The M1 Abrams is an American third-generation main battle tank produced by the United States. It is named after General Creighton Abrams, former Army Chief of Staff and Commander of U.S. military forces in the Vietnam War from 1968 to 1972. Highly mobile, designed for modern armored ground warfare,the M1 is well armed and heavily armored. Notable features include the use of a powerful gas turbine engine (multifuel capable, usually fueled with JP8 jet fuel), the adoption of sophisticated composite armor, and separate ammunition storage in a blow-out compartment for crew safety. Weighing nearly 68 short tons (almost 62 metric tons), it is one of the heaviest main battle tanks in service.
The M1 Abrams entered U.S. service in 1980, replacing the M60 tank.It served for over a decade alongside the improved M60A3, which had entered service in 1978. The M1 remains the principal main battle tank of the United States Army and Marine Corps, and the armies of Egypt, Kuwait, Saudi Arabia, Australia, and Iraq.
Three main versions of the M1 Abrams have been deployed, the M1, M1A1, and M1A2, incorporating improved armament, protection and electronics. These improvements, as well as periodic upgrades to older tanks, have allowed this long-serving vehicle to remain in front-line service. The M1A3 is currently under development.
Development
The first attempt to replace the aging M60 tank was the MBT-70, developed in partnership with West Germany in the 1960s. The MBT-70 had advanced features such as a height-adjustable pneumatic suspension and a turret design that allowed the driver to always face the direction of travel, but ultimately proved to be too heavy, complex, and expensive. As a result of the imminent failure of this project, the U.S. Army introduced the XM803. This succeeded only in producing an expensive system with capabilities similar to the M60.An XM1 Abrams, during a demonstration at Fort Knox, Kentucky in 1979
Congress canceled the MBT-70 in November and XM803 December 1971, and redistributed the funds to the new XM815, later renamed the XM1 Abrams after General Creighton Abrams. Prototypes were delivered in 1976 by Chrysler Defense and General Motors armed with the license-built version of the 105 mm Royal Ordnance L7 gun along with a Leopard 2 for comparison. The turbine-powered Chrysler Defense design was selected for development as the M1; Chrysler had significant experience designing turbine-powered land vehicles going back to the 1950s. In March 1982, General Dynamics Land Systems Division (GDLS) purchased Chrysler Defense, after Chrysler built over 1,000 M1s.
A total of 3,273 M1 Abrams were produced 1979–85 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 in Warren, Michigan from 1982 to 1996.The M1 was armed with the license-built version of the 105 mm Royal Ordnance L7 gun. An improved model called the M1IP was produced briefly in 1984 and contained small upgrades. The M1IP models were used in the Canadian Army Trophy NATO tank gunnery competition in 1985 and 1987.
105-mm M1 Abrams tank of the 11th Armored Cavalry Regiment at Grafenwöhr Training Area in Germany, 1986
About 6,000 M1A1 Abrams were produced from 1986–92 and featured the M256 120 mm (4.7 in) smoothbore cannon developed by Rheinmetall AG of Germany for the Leopard 2, improved armor, and a CBRN protection system. Production of M1 and M1A1 tanks totaled some 9,000 tanks at a cost of approximately $4.30 million per unit.By 1999 costs for the tank were upwards of US$5 million a vehicle.
In 1990, Project on Government Oversight in a report criticized the M1's high costs and low fuel efficiency in comparison with other tanks of similar power and effectiveness such as the Leopard 2. The report was based on data from U.S. Army sources and the Congressional record.
As the Abrams entered service in the 1980s, they operated alongside M60A3 within the United States military, and with other NATO tanks in numerous Cold War exercises. These exercises usually took place in Western Europe, especially West Germany, but also in some other countries, including South Korea. The exercises were aimed at countering Soviet forces. However, by January 1991 the Berlin Wall had fallen and the Abrams was instead employed in the Middle East.
Design
Countermeasures
Camouflage
Unlike earlier U.S. military vehicles used from World War II through the Vietnam War, which used a scheme of dark brownish green known as "olive drab" with large white stars, prototypes and early production M1 (105 mm gun) & M1-IP models used the flat medium green paint; and the large white insignia stars have transitioned to much smaller black markings. Some units painted their M1s with the older MERDC 4-color paint scheme but the turn-in requirements for these tanks required repainting them to solid green. Therefore, even though a large number of the base model M1s were camouflaged in the field, few or none exist today.
M1A1s came from the factory with the NATO three color camouflage Black/Med-Green/Dark-Brown CARC paint jobs. Today M1A1s are given the NATO three color paint job during rebuilds. M1s and M1A1s deployed to Desert Storm were hastily painted desert tan. Some, but not all, of these tanks were re-painted to their "authorized" paint scheme. M1A2s built for Middle Eastern countries were painted in desert tan. Some M1 series tanks are being painted desert tan for service in Iraq and some are not. Replacement parts (roadwheels, armor skirt panels, drive sprockets, etc.) are painted overall green, which can sometimes lead to vehicles with a patchwork of green and desert tan parts.
Australian M1A1s were desert tan when delivered but have undergone a transition to the Australian Army vehicle standard 'Disruptive Pattern Camouflage'; a scheme that consists of black, olive drab and brown.
Concealment
The turret is fitted with two six-barreled smoke grenade launchers (USMC M1A1s use an eight-barreled version). These can create a thick smoke that blocks both vision and thermal imaging. The engine is also equipped with a smoke generator that is triggered by the driver. When activated, fuel is sprayed into the hot turbine exhaust, creating the thick smoke. However, due to change from diesel as a primary fuel to the use of JP-8, this system is disabled on most Abrams today because of a slightly elevated risk of fire damage to the engine compartment.Active protection system
In addition to the armor, some Abrams are equipped with a Softkill Active protection system, the AN/VLQ-6 Missile Countermeasure Device (MCD) that can impede the function of guidance systems of some semi-active control line-of-sight (SACLOS) wire and radio guided anti-tank missiles (such as the Russian AT-3, AT-4, AT-5, AT-6 and the like) and thermally and infrared guided missiles.The MCD works by emitting a massive, condensed infrared signal to confuse the seeker of an anti-tank guided missile (ATGM). However, the drawback to the system is that the ATGM is not destroyed, it is merely directed away from its intended target, leaving the missile to detonate elsewhere. This device is mounted on the turret roof in front of the loader's hatch, and can lead some people to mistake Abrams fitted with these devices for the M1A2 version, since the Commander's Independent Thermal Viewer on the latter is mounted in the same place, though the MCD is box-shaped and fixed in place as opposed to cylindrical and rotating like the CITV.Armor
The Abrams is protected by armor based on the British-designed Chobham armor, a further development of the British 'Burlington' armor. Chobham is a composite armor formed by spacing multiple layers of various alloys of steel, ceramics, plastic composites, and kevlar, giving an estimated maximum (frontal turret) 1,320–1,620 millimetres (52–64 in) of RHAe versus HEAT (and other chemical energy rounds) and 940–960 mm (37–38 in) versus kinetic energy penetrators. It may also be fitted with reactive armor over the track skirts if needed (as in the Urban Survival Kit) and slat armor over the rear of the tank and rear fuel cells to protect against ATGMs. Protection against spalling is provided by a Kevlar liner. Beginning in 1987, M1A1 tanks received improved armor packages that incorporated depleted uranium (DU) mesh in their armor at the front of the turret and the front of the hull. Armor reinforced in this manner offers significantly increased resistance towards all types of anti-tank weaponry, but at the expense of adding considerable weight to the tank, as depleted uranium is 1.7 times more dense than lead.
The first M1A1 tanks to receive this upgrade were tanks stationed in Germany, since they were the first line of defense against the Soviet Union. US-based tank battalions participating in Operation Desert Storm received an emergency program to upgrade their tanks with depleted uranium armor immediately before the onset of the campaign. M1A2 tanks uniformly incorporate depleted uranium armor, and all M1A1 tanks in active service have been upgraded to this standard as well. The added protection from the depleted uranium armor is believed to be equivalent to 24 inches (610 mm) of RHA. In the Gulf War, Abrams tanks survived multiple hits at relatively close ranges from Iraqi Lion of Babylon tanks and ATGMs. M829A1 "Silver Bullet" APFSDS rounds from other M1A1 Abrams were unable to penetrate the front and side armor (even at close ranges) in friendly fire incidents as well as an incident in which an Abrams tried to destroy an abandoned Abrams stuck in the mud.
Damage control
If the Abrams does suffer damage resulting in a fire in the crew compartment, the tank is equipped with a halon fire-suppression system that automatically engages and extinguishes fires in seconds. The engine compartment is equipped with a second fire-suppression system which is engaged by pulling a T-handle located on the left side of the hull. In addition, several small hand-held fire extinguishers are located in the crew compartment. Fuel and ammunition are in armored compartments with blowout panels to protect the crew from the risk of the tank's own ammunition cooking off if the tank is damaged.Armament
Primary
M68A1 rifled gun
The main armament of the original model M1 was the M68A1 105 mm rifled tank gun firing a variety of high explosive anti-tank, high explosive, white phosphorus and an anti-personnel (multiple flechette) round. This gun is a license-built version of the British Royal Ordnance L7 gun. However, it proved to be inadequate; a cannon with lethality beyond the 3-kilometer (1.9 mi) range was needed to combat newer armor technologies. To attain that lethality, projectile diameter needed to be increased.
- M256 smoothbore gun
The main armament of the M1A1 and M1A2 is the M256A1 120 mm smoothbore gun, designed by Rheinmetall AG of Germany, manufactured under license in the United States by Watervliet Arsenal, New York. The M256A1 is a variant of the Rheinmetall 120 mm L/44 gun carried on the German Leopard 2 on all variants up to the Leopard 2A5. Leopard 2A6 replaced the L/44 barrel with a longer L/55.
The M256A1 fires a variety of rounds. The M829A2 APFSDS round was developed specifically to address the improved protection of a Russian T-72, T-80U or T-90 main battle tank equipped with Kontakt-5Explosive Reactive Armor.Later, the M829A3 APFSDS round was introduced to improve its effectiveness against next generation ERA equipped tanks. As a counter to that, the Russian army introduced
Relikt, the most modern Russian ERA, which is claimed to be twice as effective as Kontakt-5.Development of the M829 series is continuing with the M829E4 currently in development.The Abrams also fires HEAT shaped charge rounds such as the M830, the latest version of which (M830A1) incorporates a sophisticated multi-mode electronic sensing fuse and more fragmentation which allows it to be used effectively against armored vehicles, personnel, and low-flying aircraft. The Abrams uses a manual loader. The fourth tank crew member on the Abrams also provides additional support for maintenance, observation post/listening post (LP/OP) operations, and other tasks.
The new M1028 120 mm anti-personnel canister cartridge was brought into service early for use in the aftermath of the 2003 invasion of Iraq. It contains 1,098 3⁄8-inch (9.5 mm) tungsten balls which spread from the muzzle to produce a shotgun effect lethal out to 600 meters (2,000 ft). The tungsten balls can be used to clear enemy dismounts, break up hasty ambush sites in urban areas, clear defiles, stop infantry attacks and counter-attacks and support friendly infantry assaults by providing covering fire. The canister round is also a highly effective breaching round and can level cinder block walls and knock man-sized holes in reinforced concrete walls for infantry raids at distances up to 75 meters (246 ft). Also in use is the M908 obstacle-reduction round. It is designed to destroy obstacles and barriers. The round is a modified M830A1 with the front fuse replaced by a steel nose to penetrate into the obstacle before detonation.
The Army is developing a new round to replace the M830A1, M1028, and M908. Called the Advanced Multi-Purpose (AMP) round, it will have point detonation, delay, and airburst modes of operation in a single munition. Having one round that does the job of three would simplify logistics and be able to be used on a variety of targets. The AMP is to be effective against bunkers, infantry, light armor, and obstacles. It will be able to breach reinforced concrete walls and defeat ATGM teams beyond 500 meters.
In addition to these, the XM1111 (Mid-Range-Munition Chemical Energy) was also in development. The XM1111 was a guided munition using a dual-mode seeker that combined imaging-infrared and semi-active laser guidance. The MRM-CE was selected over the competing MRM-KE which used a rocket-assisted kinetic energy penetrator. The CE variant was chosen due to its better effects against secondary targets, providing a more versatile weapon. The Army hoped to achieve IOC with the XM1111 by 2013.However, the Mid-Range Munition was cancelled in 2009 along with Future Combat Systems.
Secondary
The Abrams tank has three machine guns:
- A .50 cal. (12.7 mm) M2HB machine gun in front of the commander's hatch. On the M1, M1IP and M1A1, this gun is on a powered mount and can be fired using a 3× magnification sight, known as the Commander's Weapon Station (CWS), while the vehicle is "buttoned up" with all its hatches closed to protect the crew. On the M1A2 and M1A2 SEP, this gun is on a flex mount, the commander having to expose himself to fire the weapon manually. With the TUSK add-on kit, an M2HB or a Mk 19 grenade launcher can be mounted on a CROWS remote weapons platform (similar to the Protector M151 remote weapon station used on the Stryker family of vehicles). However current variants of the TUSK kit on the M1A2 have forgone this, instead adding transparent gun shields to the commander's weapon station. The upgrade variant called M1A1 Abrams Integrated Management (AIM) equips the .50 caliber gun with a thermal sight for accurate night and other low-visibility shooting.
- A 7.62 mm M240 machine gun in front of the loader's hatch on a skate mount (seen at right). Some of these have been fitted with gun shields during the Iraq War, as well as night-vision scopes for low-visibility engagements.
- A second 7.62 mm M240 machine gun in a coaxial mount to the right of the main gun. The coaxial MG is aimed and fired with the same computer fire control system used for the main gun.
- (Optional) A second coaxial 12.7 mm M2HB machine gun can be mounted directly above the main gun in a remote weapons platform as part of the TUSK upgrade kit.
Aiming
The Abrams is equipped with a ballistic fire-control computer that uses user and system-supplied data from a variety of sources, to compute, display, and incorporate the three components of a ballistic solution—lead angle, ammunition type, and range to the target—to accurately fire the tankThese three components are determined using a YAG rod laser rangefinder, crosswind sensor, a pendulum static cant sensor, data concerning performance and flight characteristics of each specific type of round, tank-specific boresight alignment data, ammunition temperature, air temperature, barometric pressure, a muzzle reference system (MRS) that determines and compensates for barrel droop at the muzzle due to gravitational pull and barrel heating due to firing or sunlight, and target speed determined by tracking rate tachometers in the Gunner's or Commander's Controls Handles. All of these factors are computed into a ballistic solution and updated 30 times per second. The updated solution is displayed in the Gunner's or Tank Commander's field of view in the form of a reticle in both day and Thermal modes. The ballistic computer manipulates the turret and a complex arrangement of mirrors so that all one has to do is keep the reticle on the target and fire to achieve a hit. Proper lead and gun tube elevation are applied to the turret by the computer, greatly simplifying the job of the gunner.
The fire-control system uses these data to compute a firing solution for the gunner. The ballistic solution generated ensures a hit percentage greater than 95 percent at nominal ranges. Either the commander or gunner can fire the main gun. Additionally, the Commander's Independent Thermal Viewer (CITV) on the M1A2 can be used to locate targets and pass them on for the gunner to engage while the commander scans for new targets. In the event of a malfunction or damage to the primary sight system, the main and coaxial weapons can be manually aimed using a telescopic scope boresighted to the main gun known as the Gunner's Auxiliary Sight (GAS). The GAS has two interchangeable reticles; one for HEAT and MPAT (MultiPurpose AntiTank) rounds and one for APFSDS and STAFF (Smart Target-Activated Fire and Forget) ammunition. Turret traverse and main gun elevation can be accomplished with manual handles and cranks in the event of a Fire Control System or Hydraulic System failure. The commander's M2 .50 caliber machine gun on the M1 and M1A1 is aimed by a 3× magnification sight incorporated into the Commander's Weapon Station (CWS), while the M1A2 uses either the machine gun's own iron sights, or a remote aiming system such as the CROWS system when used as part of the TUSK (Tank Urban Survival Kit). The loader's M240 machine gun is aimed either with the built-in iron sights or with a thermal scope mounted on the machine gun.
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