T30 heavy tank

The Heavy Tank T30 was a World War II American tank project developed to counter new German tanks, such as Tiger I, Tiger II, and tank destroyers, such as the Jagdtiger, or Soviet heavy tanks, such as IS-2 or IS-3. The T30 was designed at the same time as the T29 Heavy Tank.

The poor results of the Heavy Tank M6 program led to lethargy in American heavy tank development by the first half of 1944. The success of American medium tanks in North Africa led the American military to believe that they would not need heavy tanks. However, the summer of 1944 in Normandy proved sobering. It turned out that the Germans had new types of heavy tanks that were tough nuts to crack for American tanks and tank destroyers. As a result, the development of several new heavy tanks was expedited in late July 1944, and the Heavy Tank T30 was one of them.

In early August 1944, discussions cropped up about the brand-new Heavy Tank M6A2E1, a thorough modernization of the Heavy Tank M6. General Lucius Clay spoke out against this idea, due to it lacking mobility and having an estimated mass of 77 tons. The idea of developing a brand-new tank called Heavy Tank T29 was first voiced on 14 August. The chassis was inspired by the Heavy Tank T26, the turret and armament were similar to those of the M6A2E1.

However, there were questions about the T29 from the very beginning. The primary enemy of the future T29 would have been the Tiger II, which had a 150 mm thick upper glacis plate. Doubts that the 105 mm T5E1 gun could penetrate this much armor were raised early on. Because of this, one more prospective tank was announced on 14 August: the Heavy Tank T30. Its hull and turret were identical to the T29, but the gun was different.

The 155 mm M1A1 gun, known as the Long Tom, was chosen as the starting point for this weapon. This gun was developed in the late 1930s to replace the 155 mm M1918 gun, a copy of the French GPF. The characteristics of this new gun were close to that of the Soviet 152 mm special power Br-2 gun. The muzzle velocity was slightly lower, the shell was slightly lighter, but generally the performance was the same. While only 39 Br-2 guns were built, American industry put out 1882 guns from the M1 family between October 1940 and June 1945. Few operations in North Africa and Europe were performed without the Long Tom taking part.

Officially, work on the Heavy Tank T30 began on 14 September 1944. Plans were made to produce two prototypes, the same number as for the T29. Unlike its brother, which was scheduled to be produced in a series of 1200 tanks, the T30 was never going to be ordered in bulk. This indicates that the T30 was always going to be a backup plan and was chiefly meant to test the 155 mm gun, which was given the index T7. The length of the barrel was reduced to 6414 mm (41.4 calibers). The muzzle velocity decreased to 717 m/s. Nevertheless, this was the most powerful tank gun built in metal to that day. However, the M1A1 did not yet have an armor piercing shell, which was designed later.

The first changes to the Heavy Tank T30 program were made towards the end of 1944. It was clear that the heavy tanks would be late to the war, and not only was the volume of the orders reduced, but the chassis was revised. The engine was the first to change. Initially, the plan was to use the 27 L Ford GAC, which put out 770 hp. However, even initial estimates showed that the power to weight ratio of the T29 and T30 would be low, and a new engine was suggested: the air cooled 29 L Continental AV-1790. This engine could produce up to 810 hp. The transmission also changed. Like the T29, the final selection was made in favour of the Alisson CD-850-1.

Changes were also made to the turret. Like the T29, the turret of the T30 was initially the same as on the M6A2E1. This turret was referred to as the T29 turret: the M6A2E1 was nothing but a test platform. A number of issues were discovered, such as the possibility that fragments and bullets could enter the turret through slits, and the turret had to be redesigned. It ended up changing significantly, but the T29 and T30 still had identical turrets. The only difference was the number of coaxial machine guns: one or two. The new gun mount was indexed T124.