military knowledge: M1 Abrams Main Battle Tank

The M1 Abrams is an American third-generation main battle tank. It is named after General Creighton Abrams. Highly mobile, designed for modern armored ground warfare, the M1 is well armed and heavily armored. Notable features include the use of a powerful multifuel turbine engine, 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.

Three main versions of the M1 Abrams have been deployed, the M1, M1A1, and M1A2, incorporating improved armament, protection, and electronics. These improvements and other upgrades to in-service tanks have allowed this long-serving vehicle to remain in front-line service. In addition, development of the improved M1A3 version was first publicly disclosed in 2009. Extensive improvements have been implemeted to the latest M1A2SEPV3 version
Approved for production in 1990, the M1A2 represents the U.S. Army’s technological improvement of the basic M1A1 design and the most modern battle tank in the world. Outwardly similar in appearance to the M1A1, the most notable exterior changes on the M1A2 are the redesigned Commander's Weapon Station (CWS) and the addition of a Commander's Independent Thermal Viewer) on the left side of the turret forward of the loader's hatch. Internally, however, the M1A2 has been radically redesigned to take advantage of newer technology.

Most notable of these improvements is the addition of the Inter-Vehicle Information System (IVIS.) The IVIS system allows for the automatic and continual exchange of information between vehicles. By incorporating information provided by an on board Position/Navigation (POSNAV) system, unit commander's can track the location and progress of subordinate elements automatically, without tasking vehicle crews. In addition enemy positions can be identified, plotted and disseminated, while reports and artillery requests can be automatically formatted, transmitted, and processed. Lastly, map graphic control measures and operational orders can be rapidly distributed via the IVIS system.

To ensure information security, all IVIS data transmissions are routed through the M1A2's SINCGARS radio system. Improving on the "hunter-killer" tank commander-gunner target hand off method pioneered on the German Leopard II, the M1A2 takes this a step further by providing the Tank Commander with an independent thermal sight. This CITV sight allows the commander to independently scan for targets in all weather conditions and through battlefield obscurants. In addition to IVIS and the CITV, the M1A2 incorporates a number of additional electronic upgrades. Power distribution throughout the tank has been improved, relying on multiple bus paths so that in the event one conduit is damaged, power may still be delivered to a component via an alternate path. The driver's instrument display has been upgraded to a more detailed digital display and the Gunner's Primary Sight has been stabilized in two axes for increased accuracy.

Approved for implementation in 1995, the M1A2 SEP (System Enhancement Package) is a technology upgrade and standardization program, whereby the Army's fleet of M1s and M1A2s will all be brought to a common standard. Most notable among the modifications will be the introduction of a standard under armor auxiliary power unit and the addition a crew compartment air conditioning and cooling unit.

Other modifications within the vehicle will include upgrades to the IVIS system (color display, full size keyboard, digital mapping and graphics generation capability, and voice recognition capabilities), upgrades to the Gunner's Primary Sight assembly, and improvement in the tank's intercom and radio communications systems. Production of the M1A2 was halted after the initial run of 627 vehicles. As part of the fleet upgrade program, 547 of the Army's current inventory of M1s are being upgraded to M1A2 SEP standards, which will require the complete remanufacturing of the turret, while the current fleet of M1A2s will undergo a retrofit to bring them up to SEP standards.

M1 Abrams

Type	Main battle tank
Place of origin	United States
Service history
In service	1980–present
Used by	See Operators below
Wars	Persian Gulf War War in Afghanistan Iraq War Iraqi Civil War Saudi Arabian–led intervention in Yemen
Production history
Designer	Chrysler Defense (now General Dynamics Land Systems)
Designed	1972–1979
Manufacturer	Lima Army Tank Plant (since 1980) Detroit Arsenal Tank Plant (1982–1996)
Unit cost	US$6.21 million (M1A2 / FY99) Estimated in 2016 as US$8.92 million (with inflation adjustment)
Produced	1979–present
No. built	approx. 10,000
Variants	See variants
Specifications
Weight	M1: 60 short tons (54 t) M1A1: 63 short tons (57 t) M1A2: 72 short tons (65 t)
Length	Gun forward: 32.04 ft (9.77 m) Hull length: 26.02 ft (7.93 m)
Width	12 ft (3.66 m)
Height	8 ft (2.44 m)
Crew	4 (commander/machine gunner, gunner, loader, driver)

Armor	M1, M1A1: Burlington composite armor M1A1HA, M1A2: depleted uranium mesh-reinforced composite armor M1: Hull & turret – 350 mm / 470 mm vs APFSDS, 650 mm / 700 mm vs HEAT M1A1: Hull & turret – 600 mm vs APFSDS, 700 mm vs HEAT M1A1HA: Hull – 600 mm vs APFSDS, 700 mm vs HEAT, Turret – 600 mm / 800 mm vs APFSDS, 1,300 mm vs HEAT
Main armament	M1: 105 mm L/52 M68 rifled gun (55 rounds) M1A1: 120 mm L/44 M256A1 smoothbore gun (40 rounds) M1A2: 120 mm L/44 M256A1 smoothbore gun (42 rounds)
Secondary armament	1 × .50-caliber (12.7 mm) M2HB heavy machine gun with 900 rounds 2 × 7.62 mm (.308 in) M240 machine guns with 10,400 rounds (1 pintle-mounted, 1 coaxial)
Engine	Honeywell AGT1500C multi-fuel turbine engine 1,500 shp (1,120 kW)
Power/weight	From 26.9 hp/t (20.05 kW/t) to 23.8 hp/t (17.74 kW/t)
Transmission	Allison DDA X-1100-3B
Suspension	High-hardness-steel torsion bars with rotary shock absorbers
Ground clearance	M1, M1A1: 0.48 m (1 ft 7 in) M1A2: 0.43 m (1 ft 5 in)
Fuel capacity	500 US gallons (1,900 l; 420 imp gal)
Operational range	M1A2: 426 km (265 mi)
Speed	M1A1: Road 45 mph (72 km/h) (governed); Off-road: 30 mph (48 km/h) M1A2: Road 42 mph (67 km/h) (governed); Off-road: 25 mph (40 km/h)