U.S.A (1954)

Heavy Tank Concept – Wooden Mockup Built

Improving the Breed

Even while the T43 (M103) was still in development, the U.S.A. was not done with attempts at making better heavy tanks. Development was split into two schools of thought. One based its work on the T43, leading to the T57 and T58 auto loading tanks; and the other started from scratch.

In June 1954, the Detroit Arsenal held its third Question Mark Conference, the goal of which was brainstorming ideas for new heavy tanks. Suggested designs included the TS-2, TS-5, TS-6, and TS-31.

Conditions these proposals had to meet were that a prototype had to be constructed within two years (hence “TS”, for “Tracked vehicle Short Development”), and it had to be able to fit within the confines of the Berne International Clearance Diagram; a code of standardization for rail tunnels established at the international conference at Berne, Switzerland, in 1913. (There is no single Berne National Tunnel, as claimed by Hunnitcutt’s ‘Firepower’; this was merely a building code for rail tunnels)

The TS-2 and TS-5 were both armed with a 105 mm (4.13 in) T210 smoothbore gun; in a turret on the TS-2, and in a fixed casemate on the TS-5.

The TS-6 and TS-31 were armed with the 120 mm (4.72 in) T123E1 gun; again in a turret on the TS-6, and casemate on the TS-31.

Power for the tanks would have been supplied by either a 700 hp Continental AOI-1490-1 engine with an XT-500 transmission (TS-2 and TS-5), or an 810 hp Continental AVI-1790-8 with an XT-500 transmission (TS-6 and TS-31).

In the end, the TS-31 was chosen for further development; it had a gimbal gun mount, and was estimated to weigh 45 tons. Chrysler was assigned to the development of the TS-31, which was given the designation “120mm gun tank T110”; at the same time, the T43 was entering pre-production.

The TS-31/T110 had a driver in the hull, a gunner to the left of the gun, a commander and his machine gun cupola to the right of the gun, and two loaders. It was rear-engined and had six roadwheels on either side. Armor was to be as thick as 9 inches (228.6 mm) on the gun mantlet. Despite the TS-31 concept being chosen as the winner, it still was slightly too big to fit through the Berne Clearance Dimensions. Additional problems were found with the off-center commander’s cupola: the additional metal to support it added to the tank’s weight and increased its size. These flaws led to Chrysler redesigning the tank.

Losing Some Weight

The second draft was an improvement over the original TS-31. It was slightly smaller, becoming shorter and the front becoming flat. The driver was moved into the casemate, to the left of the gun, with the gunner being moved to the right of the gun. Behind the driver and gunner were two loaders and the commander behind them. The commander was placed directly in the middle of the tank, leaving him to sit almost directly atop the engine and with his feet worryingly close to the gun breech. Despite all this, it was still too big to fit through the Berne Clearance Dimensions. Size, in addition to the Detroit Arsenal’s disapproval of the driver’s position, led to a second redesign.

The third draft was sort of a reversion to the original; the driver was moved back to the hull outside of the casemate, and the gunner was moved back to the left of the gun. The commander’s turret was moved slightly forward, so he would no longer have to sit on the engine, but was now forced to sit in a very awkward and cramped position in order to avoid being crushed by the gun’s recoil every time it fired. The casemate reverted to being rounded at the front. The third draft was no smaller in size than the second.

Detroit Fires Back

The Detroit Arsenal replied to Chrysler’s two proposals with the fourth draft of the T110. The casemate was moved to the back, hanging over the rear of the tank. The transmission was moved to the rear as well, joining the engine. In its place up front was a massive fuel tank, nearly encompassing the driver. The power plant (which was now a Continental 700 hp AOI-1490) was pushed to the left to afford the commander a more comfortable (but still probably hot) position on the far rear right. The suspension was changed to a more conventional (for the Americans) type, with smaller road wheels; although the original draft is without them, return rollers would have been necessary.

Hammering out a Design

Chrysler rejected the Detroit Arsenal’s idea to put the casemate on the very back on the tank and kept it in the middle. The driver was moved back inside the casemate, to the right of the gun. You may know this vehicle as the T110E3 or E4, although these designations are completely fictional. Chrysler originally tried to simplify maintenance on this design by allowing the engine to be pulled out, on rails, via a hatch in the rear of the tank. This feature created rigidity issues and the engine was returned to a standard position, now turned lengthwise in the tank. This new engine placement again left the commander stuck between the engine and the gun breech. The gun mantlet, which had been relatively tiny before, was much bigger in this iteration; weighing 2 tons and being 9 inches (228.6 mm) thick. The tank was now short enough to fit through the Berne Tunnel, but it was still too wide.

This version of the T110 was the first to have serious work done on it. A wooden mockup was built and engineering diagrams were drawn up. Gun traverse was 15 degrees to each side, with 20 degrees of gun elevation and 10 degrees of gun depression. Armor was 5 inches (127 mm) at a 60 degree slope from vertical. Secondary weaponry comprised the commander’s .50 cal (12.7 mm) M2 Browning, as well as a .30 cal (7.62 mm) paired with the main gun.



Artist’s interpretation of design five



Small scale model of design five

At some point, Chrysler realized that there was no need to stick with a casemate design, as a turret could be accounted for within the weight requirements for the tank. In its sixth iteration, the T110 was completely changed, becoming a far more conventional tank. The driver was moved to the middle of the hull, under the gun barrel. The crew was reduced to four instead of five men by dropping a loader. To ease the life of the remaining loader, a gun rammer was fitted. The gunner was on the left of the turret, with the commander above and behind him, and the loader on the right. This, the last version of the T110, shared the 85 inch (2.16 m) turret ring with the M103. Engineering diagrams and a full-size mockup were made, but by this time the T43E2 had been built and showed promise. The success of the M103, as well as changing ideas in terms of tank design, were the doom of the T110, and the project was canceled.



Artist’s interpretation of design six



Small scale model of design six

Even the definitive version of the T110 failed its main goal, as it was still too big to fit through the Berne Clearance Dimensions.



The original TS-31/T110



Chrysler’s first revised T110



Chrysler’s second revised T110



The Detroit Arsenal’s T110 counter-proposal



The fifth T110 design -Chrysler





Schematics of the fifth T110 design



The sixth T110 design -Chrysler



Schematic of the sixth T110 design

T110, Draft Six specifications Total weight, battle ready Probably around 50 tons Crew 4 (driver, gunner, commander, loader) Propulsion Continental 700hp AOI-1490 Suspension Torsion Bar Armament 120 mm (4.72 in) T123E1 rifled cannon Total production A few wooden mockups

Sources

Presidio Press, Firepower: A History of the American Heavy Tank, R.P. Hunnicutt.

(This is also the source for every image used in the article)

Originally published on November 13, 2016.



The fifth T110 design submitted by Chrysler. The 120 mm cannon is mounted in a fixed superstructure, with a machine gun armed commander’s cupola on the roof. Illustration by Jaroslaw “Jarja” Janas.