The M1A1 Abrams Main Battle Tank
[Specifications of the M1A1 Abrams] [Tank Table XII] [11M MOSQ] [Canadian Invasion] [Bradley]
Story by SSG Jeff Clayton - Photos by MAJ Philip Logan & courtesy U.S. Army
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- Overview
- Production History
- Armament
- Crew Stations & Fire Control
- Survivability
- The Gulf War Trial By Fire
The purpose of this vehicle is to provide mobile firepower for our 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.
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 our allies as well. The M1A1, currently in service with the Washington Army National Guard. It features a 120mm main gun, and includes many advanced features such as a Nuclear, Biological, Chemical (NBC) Cooling System which allows the tank to operate in a chemical warfare situation, a complete array of state-of-the-art night vision equipment and an automatic fire suppression system. When required, the Abrams may be fitted with "reactive armor" to thwart armor-defeating munitions.
The Washington Army National Guard has currently upgraded it's Abrams fleet to the M1A1, and operates 69 of these tanks in the 1st Battalion, 303rd Armor, headquartered in Yakima, Washington.
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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 Abrams is 26 feet long (over 32' with the gun forward), 12 feet wide, and just under 8 feet high. It's tactical cruising range is approximately 275 miles. Despite it's 63-ton weight, the M1A1 can attain a top speed of nearly 45 miles per hour.
Designed in the 1970's by the Land Systems Division of the General Dynamics Corporation in response to the U.S. Army's MBT-70 program, the first M1 rolled off the assembly line in 1978. After two years of acceptance trials, the first of these vehicles was delivered to the U.S. Army on February 28, 1980. By 1985, evaluations of field service had prompted the first modification requests, and production shifted to the M1A1. The first M1A1's were delivered to units in August of 1985. Over 8,800 M1 and M1A1 tanks have been produced for the U.S. Army and Marine Corps, and the armies of Egypt, Saudi Arabia and Kuwait.
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The main weapon of the M1A1 is the M256 120mm smoothbore cannon, designed by the Rheinmetall Corporation of Germany. 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 U.S., 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 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.
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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 M1A1 is equipped with a 1500 horsepower Lycoming Textron gas turbine engine coupled to an Allison hydrokenetic transmission with four forward and two reverse gears.
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.
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The hull and turret are protected by advanced armor similar to the Chobam armor developed by the British Ministry of Defense. An improvement program will eventually upgrade all M1A1 tanks with steel encased depleted uranium armor. A non-radioactive substance, depleted uranium 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.
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Although fielded in 1980, the Abrams remained untested for over 10 years. When Iraq invaded Kuwait many critiques of the high production cost of the Abrams predicted that America's "supertank" would fall victim to the sand and long months of continuous operation without the luxury of peacetime maintenance facilities. They doubted the combat survivability of the extensive turret electronics. They would soon be proven wrong.
Immediately following President Bush's decision to commit U.S. forces to the Gulf region in defense of Kuwait and Saudi Arabia, American armored units began the difficult process of relocating to the threatened area. Due to the shear size and weight of the Abrams, the C-5 Galaxy, the largest cargo aircraft in the U.S. Air Force inventory, was only able to handle one tank at a time. This meant that nearly all of the Abrams tanks deployed in the Gulf War were shipped by cargo ship. Although slow in coming, the arrival of the Abrams was much welcomed by Allied forces, as it is capable of defeating any tank in the Iraqi inventory.
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The Iraqi Army had a considerable array of tanks, mostly purchased from the former Soviet Union. Chief among these were about 500 T-72's. These modern Soviet tanks were armed with an excellent 125mm smoothbore weapon and had many of the same advanced features found on the Abrams.
Despite it's advanced design, the T-72 proved to be inferior to the M1A1's deployed during the Gulf War, and compared more closely with the older M60A3 tanks used there by the U.S. Marine Corps. In addition, Iraq had a number of earlier Soviet models: perhaps as many as 1,600 T-62 and about 700 T-54, both of which were developed in the 1960's. These tanks were widely regarded as clearly inferior to the Abrams, but were expected to be highly reliable mechanically. Of course, our allies each brought to the fray their own tanks: the British Challenger and the German Leopard are two superb examples of state-of-the-art armor technology. All in all, the Gulf War provided military tacticians with an opportunity to evaluate developments in tank design that had not been available since World War II.
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For months, the American Army had practiced, patrolled and maneuvered in their Abrams tanks, putting thousands of miles and hundreds of hours into their machines. So far they had performed admirably. In fact, in many units, equipment downtime was actually lower that it had been state-side! As diplomatic options failed, one by one, and tensions mounted, it became clear that the real test of this vehicle was finally at hand.
In his book "Desert Victory - The War for Kuwait", author Norman Friedman writes that "The U.S. Army in Saudi Arabia probably had about 1,900 M1A1 tanks. Its ability to fire reliably when moving at speed over rough ground (because of the stabilized gun mount) gave it a capability that proved valuable in the Gulf. The Abrams tank also has… vision devices that proved effective not only at night, but also in the dust and smoke of Kuwaiti daytime. On average, an Abrams outranged an Iraqi tank by about 1,000 meters." The actual numbers of Abrams M1 and M1A1 tanks deployed to the Gulf War (according to official DOD sources) are as follows: A total of 1,848 M1A1 and M1A1 "Heavy Armor" (or HA) tanks were deployed between the U.S. Army and Marine Corp (who fielded 16 M1A1's and 60 M1A1(HA) tanks).
As the Gulf War shifted pace from Operation Desert Shield to Operation Desert Storm, and the preparatory bombardment lifted, U.S. Abrams tanks spearheaded the attack on Iraqi fortifications and engaged enemy tanks whenever and wherever possible.
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Just as they had done in the Iran-Iraq War, the Iraqi Army used it's tanks as fixed anti-tank and artillery pieces, digging them into the ground to reduce target signature. However, this also prevented their quick movement and Allied air power smashed nearly 50% of Iraq's tank threat before Allied armor had moved across the border. After that the Abrams tanks quickly destroyed a number of Iraqi tanks that did manage to go mobile.
The Abrams now began to prove that American dollars had been well spent. Reports indicated that it's thermal sights were unhampered by the clouds of thick black smoke over the battlefield that were the result of burning Kuwaiti oil wells. In fact many Gunners relied on their "night" sights in full daylight. Such was not the case with the sights in the Iraqi tanks, which were being hit from units they could not even see. Concerns about the M1A1's range were eliminated by a massive resupply operation that will be studied for years as a model of tactical efficiency.
During the Gulf War only 18 Abrams tanks were taken out of service due to battle damage: nine were permanent losses, and another nine suffered repairable damage, mostly from mines. Not a single Abrams crewman was lost in the conflict. There were few reports of mechanical failure. U.S. armor commanders maintained an unprecedented 90% operational readiness for their Abrams Main Battle Tanks.
As it turned out the Abrams was money well spent.
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