M103 heavy tank

Heavy Tank M103

An M103A2 at Bovington tank museum in the UK
Type Heavy tank[1]
Place of origin United States
Service history
In service 1957–74
Wars Vietnam war
Production history
Manufacturer Chrysler
Number built 300
Variants M103A1, M103A2
Specifications
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 180 mm (7.1 in) or 7.34 in (186 mm)
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/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
Suspension torsion bar
Fuel capacity 280 US gallons (710 liters)
Operational
range
 M103: 80 mi (130 km)
M103A2: 295 mi (480 km)
Speed M103: 21 mph (34 km/h)
M103A2: 23 mph (37 km/h)

The Heavy Tank M103 served the United States Army and the United States Marine Corps during the Cold War. Until the development of the M1 Abrams in the mid-1970s, it was the heaviest and most heavily armed tank in US service. The M103 was manufactured at the Detroit Arsenal Tank Plant and the first units were accepted in 1957. The last M103s were withdrawn from service in 1974.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..[2] 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.

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.

Armor

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

Aspect mm inches
Hull front 127 (flat), 114 (angled) 5 (flat), 4.48 (angled)
Hull side 50 2
Hull top 25 1
Turret mantlet 245 9.7
Turret front 127 5
Turret side 70 2.75
Turret top 38 1.5

Service

In Europe, the US Army fielded only one battalion of heavy tanks, from January 1958, originally assigned to the 899th Armor, 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). The US Marine Corps assigned one M103 company to each of its 3 Marine tank battalions, including its Marine reserve units.[4] 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.[5] Although the 21st century's M1 Abrams main battle tank utilizes the same caliber of main gun, 120mm, 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 120mm 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 120mm shell casing is consumed during firing.

Ammunition fired by the M103's M58 cannon included:

Variants

Operators

 United States

Surviving examples

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

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

Notes

  1. ↑ Hunnicutt, p. 35
  2. ↑ Hunnicut p124
  3. ↑ Hunnicutt/Firepower, p. 134
  4. ↑ Hunnicutt/Firepower, p. 140
  5. ↑ Hunnicutt
  6. ↑ Hunnicutt p115
  7. ↑ Hunnicut p161-162
  8. ↑ Hunnicut p160

References

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