M2 / M3 / M5 Stuart Light Tank
The US light tanks of the M2, M3, and M5 series were the first US tanks to see combat. They were used by the British Eighth Army at Sidi Rezegh in November 1941 and by US forces in the Phillipines in 1941-42. They were also the only prewar light tanks to see the war through - every other design was found to be useless in combat.
The James Cunningham and Sons Company, of Rochester, New York, built the first T2 in 1930. With a crew of four, this 15-ton tank was able to reach a top speed of 25mph. The T2 was a well-armed tank, carrying a 47mm gun and a .50 machine-gun in the turret, plus a 37mm gun and .30 machine-gun on the right side of the hull. Production was limited to the prototype model due to funding limitations during the Depression.
The M2 light tank dated back to 1933. From the Infantry's requirements came the T2 tank, with a .50in machine gun in a turret and a .30in machine gun in the hull. Powered by a converted airplane engine of 250hp, it weighed about 6.5 tons. This design, which had been developed at the Rock Island Arsenal, was gradually improved throughout the 1930s, small numbers being built as financing was available.
The T2E1 would become the standardized M2A1 tank, the first tank produced in any numbers in the United States since the WWI period. The Infantry's M2A1 Light Tank can be differentiated from the Cavalry's M1 Combat Car by the vehicles' turrets: the light tank's was cylindrical in cross-section with an extention for the weapons, while the turret of the combat car was either D-shaped or octagonal. The light tank also had a cupola on the left rear of the turret roof. The M2A1's sliding mesh transmission was later replaced by a synchromesh model. A total of 19 were built at the Rock Island Arsenal beginning in 1935.
The T2E2 was the designation given to the twin turret design for the infantry (the only army units technically allowed to own tanks). This unit was later standardized as the M2A2. The M2A2 featured twin turrets placed side-by-side on the hull and was very unofficially dubbed "Mae West," since the turrets gave the tank a passing resemblence to the actress. A vision cupola was installed on the left turret for the tank commander. On early tanks the turrets were cylindrical with an extension on the front for weapon mounting, like those of the M2A1 light tank. Later tanks had turrets comprised of flat vertical armor plates: seven on the small turret and eight for the large turret. Later tanks were also fitted with flat, rather than rounded, engine covers. A total of 237 were built.
On the light tank M2A3 the distance between the bogies was increased. This greater distance between the bogies, combined with longer stroke volute springs, improved the vehicle's ride. The distance between the turrets was also increased. The M2A3's rear hull was redesigned to ease engine maintenance, its gear ratios were increased, and its engine cooling was improved, among other changes. The transmissions in M2A3s were also swapped out for a synchromesh model. A total of 73 were built.
By the spring of 1939 the M2A4, based on M2A3, was the latest Light Tank variant. It had a 37mm gun in a rotating turret, two machine guns mounted in sponsons at the sides of the hull, and a third in the turret alongside the 37mm gun. The new tank's single flat-sided octagonal turret was fitted with a vision cupola in the left rear part of the turret. The armor thickness had been increased to 25mm, and a new syncromesh gearbox installed. This might have followed the same course as its predecessors, with perhaps only a dozen being built. But in September 1939 Germany invaded Poland, and the US suddenly found the money to to equip its army. In early October 1939 the first tank order of the World War II period called for over 300 light (11 ½ tons) M2A4 tanks. The M2A4 tank went into production in April 1940; a total of 375 were eventually built.
M3 Stuart Combat Car
After the German triumph over France in 1940 the US Ordnance Department set about redesigning the M2A4 in the light of reports from the battle area. A much improved light tank, the M3, known in England as the General Stuart, was adopted. Although very similar to the M2A4, the M3 was 3 ½ tons heavier, mounted a 37-mm. gun, and had a maximum speed of 35 miles per hour. The armor was increased to 37mm thickness which, bringing the weight up to over 13 tons, necessitated a longer suspension and track. Other modifications were made so that it eventually became a completely new vehicle - on 5 July 1940 this was standardized as the Light Tank M3, the first model passing from the production line in March 1941.
This tank was built a bit on the heavy side of light tanks of the period as it came complete with a 37mm main gun and five .30cal machine guns (what other "light" tank can claim that). It was also noted for having stronger and heavier armor than it's foreign sisters (10 - 44mm). Fast and reliable, the only downside of this vehicle was that the crew compartment was designed a bit on the clumsy side.
The crew of four consisted of a loader, a gunner, a driver and the co-driver who operated the hull machine gun. The rear idler wheel, unlike most tracked AFVs, was mounted on a trailing arm designed to increase the length of track in contact with the ground. The turret had no basket, which caused the gunner and loader to "walk" with the turret as it turned.
The Mk 1 was gasoline powered and the Mk 2 was diesel powered. Test variations were numbered M3E1, M3E2, M3E3 and mostly centered around diesel versus gasoline engines. No diesel tanks were adopted for US Army use. The M3E2 was a twin Cadillac V8 engine combination driven through twin automatic transmissions. The Ordance Department expressed doubt in the design and so GM had the tank driven from Detroit all the way to Aberdeen under it's own power, achieving 50mph, and with no problems. The M3E1 involved a Cummins Diesel and was rated as "satisfactory" but was "not adopted due to diesel policy". That was a reference to a priority the Navy had on all diesel fuel. The M3E2 went on to become the M5. M3E3 involved tests with a cast homogenous turret, a sloping front plate, storage box, and an attempt to reduce bullet "splash". All M3 tanks were built by American Car & Foundry.
The M3 Stuart played a pivotal role in the early days of WW II. The tank weighed more than 14 tons and had a 4-man crew. The M3 Light tank was standardized in July 1940, and was based on the chassis of the M2 series tanks developed in the late 1930's. The tank that just arrived is the M3A1, a slightly improved version with a better-designed turret, which featured a power traverse and gyro-stabilization.
The M3 was the first tank to be used in combat by the US Army's 1st Armored Division, and was used extensively in the North African campaign against the light skinned Italian armor. The 1st Armored Division defeated at Oran, Algeria, a larger force of Vichy French Renault tanks. With the French surrender, these tanks were used next against the German "Afrika Korps" of Field Marshall Erwin Rommel.
Once Germany moved into Africa with their heavy armor, the Stuart was reduced to a reconnaissance and infiltration role due to its low weight and high speed. In 1942, an improved version was developed with sloping armor. It was designated the M3A3, and was nearly the same as the next version, called the M5. All of these tanks were nicknamed the "General Stuart", after the famous Confederate cavalry commander of the Civil War, J.E.B. Stuart.
M5 Stuart Combat Car
Several design changes resulted in a new model, the M4, but its number was soon changed to the M5 to avoid confusion with the M4 medium tank. Logically, the M3's replacement should have been the M4, however there was already an M4 in production - the M4 "Sherman". A decision was made to name this new model the M5 in an attempt to hold down on confusion. The reasons for making the M5 were many, but the main two were for improvement in design and to address an engine shortage caused by war needs for aircraft engines. The M5 was powered by twin Cadillac V8 engines. The M5's weight was increased to 16 tons and its top speed to 40 miles per hour.
With the approach of war and the acceleration of the US armaments program, many automobile manufacturers were brought into the tank production field bringing with them considerable expertise in mass-production and utilization of components which was new to the armoured vehicle world. One such company, Cadillac Division of General Motors, suggested mounting two Cadillac engines and a Hydromatic transmission in the M3 tank to compensate for the shortage of Continental engines. In October 1941 the company converted a tank and drove it 500 miles to a proving ground to demonstrate it. The trip alone was sufficient to prove the soundness of the idea, and the M3, fitted with the Cadillac engines and transmission, extra thickness of armour and some other changes, was standardized in November 1941 as the Light Tank M5.
It can be seen from the foregoing that all three tanks were closely related, which is why they were call 'Stuart' in British service without any distinction being made. All had a crew of four, a driver, assistant driver/hull gunner, turret gunner, and commander; all mounted a 37mm gun as their principal armament; all had a narrow, boxy hull and a top speed of about 35mph.
With only a 37mm main gun and relatively light armor, the entire Stuart series light tanks were replaced in 1944. With the trend toward heavier tanks and more powerful guns, the M5 was replaced in 1944 by the M24 light tank, mounting a 75-mm. gun and weighing 20 tons. Of 3,427 produced, 2,433 went to the Allies receiving Lease Lend (mainly to Britain but some to China), the rest to the US Army.
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