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The M1 Abrams (/ˈeɪbrəmz/)[9] is a third-generation American main battle tank designed by Chrysler Defense (now General Dynamics Land Systems) and named for General Creighton Abrams. Conceived for modern armored ground warfare, it is one of the heaviest tanks in service at nearly 73.6 short tons (66.8 metric tons). It introduced several modern technologies to the United States armored forces, including a multifuel turbine engine, sophisticated Chobham composite armor, a computer fire control system, separate ammunition storage in a blowout compartment, and NBC protection for crew safety. Initial models of the M1 were armed with a 105 mm M68 gun, while later variants feature a license-produced Rheinmetall 120 mm L/44 designated M256.
The M1 Abrams was developed from the failed joint American-West German MBT-70 project that intended to replace the dated M60 tank. There are three main operational Abrams versions: the M1, M1A1, and M1A2, with each new iteration seeing improvements in armament, protection, and electronics.[10]
The Abrams was to be replaced in U.S. Army service by the XM1202 Mounted Combat System, but following the project's cancellation, the Army opted to continue maintaining and operating the M1 series for the foreseeable future by upgrading optics, armor, and firepower.
The M1 Abrams entered service in 1980 and serves as the main battle tank of the United States Army, and formerly of the U.S. Marine Corps (USMC) until the decommissioning of all USMC tank battalions in 2021. The export modification is used by the armed forces of Egypt, Kuwait, Saudi Arabia, Australia, Poland and Iraq. The Abrams was first used in combat by the U.S. in the Gulf War. It was later deployed by the U.S. in the War in Afghanistan and the Iraq War, as well as by Iraq in the war against the Islamic State, Saudi Arabia in the Yemeni Civil War, and Ukraine during the Russian invasion of Ukraine.
History[edit]Main article: History of the M1 AbramsPrevious developments[edit]Main article: MBT-70
In 1963, the U.S. Army and the West German Bundeswehr began collaborating on a main battle tank (MBT) design that both nations would use, improving interoperability between the two NATO partners.[11][12][13] The MBT-70, or Kampfpanzer 70 as it was known in Germany,[14] incorporated many new unconventional technologies across the board. Conventional tanks of the time had a crew of four, with the driver located in the hull. In the MBT-70, the loader crewmember would be replaced by a mechanical autoloader and the driver would be located inside the NBC-protected turret with the other two crewmembers.[15][16] Like the M60A2 MBT and M551 Sheridan light tank then under development, the MBT-70 was armed with a 152 mm gun-launcher that, in addition to firing conventional ammunition, would also fire the Shillelagh missile.[17][12][18] A hydropneumatic suspension provided improved cross-country ride quality and also allowed the entire tank to be raised or lowered by the driver.[19]
The United States team was led by General Motors while the German team consisted of a consortium of firms.[20] The collaboration between the two teams was rocky from the start, with many cultural differences and disagreements about the design hampering progress.[12] Germany favored a tank optimized for the terrain of central Europe while the U.S. attached importance to operating anywhere in the world.[21] The Germans had reservations about the Shillelagh missile and developed a 120 mm high-velocity gun as an alternative.[18][11] Perhaps the most contentious disagreement, never fully resolved, concerned the measurement system to be used in drafting.[22] Germany became concerned with the excessive weight of the tank.[23] In light of growing costs, delays and overall uncertainty as to the soundness of the tank design,[24] the United States and Germany ended their MBT-70 partnership in 1970.[25] The U.S. Army began work on an austere version of the MBT-70, named XM803. Systems were simplified or eliminated altogether and the unreliable autoloader was improved.[26] These changes were ultimately insufficient to allay concerns about the tank's cost.[15] Congress canceled the XM803 in December 1971 but permitted the Army to reallocate remaining funds to develop a new main battle tank.[27]
Starting over[edit]
The Army began the XM815 project in January 1972. The Main Battle Tank Task Force (MBTTF) was established under Major General William Desobry. The task force prepared design studies with the technical support of Tank-automotive and Armaments Command (TACOM).[28] TACOM began examining specific goals. To this end, a new design basis emerged in February 1973. It had to defeat any hit from a Soviet gun within 800 m (2,600 ft) and 30 degrees to either side. The tank would be armed with the 105 mm M68 gun, a licensed version of the Royal Ordnance L7, and a 20 mm version of the M242 Bushmaster.[29] The Army later deleted the latter from the design, seeing it as superfluous.[30]
In spring 1972, Desobry was briefed by the British on their own newly developed "Burlington" armor from the British Army's labs. The armor performed exceptionally against shaped charges such as HEAT rounds. In September, Desobry convinced the Army to incorporate the new armor. To take full advantage of Burlington, also known as Chobham, the new tank would have to have armor around two feet thick (for comparison, the armor on the M60 is around four inches thick). General Creighton Abrams set the weight of the new tank at 53 tonnes (52 long tons; 58 short tons). The original goal of keeping weight under 45 tonnes (44 long tons; 50 short tons) was abandoned.[31]
At the time, the Pentagon's procurement system was beset with problems being caused by the desire to have the best possible design. This often resulted in programs being canceled due to cost overruns, leaving the forces with outdated systems, as was the case with the MBT-70. There was a strong movement within the Army to get a new design within budget to prevent the MBT-70 experience from repeating itself. For the new design, the Army set the design-to-unit cost at no more than $507,790 (equivalent to $3,817,000 in 2024).[32]
The Pentagon's approach to control of research and development was modified with the XM1. Previous acquisition strategy called for a significant amount of the design work to be done by the government. Under the new framework, contractors would competitively bid their own designs rather than compete solely for the right to manufacture the end product.[33]
In January 1973, the U.S. Army issued the XM1 (as the XM815 had been renamed in November 1972) request for proposals.[34] In May 1973, Chrysler Defense and General Motors submitted proposals. Both were armed with the 105 mm M68 gun, the licensed L7, and the 20 mm Bushmaster. Chrysler chose a 1,500 hp Lycoming AGT1500 gas turbine engine. GM's model was powered by a 1,500 hp diesel engine similar to that used on the American MBT-70 and XM803.[35]
Prototypes[edit]Chrysler XM1 prototypeGeneral Motors XM1 prototype
Prototypes were delivered in 1976 by Chrysler and GM armed with the M68E1 105 mm gun. They entered head-to-head testing at Aberdeen Proving Ground.[36][36] The testing showed that the GM design was generally superior to Chrysler's, offering better armor protection, and better fire control and turret stabilization systems.[32]
During testing, the power packs of both designs proved to have issues. The Chrysler gas turbine engine had extensive heat recovery systems in an attempt to improve its fuel efficiency to something similar to a traditional internal combustion engine. This goal was not achieved: the engine consumed much more fuel than expected, burning 890 liters per 100 kilometers (3.8 U.S. gal/mi). The GM design used a new variable-compression diesel design.[32]
By spring 1976, the decision to choose the GM design was largely complete. In addition to offering better overall performance, there were concerns about Chrysler's engine both from a reliability and fuel consumption standpoint. The GM program was also slightly cheaper overall at $208 million compared to $221 million for Chrysler. In July 1976, the Army prepared to inform Congress of the decision to move ahead with the GM design. All that was required was the final sign-off by the U.S Secretary of Defense, Donald Rumsfeld.[32]
Back to the drawing board[edit]Finalized M1 scale model
On 20 July 1976, United States Secretary of the Army Martin Hoffmann and a group of generals visited Deputy Defense Secretary Bill Clements and Director of Defense Research and Engineering Malcolm Currie on their decision. They were surprised when Clements and Currie criticized their decision and demanded that the new tank have a turbine. Defense Secretary Rumsfeld heard arguments from both parties in the afternoon. The Army team spent the night writing briefs and presented them to Rumsfeld the next morning, who then announced a four-month delay.[32]
Within days, GM was asked to present a new design with a turbine engine. According to Assistant Secretary for Research and Development Ed Miller, "It became increasingly clear that the only solution which would be acceptable to Clements and Currie was the turbine... It was a political decision that was reached, and for all intents and purposes that decision gave the award to Chrysler since they were the only contractor with a gas turbine."[32]
In the meantime, in September 1976 three West German Leopard 2AV prototypes were belatedly sent to Aberdeen for comparison testing.[37] Germany had signed a somewhat vague memorandum of understanding in 1974 committing both parties toward commonality in tank parts. Germany had assumed that its tank would be evaluated against the GM and Chrysler's prototypes and that the best tank would be chosen for production. This misunderstanding arose from the fact that in public statements both countries had overrepresented the MOU as an agreement that Germany and the U.S. would select a common MBT. In reality, the U.S. Army was unwilling to choose a foreign tank unless it was obviously superior in design and cost.[38] In any case, in evaluations the Leopard 2AV was found to meet U.S. requirements but was thought to cost more.[36] The U.S. Army announced in January 1977 that Germany had withdrawn the tank from consideration.[39]
Chrysler is chosen[edit]
Having narrowly averted losing the contract, Chrysler set about improving the design. Expensive components were replaced with less expensive ones. Chrysler's team also negotiated lower costs from their subcontractors. The price of the redesigned tank's turret especially was decreased, but other improvements came from unexpected places, such as a $600 hydraulic oil reservoir replaced with a $25 one.[40] Chrysler also submitted a version with a Teledyne AVCR-1360 diesel engine.[41] Chrysler's new bid came to $196 million, down from $221 million in the original proposal.[40]
An XM1 pilot during trials in 1979
GM's proposal replaced the diesel engine with an AGT1500 turbine and integrated a turret capable of mounting either the 105 mm or 120 mm gun.[41] Cost growth pushed the tank bid to $232 million from $208 million.[40]
Although the GM team had successfully integrated the turbine, Baer was more impressed by the cost savings introduced by the Chrysler team's redesign.[40] On 12 November 1976, the Defense Department awarded the $4.9 billion development contract to Chrysler.[42]
The turbine engine and cost do not appear to be the only reason for the selection of Chrysler. Chrysler was the only company that appeared to be seriously interested in tank development; the M60 had been lucrative for the company. In contrast, GM made only about 1% of its income from military sales, compared to 5% for Chrysler, and only submitted their bid after a "special plea" from the Pentagon.[32]
Eleven XM1 preproduction models were manufactured between February and July 1978 at Detroit Arsenal Tank Plant.[43] Quality problems with the engine quickly became apparent in testing. The first preproduction units that arrived at Aberdeen Proving Ground in March 1978 had serious problems. The tank accumulated mud and dirt under the hull which led to thrown tracks. Chrysler installed a scraper to prevent the build-up of dirt. This did not solve the issue entirely. It was determined months later that a gauge used to tension tracks was miscalibrated. This caused the tracks to be fitted too loosely.[44] Another problem was the ingestion of debris by the engine. The problem was determined to be caused by poorly fitting air filters.[44] At Fort Bliss, several tanks experienced transmission issues. It was determined that the tankers at Fort Bliss had discovered that they could throw the vehicle directly from acceleration into reverse, a tactically advantageous maneuver called the "bow tie". Chrysler resolved this by installing a device that prevented this.[44] The problems found during testing were easily surmounted. Critics of the M1 program emerged in the early 1980s, particularly the newly formed Project on Military Procurement (PMP) (later renamed the Project on Government Oversight). PMP took issue with the tank's vulnerability, high price, reliance on flammable hydraulics, and high fuel consumption.[45] American tank historian Steven J. Zaloga characterized American press criticism of the M1 during this time as "ill-founded". Zaloga wrote the issues uncovered by the tank trials were "not particularly serious".[46] PMP's criticism failed to generate any serious opposition to the program, which maintained strong support from Congress and the Pentagon.[47] Responding to some of the alleged issues with the tank in King of the Killing Zone (1989), journalist Orr Kelly wrote that "The truth is close to the opposite." Kelly said the program "ranks as one of the Army's best managed", producing a tank in "a remarkably short time" while avoiding "gold-plating" and utilizing effective competition.[48]
Production starts[edit]Early production vehicle in 1983
Low rate initial production (LRIP) of the vehicle was approved in May 1979.[29] In February 1982, General Dynamics Land Systems Division (GDLS) purchased Chrysler Defense, after Chrysler built over 1,000 M1s.[49]
A total of 3,273 M1 Abrams tanks were produced during 1979–1985 and first entered U.S. Army service in 1980. Production at the government-owned, GDLS-operated Lima Army Tank Plant in Lima, Ohio, was joined by vehicles built at the Detroit Arsenal Tank Plant (DATP) in Warren, Michigan from 1982 to 1991 (DATP also produced the 11 preproduction models in 1978.[43]).[50][51] The U.S. Army Laboratory Command (LABCOM), under the supervision of the United States Army Research Laboratory (ARL), was also heavily involved with designing the tank with M1A1 armor resistant shells, M829A2 armor-penetrating rounds, and improved weapon range.[52]
The M1 was armed with the license-built M68A1 version of the 105 mm Royal Ordnance L7 gun. The tank featured the first-of-its-kind Chobham armor. The M1 Abrams was the first to use this advanced armor. It consisted of an arrangement of metal and ceramic plates.[53] An improved model called the IPM1 was produced briefly in 1984 and contained upgrades to armor and other small improvements.
120 mm gun M1A1[edit]M1 Abrams tanks being refurbished at the Anniston Army Depot in 1989
A number of considerations had led the service and its contractors to favor the Army's standard M68 105 mm gun over Germany's 120 mm Rheinmetall Rh-120 smoothbore gun for the XM1. To begin with, the 105 mm gun was "the smallest, lightest, and least costly gun adequate for the job."[54] Indeed, new kinetic energy ammunition for the weapon then under development by the Army promised to extend the gun's usefulness well into the future. And because the Army's other tanks, the M60 and the upgraded M48, as well as the tanks of virtually every other NATO nation, used the 105 mm gun, mounting that gun on the XM1 promised to increase standardization within the alliance. Moreover, the continuing development of the new ammunition for the XM1 automatically upgraded every other gun in NATO. For all of these reasons, the XM1's development proceeded "on the assumption that the 105 mm gun would probably be the eventual main armament."[54][55] The tripartite British—American—German gun trials of 1975 produced a general agreement in the U.S. Defense Department that at some future point, a 120 mm gun of some design would be added to the XM1. Apparently anticipating this, Chrysler and GM had both made changes to their tanks during development to make them compatible with a variety of main guns.[56] In January 1978, the Secretary of the Army announced that the Rheinmetall 120 mm gun would be mounted on future production versions of the XM1. This d
The M1 Abrams (/ˈeɪbrəmz/)[9] is a third-generation American main battle tank designed by Chrysler Defense (now General Dynamics Land Systems) and named for General Creighton Abrams. Conceived for modern armored ground warfare, it is one of the heaviest tanks in service at nearly 73.6 short tons (66.8 metric tons). It introduced several modern technologies to the United States armored forces, including a multifuel turbine engine, sophisticated Chobham composite armor, a computer fire control system, separate ammunition storage in a blowout compartment, and NBC protection for crew safety. Initial models of the M1 were armed with a 105 mm M68 gun, while later variants feature a license-produced Rheinmetall 120 mm L/44 designated M256.
The M1 Abrams was developed from the failed joint American-West German MBT-70 project that intended to replace the dated M60 tank. There are three main operational Abrams versions: the M1, M1A1, and M1A2, with each new iteration seeing improvements in armament, protection, and electronics.[10]
The Abrams was to be replaced in U.S. Army service by the XM1202 Mounted Combat System, but following the project's cancellation, the Army opted to continue maintaining and operating the M1 series for the foreseeable future by upgrading optics, armor, and firepower.
The M1 Abrams entered service in 1980 and serves as the main battle tank of the United States Army, and formerly of the U.S. Marine Corps (USMC) until the decommissioning of all USMC tank battalions in 2021. The export modification is used by the armed forces of Egypt, Kuwait, Saudi Arabia, Australia, Poland and Iraq. The Abrams was first used in combat by the U.S. in the Gulf War. It was later deployed by the U.S. in the War in Afghanistan and the Iraq War, as well as by Iraq in the war against the Islamic State, Saudi Arabia in the Yemeni Civil War, and Ukraine during the Russian invasion of Ukraine.
History[edit]Main article: History of the M1 AbramsPrevious developments[edit]Main article: MBT-70
In 1963, the U.S. Army and the West German Bundeswehr began collaborating on a main battle tank (MBT) design that both nations would use, improving interoperability between the two NATO partners.[11][12][13] The MBT-70, or Kampfpanzer 70 as it was known in Germany,[14] incorporated many new unconventional technologies across the board. Conventional tanks of the time had a crew of four, with the driver located in the hull. In the MBT-70, the loader crewmember would be replaced by a mechanical autoloader and the driver would be located inside the NBC-protected turret with the other two crewmembers.[15][16] Like the M60A2 MBT and M551 Sheridan light tank then under development, the MBT-70 was armed with a 152 mm gun-launcher that, in addition to firing conventional ammunition, would also fire the Shillelagh missile.[17][12][18] A hydropneumatic suspension provided improved cross-country ride quality and also allowed the entire tank to be raised or lowered by the driver.[19]
The United States team was led by General Motors while the German team consisted of a consortium of firms.[20] The collaboration between the two teams was rocky from the start, with many cultural differences and disagreements about the design hampering progress.[12] Germany favored a tank optimized for the terrain of central Europe while the U.S. attached importance to operating anywhere in the world.[21] The Germans had reservations about the Shillelagh missile and developed a 120 mm high-velocity gun as an alternative.[18][11] Perhaps the most contentious disagreement, never fully resolved, concerned the measurement system to be used in drafting.[22] Germany became concerned with the excessive weight of the tank.[23] In light of growing costs, delays and overall uncertainty as to the soundness of the tank design,[24] the United States and Germany ended their MBT-70 partnership in 1970.[25] The U.S. Army began work on an austere version of the MBT-70, named XM803. Systems were simplified or eliminated altogether and the unreliable autoloader was improved.[26] These changes were ultimately insufficient to allay concerns about the tank's cost.[15] Congress canceled the XM803 in December 1971 but permitted the Army to reallocate remaining funds to develop a new main battle tank.[27]
Starting over[edit]
The Army began the XM815 project in January 1972. The Main Battle Tank Task Force (MBTTF) was established under Major General William Desobry. The task force prepared design studies with the technical support of Tank-automotive and Armaments Command (TACOM).[28] TACOM began examining specific goals. To this end, a new design basis emerged in February 1973. It had to defeat any hit from a Soviet gun within 800 m (2,600 ft) and 30 degrees to either side. The tank would be armed with the 105 mm M68 gun, a licensed version of the Royal Ordnance L7, and a 20 mm version of the M242 Bushmaster.[29] The Army later deleted the latter from the design, seeing it as superfluous.[30]
In spring 1972, Desobry was briefed by the British on their own newly developed "Burlington" armor from the British Army's labs. The armor performed exceptionally against shaped charges such as HEAT rounds. In September, Desobry convinced the Army to incorporate the new armor. To take full advantage of Burlington, also known as Chobham, the new tank would have to have armor around two feet thick (for comparison, the armor on the M60 is around four inches thick). General Creighton Abrams set the weight of the new tank at 53 tonnes (52 long tons; 58 short tons). The original goal of keeping weight under 45 tonnes (44 long tons; 50 short tons) was abandoned.[31]
At the time, the Pentagon's procurement system was beset with problems being caused by the desire to have the best possible design. This often resulted in programs being canceled due to cost overruns, leaving the forces with outdated systems, as was the case with the MBT-70. There was a strong movement within the Army to get a new design within budget to prevent the MBT-70 experience from repeating itself. For the new design, the Army set the design-to-unit cost at no more than $507,790 (equivalent to $3,817,000 in 2024).[32]
The Pentagon's approach to control of research and development was modified with the XM1. Previous acquisition strategy called for a significant amount of the design work to be done by the government. Under the new framework, contractors would competitively bid their own designs rather than compete solely for the right to manufacture the end product.[33]
In January 1973, the U.S. Army issued the XM1 (as the XM815 had been renamed in November 1972) request for proposals.[34] In May 1973, Chrysler Defense and General Motors submitted proposals. Both were armed with the 105 mm M68 gun, the licensed L7, and the 20 mm Bushmaster. Chrysler chose a 1,500 hp Lycoming AGT1500 gas turbine engine. GM's model was powered by a 1,500 hp diesel engine similar to that used on the American MBT-70 and XM803.[35]
Prototypes[edit]Chrysler XM1 prototypeGeneral Motors XM1 prototype
Prototypes were delivered in 1976 by Chrysler and GM armed with the M68E1 105 mm gun. They entered head-to-head testing at Aberdeen Proving Ground.[36][36] The testing showed that the GM design was generally superior to Chrysler's, offering better armor protection, and better fire control and turret stabilization systems.[32]
During testing, the power packs of both designs proved to have issues. The Chrysler gas turbine engine had extensive heat recovery systems in an attempt to improve its fuel efficiency to something similar to a traditional internal combustion engine. This goal was not achieved: the engine consumed much more fuel than expected, burning 890 liters per 100 kilometers (3.8 U.S. gal/mi). The GM design used a new variable-compression diesel design.[32]
By spring 1976, the decision to choose the GM design was largely complete. In addition to offering better overall performance, there were concerns about Chrysler's engine both from a reliability and fuel consumption standpoint. The GM program was also slightly cheaper overall at $208 million compared to $221 million for Chrysler. In July 1976, the Army prepared to inform Congress of the decision to move ahead with the GM design. All that was required was the final sign-off by the U.S Secretary of Defense, Donald Rumsfeld.[32]
Back to the drawing board[edit]Finalized M1 scale model
On 20 July 1976, United States Secretary of the Army Martin Hoffmann and a group of generals visited Deputy Defense Secretary Bill Clements and Director of Defense Research and Engineering Malcolm Currie on their decision. They were surprised when Clements and Currie criticized their decision and demanded that the new tank have a turbine. Defense Secretary Rumsfeld heard arguments from both parties in the afternoon. The Army team spent the night writing briefs and presented them to Rumsfeld the next morning, who then announced a four-month delay.[32]
Within days, GM was asked to present a new design with a turbine engine. According to Assistant Secretary for Research and Development Ed Miller, "It became increasingly clear that the only solution which would be acceptable to Clements and Currie was the turbine... It was a political decision that was reached, and for all intents and purposes that decision gave the award to Chrysler since they were the only contractor with a gas turbine."[32]
In the meantime, in September 1976 three West German Leopard 2AV prototypes were belatedly sent to Aberdeen for comparison testing.[37] Germany had signed a somewhat vague memorandum of understanding in 1974 committing both parties toward commonality in tank parts. Germany had assumed that its tank would be evaluated against the GM and Chrysler's prototypes and that the best tank would be chosen for production. This misunderstanding arose from the fact that in public statements both countries had overrepresented the MOU as an agreement that Germany and the U.S. would select a common MBT. In reality, the U.S. Army was unwilling to choose a foreign tank unless it was obviously superior in design and cost.[38] In any case, in evaluations the Leopard 2AV was found to meet U.S. requirements but was thought to cost more.[36] The U.S. Army announced in January 1977 that Germany had withdrawn the tank from consideration.[39]
Chrysler is chosen[edit]
Having narrowly averted losing the contract, Chrysler set about improving the design. Expensive components were replaced with less expensive ones. Chrysler's team also negotiated lower costs from their subcontractors. The price of the redesigned tank's turret especially was decreased, but other improvements came from unexpected places, such as a $600 hydraulic oil reservoir replaced with a $25 one.[40] Chrysler also submitted a version with a Teledyne AVCR-1360 diesel engine.[41] Chrysler's new bid came to $196 million, down from $221 million in the original proposal.[40]
An XM1 pilot during trials in 1979
GM's proposal replaced the diesel engine with an AGT1500 turbine and integrated a turret capable of mounting either the 105 mm or 120 mm gun.[41] Cost growth pushed the tank bid to $232 million from $208 million.[40]
Although the GM team had successfully integrated the turbine, Baer was more impressed by the cost savings introduced by the Chrysler team's redesign.[40] On 12 November 1976, the Defense Department awarded the $4.9 billion development contract to Chrysler.[42]
The turbine engine and cost do not appear to be the only reason for the selection of Chrysler. Chrysler was the only company that appeared to be seriously interested in tank development; the M60 had been lucrative for the company. In contrast, GM made only about 1% of its income from military sales, compared to 5% for Chrysler, and only submitted their bid after a "special plea" from the Pentagon.[32]
Eleven XM1 preproduction models were manufactured between February and July 1978 at Detroit Arsenal Tank Plant.[43] Quality problems with the engine quickly became apparent in testing. The first preproduction units that arrived at Aberdeen Proving Ground in March 1978 had serious problems. The tank accumulated mud and dirt under the hull which led to thrown tracks. Chrysler installed a scraper to prevent the build-up of dirt. This did not solve the issue entirely. It was determined months later that a gauge used to tension tracks was miscalibrated. This caused the tracks to be fitted too loosely.[44] Another problem was the ingestion of debris by the engine. The problem was determined to be caused by poorly fitting air filters.[44] At Fort Bliss, several tanks experienced transmission issues. It was determined that the tankers at Fort Bliss had discovered that they could throw the vehicle directly from acceleration into reverse, a tactically advantageous maneuver called the "bow tie". Chrysler resolved this by installing a device that prevented this.[44] The problems found during testing were easily surmounted. Critics of the M1 program emerged in the early 1980s, particularly the newly formed Project on Military Procurement (PMP) (later renamed the Project on Government Oversight). PMP took issue with the tank's vulnerability, high price, reliance on flammable hydraulics, and high fuel consumption.[45] American tank historian Steven J. Zaloga characterized American press criticism of the M1 during this time as "ill-founded". Zaloga wrote the issues uncovered by the tank trials were "not particularly serious".[46] PMP's criticism failed to generate any serious opposition to the program, which maintained strong support from Congress and the Pentagon.[47] Responding to some of the alleged issues with the tank in King of the Killing Zone (1989), journalist Orr Kelly wrote that "The truth is close to the opposite." Kelly said the program "ranks as one of the Army's best managed", producing a tank in "a remarkably short time" while avoiding "gold-plating" and utilizing effective competition.[48]
Production starts[edit]Early production vehicle in 1983
Low rate initial production (LRIP) of the vehicle was approved in May 1979.[29] In February 1982, General Dynamics Land Systems Division (GDLS) purchased Chrysler Defense, after Chrysler built over 1,000 M1s.[49]
A total of 3,273 M1 Abrams tanks were produced during 1979–1985 and first entered U.S. Army service in 1980. Production at the government-owned, GDLS-operated Lima Army Tank Plant in Lima, Ohio, was joined by vehicles built at the Detroit Arsenal Tank Plant (DATP) in Warren, Michigan from 1982 to 1991 (DATP also produced the 11 preproduction models in 1978.[43]).[50][51] The U.S. Army Laboratory Command (LABCOM), under the supervision of the United States Army Research Laboratory (ARL), was also heavily involved with designing the tank with M1A1 armor resistant shells, M829A2 armor-penetrating rounds, and improved weapon range.[52]
The M1 was armed with the license-built M68A1 version of the 105 mm Royal Ordnance L7 gun. The tank featured the first-of-its-kind Chobham armor. The M1 Abrams was the first to use this advanced armor. It consisted of an arrangement of metal and ceramic plates.[53] An improved model called the IPM1 was produced briefly in 1984 and contained upgrades to armor and other small improvements.
120 mm gun M1A1[edit]M1 Abrams tanks being refurbished at the Anniston Army Depot in 1989
A number of considerations had led the service and its contractors to favor the Army's standard M68 105 mm gun over Germany's 120 mm Rheinmetall Rh-120 smoothbore gun for the XM1. To begin with, the 105 mm gun was "the smallest, lightest, and least costly gun adequate for the job."[54] Indeed, new kinetic energy ammunition for the weapon then under development by the Army promised to extend the gun's usefulness well into the future. And because the Army's other tanks, the M60 and the upgraded M48, as well as the tanks of virtually every other NATO nation, used the 105 mm gun, mounting that gun on the XM1 promised to increase standardization within the alliance. Moreover, the continuing development of the new ammunition for the XM1 automatically upgraded every other gun in NATO. For all of these reasons, the XM1's development proceeded "on the assumption that the 105 mm gun would probably be the eventual main armament."[54][55] The tripartite British—American—German gun trials of 1975 produced a general agreement in the U.S. Defense Department that at some future point, a 120 mm gun of some design would be added to the XM1. Apparently anticipating this, Chrysler and GM had both made changes to their tanks during development to make them compatible with a variety of main guns.[56] In January 1978, the Secretary of the Army announced that the Rheinmetall 120 mm gun would be mounted on future production versions of the XM1. This d
The M1 Abrams (/ˈeɪbrəmz/)[9] is a third-generation American main battle tank designed by Chrysler Defense (now General Dynamics Land Systems) and named for General Creighton Abrams. Conceived for modern armored ground warfare, it is one of the heaviest tanks in service at nearly 73.6 short tons (66.8 metric tons). It introduced several modern technologies to the United States armored forces, including a multifuel turbine engine, sophisticated Chobham composite armor, a computer fire control system, separate ammunition storage in a blowout compartment, and NBC protection for crew safety. Initial models of the M1 were armed with a 105 mm M68 gun, while later variants feature a license-produced Rheinmetall 120 mm L/44 designated M256.
The M1 Abrams was developed from the failed joint American-West German MBT-70 project that intended to replace the dated M60 tank. There are three main operational Abrams versions: the M1, M1A1, and M1A2, with each new iteration seeing improvements in armament, protection, and electronics.[10]
The Abrams was to be replaced in U.S. Army service by the XM1202 Mounted Combat System, but following the project's cancellation, the Army opted to continue maintaining and operating the M1 series for the foreseeable future by upgrading optics, armor, and firepower.
The M1 Abrams entered service in 1980 and serves as the main battle tank of the United States Army, and formerly of the U.S. Marine Corps (USMC) until the decommissioning of all USMC tank battalions in 2021. The export modification is used by the armed forces of Egypt, Kuwait, Saudi Arabia, Australia, Poland and Iraq. The Abrams was first used in combat by the U.S. in the Gulf War. It was later deployed by the U.S. in the War in Afghanistan and the Iraq War, as well as by Iraq in the war against the Islamic State, Saudi Arabia in the Yemeni Civil War, and Ukraine during the Russian invasion of Ukraine.
History[edit]Main article: History of the M1 AbramsPrevious developments[edit]Main article: MBT-70
In 1963, the U.S. Army and the West German Bundeswehr began collaborating on a main battle tank (MBT) design that both nations would use, improving interoperability between the two NATO partners.[11][12][13] The MBT-70, or Kampfpanzer 70 as it was known in Germany,[14] incorporated many new unconventional technologies across the board. Conventional tanks of the time had a crew of four, with the driver located in the hull. In the MBT-70, the loader crewmember would be replaced by a mechanical autoloader and the driver would be located inside the NBC-protected turret with the other two crewmembers.[15][16] Like the M60A2 MBT and M551 Sheridan light tank then under development, the MBT-70 was armed with a 152 mm gun-launcher that, in addition to firing conventional ammunition, would also fire the Shillelagh missile.[17][12][18] A hydropneumatic suspension provided improved cross-country ride quality and also allowed the entire tank to be raised or lowered by the driver.[19]
The United States team was led by General Motors while the German team consisted of a consortium of firms.[20] The collaboration between the two teams was rocky from the start, with many cultural differences and disagreements about the design hampering progress.[12] Germany favored a tank optimized for the terrain of central Europe while the U.S. attached importance to operating anywhere in the world.[21] The Germans had reservations about the Shillelagh missile and developed a 120 mm high-velocity gun as an alternative.[18][11] Perhaps the most contentious disagreement, never fully resolved, concerned the measurement system to be used in drafting.[22] Germany became concerned with the excessive weight of the tank.[23] In light of growing costs, delays and overall uncertainty as to the soundness of the tank design,[24] the United States and Germany ended their MBT-70 partnership in 1970.[25] The U.S. Army began work on an austere version of the MBT-70, named XM803. Systems were simplified or eliminated altogether and the unreliable autoloader was improved.[26] These changes were ultimately insufficient to allay concerns about the tank's cost.[15] Congress canceled the XM803 in December 1971 but permitted the Army to reallocate remaining funds to develop a new main battle tank.[27]
Starting over[edit]
The Army began the XM815 project in January 1972. The Main Battle Tank Task Force (MBTTF) was established under Major General William Desobry. The task force prepared design studies with the technical support of Tank-automotive and Armaments Command (TACOM).[28] TACOM began examining specific goals. To this end, a new design basis emerged in February 1973. It had to defeat any hit from a Soviet gun within 800 m (2,600 ft) and 30 degrees to either side. The tank would be armed with the 105 mm M68 gun, a licensed version of the Royal Ordnance L7, and a 20 mm version of the M242 Bushmaster.[29] The Army later deleted the latter from the design, seeing it as superfluous.[30]
In spring 1972, Desobry was briefed by the British on their own newly developed "Burlington" armor from the British Army's labs. The armor performed exceptionally against shaped charges such as HEAT rounds. In September, Desobry convinced the Army to incorporate the new armor. To take full advantage of Burlington, also known as Chobham, the new tank would have to have armor around two feet thick (for comparison, the armor on the M60 is around four inches thick). General Creighton Abrams set the weight of the new tank at 53 tonnes (52 long tons; 58 short tons). The original goal of keeping weight under 45 tonnes (44 long tons; 50 short tons) was abandoned.[31]
At the time, the Pentagon's procurement system was beset with problems being caused by the desire to have the best possible design. This often resulted in programs being canceled due to cost overruns, leaving the forces with outdated systems, as was the case with the MBT-70. There was a strong movement within the Army to get a new design within budget to prevent the MBT-70 experience from repeating itself. For the new design, the Army set the design-to-unit cost at no more than $507,790 (equivalent to $3,817,000 in 2024).[32]
The Pentagon's approach to control of research and development was modified with the XM1. Previous acquisition strategy called for a significant amount of the design work to be done by the government. Under the new framework, contractors would competitively bid their own designs rather than compete solely for the right to manufacture the end product.[33]
In January 1973, the U.S. Army issued the XM1 (as the XM815 had been renamed in November 1972) request for proposals.[34] In May 1973, Chrysler Defense and General Motors submitted proposals. Both were armed with the 105 mm M68 gun, the licensed L7, and the 20 mm Bushmaster. Chrysler chose a 1,500 hp Lycoming AGT1500 gas turbine engine. GM's model was powered by a 1,500 hp diesel engine similar to that used on the American MBT-70 and XM803.[35]
Prototypes[edit]Chrysler XM1 prototypeGeneral Motors XM1 prototype
Prototypes were delivered in 1976 by Chrysler and GM armed with the M68E1 105 mm gun. They entered head-to-head testing at Aberdeen Proving Ground.[36][36] The testing showed that the GM design was generally superior to Chrysler's, offering better armor protection, and better fire control and turret stabilization systems.[32]
During testing, the power packs of both designs proved to have issues. The Chrysler gas turbine engine had extensive heat recovery systems in an attempt to improve its fuel efficiency to something similar to a traditional internal combustion engine. This goal was not achieved: the engine consumed much more fuel than expected, burning 890 liters per 100 kilometers (3.8 U.S. gal/mi). The GM design used a new variable-compression diesel design.[32]
By spring 1976, the decision to choose the GM design was largely complete. In addition to offering better overall performance, there were concerns about Chrysler's engine both from a reliability and fuel consumption standpoint. The GM program was also slightly cheaper overall at $208 million compared to $221 million for Chrysler. In July 1976, the Army prepared to inform Congress of the decision to move ahead with the GM design. All that was required was the final sign-off by the U.S Secretary of Defense, Donald Rumsfeld.[32]
Back to the drawing board[edit]Finalized M1 scale model
On 20 July 1976, United States Secretary of the Army Martin Hoffmann and a group of generals visited Deputy Defense Secretary Bill Clements and Director of Defense Research and Engineering Malcolm Currie on their decision. They were surprised when Clements and Currie criticized their decision and demanded that the new tank have a turbine. Defense Secretary Rumsfeld heard arguments from both parties in the afternoon. The Army team spent the night writing briefs and presented them to Rumsfeld the next morning, who then announced a four-month delay.[32]
Within days, GM was asked to present a new design with a turbine engine. According to Assistant Secretary for Research and Development Ed Miller, "It became increasingly clear that the only solution which would be acceptable to Clements and Currie was the turbine... It was a political decision that was reached, and for all intents and purposes that decision gave the award to Chrysler since they were the only contractor with a gas turbine."[32]
In the meantime, in September 1976 three West German Leopard 2AV prototypes were belatedly sent to Aberdeen for comparison testing.[37] Germany had signed a somewhat vague memorandum of understanding in 1974 committing both parties toward commonality in tank parts. Germany had assumed that its tank would be evaluated against the GM and Chrysler's prototypes and that the best tank would be chosen for production. This misunderstanding arose from the fact that in public statements both countries had overrepresented the MOU as an agreement that Germany and the U.S. would select a common MBT. In reality, the U.S. Army was unwilling to choose a foreign tank unless it was obviously superior in design and cost.[38] In any case, in evaluations the Leopard 2AV was found to meet U.S. requirements but was thought to cost more.[36] The U.S. Army announced in January 1977 that Germany had withdrawn the tank from consideration.[39]
Chrysler is chosen[edit]
Having narrowly averted losing the contract, Chrysler set about improving the design. Expensive components were replaced with less expensive ones. Chrysler's team also negotiated lower costs from their subcontractors. The price of the redesigned tank's turret especially was decreased, but other improvements came from unexpected places, such as a $600 hydraulic oil reservoir replaced with a $25 one.[40] Chrysler also submitted a version with a Teledyne AVCR-1360 diesel engine.[41] Chrysler's new bid came to $196 million, down from $221 million in the original proposal.[40]
An XM1 pilot during trials in 1979
GM's proposal replaced the diesel engine with an AGT1500 turbine and integrated a turret capable of mounting either the 105 mm or 120 mm gun.[41] Cost growth pushed the tank bid to $232 million from $208 million.[40]
Although the GM team had successfully integrated the turbine, Baer was more impressed by the cost savings introduced by the Chrysler team's redesign.[40] On 12 November 1976, the Defense Department awarded the $4.9 billion development contract to Chrysler.[42]
The turbine engine and cost do not appear to be the only reason for the selection of Chrysler. Chrysler was the only company that appeared to be seriously interested in tank development; the M60 had been lucrative for the company. In contrast, GM made only about 1% of its income from military sales, compared to 5% for Chrysler, and only submitted their bid after a "special plea" from the Pentagon.[32]
Eleven XM1 preproduction models were manufactured between February and July 1978 at Detroit Arsenal Tank Plant.[43] Quality problems with the engine quickly became apparent in testing. The first preproduction units that arrived at Aberdeen Proving Ground in March 1978 had serious problems. The tank accumulated mud and dirt under the hull which led to thrown tracks. Chrysler installed a scraper to prevent the build-up of dirt. This did not solve the issue entirely. It was determined months later that a gauge used to tension tracks was miscalibrated. This caused the tracks to be fitted too loosely.[44] Another problem was the ingestion of debris by the engine. The problem was determined to be caused by poorly fitting air filters.[44] At Fort Bliss, several tanks experienced transmission issues. It was determined that the tankers at Fort Bliss had discovered that they could throw the vehicle directly from acceleration into reverse, a tactically advantageous maneuver called the "bow tie". Chrysler resolved this by installing a device that prevented this.[44] The problems found during testing were easily surmounted. Critics of the M1 program emerged in the early 1980s, particularly the newly formed Project on Military Procurement (PMP) (later renamed the Project on Government Oversight). PMP took issue with the tank's vulnerability, high price, reliance on flammable hydraulics, and high fuel consumption.[45] American tank historian Steven J. Zaloga characterized American press criticism of the M1 during this time as "ill-founded". Zaloga wrote the issues uncovered by the tank trials were "not particularly serious".[46] PMP's criticism failed to generate any serious opposition to the program, which maintained strong support from Congress and the Pentagon.[47] Responding to some of the alleged issues with the tank in King of the Killing Zone (1989), journalist Orr Kelly wrote that "The truth is close to the opposite." Kelly said the program "ranks as one of the Army's best managed", producing a tank in "a remarkably short time" while avoiding "gold-plating" and utilizing effective competition.[48]
Production starts[edit]Early production vehicle in 1983
Low rate initial production (LRIP) of the vehicle was approved in May 1979.[29] In February 1982, General Dynamics Land Systems Division (GDLS) purchased Chrysler Defense, after Chrysler built over 1,000 M1s.[49]
A total of 3,273 M1 Abrams tanks were produced during 1979–1985 and first entered U.S. Army service in 1980. Production at the government-owned, GDLS-operated Lima Army Tank Plant in Lima, Ohio, was joined by vehicles built at the Detroit Arsenal Tank Plant (DATP) in Warren, Michigan from 1982 to 1991 (DATP also produced the 11 preproduction models in 1978.[43]).[50][51] The U.S. Army Laboratory Command (LABCOM), under the supervision of the United States Army Research Laboratory (ARL), was also heavily involved with designing the tank with M1A1 armor resistant shells, M829A2 armor-penetrating rounds, and improved weapon range.[52]
The M1 was armed with the license-built M68A1 version of the 105 mm Royal Ordnance L7 gun. The tank featured the first-of-its-kind Chobham armor. The M1 Abrams was the first to use this advanced armor. It consisted of an arrangement of metal and ceramic plates.[53] An improved model called the IPM1 was produced briefly in 1984 and contained upgrades to armor and other small improvements.
120 mm gun M1A1[edit]M1 Abrams tanks being refurbished at the Anniston Army Depot in 1989
A number of considerations had led the service and its contractors to favor the Army's standard M68 105 mm gun over Germany's 120 mm Rheinmetall Rh-120 smoothbore gun for the XM1. To begin with, the 105 mm gun was "the smallest, lightest, and least costly gun adequate for the job."[54] Indeed, new kinetic energy ammunition for the weapon then under development by the Army promised to extend the gun's usefulness well into the future. And because the Army's other tanks, the M60 and the upgraded M48, as well as the tanks of virtually every other NATO nation, used the 105 mm gun, mounting that gun on the XM1 promised to increase standardization within the alliance. Moreover, the continuing development of the new ammunition for the XM1 automatically upgraded every other gun in NATO. For all of these reasons, the XM1's development proceeded "on the assumption that the 105 mm gun would probably be the eventual main armament."[54][55] The tripartite British—American—German gun trials of 1975 produced a general agreement in the U.S. Defense Department that at some future point, a 120 mm gun of some design would be added to the XM1. Apparently anticipating this, Chrysler and GM had both made changes to their tanks during development to make them compatible with a variety of main guns.[56] In January 1978, the Secretary of the Army announced that the Rheinmetall 120 mm gun would be mounted on future production versions of the XM1. This d
The M1 Abrams (/ˈeɪbrəmz/)[9] is a third-generation American main battle tank designed by Chrysler Defense (now General Dynamics Land Systems) and named for General Creighton Abrams. Conceived for modern armored ground warfare, it is one of the heaviest tanks in service at nearly 73.6 short tons (66.8 metric tons). It introduced several modern technologies to the United States armored forces, including a multifuel turbine engine, sophisticated Chobham composite armor, a computer fire control system, separate ammunition storage in a blowout compartment, and NBC protection for crew safety. Initial models of the M1 were armed with a 105 mm M68 gun, while later variants feature a license-produced Rheinmetall 120 mm L/44 designated M256.
The M1 Abrams was developed from the failed joint American-West German MBT-70 project that intended to replace the dated M60 tank. There are three main operational Abrams versions: the M1, M1A1, and M1A2, with each new iteration seeing improvements in armament, protection, and electronics.[10]
The Abrams was to be replaced in U.S. Army service by the XM1202 Mounted Combat System, but following the project's cancellation, the Army opted to continue maintaining and operating the M1 series for the foreseeable future by upgrading optics, armor, and firepower.
The M1 Abrams entered service in 1980 and serves as the main battle tank of the United States Army, and formerly of the U.S. Marine Corps (USMC) until the decommissioning of all USMC tank battalions in 2021. The export modification is used by the armed forces of Egypt, Kuwait, Saudi Arabia, Australia, Poland and Iraq. The Abrams was first used in combat by the U.S. in the Gulf War. It was later deployed by the U.S. in the War in Afghanistan and the Iraq War, as well as by Iraq in the war against the Islamic State, Saudi Arabia in the Yemeni Civil War, and Ukraine during the Russian invasion of Ukraine.
History[edit]Main article: History of the M1 AbramsPrevious developments[edit]Main article: MBT-70
In 1963, the U.S. Army and the West German Bundeswehr began collaborating on a main battle tank (MBT) design that both nations would use, improving interoperability between the two NATO partners.[11][12][13] The MBT-70, or Kampfpanzer 70 as it was known in Germany,[14] incorporated many new unconventional technologies across the board. Conventional tanks of the time had a crew of four, with the driver located in the hull. In the MBT-70, the loader crewmember would be replaced by a mechanical autoloader and the driver would be located inside the NBC-protected turret with the other two crewmembers.[15][16] Like the M60A2 MBT and M551 Sheridan light tank then under development, the MBT-70 was armed with a 152 mm gun-launcher that, in addition to firing conventional ammunition, would also fire the Shillelagh missile.[17][12][18] A hydropneumatic suspension provided improved cross-country ride quality and also allowed the entire tank to be raised or lowered by the driver.[19]
The United States team was led by General Motors while the German team consisted of a consortium of firms.[20] The collaboration between the two teams was rocky from the start, with many cultural differences and disagreements about the design hampering progress.[12] Germany favored a tank optimized for the terrain of central Europe while the U.S. attached importance to operating anywhere in the world.[21] The Germans had reservations about the Shillelagh missile and developed a 120 mm high-velocity gun as an alternative.[18][11] Perhaps the most contentious disagreement, never fully resolved, concerned the measurement system to be used in drafting.[22] Germany became concerned with the excessive weight of the tank.[23] In light of growing costs, delays and overall uncertainty as to the soundness of the tank design,[24] the United States and Germany ended their MBT-70 partnership in 1970.[25] The U.S. Army began work on an austere version of the MBT-70, named XM803. Systems were simplified or eliminated altogether and the unreliable autoloader was improved.[26] These changes were ultimately insufficient to allay concerns about the tank's cost.[15] Congress canceled the XM803 in December 1971 but permitted the Army to reallocate remaining funds to develop a new main battle tank.[27]
Starting over[edit]
The Army began the XM815 project in January 1972. The Main Battle Tank Task Force (MBTTF) was established under Major General William Desobry. The task force prepared design studies with the technical support of Tank-automotive and Armaments Command (TACOM).[28] TACOM began examining specific goals. To this end, a new design basis emerged in February 1973. It had to defeat any hit from a Soviet gun within 800 m (2,600 ft) and 30 degrees to either side. The tank would be armed with the 105 mm M68 gun, a licensed version of the Royal Ordnance L7, and a 20 mm version of the M242 Bushmaster.[29] The Army later deleted the latter from the design, seeing it as superfluous.[30]
In spring 1972, Desobry was briefed by the British on their own newly developed "Burlington" armor from the British Army's labs. The armor performed exceptionally against shaped charges such as HEAT rounds. In September, Desobry convinced the Army to incorporate the new armor. To take full advantage of Burlington, also known as Chobham, the new tank would have to have armor around two feet thick (for comparison, the armor on the M60 is around four inches thick). General Creighton Abrams set the weight of the new tank at 53 tonnes (52 long tons; 58 short tons). The original goal of keeping weight under 45 tonnes (44 long tons; 50 short tons) was abandoned.[31]
At the time, the Pentagon's procurement system was beset with problems being caused by the desire to have the best possible design. This often resulted in programs being canceled due to cost overruns, leaving the forces with outdated systems, as was the case with the MBT-70. There was a strong movement within the Army to get a new design within budget to prevent the MBT-70 experience from repeating itself. For the new design, the Army set the design-to-unit cost at no more than $507,790 (equivalent to $3,817,000 in 2024).[32]
The Pentagon's approach to control of research and development was modified with the XM1. Previous acquisition strategy called for a significant amount of the design work to be done by the government. Under the new framework, contractors would competitively bid their own designs rather than compete solely for the right to manufacture the end product.[33]
In January 1973, the U.S. Army issued the XM1 (as the XM815 had been renamed in November 1972) request for proposals.[34] In May 1973, Chrysler Defense and General Motors submitted proposals. Both were armed with the 105 mm M68 gun, the licensed L7, and the 20 mm Bushmaster. Chrysler chose a 1,500 hp Lycoming AGT1500 gas turbine engine. GM's model was powered by a 1,500 hp diesel engine similar to that used on the American MBT-70 and XM803.[35]
Prototypes[edit]Chrysler XM1 prototypeGeneral Motors XM1 prototype
Prototypes were delivered in 1976 by Chrysler and GM armed with the M68E1 105 mm gun. They entered head-to-head testing at Aberdeen Proving Ground.[36][36] The testing showed that the GM design was generally superior to Chrysler's, offering better armor protection, and better fire control and turret stabilization systems.[32]
During testing, the power packs of both designs proved to have issues. The Chrysler gas turbine engine had extensive heat recovery systems in an attempt to improve its fuel efficiency to something similar to a traditional internal combustion engine. This goal was not achieved: the engine consumed much more fuel than expected, burning 890 liters per 100 kilometers (3.8 U.S. gal/mi). The GM design used a new variable-compression diesel design.[32]
By spring 1976, the decision to choose the GM design was largely complete. In addition to offering better overall performance, there were concerns about Chrysler's engine both from a reliability and fuel consumption standpoint. The GM program was also slightly cheaper overall at $208 million compared to $221 million for Chrysler. In July 1976, the Army prepared to inform Congress of the decision to move ahead with the GM design. All that was required was the final sign-off by the U.S Secretary of Defense, Donald Rumsfeld.[32]
Back to the drawing board[edit]Finalized M1 scale model
On 20 July 1976, United States Secretary of the Army Martin Hoffmann and a group of generals visited Deputy Defense Secretary Bill Clements and Director of Defense Research and Engineering Malcolm Currie on their decision. They were surprised when Clements and Currie criticized their decision and demanded that the new tank have a turbine. Defense Secretary Rumsfeld heard arguments from both parties in the afternoon. The Army team spent the night writing briefs and presented them to Rumsfeld the next morning, who then announced a four-month delay.[32]
Within days, GM was asked to present a new design with a turbine engine. According to Assistant Secretary for Research and Development Ed Miller, "It became increasingly clear that the only solution which would be acceptable to Clements and Currie was the turbine... It was a political decision that was reached, and for all intents and purposes that decision gave the award to Chrysler since they were the only contractor with a gas turbine."[32]
In the meantime, in September 1976 three West German Leopard 2AV prototypes were belatedly sent to Aberdeen for comparison testing.[37] Germany had signed a somewhat vague memorandum of understanding in 1974 committing both parties toward commonality in tank parts. Germany had assumed that its tank would be evaluated against the GM and Chrysler's prototypes and that the best tank would be chosen for production. This misunderstanding arose from the fact that in public statements both countries had overrepresented the MOU as an agreement that Germany and the U.S. would select a common MBT. In reality, the U.S. Army was unwilling to choose a foreign tank unless it was obviously superior in design and cost.[38] In any case, in evaluations the Leopard 2AV was found to meet U.S. requirements but was thought to cost more.[36] The U.S. Army announced in January 1977 that Germany had withdrawn the tank from consideration.[39]
Chrysler is chosen[edit]
Having narrowly averted losing the contract, Chrysler set about improving the design. Expensive components were replaced with less expensive ones. Chrysler's team also negotiated lower costs from their subcontractors. The price of the redesigned tank's turret especially was decreased, but other improvements came from unexpected places, such as a $600 hydraulic oil reservoir replaced with a $25 one.[40] Chrysler also submitted a version with a Teledyne AVCR-1360 diesel engine.[41] Chrysler's new bid came to $196 million, down from $221 million in the original proposal.[40]
An XM1 pilot during trials in 1979
GM's proposal replaced the diesel engine with an AGT1500 turbine and integrated a turret capable of mounting either the 105 mm or 120 mm gun.[41] Cost growth pushed the tank bid to $232 million from $208 million.[40]
Although the GM team had successfully integrated the turbine, Baer was more impressed by the cost savings introduced by the Chrysler team's redesign.[40] On 12 November 1976, the Defense Department awarded the $4.9 billion development contract to Chrysler.[42]
The turbine engine and cost do not appear to be the only reason for the selection of Chrysler. Chrysler was the only company that appeared to be seriously interested in tank development; the M60 had been lucrative for the company. In contrast, GM made only about 1% of its income from military sales, compared to 5% for Chrysler, and only submitted their bid after a "special plea" from the Pentagon.[32]
Eleven XM1 preproduction models were manufactured between February and July 1978 at Detroit Arsenal Tank Plant.[43] Quality problems with the engine quickly became apparent in testing. The first preproduction units that arrived at Aberdeen Proving Ground in March 1978 had serious problems. The tank accumulated mud and dirt under the hull which led to thrown tracks. Chrysler installed a scraper to prevent the build-up of dirt. This did not solve the issue entirely. It was determined months later that a gauge used to tension tracks was miscalibrated. This caused the tracks to be fitted too loosely.[44] Another problem was the ingestion of debris by the engine. The problem was determined to be caused by poorly fitting air filters.[44] At Fort Bliss, several tanks experienced transmission issues. It was determined that the tankers at Fort Bliss had discovered that they could throw the vehicle directly from acceleration into reverse, a tactically advantageous maneuver called the "bow tie". Chrysler resolved this by installing a device that prevented this.[44] The problems found during testing were easily surmounted. Critics of the M1 program emerged in the early 1980s, particularly the newly formed Project on Military Procurement (PMP) (later renamed the Project on Government Oversight). PMP took issue with the tank's vulnerability, high price, reliance on flammable hydraulics, and high fuel consumption.[45] American tank historian Steven J. Zaloga characterized American press criticism of the M1 during this time as "ill-founded". Zaloga wrote the issues uncovered by the tank trials were "not particularly serious".[46] PMP's criticism failed to generate any serious opposition to the program, which maintained strong support from Congress and the Pentagon.[47] Responding to some of the alleged issues with the tank in King of the Killing Zone (1989), journalist Orr Kelly wrote that "The truth is close to the opposite." Kelly said the program "ranks as one of the Army's best managed", producing a tank in "a remarkably short time" while avoiding "gold-plating" and utilizing effective competition.[48]
Production starts[edit]Early production vehicle in 1983
Low rate initial production (LRIP) of the vehicle was approved in May 1979.[29] In February 1982, General Dynamics Land Systems Division (GDLS) purchased Chrysler Defense, after Chrysler built over 1,000 M1s.[49]
A total of 3,273 M1 Abrams tanks were produced during 1979–1985 and first entered U.S. Army service in 1980. Production at the government-owned, GDLS-operated Lima Army Tank Plant in Lima, Ohio, was joined by vehicles built at the Detroit Arsenal Tank Plant (DATP) in Warren, Michigan from 1982 to 1991 (DATP also produced the 11 preproduction models in 1978.[43]).[50][51] The U.S. Army Laboratory Command (LABCOM), under the supervision of the United States Army Research Laboratory (ARL), was also heavily involved with designing the tank with M1A1 armor resistant shells, M829A2 armor-penetrating rounds, and improved weapon range.[52]
The M1 was armed with the license-built M68A1 version of the 105 mm Royal Ordnance L7 gun. The tank featured the first-of-its-kind Chobham armor. The M1 Abrams was the first to use this advanced armor. It consisted of an arrangement of metal and ceramic plates.[53] An improved model called the IPM1 was produced briefly in 1984 and contained upgrades to armor and other small improvements.
120 mm gun M1A1[edit]M1 Abrams tanks being refurbished at the Anniston Army Depot in 1989
A number of considerations had led the service and its contractors to favor the Army's standard M68 105 mm gun over Germany's 120 mm Rheinmetall Rh-120 smoothbore gun for the XM1. To begin with, the 105 mm gun was "the smallest, lightest, and least costly gun adequate for the job."[54] Indeed, new kinetic energy ammunition for the weapon then under development by the Army promised to extend the gun's usefulness well into the future. And because the Army's other tanks, the M60 and the upgraded M48, as well as the tanks of virtually every other NATO nation, used the 105 mm gun, mounting that gun on the XM1 promised to increase standardization within the alliance. Moreover, the continuing development of the new ammunition for the XM1 automatically upgraded every other gun in NATO. For all of these reasons, the XM1's development proceeded "on the assumption that the 105 mm gun would probably be the eventual main armament."[54][55] The tripartite British—American—German gun trials of 1975 produced a general agreement in the U.S. Defense Department that at some future point, a 120 mm gun of some design would be added to the XM1. Apparently anticipating this, Chrysler and GM had both made changes to their tanks during development to make them compatible with a variety of main guns.[56] In January 1978, the Secretary of the Army announced that the Rheinmetall 120 mm gun would be mounted on future production versions of the XM1. This d
The M1 Abrams (/ˈeɪbrəmz/)[9] is a third-generation American main battle tank designed by Chrysler Defense (now General Dynamics Land Systems) and named for General Creighton Abrams. Conceived for modern armored ground warfare, it is one of the heaviest tanks in service at nearly 73.6 short tons (66.8 metric tons). It introduced several modern technologies to the United States armored forces, including a multifuel turbine engine, sophisticated Chobham composite armor, a computer fire control system, separate ammunition storage in a blowout compartment, and NBC protection for crew safety. Initial models of the M1 were armed with a 105 mm M68 gun, while later variants feature a license-produced Rheinmetall 120 mm L/44 designated M256.
The M1 Abrams was developed from the failed joint American-West German MBT-70 project that intended to replace the dated M60 tank. There are three main operational Abrams versions: the M1, M1A1, and M1A2, with each new iteration seeing improvements in armament, protection, and electronics.[10]
The Abrams was to be replaced in U.S. Army service by the XM1202 Mounted Combat System, but following the project's cancellation, the Army opted to continue maintaining and operating the M1 series for the foreseeable future by upgrading optics, armor, and firepower.
The M1 Abrams entered service in 1980 and serves as the main battle tank of the United States Army, and formerly of the U.S. Marine Corps (USMC) until the decommissioning of all USMC tank battalions in 2021. The export modification is used by the armed forces of Egypt, Kuwait, Saudi Arabia, Australia, Poland and Iraq. The Abrams was first used in combat by the U.S. in the Gulf War. It was later deployed by the U.S. in the War in Afghanistan and the Iraq War, as well as by Iraq in the war against the Islamic State, Saudi Arabia in the Yemeni Civil War, and Ukraine during the Russian invasion of Ukraine.
History[edit]Main article: History of the M1 AbramsPrevious developments[edit]Main article: MBT-70
In 1963, the U.S. Army and the West German Bundeswehr began collaborating on a main battle tank (MBT) design that both nations would use, improving interoperability between the two NATO partners.[11][12][13] The MBT-70, or Kampfpanzer 70 as it was known in Germany,[14] incorporated many new unconventional technologies across the board. Conventional tanks of the time had a crew of four, with the driver located in the hull. In the MBT-70, the loader crewmember would be replaced by a mechanical autoloader and the driver would be located inside the NBC-protected turret with the other two crewmembers.[15][16] Like the M60A2 MBT and M551 Sheridan light tank then under development, the MBT-70 was armed with a 152 mm gun-launcher that, in addition to firing conventional ammunition, would also fire the Shillelagh missile.[17][12][18] A hydropneumatic suspension provided improved cross-country ride quality and also allowed the entire tank to be raised or lowered by the driver.[19]
The United States team was led by General Motors while the German team consisted of a consortium of firms.[20] The collaboration between the two teams was rocky from the start, with many cultural differences and disagreements about the design hampering progress.[12] Germany favored a tank optimized for the terrain of central Europe while the U.S. attached importance to operating anywhere in the world.[21] The Germans had reservations about the Shillelagh missile and developed a 120 mm high-velocity gun as an alternative.[18][11] Perhaps the most contentious disagreement, never fully resolved, concerned the measurement system to be used in drafting.[22] Germany became concerned with the excessive weight of the tank.[23] In light of growing costs, delays and overall uncertainty as to the soundness of the tank design,[24] the United States and Germany ended their MBT-70 partnership in 1970.[25] The U.S. Army began work on an austere version of the MBT-70, named XM803. Systems were simplified or eliminated altogether and the unreliable autoloader was improved.[26] These changes were ultimately insufficient to allay concerns about the tank's cost.[15] Congress canceled the XM803 in December 1971 but permitted the Army to reallocate remaining funds to develop a new main battle tank.[27]
Starting over[edit]
The Army began the XM815 project in January 1972. The Main Battle Tank Task Force (MBTTF) was established under Major General William Desobry. The task force prepared design studies with the technical support of Tank-automotive and Armaments Command (TACOM).[28] TACOM began examining specific goals. To this end, a new design basis emerged in February 1973. It had to defeat any hit from a Soviet gun within 800 m (2,600 ft) and 30 degrees to either side. The tank would be armed with the 105 mm M68 gun, a licensed version of the Royal Ordnance L7, and a 20 mm version of the M242 Bushmaster.[29] The Army later deleted the latter from the design, seeing it as superfluous.[30]
In spring 1972, Desobry was briefed by the British on their own newly developed "Burlington" armor from the British Army's labs. The armor performed exceptionally against shaped charges such as HEAT rounds. In September, Desobry convinced the Army to incorporate the new armor. To take full advantage of Burlington, also known as Chobham, the new tank would have to have armor around two feet thick (for comparison, the armor on the M60 is around four inches thick). General Creighton Abrams set the weight of the new tank at 53 tonnes (52 long tons; 58 short tons). The original goal of keeping weight under 45 tonnes (44 long tons; 50 short tons) was abandoned.[31]
At the time, the Pentagon's procurement system was beset with problems being caused by the desire to have the best possible design. This often resulted in programs being canceled due to cost overruns, leaving the forces with outdated systems, as was the case with the MBT-70. There was a strong movement within the Army to get a new design within budget to prevent the MBT-70 experience from repeating itself. For the new design, the Army set the design-to-unit cost at no more than $507,790 (equivalent to $3,817,000 in 2024).[32]
The Pentagon's approach to control of research and development was modified with the XM1. Previous acquisition strategy called for a significant amount of the design work to be done by the government. Under the new framework, contractors would competitively bid their own designs rather than compete solely for the right to manufacture the end product.[33]
In January 1973, the U.S. Army issued the XM1 (as the XM815 had been renamed in November 1972) request for proposals.[34] In May 1973, Chrysler Defense and General Motors submitted proposals. Both were armed with the 105 mm M68 gun, the licensed L7, and the 20 mm Bushmaster. Chrysler chose a 1,500 hp Lycoming AGT1500 gas turbine engine. GM's model was powered by a 1,500 hp diesel engine similar to that used on the American MBT-70 and XM803.[35]
Prototypes[edit]Chrysler XM1 prototypeGeneral Motors XM1 prototype
Prototypes were delivered in 1976 by Chrysler and GM armed with the M68E1 105 mm gun. They entered head-to-head testing at Aberdeen Proving Ground.[36][36] The testing showed that the GM design was generally superior to Chrysler's, offering better armor protection, and better fire control and turret stabilization systems.[32]
During testing, the power packs of both designs proved to have issues. The Chrysler gas turbine engine had extensive heat recovery systems in an attempt to improve its fuel efficiency to something similar to a traditional internal combustion engine. This goal was not achieved: the engine consumed much more fuel than expected, burning 890 liters per 100 kilometers (3.8 U.S. gal/mi). The GM design used a new variable-compression diesel design.[32]
By spring 1976, the decision to choose the GM design was largely complete. In addition to offering better overall performance, there were concerns about Chrysler's engine both from a reliability and fuel consumption standpoint. The GM program was also slightly cheaper overall at $208 million compared to $221 million for Chrysler. In July 1976, the Army prepared to inform Congress of the decision to move ahead with the GM design. All that was required was the final sign-off by the U.S Secretary of Defense, Donald Rumsfeld.[32]
Back to the drawing board[edit]Finalized M1 scale model
On 20 July 1976, United States Secretary of the Army Martin Hoffmann and a group of generals visited Deputy Defense Secretary Bill Clements and Director of Defense Research and Engineering Malcolm Currie on their decision. They were surprised when Clements and Currie criticized their decision and demanded that the new tank have a turbine. Defense Secretary Rumsfeld heard arguments from both parties in the afternoon. The Army team spent the night writing briefs and presented them to Rumsfeld the next morning, who then announced a four-month delay.[32]
Within days, GM was asked to present a new design with a turbine engine. According to Assistant Secretary for Research and Development Ed Miller, "It became increasingly clear that the only solution which would be acceptable to Clements and Currie was the turbine... It was a political decision that was reached, and for all intents and purposes that decision gave the award to Chrysler since they were the only contractor with a gas turbine."[32]
In the meantime, in September 1976 three West German Leopard 2AV prototypes were belatedly sent to Aberdeen for comparison testing.[37] Germany had signed a somewhat vague memorandum of understanding in 1974 committing both parties toward commonality in tank parts. Germany had assumed that its tank would be evaluated against the GM and Chrysler's prototypes and that the best tank would be chosen for production. This misunderstanding arose from the fact that in public statements both countries had overrepresented the MOU as an agreement that Germany and the U.S. would select a common MBT. In reality, the U.S. Army was unwilling to choose a foreign tank unless it was obviously superior in design and cost.[38] In any case, in evaluations the Leopard 2AV was found to meet U.S. requirements but was thought to cost more.[36] The U.S. Army announced in January 1977 that Germany had withdrawn the tank from consideration.[39]
Chrysler is chosen[edit]
Having narrowly averted losing the contract, Chrysler set about improving the design. Expensive components were replaced with less expensive ones. Chrysler's team also negotiated lower costs from their subcontractors. The price of the redesigned tank's turret especially was decreased, but other improvements came from unexpected places, such as a $600 hydraulic oil reservoir replaced with a $25 one.[40] Chrysler also submitted a version with a Teledyne AVCR-1360 diesel engine.[41] Chrysler's new bid came to $196 million, down from $221 million in the original proposal.[40]
An XM1 pilot during trials in 1979
GM's proposal replaced the diesel engine with an AGT1500 turbine and integrated a turret capable of mounting either the 105 mm or 120 mm gun.[41] Cost growth pushed the tank bid to $232 million from $208 million.[40]
Although the GM team had successfully integrated the turbine, Baer was more impressed by the cost savings introduced by the Chrysler team's redesign.[40] On 12 November 1976, the Defense Department awarded the $4.9 billion development contract to Chrysler.[42]
The turbine engine and cost do not appear to be the only reason for the selection of Chrysler. Chrysler was the only company that appeared to be seriously interested in tank development; the M60 had been lucrative for the company. In contrast, GM made only about 1% of its income from military sales, compared to 5% for Chrysler, and only submitted their bid after a "special plea" from the Pentagon.[32]
Eleven XM1 preproduction models were manufactured between February and July 1978 at Detroit Arsenal Tank Plant.[43] Quality problems with the engine quickly became apparent in testing. The first preproduction units that arrived at Aberdeen Proving Ground in March 1978 had serious problems. The tank accumulated mud and dirt under the hull which led to thrown tracks. Chrysler installed a scraper to prevent the build-up of dirt. This did not solve the issue entirely. It was determined months later that a gauge used to tension tracks was miscalibrated. This caused the tracks to be fitted too loosely.[44] Another problem was the ingestion of debris by the engine. The problem was determined to be caused by poorly fitting air filters.[44] At Fort Bliss, several tanks experienced transmission issues. It was determined that the tankers at Fort Bliss had discovered that they could throw the vehicle directly from acceleration into reverse, a tactically advantageous maneuver called the "bow tie". Chrysler resolved this by installing a device that prevented this.[44] The problems found during testing were easily surmounted. Critics of the M1 program emerged in the early 1980s, particularly the newly formed Project on Military Procurement (PMP) (later renamed the Project on Government Oversight). PMP took issue with the tank's vulnerability, high price, reliance on flammable hydraulics, and high fuel consumption.[45] American tank historian Steven J. Zaloga characterized American press criticism of the M1 during this time as "ill-founded". Zaloga wrote the issues uncovered by the tank trials were "not particularly serious".[46] PMP's criticism failed to generate any serious opposition to the program, which maintained strong support from Congress and the Pentagon.[47] Responding to some of the alleged issues with the tank in King of the Killing Zone (1989), journalist Orr Kelly wrote that "The truth is close to the opposite." Kelly said the program "ranks as one of the Army's best managed", producing a tank in "a remarkably short time" while avoiding "gold-plating" and utilizing effective competition.[48]
Production starts[edit]Early production vehicle in 1983
Low rate initial production (LRIP) of the vehicle was approved in May 1979.[29] In February 1982, General Dynamics Land Systems Division (GDLS) purchased Chrysler Defense, after Chrysler built over 1,000 M1s.[49]
A total of 3,273 M1 Abrams tanks were produced during 1979–1985 and first entered U.S. Army service in 1980. Production at the government-owned, GDLS-operated Lima Army Tank Plant in Lima, Ohio, was joined by vehicles built at the Detroit Arsenal Tank Plant (DATP) in Warren, Michigan from 1982 to 1991 (DATP also produced the 11 preproduction models in 1978.[43]).[50][51] The U.S. Army Laboratory Command (LABCOM), under the supervision of the United States Army Research Laboratory (ARL), was also heavily involved with designing the tank with M1A1 armor resistant shells, M829A2 armor-penetrating rounds, and improved weapon range.[52]
The M1 was armed with the license-built M68A1 version of the 105 mm Royal Ordnance L7 gun. The tank featured the first-of-its-kind Chobham armor. The M1 Abrams was the first to use this advanced armor. It consisted of an arrangement of metal and ceramic plates.[53] An improved model called the IPM1 was produced briefly in 1984 and contained upgrades to armor and other small improvements.
120 mm gun M1A1[edit]M1 Abrams tanks being refurbished at the Anniston Army Depot in 1989
A number of considerations had led the service and its contractors to favor the Army's standard M68 105 mm gun over Germany's 120 mm Rheinmetall Rh-120 smoothbore gun for the XM1. To begin with, the 105 mm gun was "the smallest, lightest, and least costly gun adequate for the job."[54] Indeed, new kinetic energy ammunition for the weapon then under development by the Army promised to extend the gun's usefulness well into the future. And because the Army's other tanks, the M60 and the upgraded M48, as well as the tanks of virtually every other NATO nation, used the 105 mm gun, mounting that gun on the XM1 promised to increase standardization within the alliance. Moreover, the continuing development of the new ammunition for the XM1 automatically upgraded every other gun in NATO. For all of these reasons, the XM1's development proceeded "on the assumption that the 105 mm gun would probably be the eventual main armament."[54][55] The tripartite British—American—German gun trials of 1975 produced a general agreement in the U.S. Defense Department that at some future point, a 120 mm gun of some design would be added to the XM1. Apparently anticipating this, Chrysler and GM had both made changes to their tanks during development to make them compatible with a variety of main guns.[56] In January 1978, the Secretary of the Army announced that the Rheinmetall 120 mm gun would be mounted on future production versions of the XM1. This d