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i know this topic and something similar has been covered many times, but your comments for this proposal would be greatly appreciated.

In 1928 the general characteristics for a new HAA gun were agreed, a bore of 3.7 inches firing 25 lb shells with a ceiling of 28,000 feet a towed road speed of 25 mph, maximum weight of eight tons and an into action time of 15 minutes. Each regiment usually had three batteries, each of eight guns in two troops. = 24 AA guns.

The guns were used in the field artillery role quite extensively in the second half of the war in Italy, north-west Europe, Burma and the south-west Pacific. Batteries were issued with the necessary fire control equipment. Counter-battery or counter-mortar fire was the usual role. However, their HE ammunition seems to have always been fuzed for airburst; this means maximum ranges were limited to 9,200 yards with the No. 199 fuze and 16,200 yards with the No. 208 fuze.

Like other British guns the 3.7 had a secondary anti-tank role. This meant that if the gun position came under tank attack it would engage the tanks. However, during the campaign in North Africa, the shortage of capable anti-tank guns led to some agitation to use the 3.7 in a primary anti-tank role.

The Churchill had armour of 0.63 to 4 in armour thickness, which was greater than that of the Matilda, and promised near immunity against most antitank guns of the time, or heavy shrapnel. It was, in 1941, the most heavily protected tank in the world. What was needed was an anti-tank gun that could defeat the Churchill's armour at a minimum of 1740 yds. Tested for real in the deserts of Egypt at the end of 1941 the 3.7" was more than adequate. This gun could fire AP rounds which penetrate 6" of armour at over a mile and HE shells at a range of up to 5 miles.

At this time also the Russian T34 was making an appearance on the Eastern Front. What was required was a British T34.

As early as 1941, there were concerns about the A22 Churchill tank. Its performance had been unsatisfactory, due mostly to its mechanical unreliability and poor speed. This lead to several mock-ups and designs, which were part of a project known as the “Cromwell Rationalization Programme”. These used the A27 Cromwell chassis and automotive components as a basis for future vehicles. The Directorate of Tank Design (DTD), on 27 April 1941, supported production of the Meteor, eventually placing orders direct with Rolls-Royce to maintain development in connection with the new tank specification, A27M, was produced for design of the Meteor-powered tank. The Meteor engine went on to become one of the most successful British tank engines, leading to the Universal tank concept. The first Merlin prepared for tank use was tried in a modified Crusader in September 1941 at Aldershot. The test team had trouble timing its runs because it was so fast, estimating it reached 50 miles per hour. This proved the concept, and the engine was tried in the Crusader tank, surpassing all expectations. The engine was commissioned for use in the new universal tank. This was combined with the Merrit-Brown gearbox that allowed the tank to steer while still powering both tracks, allowing it to maintain speed while maneuvering, while tanks like the Sherman or T-34 lost power while turning and necessarily slowed down.

TheAustralian AC1 sentinel hull fitted the bill. It's 54" turret ring was enlarged to 72" enabling her to take the 17 pounder gun. (The Sherman's 69" ring could take the French 105mm gun & the Pershing's similar ring the American 90mm gun. The Canadians put a 3.7" on a Ram so theoretically the 32 pounder should fit the AC4)

Sketches of what would become the Australian Cruiser (AC) tank were first drawn in June 1940, when the situation in Europe was so dire that the Commonwealth was mobilised. It had several notable features such as the mostly cast hull, whereas most contemporary British tanks still had welded/riveted plates. Minimum required top speed was to be 35 mph on level ground, with a slope traverse of 45 degrees, and trench and vertical obstacle crossing capabilities of 6 foot 6 inches and 3 foot 6 inches respectively. Operational range was specified as a minimum cruising range of 150 miles. No weight restriction was issued beyond the lowest possible allowing for all other requirements to be met. In common with British tank doctrine of the time, the vehicle was designed to fire on the move. The turret offered hydraulically powered turret traverse motors with proportional speed control. Later vehicles fitted an all-round view cupola for the commander to identify and track targets. Both gunner and commander had Vickers rotating and pivoting periscopes, while episcopes were fitted in the cupola.

Production of the new tank was planned to be conducted at a new tank assembly annex to be constructed in Port Melbourne, Victoria, in order to supplement the output of the Chullora Tank Assembly Workshops in Sydney. Hull castings were to be produced locally in a purpose built foundry operated by the Charles Ruwolts Company. An immediate requirement for 340 tanks to equip one armoured division and a further 119 tanks for the 1st Australian Corps and the AMF (84 and 35 respectively), an additional 400 tanks for 12 months reserve, with a total production of 859 tanks.

The Canadian industry was probably the most capable of all Commonwealth nations to provide large supplies of materiel to the Allies. It was already the fifth largest car manufacturer and fourth largest locomotive builder. The Government prospected the Canadian Pacific Railway’s Angus Shops in Montreal (CPR), the only factory capable of large scale production of such vehicles, equipped with the heavy infrastructure required. The final assembly was given to the specially funded Canadian Tank Arsenal at Longue Pointe, Québeck. (2188 built)

In South Africa the tank was assembled locally at Dorman with parts from Canada and armored plates from the South African Iron & Steel Industrial Corporation, ISCOR. (1180 built)

Several British firms including Leyland, LMS Railway, Morris Motors, Metro-Cammell, Birmingham Railway Carriage and Wagon Company, Royal Ordnance Leeds, Royal Arsenal,Harland & Wolf, John Fowler & Co., Ruston-Bucyrus, Vickers at Elswick and English Electric. Vauxhall would also manufacture the tank once production of Churchill was terminated in 1943. (4016 Cromwells + 1186 Comets)

The original design for the A.33 was meant to produce a “Heavy Assault Tank based on the Cromwell using thicker armor and redesigned suspension”, “re-introducing armored skirting plates over the suspension”. The project directly challenging the Churchill tank, as several mentions are made of the automotive unreliability, poor speed, and overall negative opinion of the Churchill. (3663 built = Churchill's built in time frame)

To make room for the more voluminous ammunition, the hull machine gun was eliminated and the crew reduced to four, although, again contrary to popular belief, the turret coaxial machinegun was not deleted from the design. ‘Accordingly, a magazine containing 18 shells has been designed and this is located across the rear of the turret. The noses of the shells point towards the gun and the magazine has been equipped with gear to traverse each shell in turn to the centre for loading.

The hull was remodelled with the deletion of the machinegun position, with an increased frontal slope and new design for the driver’s primary and escape hatches.

The Merlin engine is a legend. This new generation of compact and lightweight aircraft engines was quickly found suitable for the new tanks urgently needed by the Royal Armored Corps in 1941.The RR Meteor was an in-line V12 water-cooled gasoline engine that was heavily adapted by Chief Engineer W.A. Robotham at the development division in Belper.

The Meteor engine, in its first version, developed 540 hp at 2,250 maximum rpm. It was shown indeed that the pilot tanks could easily reach 47 MPH, with 3.7:1 final reduction drive and around 25 mph off-road something unheard of for a British tank, the Christie suspension was reinforced by adding more tension to cope with these speeds. Plenty of torque was there, available both for mobility and traction. The gearbox had five forward and one reverse gears. Fuel consumption (on “pool” 67 octane petrol) per gallon ranged from 0.5 (off-road) to 1.5 miles (road) for a total 110 gallons of internal capacity. The A33 version Infantry tank the side armour protection was added, consisted of a 1.875” inch thick skirt, a 1.062” inch outer plate, and 0.562 inch inner plate. This brought the total combined thickness of the side armor to 3.5 inches. While the maximum thickness of the frontal armour was 3.5 inches. The engine was re-rated to 650bhp, to cope with the additional weight. To face muddy terrain or snow encountered in Northern Europe, later versions were given 14 in wide or even 15.5 in wide tracks. In all cases, ground clearance was 16 inches.

Final production was officially started on 1st April 1943, although the first trials began in September 1941.

At a weight of 32 tons it was the heaviest which could be carried on a standard Christie suspension of 5 wheels per side.

Length 20'10" breadth 9'6" height 8'4".

Primary armament 1X 3.7" DP gun with 5 rds, Secondary armament 1 co-axial .303 Vickers with 2,500 rds, and occasionally a .303 Vickers K gun with 500 rds on the turret roof.

Crew 4:- Commander, gunner, loader & driver.

Total tanks produced 13,092 (9,429 cruiser + 3,663 infantry).

Typical tank regiment:-
8th Royal Irish Hussars
HQ– 4 Tanks
A Squadron – 20 Tanks triangle marking
B Squadron – 20 Tanks box marking
C Squadron – 20 Tanks circle marking
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