The T31 Demolition Tank – Rocket Launchers and Flamethrowers
Today we are taking a quick look at the absolutely bizarre T31 demolition tank, a vehicle developed towards the end of the Second World War that was armed with two automatic rocket launchers, four machine guns and a flame thrower, just for good measure.
The T31 came after a number of specialised projects based on the Sherman, such as arming it with a flamethrower, or attaching a rocket launching system. It was meant to combine many of these features into a single vehicle, capable of tackling enemy positions with its heavy ordnance and flamethrower, while possessing the ability to clear mines.
As with so many ambitious projects though, the T31 was troubled by development glitches. Sufficient efforts would have likely solve these problems, but the end of the war and the sudden reduction in urgency meant the T31 was not to be, leaving the the single prototype as a mere footnote in tank history.
The development of the T31 began near the end of 1944, when a US testing committee put in a request for an engineering vehicle based on the Sherman tank, designated the T2. In relation to warfare, an engineering vehicle is typically one that has the task of aiding the movement of forces through a battlefield or the environment in general.
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The most common jobs for these vehicles are clearing mines, filling ditches, destroying hardened enemy positions, clearing obstacles and creating friendly defenses (trenches, earthworks etc.). They are essentially a Swiss army knife for a mobile force.
The British had already popularised the class of engineering vehicles with the AVRE (Armoured Vehicle, Royal Engineers), but by late 1944, the US was yet to introduce their own dedicated type to the same extent.
Some efforts had been made previously with individual vehicles, such as with the mounting of dozer blades and mine clearing devices on Shermans. In addition, work on vehicles tasked with eliminating enemy fortifications had also been done, with the fitment of flame throwers and rocket launchers onto Shermans.
The T2 engineer vehicle was to combine many of these concepts into a single machine.
The committee requested that the T2 was to be based on the M4A3 variant of Sherman, which was powered by the Ford GAA V8 petrol engine. It was also to roll on the improved horizontal volute spring suspension system (HVSS) and have thicker belly armor for greater mine resistance.
For the actual engineering part of the request though, it seemed like the committee ticked every box of available weapons and tools. The T2 was to have a dozer blade, two 7.2 inch automatic rocket launchers, a flame thrower and three .30 caliber machine guns.
The rocket launchers were to be installed inside a newly-designed turret, with one launcher on each side.
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The premise behind the T2 was that its design would enable it to push its way through heavily defended terrain, clearing mines in front of the tank with its dozer blade, while possessing increased protection against any untouched mines thanks to its thick belly. In theory, this would permit the T2 to push its way through enemy obstacles to get into range to engage and destroy enemy fortifications with its short-range demolition rockets.
The flamethrower and machine-guns were mounted on the T2 for dealing with any enemy infantry.
Actual designing began in January 1945, after a recommendation was made for the construction of four pilot models of the vehicle, which was now designated the demolition tank T31.
The T31 was a wild-looking machine, with a large, box-shaped turret atop the already-tall Sherman hull. As mentioned, the base Sherman used for the pilot was an M4A3, which was the type powered by the Ford GAA V8 petrol engine. This was an 18 litre (1,100 cu in) beast that produced 500 hp and 1,300 Nm (950 ft-lb) of torque.
The hull was of the “large hatch” type, which had a thicker (63.5 mm), but less-sloped front plate that eliminated the driver bulge weakpoints. The sides remained the same 38 mm as on the standard Sherman, but the floor was thickened from 25 mm to 38 mm.
The most unique feature of the T31 was its large and unconventional looking turret. It was comprised of a central cube-shaped compartment, which housed the crew, and cylindrical protrusions on each side that housed the rocket launchers and their mechanisms. The front and sides of this turret were 63.5 mm thick, and there was a 38 mm thick double door at the rear. The double door also had a small viewing block and pistol port.
The turret roof was so large that the commander’s cupola had to be raised by almost 80 mm. This improved the commander’s downward vision that would have otherwise been obscured due to the turret’s unique design.
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On each side of the T31’s turret was a T94 7.2 inch (183mm) rocket launcher. Each T94 rocket launcher was enclosed in an armoured blister on the sides of the turret, almost giving the appearance that the enclosed rocket launchers were the turret’s “ears”.
Each T94 was a revolver style launcher that was designed to automatically rotate and cycle a new rocket each time the launcher was fired. If the launcher’s automatic rotation feature malfunctioned, the cylinder could be rotated manually. Each T94 rocket launcher carried five rockets and there were two full five round reloads for each launcher for a total of 30 rounds, or 15 rounds per T94 rocket launcher.
The rocket for the T94, the T37, was the same unguided rocket used by the T34E2 Calliope multiple rocket launcher that was mounted on some Sherman tanks. The T37 was originally an anti-submarine warfare rocket developed by the US Navy for its smaller warships, as it could be fired with no recoil, unlike other systems.
This rocket was adopted for Army use in 1943 in several forms: the T37 demolition rocket, the T24 High-Explosive Rocket and the M25 and M27 Chemical Rockets (smoke rounds).
Although there were several rockets to select from, the T37 would have likely been the main rocket used by the T31. The T37 was fin-stabilized with a thin 57.15 mm (2.25 inch) motor and a large warhead (183 mm, or 7.2 inch). It had an overall length of 89 cm (2 feet, 11 inch), a weight of 27 kg (61 lbs) and a range of 275 m (300 yards).
In the centre of the turret was a dummy 105mm howitzer. The layout of the turret and the numerous weapons and ammunition did not provide enough space for a real cannon, and while dummy guns might have been a feature on some WW2 specialist tanks to make them look like a real tank as they had little to no armament, there is no information as to why a dummy barrel was considered necessary for the T31 when it already possessed several types of weapons.
On either side of the dummy howitzer was a .30-caliber M1919 machine-gun in a ball mount. There was also a .50-caliber machine-gun at the rear of the turret.
In addition to its rockets, the T31 also had a flamethrower. The M3-4-E6R3 flamethrower was located at the front of the hull, operated by the assistant driver. It was positioned above his hatch, and could be operated even when buttoned down.
This weapon possessed 95 litres of fuel and had a range between 20-60 meters, depending on how much propellant pressure was applied from the cylinders. Because of its unusual location, the flamethrower’s traverse limit was 45 degrees to the left and 90 degrees to the right of assistant driver’s hatch location.
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The T31 had a crew of five: driver, assistant driver, crew commander and two gunners. The two gunners were responsible for aiming and firing the T94 rocket launcher on their respective side of the turret. There were no loaders for the T31 as the gunners were expected to load the rockets as well as fire them. The gunners also operated the .30-caliber machine gun on their respective side of the dummy 105mm gun on the turret.
The life of the T31 is a very short one. The Heinz Manufacturing Company was awarded a contract to produce four pilot models. Work commenced on the first pilot model in April 1945, which was ready for testing that August. Although the War in Europe was over by this point, the War in the Pacific was still ongoing, so the single T31 was tested at Aberdeen Proving Ground in Maryland.
While there is limited information available on the tests, available reporting suggests that there were serious problems with the T94 rocket launchers, as the left mounted launcher would not rotate at all and the right mounted T94 could only be rotated by hand.
With the war over and priority for such a vehicle now reduced, no further pilot models were produced and no work was conducted to fix the issues with the T94 rocket launchers. The T31 project was quietly cancelled on 14 January 1946 with the sole T31 being placed into storage shortly thereafter and eventually dissembled, which is a rather unfortunate end for such a unique vehicle.
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Even though there was only one model built and tests were unsuccessful, the uniqueness of the T31 would have certainly made it an exclusive exhibit piece for a military museum.