The
M1 Abrams main battle tank is the principal combat tank of the
United States Army and the
United States Marine Corps, with three main versions being deployed starting in
1980: the
M1,
M1A1, and
M1A2. The latest versions of the M1A2 have a new armor and electronics package. It is named after
General Creighton Abrams, former
Army Chief of Staff and commander of the Army's
37th Armored Regiment.
The M1 Abrams replaced the M60 Patton in US service, as well as the M48A5. It did, however, serve alongside the M60A3, which had entered service just two years before (1978) the M1, for over a decade.
A left front view of the XM1 Abrams tank, which replaced the M60 series, during a demonstration on the test range in 1979.
The M1 Abrams was designed by Chrysler Defense (in 1979, General Dynamics Land Systems Division purchased Chrysler Defense Division) and is currently produced by General Dynamics Corporation in Lima, Ohio, and first entered US Army service in 1980. An improved version of the M1, the M1A1, was introduced in 1985. The M1A1 has the M256 120 mm smoothbore cannon developed by Rheinmetall AG of Germany for the Leopard 2, improved armor, and a CBRN protection system. The M1A2 is a further improvement of the M1A1 with a commander's thermal viewer and weapon station, position navigation equipment, digital data bus and a radio interface unit.
Further upgrades include depleted uranium armor for all variants, a system overhaul that returns all A1s to like-new condition (M1A1 AIM), a digital enhancement package for the A1 (M1A1D), a commonality program to standardize parts between the US Army and the Marine Corps (M1A1HC) and an electronic upgrade for the A2 (M1A2 SEP).
During Operations Desert Shield and Desert Storm and for Bosnia, some M1A1s were modified with armor upgrades. The M1 can be equipped with mine plow and mine roller attachments if needed. The M1 chassis also serves as a basis for the Grizzly combat engineering vehicle and the M104 Wolverine heavy assault bridge.
Over 8,800 M1 and M1A1 tanks have been produced at a cost of $2,350,000-4,300,000 per unit, depending on the variant.
Export variants, with the export armor package and different options (such as multi-fuel diesel engines) of the M1 Abrams are also used by the militaries of:
Armor
The Abrams is protected by Chobham armor, a type of composite armor formed by multiple layers of steel and ceramics. It may also be fitted with reactive armor if needed (as in the Urban Survival Kit). 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. Protection against spalling is provided by a Kevlar liner. Beginning in 1988, 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.
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 tankers 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 armor thickness believed to be equivalent to 24 inches (610 mm) of RHA. The strength of the armor is estimated to be about the same as similar western, contemporary main battle tanks such as the Leopard 2. The M1A1/M1A2 can survive multiple hits from the most powerful tank munitions (including 120 mm depleted uranium APFSDS) and anti-tank missiles.[citation needed] In the Persian Gulf War, Abrams tanks survived multiple hits at relatively close ranges from Iraqi T-72s and ATGMs. M829 "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 another Abrams tried to destroy an Abrams that got stuck in mud and had to be abandoned.
In addition to the Abrams' advanced armor, some Abrams, most notably M1A1s of the US Marine Corps, are equipped with a Missile Countermeasure Device that can detect and jam the guidance systems of laser-guided anti-tank guided missiles (ATGM)[1]. 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.
Armament
Main armament
M68A1 rifled gun
The main armament of the original model M1 was the M68A1 105 mm rifled tank gun firing a variety of HEAT, high explosive, white phosphorus (smoke), and a highly efficient and lethal anti-personnel (multiple flechette) round. This gun is a license-built version of the British Royal Ordnance L7 gun. While being a reliable weapon, the 105 mm was becoming obsolete in the face of advances in armor technology and was installed as a placeholder on the M1 until the M256 120 mm smoothbore could be completed.
M256 smoothbore gun
The main armament of the M1A1 and M1A2 is the M256 120 mm smoothbore gun, designed by Rheinmetall AG of Germany and manufactured under license in the US by General Dynamics Land Systems Division in their plant in Lima, Ohio. It is the same armament carried by the German Leopard 2A5 (L44), and is swappable between tanks with modification, however, the version Leopard 2A6 uses is an improved longer gun (L55). Rounds like the M829A2 were developed specifically to address the threats posed by a T-90 or T-80U tank, given their high level of protection provided the tanks by kontakt-5 Explosive Reactive Armor), and high explosive anti-tank (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 both armored vehicles and personnel and low-flying aircraft. Unlike the Soviet-built tanks it was designed to go up against, the Abrams uses a manual loader rather than an automatic device, due to the belief that having a person reload the gun is faster and more reliable.
The new M1028 120 mm anti-personnel canister cartridge has been brought into service early for use in the aftermath of the 2003 invasion of Iraq. It contains 1,150 ten-millimetre tungsten shot projectiles which spread from the muzzle to produce a shotgun effect lethal out to 500 m. 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 cover-by-fire.
In addition to this the new MRM-KE (Mid-Range-Munition Kinetic Energy) is also in development. Essentially a cannon-fired guided round, it has a range of roughly 12 km and uses a KE warhead which is rocket assisted in its final phase of flight. This is intended to be the best penetrator yet, an improvement over the US 3rd generation DU penetrator (estimated penetration 790mm).
Secondary armament
U.S. Army M1A2 Abrams tanks maneuver in the streets as they conduct a combat patrol in the city of Tall Afar, Iraq, on February 3, 2005. Note the TAGS shield installed on the loader's M240 machine gun.
The Abrams tank has three machine guns:
- A .50 cal. (12.7 mm) M2 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 for short), while the vehicle is buttoned up. On the M1A2 & M1A2SEP, this gun is on a flex mount (seen at right), the Commander having to expose himself to fire the weapon manually. With the forthcoming TUSK addon kit, an M2 or a Mk 19 grenade launcher can be mounted on the CROWS remote weapons platform (similar to the Protector M151 remote weapon station used on the Stryker family of vehicles).
- A 7.62 mm M240 machine gun in front of the loader's hatch on a skate mount.
- A 7.62 mm M240 machine gun in a coaxial mount. The coaxial MG is aimed and fired with the computer fire control system used for the main gun.
The turret is fitted with two six-barreled smoke grenade launchers (USMC Abrams use an eight-barreled version). These can create a thick smoke that blocks both vision and thermal imaging, and can also be armed with chaff. The engine is also equipped with a smoke generator that is triggered by the driver. The Abrams also has provisions for storing an M16 rifle or M4 carbine inside the crew compartment for when they have to leave the protection of the tank under potentially hostile conditions, plus Abrams crews always carry personal sidearms, the M9 Beretta pistols.[citation needed]
Aiming
The Abrams is equipped with a ballistic fire-control computer that uses data from a variety of sources, including the thermal or daylight gunner's primary sight (GPS), a laser rangefinder, a crosswind sensor, a pendulum static cant sensor, data on the ammunition type, ammunition temperature, and a muzzle reference sensor (MRS) that determines barrel drop due to gravity and temperature. The fire-control system uses this 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 can be used to locate targets and pass them on for the gunner to engage while the commander scans for new targets.
[edit] Mobility
The M1 Abrams is powered by a 1500 hp (1119 kW) Honeywell AGT1500 (originally made by Lycoming) gas turbine, and a 6 speed (4 forward, 2 reverse) Allison X-1100-3B Hydro-Kinetic Automatic transmission, giving it a governed top speed of 45 mph (72 km/h) on paved roads, and 30 mph (48 km/h) cross-country. With the engine governor removed, speeds of around 60 mph (100 km/h) are possible on an improved surface; however, damage to the drive train (especially to the tracks) and an increased risk of injuries to the crew can occur at speeds above 45 mph. The tank can be fueled with diesel fuel, kerosene, any grade of MOGAS (motor gasoline), or JP-4 or JP-8 jet fuel; the U.S. Army uses JP-8 jet fuel in order to simplify logistics.
The gas turbine propulsion system has proven quite reliable in practice and combat, but its high fuel consumption is a serious logistic issue (starting up the turbine alone consumes 40 liters of fuel).[citation needed] The high speed, high temperature jet exhaust emitted from the rear of M1 Abrams tanks makes it difficult for the infantry to proceed shadowing the tank in urban combat. The turbine is noisy, comparable to a helicopter engine, although the noise character (pitch) is significantly different from a contemporary diesel tank engine, reducing the audible distance of the sound, thus the nickname, "whispering death". Future US tanks may return to reciprocating engines for propulsion, as 4-stroke diesel engines have proven quite successful in other modern heavy tanks, e.g. the Leopard 2, Challenger 2 and Merkava. The small size, simplicity, power-to-weight ratio, and easy removal/replacement of the turbine powerpack does, however, present significant advantages over any proposed reciprocating replacement.
The Abrams can be carried by the C-5 Galaxy and C-17 Globemaster III. The limited capacity (one combat-ready tank or two transport-ready tanks in a C-5, one combat-ready tank in a C-17) caused serious logistical problems when deploying the tanks for the First Gulf War, though there was enough time for 1,848 tanks to be transported by ship. Tanks shipped in the transport-ready configuration require depot-level maintenance to install a number of sections of armor, and need to be fueled and loaded with ammunition. Tanks shipped in the combat-ready configuration can enter combat immediately
Billed as among the most accurate .44 Magnum revolvers on the regular market, Colt's Anaconda is among the best selling quality large caliber revolvers in the United States. Similar in design to the .357 Colt Python and based on the .357 Colt Trooper, but chambered for a more powerful round, the Anaconda was designed to compete against the Smith and Wesson Model 29 revolver. The Anaconda holds six rounds, and is available with a four, six or eight inch barrel. There was also a version chambered for .45LC, but it is no longer offered . 
