M103 heavy tank
|Heavy Tank M103|
An M103A2 at The Tank Museum in the UK
|Place of origin||United States|
|Weight||65 short tons (58 long tons; 59 t)|
|Length||22 ft 8 in (6.91 m)|
|Width||12 ft 2 in (3.71 m)|
|Height||10 ft 6 in (3.20 m)|
|Crew||5 (commander, gunner, driver, 2 loaders)|
|Armor||254 mm (10 in)|
|120 mm gun M58, 34 rounds|
|2×.30-cal (7.62 mm) M1919A4E1 machine gun
1×.50-cal (12.7 mm) M2 AA machine gun
|Engine||(M103A1) Continental AV1790 12-cylinder air-cooled gasoline
810 hp (604 kW) (M103A2) Continental AVDS-1790-2, V12, air-cooled, twin turbocharged diesel
|Power/weight||M103: 12.4 hp/short ton
M103A2: 11.5 hp/ton
|Transmission||General Motors CD-850-4A or -4B, 2 ranges forward, 1 reverse|
|Fuel capacity||280 US gallons (710 liters)|
|M103: 80 mi (130 km)
M103A2: 295 mi (480 km)
|Speed||M103: 21 mph (34 km/h)
M103A2: 23 mph (37 km/h)
The M103 (officially designated 120mm Gun Combat Tank M103) served the United States Army and the United States Marine Corps during the Cold War. The last M103s were withdrawn from service in 1974.
Design and development
Like the contemporary British Conqueror tank, the M103 was designed to counter Soviet heavy tanks, such as the Joseph Stalin tank or the T-10 if a conventional World War III broke out. Its long-ranged 120 mm cannon was designed to hit enemy tanks at extreme distances. In 1953–54 a series of 300 tanks, initially designated T43E1, were built by Chrysler at the Newark plant. Testing was unsatisfactory; the tanks failing to meet Continental Army Command's standards and the tanks were put into storage in August 1955. After 98 improvement modifications were approved, on 26 April, 1956 the tank was designated the M103 Heavy Tank. Of the 300 T43E1s built, 80 went to the US Army (74 of which were rebuilt to M103 standard), and 220 were accepted by the US Marine Corps, to be used as infantry support, rebuilt to improved M103A1, then M103A2 standards.
The engine and transmission were never modified enough to give the extra power needed for the greater weight of the M103, and as a result, the tank was relatively underpowered and the drive systems were fragile. Early models also suffered from an extremely limited range, which was somewhat rectified in the M103A2 with the addition of the new AVDS-1790-2 diesel engine.
The turret of the M103 was larger than that of the M48 or the M60 to make room for the huge 120 mm gun and the two loaders assigned to it, in addition to the gunner and the commander. The driver sat in the hull. The gun was capable of elevation from +15 to -8 degrees.
The tank was built with a two-piece, cast elliptic armor scheme, similar to the M48’s design. In comparison to traditional welded uniform plate, the design was highly mass efficient, with weight savings estimated to be up to 14 tons. As a result, the tank was both very well protected and lighter than it’s contemporaries. The frontal hull was an compound pike, with a thickness of 10 inches at the center and 5-6 inches at the top and lower glacis. The turret was single-piece cast, and up to 10 inches thick at the direct front, fanning out to 6 inches minimum. The sides and rear, however, were much less armored, with only 2 inches of hull and 5.4 inches of turret RHA. At introduction, it was the heaviest tank ever fielded by the United States.
The armor was made from welded rolled and cast homogeneous steel of varying thickness.
|Hull front||254 (flat), 160 (angled)||10 (flat), 6.29 (angled)|
In Europe, the US Army fielded only one battalion of heavy tanks, from January 1958, originally assigned to the 899th Tank Battalion, later re-designated the 2d Battalion, 33d Armor. The US Army heavy armor battalion, in contrast to other armor units, was organized into four tank companies, composed of six platoons each, of which each platoon contained three M103s, for a total of 18 tanks per company. Standard US Army armor battalions at the time had three companies per battalion, each with three five-tank platoons, with 17 tanks per company (two tanks were in headquarters platoon). The US Marine Corps assigned one M103 company to each of its three Marine tank battalions, including its Marine reserve units. The M103 was never used in combat.
While the US Army deactivated its heavy armor units with the reception of the new M60 series main battle tanks in 1963, the remaining M103s stayed within the US Marine Corps inventory until they began receiving the M60 series main battle tank. With the disappearance of the heavy tank from US forces came the full acceptance of the main battle tank in 1960 for the US Army, and 1973 for the US Marine Corps. Although the 21st century's M1 Abrams main battle tank utilizes the same caliber of main gun, 120 mm, the M103's cannon was a rifled gun firing a separate-loading round, in which the projectile was loaded into the breech, followed by a cartridge case consisting of a brass case, primer, and propellant in a fixed unit. This separate-loading system necessitated the use of two loaders. The only part of the cartridge case consumed during firing was the propellant and a plastic cap on the end of the brass cartridge case. The spent brass cartridge case was ejected after firing. The M1 tank's 120 mm main gun is a smooth bore firing a semi-caseless round, ejecting only a back cap of the original loaded round; the bulk of the M1's 120 mm shell casing is consumed during firing.
The ammunition fired by the M103's M58 cannon included: the APBC-T M358 shot, the HEAT-T M469 shell, the HE-T M356 shell, the TP-T M359E2 shot, and the WP-T M357 shot.
- T43 – Six pilot vehicles produced in 1951.
- T43E1 – 300 built in 1953.
- T43E2 – Two vehicles produced from 1955–56. Turret basket and gunner moved to front of turret. New targeting system (T52 rangefinder, T33 computer, T44 gunners periscopic sight) and hydraulic turret traverse replaced with electric
- M103 – Produced in 1957. 74 converted into other models.
- M103A1 Produced in 1959. 219 converted or rebuilt. New sight (Stereoscopic T52) and M14 ballistic computer. Removed one coaxial machine gun. New turret electric amplidyne system traverse. Turret basket.
- M103A2 Produced 1964. 153 converted or rebuilt. New 750 hp (559 kW) diesel engine from the M60 tank, increasing the road range to 295 mi (480 km) and maximum speed to 23 mph (37 km/h). The M15 Stereoscopic Rangefinder is replaced to M24 Coincidence Rangefinder.
- Heavy Recovery Vehicle M51 Initially built 1954–1955 and modified 1956–58 to bring up to standard. Tank recovery version of the M103 heavy tank. 187 built by Chrysler.
- Manned Evasive Target Tank M103A2s modified in 1977 for use as targets in training TOW missile crews (firing dummy warheads).
- United States
There are several M103s in existence, including the late M103A2 version.
|Range 408A, Camp Pendleton, CA||Blown out, former practice target, now a rattlesnake nest|
|U.S. Army Ordnance Center and Museum at the Aberdeen Proving Grounds||M103|
|Fort Lewis, Washington||M103A2|
|Fort McClellan, Anniston, Alabama||M103A2|
- 45th Infantry Museum, Oklahoma City, Oklahoma (M103A2)
- Armed Forces Center, Syracuse, New York (M103A2)
- Credit Island Park, Davenport, Iowa (M103)
- Military Vehicle Technology Foundation in Portola Valley, California (M103A2)
- 3d Cavalry Regiment Museum, Fort Hood, Texas (M103)
- Marine Corps Mechanized Museum, Camp Pendleton, CA
- Pioneer Park, Nacogdoches, TX (non-functioning)
- Euclid City Hall, E. 222nd Street. Euclid, Ohio
- Heritage Center of the Yuma Proving Ground, Yuma AZ
- Dugway Proving Ground, UT, M103 hulk for testing
- VFW in Anniston, Alabama
- The Tank Museum, Bovington, UK
- American Armor Foundation Tank Museum, Danville, Virginia
- U.S. Army TACOM LCMC, Warren, Michigan
- Camp Shelby, Mississippi (M103)
- National Armor & Cavalry Museum, Fort Benning GA (M103A1, M103A2, T43 & M51)
- Range 68 MOUT site, Fort Bragg, NC (non-functioning)
- US Marine Corps Reserve Center, Yakima WA (M103A2)
- Institute of Military Technology, Titusville, Florida (M103A2)
- Hunnicutt (1984), p. 35.
- Hunnicutt (1988), p. 134
- Hunnicutt (1984) p. 124.
- Hunnicutt (1988), p. 140
- Hunnicutt (1984), p. 78.
- Hunnicutt (1984) p. 115.
- Hunnicutt (1984), pp. 161–162.
- Hunnicutt (1984), p. 160.
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