- Yes
- No
No photos of the T70 GMC during UK trials have been found
Introduction
The T70 Gun Motor Carriage (GMC), the precursor to the iconic M18 Hellcat, was conceived in response to the United States’ 1941 vision for a highly mobile vehicle capable of outmaneuvering enemy tanks and positions and delivering heavy firepower, at the expense of essentially all armour protection. In-service vehicles, such as the M10, were highly capable, but often bemoaned for being too heavy and sluggish. Early attempts to fulfill this role included designs mounting a 37 mm gun on the Light Airborne Tank T9 chassis, designated as the T42 in December 1941. In April 1942, the design evolved into the T49 with a 57 mm gun and a coil spring suspension, and by November 1942, it further developed into the T67, now equipped with the same 75 mm M3 gun as the M4 Sherman.
Testing of the T67 revealed the need for a more powerful engine and better armament, leading to the cancellation of the project in January 1943. That same month, the Ordnance Department ordered six pilot vehicles of a new design: the T70 GMC This vehicle would incorporate a 76 mm M1A1 gun, torsion bar suspension, improved hull design, and a new turret, along with the Wright R-975 radial aircraft engine. The first pilot model was delivered in April 1943, with all six completed by July of that year.
Performance testing of the T70 at General Motors’ Proving Ground was mixed. A few teething issues involving the engine, transmission, suspension, and gun mounting had to be rectified, but for a vehicle fresh off the drawing board it was a success. Despite weighing around 20 tons, the T70 could reach speeds up to 55 mph (88 kph), making it the fastest U.S. armoured fighting vehicle of the war. Following minor modifications, it was accepted into service as the M18 Hellcat later in 1943.
In terms of foreign service during WW2, five pilot models were sent to the Soviet Union for well-documented trials, and two pilot vehicles were also evaluated in the UK, in trials that were much more poorly documented, with no photos being known to exist (although I am certain there are some out there, either physical copies in archives/private collections, or digital copies on some obscure corner of the internet).
In mid 1943, the UK was seeking a replacement for its US-built M10 tank destroyers, and was considering the T70 as a potential option. The UK was positively interested in the vehicle, however, they were of the opinion that the US 76mm was insufficient against modern heavy armour, and considered the 17pdr or 90mm the minimum acceptable firepower for any new tank destroyer that was to enter service.
Lend-Lease records indicate that two T70 GMCs were sent to the UK in 1943 for trials purposes, and correspondence from the Ministry of Supply and War Office confirms that a pilot model was examined in the UK in January 1944. The UK was generally impressed with the vehicle, however, the turret was deemed incapable of housing the 17pdr. With the UK finally getting the 17pdr in a self-propelled mount, in the Achilles and Firefly, there was little appetite for a tank destroyer that offered a downgrade in firepower (in the eyes of the UK), despite the increase in mobility that the T70 offered. The T70 was considered ‘otherwise excellent’, but the UK decided to procure more M10 GMCs, with the option of domestically converting them into Achilles.
In game, the T70 GMC would give the UK much-needed mobile, hard hitting firepower (with APHE and a reverse gear!) at around 6.0, to accompany the medium and heavy tanks that currently sit at that BR.
Specifications
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Images
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T70 undergoing US trials
T70 during Soviet trials
Sources
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Ministry of Supply / War Office Correspondence, dated February 1st, 1944 - available here (cheers to Ed Francis for this one)
Lend-Lease Shipments, World War II, US War Department, December 1946 - available here
M18 Hellcat Tank Destroyer, 1943-1997, Osprey Publishing, 2004, ISBN 978-1841766874 - available here
https://www.tankarchives.ca/2017/05/hellcat-highway-tank-destroyer.html
