle Tank|date=1990|publisher=Presidio Press|isbn=0-89141-388-X }}
* {{cite book |last1=Hunnicutt |first1=Richard Pearce |title=Patton: A History of the American Main Battle Tank |date=2015 |orig-date=1984 |publisher=Echo Point Books & Media |isbn=978-1626548794}}
* {{cite report |last1=McNaugher |first1=Thomas L. |title=Collaborative Development of Main Battle Tanks: Lessons from the U.S.–German Experience|date= August 1981|work=The Rand Corporation |url=https://apps.dtic.mil/sti/tr/pdf/ADA105123.pdf}}

==External links==
{{Commons category|MBT-70 tanks}}
* {{citation|url=https://books.google.com/books?id=Bff57um2QCIC&pg=PA74|title=The Evolving Battle Tank|journal=New Scientist|first=R.M. |last=Ogorkiewicz|pages=74–75|date=8 Jul 1965|volume=27|number=451}}
* [https://books.google.com/books?id=iA3zHyjh-wcC&dq=xm+803&pg=PA232 Department of Defense Appropriations for 1972: Hearings Before the Subcommittee]

{{US tanks |style=wide}}
{{Cold War tanks}}
{{ModernGermanAFVsNav}}

{{DEFAULTSORT:Mbt-70}}
[[Category:Projects established in 1963]]
[[Category:1963 establishments in the United States]]
[[Category:Main battle tanks of the United States]]
[[Category:Main battle tanks of the Cold War]]
[[Category:Abandoned military projects of the United States]]
[[Category:Abandoned military projects of Germany]]
[[Category:Trial and research tanks of Germany]]
[[Category:Trial and research tanks of the United States]]
[[Category:Main battle tanks of Germany]]
[[Category:Cold War tanks of Germany]]
[[Category:Cold War tanks of the United States]]
[[Category:History of the tank]]
[[Category:Germany–United States military relations]]
[[Category:United States–West Germany relations]]