Skink anti-aircraft tank

Tank AA, 20 mm Quad, Skink was a Canadian Self-propelled anti-aircraft weapon, developed in 1943-44, in response to a requirement from the Canadian Army Overseas. Due to a lack of threat from the German air force, the Skink was cancelled in 1944 after only a few had been built.

Development
The development of a fully enclosed quadruple 20mm mounting on the chassis of the Grizzly tank (Canadian-built M4A1 Sherman tank) was approved by the Canadian Army Technical Development Board as Project 47 in March, 1943. In keeping with the tradition of giving Canadian armoured fighting vehicles animal names, the proposed tank was named after the skink, Ontario's only lizard.

The Canadian Ministry of Munitions and Supply had the turret designed in-house by its Army Engineering Design Branch (AEDB) with help from the Inspection Board. The Waterloo Manufacturing Co. in Waterloo, Ontario, was given the task of building a preliminary wooden mock-up. This was completed on 18 September 1943. The construction of two welded armour pilot turrets was then authorized. The first pilot turret was demonstrated in mid-December. In January 1944 a pilot turret was successfully tested on a Grizzly chassis. Due to the challenges of welding a turret of such a complex shape from Rolled homogeneous armour plate, Dominion Foundries of Hamilton was contracted to produce a fully enclosed cast turret (the largest armour casting ever made in Canada).

Originally it was planned to arm the Skink with four 20 mm Hispano-Suiza cannons and the first prototypes were so-armed. In January 1944, the 21st Army Group in Europe decided that only British 20 mm Polsten guns would be used (the Polsten was a simplified derivative of the Oerlikon cannon) by its units. This required a redesign of the turret, which was completed in April. This change delayed the project by 3 to 4 months, while 21 Army Group's reduction in the number of AA guns to be issued to its units led to a reduction in the number of Skink turrets which were required. This dwindled to zero in late July 1944, when 21 Army Group decided that as the German air force - the Luftwaffe - had been virtually eliminated over North West Europe, there was no longer a requirement for anti-aircraft tanks. The Skink contract was cancelled in mid-August and only three complete vehicles and eight turret kits were completed.

Design
The Skink’s four 20 mm guns could fire 650 rounds per minute per gun. A modified Oilgear hydraulic traverse with two pumps could rotate the turret at up to 65 degress per second and - crucially for a quick response- - accelerate from rest to 60 degrees in 2 seconds. The guns’ elevation was also hydraulically assisted so the guns could move at up to 45 degress per second in an arc from -5 to +80. The gunner controlled both elevation and rotation with a joystick, and used a Mk.IX reflector sight. Initially it had been planned to build 300 Skink turrets for the Canadian and British armies.

One Skink was sent to Britain for evaluation and was then sent to Europe for field trials with the First Canadian Army. From 6 February to 11 March 1945, the Skink visited all but one of the Canadian armoured regiments - from Nijmegen to the Cleve area - frequently engaging in actual combat. All units found it to be a valuable asset. However no enemy aircraft presented itself to the Skink's guns and its main function was to flush out stubborn pockets of enemy infantry and force their surrender. The remaining Skink pilots and the completed turrets went into long-term storage in Canada where, at some point, they were scrapped. Only some unfinished turret castings salvaged from the firing range survive.