Debut: March 2015

 




   

.: Phil Kangur's Cromwell Tank - In PROGRESS

Brand:

Airfix

Scale:

1/76

Modelling Time:

~ hrs

PE/Resin Detail:

none

Comments:

"OOB
Nic e Easy Build "

Cromwell tank

From Wikipedia, the free encyclopedia
Tank, Cruiser, Mk VIII, Cromwell (A27M)
Cromwell in the Kubinka Museum.jpg
Cromwell Mk VII in the Kubinka Tank Museum.
Type Cruiser tank
Place of origin United Kingdom
Service history
In service 1944–1955
Used by British ArmyIsraeli Army,Greek ArmyPortuguese Army
Wars World War II1948 Arab–Israeli WarKorean War
Production history
Designer Leyland, then Birmingham Railway Carriage and Wagon Company from 1942[1]
Manufacturer Nuffield Mechanisation and Aero
Number built 4,016
Specifications
Weight 27.6 long tons (28 tonnes)
Length 20 ft 10 in (6.35 m)
Width 9 ft 6 1⁄2 in (2.908 m)
Height 8 ft 2 in (2.49 m)
Crew 5 (Commander, gunner, loader/radio operator, driver, front gunner)

Armour 3 inches (76 mm)
Main
armament
Ordnance QF 75 mm
with 64 rounds
Secondary
armament
2 x 7.92 mm Besa machine gun
with 4,950 rounds
Engine Rolls-Royce Meteor V12 petrol
600 horsepower (450 kW)
Power/weight 21.4 hp/tonne
Transmission Merritt-Brown Z.5 gearbox (five forward and one reverse gear) driving rear sprockets
Suspension Improved Christie
Ground clearance 16 inches
Fuel capacity 110 gallons + optional 30 gallon auxiliary
Operational
range
170 miles (270 km) on roads, 80 miles cross country[2]
Speed 40 miles per hour (64 km/h) with 3.7:1 final reduction drive
 

Tank, Cruiser, Mk VIII, Cromwell (A27M),[nb 1] and the related Centaur (A27L) tank, were one of the most successful series of cruiser tanks fielded by Britain in the Second World War. The Cromwell tank, named after the English Civil War leader Oliver Cromwell, was the first tank put into service by the British to combine a dual-purpose gun, high speed from the powerful and reliable Meteor engine, and reasonable armour, in a balanced package. Its design formed the basis of the Comet tank.

The Cromwell and Centaur differed in the engine used. While the Centaur had the Liberty engine of the predecessor cruiser tank, the Crusader (and the interim A24 Cavalier), the Cromwell had the significantly more powerful Meteor. Apart from the engine and associated transmission differences, the two tanks were the same and many Centaurs built were fitted with the Meteor to make them Cromwells.

The Cromwell first saw action in the Battle of Normandy in June 1944. The tank equipped the armoured reconnaissance regiments, of the Royal Armoured Corps, within the 7th, 11th and Guards Armoured Divisions. While the armoured regiments of the latter two divisions were equipped with M4 Shermans, the armoured regiments of the 7th Armoured Division were equipped with Cromwell tanks. The Centaurs were not used in combat except for those fitted with a 95mm howitzer, which were used in support of the Royal Marines during the invasion of Normandy.

Development

The Cromwell and the related Centaur were the products of British cruiser tank development and they were designed as the replacement for the Crusader tank, which although not yet in service would become obsolete in time. In late 1940, the General Staff set out the specifications for the new tank, and designs were submitted in early 1941. The tank was to be fitted with the QF 6 pounder gun and was expected to enter service in 1942.

Due to the typical rushed production and lack of components of the time, the A24 Cavalier, then known as "Cromwell I", built by Nuffield had far too many problems to see combat service. One problem was its Nuffield-built Liberty engine lacked adequate power. It had been ordered as it was based on tried equipment and should have entered service with minimal delay.

Leyland and Birmingham Railway Carriage & Wagon (BRC&W) had been involved in the development and had offered similar designs to Nuffield. A second specification for a better tank was the General Staff A27. The tank would be fitted with the QF 6 pounder gun with the expectation that it would enter service in 1942. Once it became clear there would be delays, a programme was set in place to fit the 6-pounder to the Crusader, to get the 6-pounder in service as a tank gun.[3]

At the same time, a new engine was designed for tanks; the Meteor engine was based on the powerful Rolls-Royce Merlin engine, used in aircraft such as the Supermarine Spitfire. Rolls-Royce, Leyland and BRC&W produced a prototype by January 1942, based on the Crusader but using the Meteor. With nearly 600 hp (450 kW) it proved to be exceptionally mobile when tested. Leyland were lined up to produce the Meteor but withdrew in mid-1941, as they had doubts about being able to provide sufficient cooling.Rolls-Royce, the makers of the Merlin, were busy and could not spare the facilities for the Meteor and so manufacture was passed to the Rover Car Company.[4]

The General staff issued new specifications to cover the tanks. The BRC&W design using the Meteor was A27M (or "Cromwell III") and the Leyland version with the Liberty was A27L ("Cromwell II"). Nuffield's A24 with the Liberty was the Cromwell II. The naming was reworked in November 1942, with the A27L as Centaur, A27M as Cromwell and A24 as Cavalier.

Production began in November 1942. It would take considerable time for Rover to make ready production lines for the Meteor, and it was not until a few months later, in January 1943, that sufficient Meteor engines were available and the A27M Cromwell began production. The Centaur production design allowed for the later conversion to the Meteor engine and many Centaurs were converted to Cromwells before use.

Design

Silhouettes of M4 Sherman (top) and Cromwell (bottom) together

The frame was of riveted construction, though welding was used later. The armour plate was then bolted to the frame; large bosses on the outside of the plate were used on the turret. Several British firms besides Leyland contributed to production of the Cromwell and Centaur, including LMS RailwayMorris MotorsMetro-CammellBirmingham Railway Carriage and Wagon Company and English Electric.[2] Some variants were produced with 14-inch-wide (360 mm) tracks; later, 15.5-inch tracks were used.

The suspension was of the Christie type, with long helical springs (in tension) angled back to keep the hull sides low. Of the five road wheels each side, four had shock absorbers. The tracks were driven by sprocketed wheels at the rear and tension adjusted at the front idler, this being standard British practice. As with previous Christie-suspension cruiser tanks, there were no track return rollers, the track being supported instead on the tops of the road wheels. The side of the hull was made up of two spaced plates, the suspension units between them, and the outer plate having cutouts for the movement of the road-wheel axles. The gearbox had five forward and one reverse gears. The first gear was for "confined spaces, on steep inclines or...sharp turns". The Meteor engine delivered 540 hp at 2,250 rpm. This was the maximum rpm, which was limited by governors built into the magnetos. Fuel consumption on "pool" petrol (67 octane) was between 0.5 and 1.5 miles per gallon depending on terrain.

The driver sat on the right in the front of the hull, separated from the hull gunner by a bulkhead. The driver had two periscopes and a visor in the hull front. The visor could be opened fully or a small "gate" in it opened; in the latter case a thick glass block protected the driver. A bulkhead with access holes separated the driver and hull gunner from the fighting compartment. A further bulkhead separated the fighting compartment from the engine and transmission bay. The engine compartment drew cooling air in through the top of each side and the roof and exhausted it to the rear. To allow fording through up to 4 ft (1.2 m) deep water, a flap could be moved to cover the lowermost air outlet.[5] Air for the engine could be drawn from the fighting compartment or the exterior; it was then passed through oil bath cleaners.

The Cromwell had revisions to make before service, changing from the QF 6-pounder (57 mm) to the ROQF 75 mm gun, which was an adaptation of the 6-pounder design to fire the ammunition of the US M3 75 mm gun, which gave it a better HE round to use in infantry support. This meant that the 75 mm used the same mounting as the 6 pounder. In June 1944, the Cromwell saw action during Operation Overlord, the Allied invasion of Normandy. It had a mixed reception by crews, being faster, with a lower profile than the Sherman tank and thicker frontal armour plate 3 in (76 mm) as against the 2 in (51 mm) on the glacis of the early Shermans, though it was unsloped and hence less effective.[6] On later Cromwells this was increased, first to 3 1⁄4 in (83 mm), then to 4 in (100 mm). The 75 mm gun, though able to fire a useful HE shell, was not as effective against armour as the 6-pounder or theOrdnance QF 17 pounder gun. A derivative of Cromwell, the Cruiser Mk VIII Challenger, was built to take the 17-pounder but only a small number were built. Most 17-pounder armed tanks to see service in the war were theSherman Firefly variant of the Sherman.

There was a 7.92 mm Besa machine gun mounted co-axially to the main armament, operated by the gunner. A second was "gimbal" mounted in the front of the hull. The mounting gave 45 degrees of coverage to the front (it had 25 degrees of vertical movement as well) and sighting was by a No. 35 telescope, which was connected through a linkage to the mounting. In the top of the turret was a 2 inch "bombthrower" angled to fire forward and thirtysmoke grenades were carried for it.

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