The M1 Abrams Main Battle Tank (MBT) is the namesake of the late General Creighton W. Abrams, former Army Chief of Staff and commander of the 37th Armored Battalion. It is the backbone of the armored forces of the United States military, and several of US allies as well. The purpose of this vehicle is to provide mobile firepower for armored formations of sufficient capability to successfully close with and destroy any opposing armored fighting vehicle in the world, while providing protection for it's crew in any conceivable combat environment. It is capable of engaging the enemy in any weather, day or night on the multi-dimensional, non-linear battlefield using its firepower, manuever, and shock effect. The Abrams Tank System synchronizes its high tempo, distributed manuever via its digitized situational awareness and the fusion of onboard and remote battlefield sensors.

Production of M1A1 tanks for the US Army is complete. Over 8,800 M1 and M1A1 tanks have been produced for the US Army and Marine Corps, and the armies of Egypt, Saudi Arabia and Kuwait. Production of new M1A1 and M1A2 Abrams tanks is in its final phase for Foreign Military Sales. Three versions of the Abrams tank are currently in service the original M1 model, dating from the early 1980s, and two newer versions, designated M1A1 and M1A2. The M1A1 series, produced from 1985 through 1993, replaced the M1’s 105mm main gun with a 120mm gun and incorporated numerous other enhancements, including an improved suspension, a new turret, increased armor protection, and a nuclear-chemical-biological protection system. The newer M1A2 series includes all of the M1A1 features plus a commander’s independent thermal viewer, an independent commander’s weapon station, position navigation equipment, and a digital data bus and radio interface unit providing a common picture among M1A2s on the battlefield.
In lieu of new production, the Army is upgrading approximately 1,000 older M1 tanks to the M1A2 configuration. The Army also initiated a modification program for the M1A2 to enhance its digital command and control capabilities and to add the second generation forward looking infrared (FLIR) sights to improve the tank's fightability and lethality during limited visibility. This system enhancement program will be fielded in the 2000 time frame concurrently with the M2A3 Bradley and other advanced digital systems. The initial M1A2 fielding to the First Calvary Division, Ft. Hood, TX, is underway. The Army will continue to field M1A2s to the CONUS contingency corps and other first to fight units into the next decade.

The M1 series tank is equipped with a 1500 horsepower Lycoming Textron gas turbine engine coupled to an Allison hydrokenetic transmission with four forward and two reverse gears. It's tactical crusing range is approximately 275 miles. Despite it's weight, the M1 can attain a top speed of nearly 72 km/h. The main armament is a 120mm smooth bore cannon, which replaced the 105mm gun on the initial M1 version. It has day/night fire on the move capability which is provided by a laser range finder, thermal imaging night sight, optical day sight, and a digital ballistic computer. Both the fuel and ammunition are compartmented to enhance survivability. The hull and turret are protected by advanced armor similar to the Chobam armor developed by the British Ministry of Defense. When required, the Abrams may be fitted with "reactive armor" to thwart armor-defeating munitions.
 

Specifications
	M1 / IPM1	M1A1	M1A2
Manufacturer	General Dynamics (Land Systems Division)
Crew	4: Commander, Gunner, Loader & Driver
Weight	60 t	63 t	69.54 t
Length (Gun Forward)	9.7 m	9.8 m
Turret Height	2.3 m
Width	3.6 m	3.65 m
Ground Clearance	0.48 m
Ground Pressure	13.1 PSI	13.8 PSI	15.4 PSI
Obstacle Crossing	1.2 m	1.06 m
Vertical Trench	2.7m
Power plant	AGT-1500 turbine engine
Power Rating	1500 HP
Power to Weight Ratio	25 hp/ton	23.8 hp/ton	21.6 hp/ton
Hydro Kinetic Transmission	4 Speed Forward 2 Speed Reverse
Speed - Maximum	72.18 km/h (Governed)	67.3 km/h (Governed)
Speed - Cross Country	48.1 km/h
Speed - 10% Slope	32 km/h		27.2 km/h
Speed - 60% Slope	7.2 km/h		6.5 km/h
Acceleration (0 to 20 mph)	7 Seconds		7.2 Seconds
Cruising Range	441 km		425 km
Main Armament	105mm M68A1 Rifled Cannon	120mm M256 Smooth Bore Cannon
Commander's Weapon	.50 Cal M2 Machinegun
Coaxial Weapon	7.62 M240 Machinegun
Loader's Weapon	7.62 M240 Machinegun on Skate Mount
NBC System	200 SCFM - CleanCooled Air
Inventory	403 USMC
Unit Replacement Cost	$4,300,000

 

M1A1 Abrams

 

The M1A1 is an improved version of the M1 Main Battle Tank (MBT). It includes a 120mm smoothbore main gun, an NBC overpressure protection system, and an improved armor package. This tank significantly increases the capabilities of the Fleet Marine Forces across the full spectrum of conflict in the near and midterm. The M1A1 Tank, in addition to the improved armor, 120mm smoothbore gun and the NBC overpressure system, has a Deep Water Fording Kit (DWFK), a Position Location Reporting Systems (PLRS), enhanced ship tiedowns, Digital Electronic Control Unit (DECU) (which allows significant fuel savings),and Battlefield Override.

The main weapon of the M1A1 is the M256 120mm smoothbore cannon, designed by the Rheinmetall Corporation of Germany. Engagement ranges approaching 4000 meters were successfully demonstrated during Operation Desert Storm. The primary armor-defeating ammunition of this weapon is the armor-piercing, fin-stabilized, discarding sabot (APDS-FS) round, which features a depleted uranium penetrators. Depleted uranium has density two and a half times greater than steel and provides high penetration characteristics. Several other types of ammunition are available as well. It is reliable, deadly accurate and has a "hit/kill ratio" that equals or surpasses any main battle tank armament in the world.As with virtually every tank every fielded by the US, the familiar .50 caliber Browning M2 Heavy Barrel machine gun - the "Ma Duce" - is located in a powered mount at the Commander's station and is equipped with a x3 magnification sight. The Loader is provided with a 7.62mm M240 machine gun, and another M240 is mounted in-line with the main gun of the tank ("coaxially"). It is in a fixed mount and is aimed with the main gun to suppress enemy ground troops.The layout of the Abrams follows classic tank design and accommodates a crew of four: Commander, Gunner, Loader and Driver. The Commander and Gunner are seated on the right side of the turret. The Loader is seated on the left side of the turret, and the Driver is seated at the center front of the hull.

The Commander's station is equipped with six periscopes which provide all round 360 degree view. The Independent Thermal Viewer (ITV) from Texas Instruments provides him with independent, stabilized day and night vision with a 360 degree view, automatic sector scanning, automatic target cueing of the Gunner's sight with no need for verbal communication, and a complete back-up fire control system - the Commander is capable of firing the main gun independent of the Gunner.
The Gunner's Primary Sight-Line of Sight (GPS-LOS), was developed by the Electro-Optical Systems Division of Hughes Aircraft Company. The night vision Thermal Imaging System (TIS), also from Hughes, creates an image based on the differences of heat radiated by objects in the field of view. The thermal image is displayed in the eyepiece of the Gunner's sight together with the range measurement to within 10 meters of accuracy, from a Hughes laser range finder, which is integrated into all of the fire control systems. The Abrams also has an onboard digital fire control computer. Range data from the laser rangefinder is transferred directly to the fire control computer, which automatically calculates the fire control solution. The data includes 1) the lead angle measurement, 2) the bend of the gun measured by the muzzle reference system of the main armament, 3) wind velocity measurement from a wind sensor on the roof of the turret and 4) the data from a pendulum static cant sensor located at the center of the turret roof. The Gunner or Commander manually inputs the data on the ammunition type and temperature, and the barometric pressure and the weapon is prepared for engagement.
The Loader's station is located on the left side of the turret and has no special fire control equipment.
The Driver's station is located at the center front of the hull. The Driver is in a semi-reclined position when his hatch is closed, as it must be whenever the vehicle is in operation. His station is equipped with a standard array of gages and monitors reflecting the condition of vehicle fluid levels, batteries and electrical equipment. The Driver has either three observation periscopes or two periscopes on either side and a central image intensifying ("Starlight") periscope for night vision. The periscopes provide 120 degrees field of view. The Driver's night vision equipment enables the tank to maneuver at normal daytime driving speeds in darkness and in poor visibility conditions such as in the dust and smoke encountered on the battlefield.

The turret is fitted with two six-barreled M250 smoke grenade launchers, one on each side of the main gun. The standard smoke grenade contains a phosphors compound that masks thermal signature of the vehicle to the enemy. A smoke screen can also be laid by an engine operated system.An improvement program will eventually upgrade all M1A1 tanks with steel encased depleted uranium armor, which has a density at least two-and-a-half times greater than steel. The depleted uranium armor will raise the total weight of the Abrams tank to 65 tons, but offers vastly improved protection in the bargain.

The stowage for the main armament ammunition is in armored ammunition boxes behind sliding armor doors. Armor bulkheads separate the crew compartment from the fuel tanks. The tank is equipped with an automatic Halon fire extinguishing system. This system automatically activates within 2 milliseconds of either a flash or a fire within the various compartments of the vehicle. The top panels of the tank are designed to blow outwards in the event of penetration by a HEAT projectile.
Nuclear, Biological and Chemical (NBC) warfare protection is provided by an overpressure clean-air conditioning air system, a radiological warning system, and a chemical agent detector. The crew are individually equipped with protective suits and masks.

The Marine Corps has fielded the M1A1 Common Tank to replace the aging M60A1 Rise/Passive tank. The M1A1 MBT has the capability to conduct operations ashore. It is compatible with all US Navy amphibious ships and craft (to include the LCAC) and Maritime Prepositioning Ships (MPS). The M60 has reached the end of its service life and lacks the capability to survive and to defeat the threats expected to be encountered on the modern battlefield. Due to unique Marine Corps amphibious requirements, and the need for both supportability and interoperability between the Marine Corps and the US Army, the two services agreed to jointly produce the M1A1 Main Battle Tank. During Operation Desert Shield/Storm, the Marine Corps borrowed 60 M1A1s (called the M1A1 Heavy Armor) from the US Army. There were also 16 Marine Corps M1A1 Tanks delivered on an accelerated schedule for employment during the operation. This total of 76 M1A1 tanks was employed by 2d Tank Battalion and elements of 4th Tank Battalion. All loaned tanks were returned to the US Army after Desert Storm. The USMC completed fielding of all tanks, to include active, reserve, MPS, and depot maintenance float (DMF) during FY 96.
 
 

M1A2 Abrams Main Battle Tank

The mission of the M1A2 Abrams tank is to close with and destroy enemy forces using firepower, maneuver, and shock effect. The M1A2 is being fielded to armor battalions and cavalry squadrons of the heavy force. In lieu of new production, the Army is upgrading approximately 1,000 older M1 tanks to the M1A2 configuration. During the Army’s current M1A2 procurement program about 1,000 older, less capable M1 series tanks will be upgraded to the M1A2 configuration and fielded to the active forces. There is currently no plan to field the M1A2 to the ARNG. The Army has procured 62 new tanks in the A2 configuration and as of early 1997 completed the conversion of 368 older M1s to M1A2s. An additional 580 M1s are being upgraded to A2s under a five-year contract awarded in FY 1996, with a total of 998 M1 upgrades planned. In FY 1999, the Army will begin upgrading M1s to the M1A2 System Enhancement Program (SEP) configuration. This sensor also will be added to older M1A2s starting in FY 2001. When the SEP enters production, the Army will have a total of 627 M1A2s, all of which will eventually be converted to the SEP configuration. Further M1A2 improvements, called the System Enhancement Program (SEP), are underway to enhance the tank's digital command and control capabilities and to to improve the tank’s fightability and lethality. M1A2 SEP tanks are scheduled to begin fielding in 3QFY00.

The M1A2 System Enhanced Program (SEP) is an upgrade to the computer core that is in essence of the M1A2 tank. The SEP upgrade includes improved processors, color and high resolution flat panel displays, increased memory capacity, user friendly Soldier Machine Interface (SMI) and an open operating system that will allow for future growth. Major improvements include the integration of the Second Generation Forward Looking Infared (2nd Gen FLIR) sight, the Under Armor Auxiliary Power Unit (UAAPU) and a Thermal Management System (TMS).The 2nd Gen FLIR will replace the existing Thermal Image System (TIS) and the Commander's Independent Thermal Viewer. The incorporation of 2nd Gen FLIR into the M1A2 tank will require replacement of all 1st Gen FLIR components.The UAAPU consist of a turbine engine, a generator, and a hydraulic pump. The generator is capable of producing 6 Kilowatts of electrical power at 214 Amps, 28 vdc, and the hydraulic pump is capable of delivering 10 Kilowatts of hydraulic power. The UAAPU can meet the electrical and hydraulic power to operate all electronic and hydraulic components used during mounted surveilance operations and charge the tank's main batteries. The UAAPU will reduce Operational and Support cost by utilizing the same fuel as the tank at a reduced rate of 3-5 gallons per operational hour. The UAAPU is mounted on the left rear sponson fuel cell area and weighs 510 pounds.The TMS consists of an Air Handling Unit (AHU) and a Vapor Compression System Unit (VCSU) capable of providing 7.5 Kilowatts of cooling capacity for the crew and Line Repairable Units (LRUs). The AHU is mounted in the turret bustle and the VCSU is mounted forward of the Gunner's Primary Sight (GPS). The TMS uses enviromentally friendly R134a refrigerant and propylene glycol/water mixture to maintain the LRU touch temperature at less than 140 degrees Fahrenheit. The TMS is mounted in the left side of turret bussel and weighs 384 pounds.Changes to the M1A2 Abrams Tank contained in the System Enhancement Program (SEP) and "M1A2 Tank FY 2000" configuration are intended to improve lethality, survivability, mobility, sustainability and provide increased situational awareness and command & control enhancements necessary to provide information superiority to the dominant maneuver force. The Abrams Tank and the Bradley Fighting Vehicle are two central components of the dominant maneuver digital force.System Enhancement Program upgrades are intended to:

• improve target detection, recognition and identification with the addition of two 2nd generation FLIRs.
• incorporate an under armor auxiliary power unit to power the tank and sensor suites.
• incorporate a thermal management system to provide crew and electronics cooling.
• increase memory and processor speeds and provide full color map capability.
• provide compatibility with the Army Command and Control Architecture to ensure the ability to share command & control and situational awareness with all components of the combined arms team.

                                                                
Additional weight reduction, embedded battle command, survivability enhancement, signature management, safety improvement, and product upgrade modifications to the M1A2 will comprise the "M1A2 Tank FY 2000" configuration which will be fielded to units of the digital division beginning in FY 2000.The M1A2 IOT&E was conducted from September-December 1993 at Fort Hood, TX and consisted of a gunnery phase and a maneuver phase. The Director determined that the test was adequate, the M1A2 was operationally effective, but not operationally suitable and unsafe. That assessment was based on poor availability and reliability of the tank, instances of the uncommanded tube and turret movement, inadvertent .50 caliber machine gun firing, and hot surfaces which caused contact burns.FOT&E #1 was conducted in September-October 1995 in conjunction with the New Equipment Training for two battalion sized units. Despite assurances from the Army that all corrective actions were applied, numerous instances of uncommanded tube and turret movement, Commander's Independent Display (CID) lockup and contact burns continued during FOT&E #1.