The AC4 (Australian Cruiser Tank Mk. 4) was a cruiser tank designed in Australia in World War II as the intended successor to the AC3 Thunderbolt. Like its predecessors the AC4 was to have a one piece cast hull and turret. The AC4's most important characteristic would be the use of a 17 pounder tank gun.

Australian Cruiser Tank Mk. 4
[An AC4 tank illustration.]
[An AC4 tank illustration.]
A 1943 artist's illustration of the AC MkIV tank based on the production drawings
TypeCruiser tank
Place of originAustralia
Production history
Designed1943
ManufacturerNew South Wales Government Railways
Specifications
Mass30 long tons (30.5 t)[1]
Length21 feet 6 inches (6.55 m) (Maximum)[2]
Width9 feet (2.74 m) (Maximum)[2]
Height9 feet (2.74 m) (Maximum)[2]
Crew4 (Commander, Gunner, Loader/Operator, Driver)[2]

ArmourHull front 2.5 inches (64 mm)
sides and rear 1.75 inches (44 mm)
Turret 2.5 inches (64 mm) all round[2]
Main
armament
17 pounder with 50-60 rounds,[2] or 25 pounder tank gun
Secondary
armament
one .303 (7.7 mm) Vickers machine gun, 2,500-4000 rounds[2]
EnginePerrier-Cadillac
397 horsepower (296 kW)[1]
Power/weight13.2 hp/ton
SuspensionHorizontal Volute Spring
Operational
range
150 miles (240 km)[2]
Maximum speed 30 miles per hour (48 km/h)[2]

History

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AC E1 development vehicle with a test turret and 17 pounder gun

Reservations about the utility of the 25 pounder in the AC3, and the 25 pounder's limited ability to pierce armour led to experimentation with a 17 pounder mounted on an Australian cruiser.

A turret was built and mounted on one of the earlier development vehicles to assess the vehicle's ability to mount the foremost Allied anti-tank gun of the day – the British 17 pounder (76 mm, 3 in). This was achieved by mounting two 25 pounder gun-howitzers which when fired together would significantly exceed the recoil of a 17 pounder.[3] In this configuration the tank was tested on 2 November 1942. It fitted with a 17 pounder and after successful gunnery trials on 17 November 1942 the 17 pounder was selected for the AC4 design. For the AC4 the 17 pounder was to be mounted in a new and larger turret, attached by a 70-inch (1778 mm) diameter turret ring, the space for which was accommodated by changes to the upper hull permitted by the compact nature of the "Perrier-Cadillac".[4]

A design for the tank had been established, however it was subject to a redesign to alter the internal stowage, and include new features not previously considered such as removal of the turret basket, addition of a gyro-stabiliser, and swapping a hydraulic traverse for the electrical system, and torsion bar suspension for the volute spring used up until that point.[5]

The programme was authorised to build a total of 510 AC4 tanks.[6][1] Of these 510 tanks, 110 were to be the "A" variant fitted with a 25 pounder tank gun instead of the 17 pounder.[4] While the AC4 did not receive a formal name the Director of AFV Production, Alfred Code, had the name "Woomera" in mind for the tank.[7] The design was not yet finalised when the programme was terminated in July 1943.[4]

Variants

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See also

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Tanks of comparable role, performance, and era

Notes

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Footnotes
Citations
  1. ^ a b c MP730/13, 7 A) Australian Tank Production Report by Colonel G A Green: B) Related Documents. National Archives of Australia.
  2. ^ a b c d e f g h i General Staff Specification for Cruiser Tank A.C.4.
  3. ^ Bingham 1972, p. 66.
  4. ^ a b c d "MP508/1, 325/703/3084 G.S. Specifications Cruiser Tank AC3 and AC4". National Archives of Australia. {{cite journal}}: Cite journal requires |journal= (help)
  5. ^ "MP730/13, 18 Tank Production in Australia: Stage V. Liquidation of Armoured Fighting Vehicles Directorate". National Archives of Australia. {{cite journal}}: Cite journal requires |journal= (help)
  6. ^ Mellor 1958, p. 319.
  7. ^ "Australian Military Vehicles Research: Australian Sentinel Tank". September 2020. Archived from the original on 23 February 2021. Retrieved 3 June 2021.

References

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  • Bingham, James (1972). Australian Sentinel and Matildas. AFV/Weapons Profiles 31. Windsor, United Kingdom: Profile Publications. OCLC 220833374.
  • Mellor, D.P. (1958). The Role of Science and Industry. Australia in the War of 1939–1945. Series 4 – Civil. Vol. V. Canberra: Australian War Memorial. OCLC 4092792.