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M103 (Tank, Combat, Full Tracked, 120-mm, M103) Heavy Tank (1957)

Authored By Staff Writer | Last Updated: 7/1/2014

The M103 Heavy Tank was the culmination of American World War 2 tank experience and appeared only after the Korean War, living a relatively short service life primarily through the USMC.

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The M103 (formally designated as "Tank, Combat, Full Tracked, 120mm, M103") was a heavy tank design of American origination developed to counter the threat posed by the growing number of Soviet systems in use during the early stages of the Cold War. Development began during World War 2 though the project would not come to fruition until the end of the Korean War. The M103 managed a relatively short service life and saw service primarily with elements of the United States Marine Corps though the US Army proved the other notable operator in lesser numbers. No more than 300 units were ever completed and the rise of the Main Battle Tank ended the reign of the dedicated Heavy Tank for the foreseeable future. Designs such as the M103 undoubtedly paved the way for the MBT and proved the necessary stepping stone in the genesis of the modern fighting tank we know today. Many examples exist today as showpieces throughout the United States. A foreign example survived at the famous Bovington Tank Museum in the United Kingdom.

The massive tank clashes that permeated the World War 2 battlescape ushered in all-new developments during the conflict. For the Americans, its star performer became the ubiquitous M4 Sherman with its 75mm main gun, an armament not quite on par with contemporary offerings in Britain, Germany and the Soviet Union but nonetheless adequate. While Shermans were eventually handed the improved 76mm main gun, the M36 Tank Destroyer fielded the evermore powerful 90mm main gun in its open-topped turret and was designed exclusively as a tank destroyer. This proved timely with the arrival of considerably heavier, stouter and more powerful German tanks in the Panzer V "Panther", Tiger I and Tiger II series - the latter two classified as heavy tanks. The Americans were therefore forced to develop heavy-class tanks in turn to help counter the improved armor of the enemy. Additionally, advancing into German-held territories would also call into play fortification-defeating gunnery platforms which was also under consideration by the Allies on a variety of levels.

By the end of the war, the culmination of American tank engineering produced the M26 Pershing Heavy Tank with its 90mm gun and thick armor - a vast improvement over the wartime Shermans. However, these managed only a small role during the final weeks of World War 2 in Europe and were not in play before the fall of Japan in the Pacific. Other imposing heavy tank projects such as the T29 and T30 eventually fell to history leaving the M26 and the various M4 Sherman variants as the primary spearhead of the American army. After the war, the M26, which was initially classified as a heavy tank, was reduced to a medium tank categorization due to a US Army weight restructuring. Many of the earlier M4 Sherman marks were also deemed obsolete as soon as 1946, leaving just the 76mm-armed variants in inventory and reducing capabilities of the US armored corps considerably. At any rate, as the world now fell into a Cold War against the mighty Soviet Union and its legions of tracked armored vehicles, the US armored inventory was woefully under-equipped to combat such beastly creations as the 122mm-armed "Josef Stalin" heavy tank of the Red Army - the IS-3 alone showcasing armor protection some eight inches thick.

The challenge to American vehicle designers now fell on devising a perfect "dual-role" tracked system capable of engaging enemy armor at range while also being able to defeat fortified structures. During World War 2, this largely fell to two different vehicle types which proved logistically unsound in the long run. With the United States Army and Marine Corps now in desperate need for a multirole gunnery platform sporting inherent mobility and strong armor protection, engineers certainly had their work cut out for them. All of this wondering this led to the "T34" proposal which sought to fulfill all of the listed requirements in a single, relatively affordable package. Design work on the new initiative began in 1948.

The T34 plan was then modified to reduce the standard operating crew by one to five personnel. There was a reduction in the proposed vehicle's operating weight to 58 tons which would, in turn, could theoretically provide the needed mobility. Armor protection would reach up to five inches across critical frontal facings and the main gun of choice became a 120mm system recognized under the T122 designation. The weapon was based on a wartime anti-aircraft gun and modified to become the T53E1 in the new design. This long-barrel assembly would be fitted to a heavily sloped and thickly armored turret with a full 360-degree rotation. The chassis was conventional with wide track links, seven double-tired road wheels to a side and a rear-set drive sprocket with forward-mounted track idler. No fewer than six track return rollers were be utilized. The engine was set in a rear compartment while the front of the hull was well sloped with a thick layer of cast armor. A massive T-style muzzle brake would cap the gun. Power would be provided by a Continental AV-1790 12-cylinder, gasoline-fueled engine outputting at 750 horsepower. The T34 proposal was then evolved to become "T43" by December of 1948. A formal request for development - and subsequent production - was signed in May of 1949. Pilot (prototype) vehicles would precede the production models for both the US Army and Marines for evaluation purposes and these would all be led by a wooden mockup which was studied extensively. Some 276 total T43 Heavy Tanks were slated for procurement though this would eventually be affected by outside changes influenced by the political and budgetary landscape.

By this time, the T43 program had begun to streamline itself for ease of production. Many technology-heavy aspects of the original design were dropped including remote-controlled external machine guns, computer assisted fire control and an automatic loader (which increased the operating crew to five personnel). In June of 1950, the communist forces of North Korea invaded the democratic South and brought upon the world its next major war - the Korean War (1950-1953). This placed the obsolete M4 Sherman marks and outdated M26 Pershing marks back into combat while also threatening the future of the now-costly T43. Engineers responded by delivering the M26-related M46 Medium Tank series for the interim while the T43 program managed to survive consistent threats to its very existence.


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Specifications for the
M103 (Tank, Combat, Full Tracked, 120-mm, M103)
Heavy Tank


Country of Origin: United States
Manufacturer: Chrysler Motors - USA
Initial Year of Service: 1957
Production: 300


Focus Model: M103 (Tank, Combat, Full Tracked, 120-mm, M103)
Crew: 5


Overall Length: 37.14ft (11.32m)
Width: 12.34ft (3.76m)
Height: 9.45ft (2.88m)
Weight: 62.5 US Short Tons (56,699kg; 125,000lbs)


Powerplant: M103/A1: 1 x Continental AV-1790 V12 gasoline engine generating 750 horsepower; M103A2: 1 x Continental AV-1790-2 V12 diesel engine generating 810 horsepower.


Maximum Speed: 21mph (34 km/h)
Maximum Range: 81 miles (130 km)


NBC Protection: None
Nightvision: None


Armament:
1 x 120mm main gun in turret
1 x 7.62mm co-axial machine gun in turret
1 x 12.7mm air-defense machine gun on turret roof


Ammunition:
38 x 120mm projectiles
5,250 x 7.62mm ammunition
1,000 x 12.7mm ammunition


Variants:
T43 - Prototype Model Designation


T43E1 - Production Model Designation

M103 - Initial production model designation appearing in 1957; 74 produced from T43E1 design; 2 x coaxial machine guns; gasoline-fueled engine.

M103A1 - Revised variant of 1959; 219 examples converted or rebuilt to new standard featuring new sight and ballistics computer; 1 x coaxial machine gun; new electric turret traverse system; revised turret basket.

M103A2 - Final variant of 1964; 153 examples converted or rebuilt to new standard; new M60 diesel engine powerplant; increased performance specifications; new sight coincidence.


Operators:
United States