M1 Abrams Main Battle Tank (USA)
The M1 Abrams is the culmination of various US attempts to replace the series of tanks starting with the M26 Pershing tank and ending with the M60 Patton tank. Its most immediate ancestor is the MBT-70 programme jointly undertaken by the United States and the Federal Republic of Germany in the late 1960s and early 1970s. This programme came just at a time when a number of advances in tank technology, such as thermal sights, new armour protection, advanced fire controls and turbine engines were starting to come to fruition. The MBT-70 project was designed to cram every last technological advancement into one tank and therefore had more than its fair share of unproven technology. Unfortunately because of this, the time delays inflicted on the programme by having to overcome each technological hurdle meant that the programme's costs had escalated to five times what was agreed upon and subsequently the Federal Republic withdrew from the programme. Congress urged the Army to terminate the programme as the costs of the Vietnam War were cutting into the defence budget. The Army agreed to develop a lower cost version of the MBT-70, the XM803, which dispensed with many of the 'gimmicks' but it too was cancelled. A task force was set up at Fort Knox to study the requirements for a new tank and both General Motors and Chrysler were invited to begin advanced design work. Consideration was given to what armament would be fitted to the new tank. The contenders were the existing M68 105mm rifled gun (developed from the British L7 105mm), a British 110mm design and the German 120mm smoothbore gun. It was decide to stay with the 105mm to maintain standardisation within NATO as the British 110mm offered few advantages over the 105mm and the German 120mm was not expected to be ready in time. The task force also looked at the question of whether to mount the Bushmaster 25mm cannon as secondary armament and to increase the survivability in respect of enemy fire. Two events in 1973 were to have an impact. The first was the discovery at the Royal Armament Research and Development Establishment (RADRE) in the UK of a new form of armour incorporating ceramic layers on top of steel called Chobham after the nearest town. The second was the Yom Kippur War, which involved the latest US tank, the M60A1 in the hands of the Israelis fighting the latest Soviet export tank, the T-62. By the end of 1973, the project had been redesignated XM1 (from XM815) to symbolise that it was a radical new start to American tank design. However, the battlefield lessons of the October 1973 war proved crucial to the XM1 programme. The first lesson was the growing importance of infantry fired shaped-charge warheads (such as the RPG-7 and AT-3 'Sagger') and the impact Chobham armour might have on their effectiveness. The second was that tanks would be likely to engage lightly armoured targets with their main gun as many of them were starting to be equipped with anti-tank missiles, and so the 25mm Bushmaster cannon was deleted. The two prime contractors revised their designs with these in mind. The prototypes were delivered in early 1976 and tests were conducted through until April. The issue was clouded by the Department of Defense requiring testing of the German Leopard 2 to compare it with the contractor designs. It was judged that it would be too expensive to build the Leopard 2 in the United States but the two Governments agreed that they would try and standardise on individual components. In November 1976 the Chrysler prototype was selected to enter Full Scale Engineering Development with Chrylser being awarded a three year US$196.2 million contract to build 11 XM1 pilot vehicles, the first of which was completed in February 1978. The operational tests were conducted by the Operational Test and Evaluation Agency at Fort Bliss, TX. These tests showed that the M1 met or exceeded the operational requirements set in most areas. A number of recommendations were set out though, including new filters to tackle sand ingestion and a simple mudscraper and track tensioner ring to stop mud fowling. Initial low rate production was authorised, and the first 110 tanks were used for extreme weather tests at Yuma, Arizona and the Cold Region Test Centre at Elgin Air Force Base, Alaska. The XM1 was accepted for full production in February 1981 and named after Creighton Abrams, a battalion commander in the 4th Armoured Division during World War 2, head of the US Army in Vietnam during the later stages and a key supporter of the XM1 programme. The M1 Abrams was produced at both the Lima, Ohio and Detroit, Michigan tank plants. The designers had allowed for quite an extensive amount of evolutionary upgrading with the tank, which has been shown by the evolutionary steps from the M1 (in production from February 1981 until February 1985), to the Improved M1 (in production until May 1986), M1A1 (in production from August 1985 until early 1993) and M1A2. The M1A2 upgrade was initially approved in February 1993, with the conversion of 210 vehicles by General Dynamics Land Systems at the Lima Tank Plant. A second phase was authorised in mid-1996 to run from October 1996 until July 2001 with the conversion of a further 580 M1s. Export customers for the M1 Abrams have included Egypt (655), Saudi Arabia (315) and Kuwait (218). The M1A1 has also been bought by the US Marine Corps (221) and a number of US Army vehicles (132) have been transferred as well. The M1A1 proved itself in combat during the Gulf War with four tanks disabled and another four damaged out of 1,955 tanks in the theatre. The hull and turret of the M1 Abrams is made of advanced composite armour, known as Chobham in the UK. The driver sits in the front in a reclining position and steers by rotating a motorcycle type T-bar, which actuates the steering lever on the transmission to produce the steering speed bias of the track. The driver also has three day periscopes, the centre of which can be replaced by an image intensification periscope for night work. The commander and gunner are seated on the right of the turret and the loader on the left. The commander has six periscopes that cover 360 degrees, a day sight (x3 magnification) for the 0.5in M2 machine gun and an optical extension of the gunner's sight. The gunner has a primary sight with duel day optics with magnifications of x10 (narrow view), x3 (wide angle view) and x1 (close-in surveillance) and thermal imaging optics with x10 and x3 magnification. The gunner also has an auxiliary day sight (Kollmorgan Model 939) with a magnification of x8. The fire control system includes a laser range finder, full-solution solid-state computer and stabilised day/thermal night sight (developed by Raytheon). The turret was designed to accept either the 105mm M68E1 rifled gun or the German 120mm smoothbore cannon, designated M256 in US service. The crew is protected from the fuel tanks by an armoured bulkhead, and from the main gun ammunition by sliding doors and armour-protected boxes. The M1 is powered by a Lycoming Textron AGT gas turbine (1,500hp) which delivers more horsepower to the drive sprocket than a diesel due to its lower cooling requirement. The M1 was followed by the Improved M1 (which had improved armour protection), both of which were armed with the 105mm rifled gun and then the M1A1. The M1A1 had the 120mm M256 smoothbore and an integrated NBC system, improved suspension, redesigned road wheels and final drive, redesigned loader's seat, redesigned stowage and new tank commander's panel. A version of the M1A1 with depleted uranium armour was developed to improve survivability well into the 1990s and beyond. The M1A2 has many improvements, including an Improved Commander's Weapon Station (ICWS), Commander's Independent Thermal Viewer (CITV), Inter-Vehicular Information System (IVIS), Position / Navigation System (POS/NAV) and a number of survivability initiatives. There is an additional programme, which seeks to introduce the M1A2 System Enhancement Package into the M1A2 upgrade programme and includes new tactical displays, communications equipment, improved reliability and power distribution. A version of the M1A2 has been developed for the export market and is equipped with a German EuroPowerPack (MTU 883 V-12 diesel engine developing 1,500hp with a Renk HSWL 295 TM automatic transmission). There are a number of specialised vehicles, including the M1 AVLB, Grizzly armoured vehicle and Abrams Recovery Vehicle (marketed by General Dynamics Land Systems for export).
(M1A1) Hull length: 7.92m. Hull width: 3.66m. Height: 2.89m. Crew: 4. Ground Clearance: 0.48m. Weight: 57,150kg (combat). Ground pressure: 0.96kg/sq.cm. Max speed: 67km/h. Max range (internal fuel): up to 465km on road. Armament: 120mm smoothbore main gun, 1 x 7.62mm MG coaxial, 1 x 0.5in MG on commander's cupola, 1 x 7.62mm machine gun for loader.
Modern American Armour , Zaloga, Stephen & Loop, James, Arms and Armour Press, London, 1982.
Zaloga, Stephen & Sarson, Peter.
M1 Abrams Main Battle Tank 1982 - 1992, Osprey UK, London, 1993, New Vanguard Series No. 2.
How to cite this article: Antill, P. (8 March 2001), M1 Abrams Main Battle Tank (USA), http://www.historyofwar.org/articles/weapons_m1abrams.html
