M103 (heavy tank)

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M103 heavy tank
An M103A2 in the Lewis Army Museum in 2015
TypeHeavy tank[1]
Place of originUnited States
Service history
In service1957–1974
Production history
ManufacturerChrysler
No. built300
VariantsM103A1, M103A2
Specifications
Mass65 short tons (58 long tons; 59 t)
Length37 ft 2 in (11.33 m)
Width12 ft 2 in (3.71 m)
Height10 ft 6 in (3.20 m)
Crew5 (commander, gunner, driver, 2 loaders)

Armor127 mm (5 in) @ 60 degrees[2]
254 mm LoS (10 in)
Main
armament
120 mm gun M58, 34 rounds
Secondary
armament
2×.30-cal (7.62 mm) M1919A4E1 machine gun
(co-axial)
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
750hp (560kW)
Power/weightM103A2: 12.7 hp (9.5 kW) / tonne
TransmissionGeneral Motors CD-850-4A or -4B, 2 ranges forward, 1 reverse
Suspensiontorsion bar
Fuel capacity280 US gallons (710 liters)
Operational
range
M103: 80 mi (130 km)
M103A2: 295 mi (480 km)
SpeedM103: 21 mph (34 km/h)
M103A2: 23 mph (37 km/h)

The M103 Heavy Tank (officially designated 120mm Gun Combat Tank M103, initially T43)[3] was a military vehicle that served in the United States Army and the United States Marine Corps during the Cold War. The last M103s were withdrawn from service in 1974. The M103 was the last heavy tank to be used by the US military as the concept of the main battle tank evolved, making heavy tanks obsolete.

Background[edit]

The heavy type tank had never encountered supporters in the US Army. During World War Two introducing a new heavy tank when US Army standardization was focused on the medium tank was seen as a problem. Besides this heavy German tanks were faced by only a few M26 Pershing tanks without providing enough evidence it was really the answer to them. After the war infantry antitank weapons, air power and a new generation of US medium tanks based on the M26 seemed to be the future for US planners.

However, Cold War started and the Soviet heavy tanks became the new threat. They had been designed to deal with the very same German heavy tanks US Army had faced. Some generals panicked in the Pentagon when they analyzed the IS-3 and IS-4 tanks with its strong sloped frontal armor and 122 mm. gun. To make things worse intelligence analysts claimed they were the standard Soviet tanks and thousands of them were in service. The same analysis urged the British Army to induct in service the Conqueror tank, even the French wanted to introduce in service the AMX-50 heavy tank. It should not be forgotten that some generals in the U.S. Army had always regretted the decision not to build heavy tanks in World War Two. They remembered how Soviet heavy tanks had been pulverized by heavy German tanks, which had a big gun and thick armor. So it was clear for these generals a US Tiger was the answer for winning World War III. M-26 Pershing was considered a heavy tank in 1945, but it was now considered outmuscled to match Soviet tanks.

In parallel US tests with 90 and 120 mm new guns ended with a more reliable gun, T122/123, and HEAT ammunition tests with the T153 round. This meant a bigger gun and round could be allocated to a new heavy tank design. US Army decided to go ahead with a new long-range 120 mm cannon design, capable of hitting enemy tanks at extreme ranges. This gun was consistent with US Doctrine as the new gun should allow decreasing US heavy tank hull armor, and therefore preserving mobility as new tank design should also maximize sloping effectiveness with an eye to save thickness and weight. The new T122 main gun matched the heavy tank request, combining them would give the heavy tank US generals wanted.

Design and development[edit]

In December 1950 the Army made blueprints for a heavy tank reference design.[4] In January 1951 the Army awarded Chrysler a $99 million contract to produce the tank.[5] Chrysler tasked Robert T. Keller, the son of Chrysler Board Chairman K.T. Keller, with overseeing the design of the tank and construction of the Newark tank plant that would be used to produce it.[4]

The first T43 pilot model was completed in November 1951 at the newly built Chrysler tank plant in Newark, Delaware. Officials said the tank would "out-slug any land-fighting machine ever built."[6]

Like the contemporary British Conqueror tank, the M103 was designed to counter Soviet heavy tanks, such as the later IS-series tanks or the T-10 if conflict with the Soviets 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 at the Newark plant. Specifics about the tank, including production plans and specifications, were kept secret. Seeking to keep the tank out of public sight, Secretary of Defense Charles E. Wilson nixed an October 1953 exhibition for the American Ordinance Association at Aberdeen Proving Ground.[7] In May 1954 the tank was debuted publicly at a demonstration at the Newark tank plant.[8]

In 1953 the Pentagon began a reversal of the President Truman administration policy of a broad production base in favor of Wilson's "single, efficient producer" concept. In September Wilson chose General Motors over Chrysler to take over production of the M48 Patton. General Motors would become heir to any additional T43 orders after Chrysler tank production wrapped up in June 1954.[9]

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, in April 1956 the tank was designated the M103 Heavy Tank.[10] 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.

A House Government Operations subcommittee report in July 1957 called for the heavy tank program to be audited. Investigators had been unable to determine the cost of the program, which was estimated in the hundreds of millions of dollars. The report said the Army had hastened production of the tank for war in Korea despite there being no need for it there. The tank was also unsuited to the rigors of the nuclear battlefield, the report said.[11]

Following contemporary American design philosophy, the M103 was built with a two-piece, cast elliptic armor scheme, similar to the M48's design. It featured seven road wheels per side, mounted with long-arm independent torsion bars. The 28-inch (71 cm) track was shoed in steel backed rubber chevron tracks, allowing for a ground pressure of 12.9 psi. The Continental AV-1790 engine was placed at the rear of the tank, and produced a maximum output of 810 horsepower (600 kW) and 1,600 pound force-feet (2,200 N⋅m) of torque, fed through a General Motors CD-850-4 two-speed transmission. This allowed the 60-ton heavy tank to achieve a maximum road speed of 34 kilometres per hour (21 mph) and a maximum climbing gradient of 60%.

Initial production versions suffered a host of drivetrain mechanical problems. The Continental powerpack, shared by the much lighter M48/M60 tanks, was insufficient to drive the much heavier M103. The resulting performance of the tank was dismal; being severely underpowered and very fuel intensive. This presented a host of logistical problems for the vehicle, most prominently the extremely limited range of just 80 miles (130 km). Though this was partially corrected with the introduction of the AV-1790-2 diesel unit, it would remain cumbersome and fuel-thirsty for the majority of its service life.

For ease of production, many of the large components of the tank were made from cast armor. This design scheme was also much more mass efficient than traditional rolled plate armor. Despite being better protected than the T29-series of prototypes which preceded it, the M103 was nearly 10 tons lighter, making it competitive with the Soviet T-10/IS-8 tank. The frontal hull glacis was a compound pike, welded at the center seam, with up to 10 inches thick armor at the front. The turret was a massive single-piece cast design, fitted with heavily sloped 10-inch (250 mm) rolled-homogenous armor.

The M103 was designed to mount the 120 mm M58 gun, fitted in the M89 turret mount. Using standard Armor-Piercing Ballistic Cap Tracer Rounds, it was capable of penetrating 221-millimetre (8.7 in) of 30-degree sloped rolled-homogenous armor at 1,000 yards and 196-millimetre (7.7 in) at 2,000 yards. It could also penetrate 124-millimetre (4.9 in) 60-degree sloped rolled-homogenous armor at 1,000 yards and 114-millimetre (4.5 in) at 2,000 yards. The commander could select from 34 rounds of either M358 Armor-Piercing Ballistic Cap Tracer Rounds or M469 HEAT shells, mounted at the rear of the turret and in the hull. With both loaders, the maximum firing rate of the gun was five rounds per minute, owing to the design of the two-piece ammunition. Using the electrohydraulic turret traverse, the gunner could turn the turret at 18 degrees per second, with 15 degrees of elevation and 8 degrees of gun depression.

The armor was made from welded rolled and cast homogeneous steel of varying thickness.

The crew of an M103A1 consisted of the driver (1), the gunner (2), the two loaders (3 & 4) and the commander (5).
Armor[12]
Aspect Thickness Angle to vertical
Hull front, upper 5 inches (127 mm) 60 degrees
Hull front, lower 4.5 inches (114 mm) 50 degrees
Hull side, upper equals 2 inches (51 mm) 40 degrees
Hull side, lower equals 1.75 inches (44 mm) 30 degrees
Hull top 1 inch (25 mm) 90 degrees
Hull floor, front 1.5 inches (38 mm) 90 degrees
Hull floor, rear 1.25 inches (32 mm) 90 degrees
Turret mantlet 10 to 4 inches (254 mm to 102 mm) 0 to 45 degrees
Turret front 5 inches (127 mm) 50 degrees
Turret side 5.38 to 2.78 inches (137 mm to 70 mm) 20 to 40 degrees
Turret rear 2 inches (51 mm) 40 degrees
Turret top 1.5 inches (38 mm) 85 to 90 degrees

Service[edit]

A Marine M103 on American-Spanish naval exercises, October 1964

US Army 7th Army wanted the new heavy tank to supplement its M48 tanks. 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.[3] 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). One of the flaws of M-103 vehicle was it did not have adequate reliability in retreat operations. US Army was aware that more Tiger tanks had been lost during retreat operations that during actual combat, and US Army in Europe could not afford that. In Europe it was found that the engine was underpowered, requiring replacement of engines and transmissions after only about 500 miles. The ammunition stowage was not convenient and repeated firing caused excess chamber erosion, tracks were easily thrown. Last but not least crew safety, comfort and ability to function were impaired by poor interior arrangement. M-103 career was over when US Army shifted to the Main Battle Tank concept, in which a single M-60 tank model fulfilled the breakthrough functions of M-103 heavy tank while retaining the mobility of M-48 medium tanks. By that time it was years since US Army had realized Soviet heavy tanks were not as potent as suspected, and thus the M103s were rather overkill and expensive to deal with T-54/55 tanks.

The US Marine Corps assigned one M103 company to each of its three Marine tank battalions, including its Marine reserve units.[13] 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.[14] Although the later 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.

Ammunition[edit]

US Marine Corps staff sergeant holding M356 HE-T from 1st Tank Battalion in 1959.

The ammunition fired by the M103's M58 cannon

  • M358 APBC-T
  • M356 HE-T
  • M357 WP-T
  • M359E2
  • M469 HEAT-T

Variants[edit]

M103A2 im Bovington Tank Museum
  • T43 – Six pilot vehicles produced in 1951.[15]
  • 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.[16]
  • Manned Evasive Target Tank M103A2s modified in 1977 for use as targets in training TOW missile crews (firing dummy warheads).[17]

Operators[edit]

  • United States
    • The U.S. Army operated 80 T43E1 tanks, 74 of them were later converted to the M103 standard.
    • The U.S. Marines operated 220 T43E1 tanks, 219 of them which were later converted to the M103A1 then 154 were rebuilt to the M103A2 standard.

Surviving examples[edit]

M103A2 at Ft. Lewis
M103A2 heavy tank in front of Armed Forces Reserve Center Syracuse
M103 tank at Camp Roberts Historical Museum

There are several M103s in existence, including the late M103A2 version.

Where Model
Range 408A, Camp Pendleton, California Blown out, former practice target, now a rattlesnake nest
U.S. Army Ordnance Center and Museum at the Aberdeen Proving Grounds M103
Radcliff, Kentucky M103
Shively, Kentucky M103A2
Rod Lowe Post #124 American Legion, Greensburg, Kentucky M103A1
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, California
Newman Park, Sweetwater, Texas non-functioning
Pioneer Park, Nacogdoches, Texas non-functioning
Euclid City Hall, E. 222nd Street. Euclid, Ohio
Heritage Center of the Yuma Proving Ground, Yuma, Arizona
Dugway Proving Ground, Utah M103 hulk for testing
Former VFW in Anniston, Alabama
The Tank Museum, Bovington, UK M103A2, running condition
American Armor Foundation Tank Museum, Danville, Virginia
United States Army TACOM Life Cycle Management Command, Warren, Michigan
Camp Shelby, Mississippi M103
National Armor & Cavalry Museum, Fort Benning, Georgia M103A1, M103A2, T43 & M51
Range 68 MOUT site, Fort Bragg, North Carolina non-functioning
US Marine Corps Reserve Center, Yakima, Washington. This command has been moved onto the Yakima Firing Center, and they took their display tanks with them. They are no longer publicly accessible. The M103 is at 46°40'59.99"N 120° 27'10.94"W M103A2
A second vehicle is on display behind the old Marine Reserve Center, Yakima WA, at the Calvary Cemetery, at 46°34'28.79" 120°32'21.26"W M103A2
Institute of Military Technology, Titusville, Florida M103A2
Clay County Veterans Memorial in Lineville City Park, Lineville, Alabama
Camp Roberts Historical Museum, Camp Roberts, California non-functioning

References[edit]

  1. ^ Hunnicutt (1984), p. 35.
  2. ^ Hunnicutt, R.P. Firepower. Presidio. p. 114.
  3. ^ a b Hunnicutt (1988), p. 134
  4. ^ a b Palmer, C.B. (27 April 1951). "Fifty-Ton Monsters With a Mighty Punch". The New York Times. Retrieved 24 August 2018.
  5. ^ Abel, Elie (19 January 1951). "Chrysler to Build a New Super-tank". The New York Times. Retrieved 25 August 2018.
  6. ^ "Super-Tank--It Will 'Outslug Anything'-- Built 10 Months After Plant Was Started". The New York Times. 19 December 1951. Retrieved 24 August 2018.
  7. ^ "New Tank Display Vetoed by Wilson". The New York Times. 4 October 1953. Retrieved 25 August 2018.
  8. ^ Weart, William G. (14 May 1954). "Long-Secret Tank Tested In Public". The New York Times. Retrieved 25 August 2018.
  9. ^ Abel, Elie (12 September 1953). "G. M. Is Heir to New Orders". The New York Times. Retrieved 25 August 2018.
  10. ^ Hunnicutt (1984) p. 124.
  11. ^ Trussell, C.P. (31 July 1957). "Tank Order Held a Costly Failure". The New York Times. Retrieved 25 August 2018.
  12. ^ Hunnicutt, R.P. Firepower. Presidio. p. 205.
  13. ^ Hunnicutt (1988), p. 140
  14. ^ Hunnicutt (1984), p. 78.
  15. ^ Hunnicutt (1984) p. 115.
  16. ^ Hunnicutt (1984), pp. 161–162.
  17. ^ Hunnicutt (1984), p. 160.

Bibliography[edit]

  • Hunnicutt, R. P. Firepower: A History of the American Heavy Tank. 1988; Presidio Press. ISBN 0-89141-304-9.
  • Hunnicutt, R. P. Patton: A History of the American Main Battle Tank. 1984; Presidio Press. ISBN 0-89141-230-1.