Design of American Heavy Tank

DESIGN OF AMERICAN HEAVY TANK

At the very beginning of his military career in 1942, Tank M4 was considered an excellent combination of reservation, firepower and mobility. 75-mm gun could hit any of the existing Germanic tanks, including the “PzKpfw IV”, his armor will withstand an attack from the standard German 50 mm anti-tank gun “Pak 38″, he had the speed and mobility on rough terrain, comparable to the German tanks, and often better, than the existing British cars. In accordance with the criteria of “combat effectiveness” of ground troops the U.S. M4 proved extremely durable and reliable construction. Tank although intended for use as a U.S. armored divisions and separate tank battalions, it features more suited to the demands of armored divisions. Infantry officers preferred the tank with thicker armor, resistant to enemy anti-tank weapons, even if it meant reducing speed. As a result, the Department of Artillery U.S. Army developed heavy tank M6, which was standardized in February 1942. It was, to put it mildly, a very mediocre car. Pre-war planners committed instructions to limit its width, and the result was tall and clumsy design. His technical reliability was low, and 3-inch gun, though superior to armor penetration 75-mm gun medium tank M4, was clearly inadequate for the heavy tank. Artillery Department continued to remake “Heavy Tank M6″ until the second half of 1943, even with a weak interest of the armed forces.

British armored doctrine was markedly different from the U.S. and included the use of heavy armored tanks to support infantry. By agreement with the Lend-Lease Artillery department began to develop Assault Tank T14, definitely going to meet the needs of the British infantry. He had the same firepower as the Medium Tank M4, but was equipped with a 100-mm front armor, twice thicker than the M4. A year later, in late 1942, the Artillery Department began to explore a similar project for the U.S. Army as a thicker frontal armor. However, since the tank to be used for infantry support, and for other purposes, required a higher mobility, including the maximum speed on highway 35 miles per hour (56 km / h). The project provides more compact than the M4 tank, building, installation of new tank tested at least three different guns, including automatic 75-mm, 3-inch “guns were used and M10 tank destroyers and heavy tanks M6 and a new 76-mm cannon being developed for the tank destroyer M18. The new tank was fitted with a new 500-horsepower Ford V8 “used to mean M4A3 tank and Assault Tank T14.

The new project, called T20, included use of hydro-mechanical transmission of torque to the conversion of such a heavy tank installed on the M6. Later the program was expanded, discussed options with the T22 and T23 manual transmission with electric transmission. In the future, the project become more complex, one of the prototypes, T20E3, was adapted for installation of a new torsion bar suspension instead of conventional weapons for the Department of spring. Another significant difference between the new family of T20 tanks and M4 was the location of the transmission. At M4 transmission was placed in front of the tank, because of which the propeller shaft runs down the center of the fighting compartment and forced to lift the tower. This led to more high-profile case, larger amounts of body weight, and more (note: The high silhouette of the M4 was called by no means the passage of propeller shaft on the floor of the fighting compartment. “Panther” Forward power-train does not hurt to have a sufficiently low silhouette. But the M4 kardan was not parallel to the floor, but with a slope that forced excessively raise Polikom tower and the tower itself. This is a consequence of poorly thought-out layout). With the deployment of transmission in the stern of the distance between the bottom of the shell and roof of the tower could be reduced. Lowering the silhouette of the tank allowed to reduce the internal volume of the body and increase the thickness of the reservation without a strong increase in the total weight of the tank. In addition, the tank became less noticeable on the battlefield.

Work on the T20, T22, and T23 were in the spring of 1943. Of all the projects, the only one worthy of serious attention of the U.S. Army was T23. Although he had some significant advantages over the tank M4, there were some problems. At T23 the use of electric transmission, which added approximately 1.9 tons to the weight of the tank compared with more traditional options. Electrical transmission experimented with tanks from the French by Saint Chaumont “(St. Chamond) during World War II, the Germans experimented with a similar system for its fighter tanks “Elefant “. Regular gasoline engine was connected to an electric generator, which handed power to the electric traction motors, driving the tracks. In the theory of electrical transmission promised to transfer more power from the engine to the drive wheel, but virtually all of these projects proved difficult and expensive.

In April 1943, an experimental model showed the command of the U.S. Army, including Army Chief of Staff Gen. George C. Marshall, Army Chief Lieutenant-General Leslie McNair and the commander of armored forces, Lieutenant General Jacob Devers. New M6 heavy tank and Medium Tank M7, a failure, clearing the way for a new tank design. Department of Arms claimed that T23 is ready for production, even though the test has not yet begun. They came to an informal agreement on the construction of 250 tanks T23.

By the time of the beginning of serious work on the pilot model T23E3 American army participated in his first major tank battles in North Africa. Defeat in the aisle Kasserine in Tunisia in February 1943 was not attributable to the quality of the tank, soon found the cause of the inexperience of American crews and commanders. During the Tunisian campaign, the U.S. army first encountered the new German heavy tank “Tiger”. “Tiger” was much more powerful medium tank M4 and the M4 could strike at any distance of a real battle, at the same time, being immune to fire 75-mm gun tank M4 except shooting at close range or from behind. Fortunately, the “Tiger” has been deployed in very small quantities and rarely seen on the battlefield.

Contact with “Tiger” has led to a reassessment of the project T23E3. Tankers have changed their opinion about the car, requiring a more powerful armor and defensive weaponry. Nevertheless T23 remained beloved child Ordnance Department, and the production of 250 tanks, launched in November 1943 lasted until December 1944. However, taking into account the views of armored forces, in May 1943 have developed two branches of the family T20. T25 was equipped with a 3-inch (75 mm) frontal armor, weighs 36 tons and was armed with 90-mm cannon. T26 was, in essence, similar to the first, but with a 4-inch (100 mm) frontal armor and weight 40 tons. T23 test in summer 1943 revealed serious shortcomings of the electric transmission, and although some experimental models T25 and T26 were built with electric transmission, it became clear that this impasse, and the main efforts were focused on the development of T25E1 and T26E1 with hydraulic transmission. The latter used liquid transformer and a planetary transmission with manual switching speeds. From February to May 1944 the company “Grand Blanc Tank Arsenal had finished only 40 prototypes T25E1 and 10 T26E1.

For scheduled for the summer 1944 invasion of France the U.S. Army began the final steps to prepare their forces for combat operations in the main European Theater of Operations. The new tank had to be ready at the end of 1943, otherwise there was little chance of its commissioning by next summer. Former head of the armored forces, Lieutenant General Devers was the interim commander of U.S. forces in the European theater until the subsequent appointment of Eisenhower. Devers was well aware that U.S. forces are once again faced with the “Tigers” in Sicily in July 1943, and really wanted to be sure that they will be able to cope with this threat. He demanded that work on T26E1 been accelerated and that 250 cars were produced as quickly as possible in the ratio of one to five medium tanks of the M4. Department agreed the arms, but wanted to release more and 1000 T23. Ministry of Defense sent these conflicting advice army for review, but Lt. Gen. McNair rejected the request. His explanations helped shed light on a formal policy of the U.S. Army at that time. The general said: “The Tank M4, especially the M4A3, today was declared the best tanks. There are indications that the enemy thinks so. Obviously, the M4 is an ideal combination of mobility, reliability, speed, armor protection and firepower. In this strange, representing British view on the issue, nor a request from one theater has been received certificates of need for 90-mm tank gun. In my opinion, no fear of the Germanic tanks T. VI ( “Tiger”), our troops do not experience … There is no basis for the production of the tank T26 is not and can not be, but the concept of the tank, tank destroyer, which, I believe, is unreasonable and not necessary. And the British and American combat experience has demonstrated that anti-tank guns in sufficient quantities and properly selected positions completely superior to the tanks. Any attempt to a highly armored and armed tanks, antitank gun capable of surpass inevitably leads to failure. There is no evidence that the 76-mm antitank gun was inadequate against German T. VI ( “Tiger”). “

In addition to its technical ignorance, argumentation McNair reflects complacency and smugness, present in U.S. Army doctrine to the invasion of Normandy. McNair was not alone in his confidence, the idea that the 76-mm gun is fully capable to cope with the “Tiger”, widely current in the American Army in 1943, although it was completely wrong. Tankers do not support the complete replacement of 75-mm cannon, 76-mm gun, agreed only to supplement the tank park at a ratio of approximately one tank with 76-mm gun on the three conventional tank with 75-mm cannon. In armored forces believed that the only advantage of 76-mm gun consisted of a few more armor penetration, the power of high-explosive fragmentation projectile was lower. In addition, the gun gave a strong muzzle flash of flame that the precise targeting of the second shell was made problematic. Preferred the old 75-mm gun was based on the doctrine that the primary role of the tank is fighting with the infantry and gun emplacements, and fight against tanks secondary task. 76-mm gun firing armor-piercing projectile M62 APC (Armor-piercing, capped), had a nominal armor at a distance of 500 yards, 109 mm at an angle of 20 degrees. Mask gun “Tiger” was a 120-mm thickness, forehead shell had a thickness of 100 mm. In practice, the 76-mm gun could penetrate the mask of the gun “Tiger” at a distance of 100 meters or less, and housing at a distance of 400 m, while “Tiger” could penetrate the armor M4 “Sherman” at twice the distance. Before the end of 1944 in the small quantities of the new 76-mm “hypervelocity, armor-piercing projectile (HVAP) 76-mm gun was usually ineffective in the battle against the” Tiger “.

While McNair continued to talk about the effectiveness of tank destroyers, to confirm his argument had nothing. Activities tank destroyers in Tunisia is not impressive, though McNair is carried on through the use of improper tactics. However, the problem lay in the concept. The idea of a tank destroyer appeared in the summer of 1940, as a possible antidote German blitzkrieg in the war with France. According to this concept, towed or self-propelled tank destroyers would be placed in the reserve corps, and at the right moment to put forward en masse to reflect German tank breakthrough. In fact, the defensive nature of these tactics to undermine its value to the U.S. Army in 1944, as the place remained obscure and objectives fighter tanks in an offensive mobile warfare. In the fighting in 1944 the German tanks are rarely used in large masses of tanks and fighter jets are often not kept pace with where they were needed. After the war, the concept of tank destroyer refused, as from a failure.

Dull convinced military commanders in the adequacy of 76-mm cannon embarrassed combatant commanders, who might otherwise have supported the request Devers production T26E1. In December 1943, Eisenhower refused to support the request for T26E1, as his only advantage to rely more strongly booking. He saw no need for such a heavy tank just for the sake of a stronger body armor, and underestimated the significant advantage, which gave the 90-mm cannon. Eisenhower was repeatedly informed that the 76-mm gun is more than sufficient to deal with the new German tanks, and after the Normandy all lamented that he had been so deceived.