Sentinel tank
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![[A production AC1 tank]](../../../upload/shared/thumb/1/1f/Sentinel_%28AWM_101156%29.jpg/250px-Sentinel_%28AWM_101156%29.jpg)
An AC MkI tank on trials |
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| Australian Cruiser Tank Mk. 1 "Sentinel" | |
|---|---|
| General characteristics | |
| Crew | 5 (Commander, Gunner, Loader/Operator, Driver, Hull MG gunner) |
| Length | 6.35 m |
| Width | 2.8 m |
| Height | 2.56 m |
| Weight | 27.5 tonnes |
| Armour and armament | |
| Armour | Hull front 65 mm sides and rear 45 mm Turret 65 mm all round |
| Main armament | 2 pounder tank gun, 130 rounds |
| Secondary armament | two .303 (7.7 mm) Vickers machine guns, 4,250 rounds |
| Mobility | |
| Power plant | 3 x Cadillac V8 330 hp (246 kW) |
| Suspension | Horizontal Volute Spring |
| Road speed | 48km/h |
| Power/weight | 12hp/tonne |
| Range | 175km |
The Sentinel tank was designed in Australia in World War II in response to the war in Europe, and to the threat of Japan expanding the war to the Pacific or even a possible Japanese invasion of Australia.
The Australian Cruiser tank Mark 1 (AC1) was designated "Sentinel", and initially intended to be a true Cruiser tank. Like the Canadian Ram it was based on the engine, drive train, and lower hull of the American M3 Medium tank but the Australian tank was built closely along the lines of a British Crusader. Trying to keep pace with German tanks the design specifications quickly became more like an American Medium tank. The few Sentinels that were built never saw action as Australia's Armoured Divisions had been equipped by that time with British and American tanks.
Contents |
[edit] History
The Sentinel was developed initially as a 2 pounder gun-equipped design in 1940. Fabrication was by Sydney's Chullora Railway Workshops with serial production vehicles emerging in August 1942, the premises also being used as a testing ground. The design used existing parts where available from other tank designs, simplified where necessary to match the machining capacity present in Australia. The hull was cast as a single piece, as was the turret; a technique not used on the hull of any other tanks of the era.
The original vehicle was designed to mount a 2 pounder this was later changed to a 6 pounder, however none of these were available and the first 65 tanks were built with the 2 pounder. The Sentinel had a hull machine gun (deleted in later versions) and a second mounted coaxially beside the main gun. The preferred engines, either a petrol Pratt & Whitney single row Wasp radial, or a Guiberson diesel radial, suitable to power a 28 tonne tank were not available within Australia, and so the Sentinel was powered by the combined output of 3 Cadillac 346 in³ (5.7 L) V8 petrol car engines installed in clover-leaf configuration. Sixty-five production vehicles had been completed by June 1943.
The Sentinel was to be succeeded by the AC3, a much improved design with better armour protection, and increased firepower. The next step up in firepower available in Australia was the 25 pounder gun-howitzer, this was quickly redesigned as a tank gun using experience gained from the work on the Short 25 pounder. Mounted in a fully traversable turret larger than that of the AC1 but using the same 54 inch turret ring, it was slightly cramped for the turret crew but gave the AC3 both armour piercing capability as well as an effective high explosive round. The hull machine gun and gunner were removed from the design to make room for stowage of the larger 25 pounder ammunition. Powered by the same three Cadillac V8 engines as the AC1, they were now mounted on a common crank case and geared together to form a single 17.1 L, 24 cylinder engine, very similar in some respects to the later A57 Chrysler multibank used in some variants of the US M3 and M4 tanks. One pilot model AC3 had been completed and work had started on producing 25 tanks for trials when the programme was terminated.
In an effort to further improve the firepower of the Australian produced tanks a turret was developed 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. This was achieved by mounting two 25 pounder gun-howitzers which when fired together would significantly exceed the recoil of a 17 pounder; it was later fitted with a 17 pounder and after successful gunnery trials the 17 pounder was selected for the AC4 design.
The completed Sentinel tanks were used for evaluation purposes only and were not issued to operational armoured units.
In 1943 the 3rd Army Tank Battalion was equipped with a squadron of AC1 tanks which had been modified to resemble German tanks. These tanks were used in the filming of the movie 'The Rats of Tobruk'. This appears to have been the only time a squadron of Sentinels was used for any purpose [1].
Surviving Sentinels can be seen at the RAAC tank museum at Puckapunyal Victoria (serial number 8030), and at the Bovington Tank Museum (serial number 8049). The only completed AC3 (serial number 8066) is located at the Treloar Technology Centre at the Australian War Memorial in Canberra.
[edit] Variants
- AC I "Sentinel"
- one 2 pounder gun (130 Rounds)
- two Vickers machine guns (4,250 Rounds)
- three Cadillac V8 engines mounted two abreast, and one centrally behind them
- AC III
- one 25 pounder gun
- one Vickers machine gun
- Crew reduced to 4 with the removal of the hull MG from the design
- three Cadillac V8 engines mounted on a common crank case
- AC IV
- one 17 pounder or 25 pounder gun
- one Vickers machine gun
- Engine as Mark III
[edit] References
- ^ Paul Handel - Dust, Sand and Jungle, 2003 RAAC Memorial and Army Tank Museum, ISBN 1-876439-75-0.
[edit] See also
M3 Lee - The design the Australian Cruisers stem from.
Crusader tank - a Crusader was imported to assist with the design.
Ram tank - a vehicle with a very similar design specification.
