Cruiser Tank Sherman VC (Firefly)

The Cruiser Tank Sherman VC Firefly was a British modification to the Medium Tank M4 that armed it with the excellent British 17 pounder antitank gun, making it one of the most effective Allied tanks available in 1944-45.

Under the British designation system any change to the standard 75mm gun was signified with a letter. A stood for the US 76mm gun, B for the 106mm howitzer and C for the 17 pounder.

The 17 pounder gun had first entered service in January 1943 in Tunisia, as a towed anti-tank gun. It was designed to be used as a tank gun, with a lightweight barrel and heavy breech ring decided to make it easy to balance in a turret. An attempt to mount it in a version of the Cromwell tank produced the Challenger, but this was a largely unsuccessful design, and by the summer of 1943 attention moved onto the possibility of installed the new gun in the Sherman.

The 17 pounder just fitted in the standard Sherman turret. The existing trunnions for the 75mm gun could be used, but a new recoil system and mount had to be developed. The mount also carried a coaxial machine gun and a direct sight telescope. In order to create more space in the turret the Number 19 radio, which was normally carried in the turret bustle, was moved to a new box welded to the back of the bustle. This also helped balance the longer gun. The turret was still crowded, but the extra firepower more than made up for this. The 17 pounder was considered to be the second most effective tank gun on the Western Front in 1944-45, only behind the 8.8cm KwK 43 in the Tiger II.

The hull machine gun was removed and the assistant driver/ gunner was removed, again to increase space. The Firefly could carry 59 shells in three storage bins under the turret floor,14 in the space saved by removing the assistant driver, and five in a ready use rack on the turret basket floor, for a total of 78 rounds. 

As well as the new gun, the Firefly also had a number of modifications that were standard in British use. This included the use of a Number 19 radio set, installed in the turret bustle, the addition of stowage bins on the turret bustle and rear hull, extra track shoes welded to the hull to provide extra armour, a 2in smoke bomb thrower, and extra fire extinguishers.

The Firefly conversion was carried out at the Royal Ordance Factories. By D-Day there were enough for each British Armoured Regiment to have twelve Fireflies, or one per company. As the campaign went on the number available increased, and it made up an increasing proportion of the British tank force.

The 17-pounder gun could fire a APCBC solid shot, or a more powerful discarding sabot shell, which began to appear in August 1944. This was known as the Super Velocity Discarding Sabot (SVDS) or armour piercing discarding sabot (APDS) shell. It had a 5.5lb high density tungsten carbide core, which was the armoured piercing part of the shell, and a light weight outer case, which was there to make the shell fit the 17 pounder. This shell reached a muzzle velocity of 3,950ft/ sec, up from 2,980ft on the APCBC shell. The outer case fell off after the shell left the barrel, leaving just the inner core to travel on. The new shell could penetrate thicker armour than the APCBC shell, but wasn't quite as accurate.

Stats
Production:
Hull Length: 309in with gun forward, 254in without gun
Hull Width: 105in
Height: 108in
Crew: 4
Weight: 72,100lb combat loaded
Engine: Chrysler A57 liquid cooled 30 cylinder multibank
Hp: 370hp at 2,400rpm
Max Speed: 20mph sustained. 25mph max
Max Range: 100 miles cruising range, roads
Armament: 17pdr Gun Mk IV or VII and 0.30 coaxial MG in turret, .50in AA MG on turret roof, 2in Bomb Thrower in turret

Armour

Armour

Front

Side

Rear

Top

Turret

3.0in

2.0in

2.5in

1.0in

Superstructure

 

 

 

 

Hull

2.0in

1.5in

1.5in

0.75in

Gun shield

3.5in

 

 

 

Mantlet

1.5in

 

 

 

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How to cite this article: Rickard, J (18 January 2017), Cruiser Tank Sherman VC (Firefly) , http://www.historyofwar.org/articles/weapons_cruiser_tank_sherman_VC_firefly.html

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