Tag Archives: British AFV

THE SHERMAN – INTRODUCTION IN THE DESERT

08 Monday Mar 2010

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J.P. Hunnicutt’s excellent work on the Sherman Tank, pp. pp.88-90 in fact. In full it states:
“INTRODUCTION IN THE DESERT
After the retreat to Gazala in early February 1942, a lull settled over the desert front. The British Eighth Army held positions stretching from Gazala on the Mediterranean to Bir Hacheim about 35 miles to the south southeast. Both sides took advantage of the quiet period to resupply their troops. A major item received during this time by the British forces was new M3 General Grant tank with its 75mm gun. By the end of March, a total of 666 Grants had been completed under the British contracts and sizable numbers had been shipped to the Middle East. Training programs were immediately started to familiarize both the maintenance and combat troops with the new tank. The advent of the 75mm gun required a new approach in gunnery training. The 2 pounder and 37mm guns of the earlier tanks were direct fire weapons using only a simple telescopic sight.
They fired solid armor piercing shot since their small caliber prevented the development of an adequate high explosive round. The larger 75 however, had an excellent high explosive shell in addition to its armor piercing projectile. For the first time, the tankers had an effective weapon to engage the enemy antitank guns. However, the required gunnery techniques were more closely related to those of field artillery then the methods previously used by tanks. The necessary instruction required considerable improvisation as the early Grants were not fitted with proper fire control equipment. For example, the 75mm gun had no range scale or clinometer. This problem was solved by the simple expedient of tiling notches in the elevation handwheel corresponding to different range settings.
The azimuth was indicated the same way on the traversing wheel. Both vane and bore sights were improvised and hoods were fabricated to shield the periscopes from the glare of the sun. Most importantly, the troops learned the workings of the new tank and how to effectively use it in action.
The training program also revealed serious problems with the high explosive (HE) ammunition. A1- though a highly effective HE round had started production in the United States, much of the stock available in Egypt was of World War I vintage. Some of this ammunition had deteriorated with age until it was dangerous to use. A number of fatalities resulted from premature explosions during the training program.
Also, the fuzes were designed not for the flat trajectories frequently used with tank guns, but for the high angle indirect fire of field artillery. In order to function properly, they required an impact on an almost perpendicular surface. If fired at a low angle, the projectile might strike on the side of the ogive and the fuze would not fire. The shell would then go bounding over the desert, frequently without ever exploding. What was needed was a creep element in the fuze which would fire, even if it only grazed the target. These early U.S. fuzes did not have such an element, but the original French World War I fuzes did. A British mission located a stock of the French fuzes in Syria and shipped 90,000 of them to Egypt. Since the U.S. ammunition was based on the French design, the fuzes were readily fitted to the American shells. This provided high explosive ammunition which could be used in ricochet fire against enemy personnel and antitank guns. When fired at the ground in front of the enemy position, the shell would ricochet into the air before exploding with a deadly fragmentation effect.
Another problem, not so easily solved, concerned the armor piercing ammunition. The armor of the Panzer III and IV being used by the Germans was either face-hardened or reinforced with face-hardened plate. Effective penetration of such plate required the use of a capped armor piercing projectile. Such a round had been developed for the 75mm tank gun, but it was not yet available In the Middle East. This was the APC M61, an armor piercing capped projectile with a ballistic cap (APCBC) to reduce wind resistance and extend its effective range.
During the development period of the APC M61, it had been necessary to introduce an interim round to meet the requirement for large quantities of armor piercing ammunition. This was the AP M72 monobloc shot. Rushed into production, this solid steel shot was variable in quality and tended to break up against face- hardened armor. Tests carried out near Cairo in March 1942 against several German tank hulls revealed that the M72 shot was relatively ineffective against the frontal armor at ranges over 500 yards.
A successful effort to provide effective armor piercing rounds resulted from the brilliant idea of Major Northy, an Australian serving with the British Royal Army Ordnance Corps. Early in 1942, about 50,000 tons of assorted German ammunition captured during the relief of Tobruk were moved to the Ninth British Army Depot along the Suez canal. Among this vast supply were many of the explosive loaded APCBC rounds for the Panzer IV’s 7.5cm Kampfwagenkanone (KwK) L/24. Major Northy noted that if the rotating band was modified, the German projectile could be fitted into a U.S. cartridge case and fired from the M3′s 75. Checking with Major G.B. Jarrett, an Ordnance ammunition expert with the U.S. Mission in the Middle East he found that Jarrett not only agreed as to the feasibility of the project, but gave it his enthusiastic support.
The German projectile differed from its U.S. counterpart in having a much wider and thicker rotating bands but the basic dimensions of the round were essentially the same. A number of the German projectiles were removed from their cartridge cases and the rotating bands turned down to the U.S. dimensions in a lathe. The rounds were then success- fully assembled into U.S. cases and they chambered properly in the M3′s 75mm gun. These were explosive loaded armor piercing projectiles fitted with a base detonating fuze. This fuze was armed by the projectile rotation when the round was fired. Fortunately, the lathe rotation was insufficient to arm the fuze during the machining operation.
Some of the converted ammunition was test fired against a Panzer III hull in comparison with a few of the new U.S. APC M61s which had been flown out to Cairo. Like the German round, the M61 was fitted with an armor piercing cap, but it was inert loaded since the development of a suitable base detonating fuze was not yet complete. The tests showed the penetration performance of the two rounds was identical, but the damage resulting from the German projectile was much greater. Both penetrated the front of the Panzer III at 1000 yards, but the German round exploded inside the tank. In combat such an explosion would almost always set off the stowed ammunition.
With the approval of Middle East Headquarters, the new round was designated as the 75mm AP-Composite and conversion began at full speed. A total of about 17,000 rounds were converted of which 15,000 were the explosive loaded APCBC. The remaining 2000 were high explosive and smoke which were also modified as any reliable round was most welcome for the M3′s gun. U.S. AP M72 and HE Mk 1 ammunition was used to provide the primed cartridge cases and propellant charges. Much of the old ammunition was found to contain variable weights of propellant so all the charges were dumped together, mixed, and re- weighed to insure a uniform muzzle velocity.
The conversion work took two to three weeks and the composite rounds were sent forward before the action opened on the Gazala line in late May. No information seems to be available on what use was made of the new ammunition. About 6000 rounds were captured by the Germans in the dumps at Capuzzo during the retreat to El Alamein. They were then moved to the German base dump at Tobruk where they were recaptured the following November.” [pp.89-90]

Churchill in Africa

22 Tuesday Dec 2009

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The poor performance of the Churchill nearly caused production to be ceased in favour of the upcoming Cromwell tank; it was saved by the production of the much improved Mk III which appeared in March 1942 and was first used in the Second Battle of El Alamein in October of that year. In this ‘second chance’ a select group of five Mk III’s, known collectively as ‘King Force’ went into battle. Although all were heavily shelled by German anti-tank guns, all but one received less than a little damage; one tank was said to have been hit up to 80 times. In the following Tunisia and Italian campaigns, the Mk III and its immediate successors continued to prove their usefulness.

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The evacuation at Dunkirk forced the British Expeditionary Force (BEF) to abandon virtually all its heavy equipment in France. Fewer than 100 tanks were left for the defense of Britain. Vauxhall Motors was charged with continuing development of the A20, slightly reducing its size, and bringing it into production as rapidly as possible. By November 1940 Vauxhall had a new version ready, the Mark IV Churchill Infantry Tank (A22). Because of the speed of the process, however, the A22 suffered from a host of teething problems, leading to considerable modifications, even to the point of sending Vauxhall engineers to the units that were using the tank. Not until 1943 were these problems entirely overcome.

The Churchill Mark IV continued the outdated concept of a light high-velocity gun in a small turret with a large low-velocity forward-firing support gun carried in the hull between the tracks. The first Churchills weighed 87,360 pounds, had a 350-hp engine and top speed of 15 mph, a crew of five, maximum 102mm armor thickness, and a hull-mounted 76mm (3-inch) gun and a turret-mounted 2- pounder and one machine gun. The original plans to outfit the new heavy infantry tank with a heavier gun were scrapped in the aftermath of the Dunkirk evacuation when priority had to be given to weapons systems already in production.

The Churchill incorporated the Merritt-Brown regenerative steering system that saved much of the power lost during steering. The turning circle could also be reduced depending on the gear engaged; a lower gear enabled a tighter turning radius, and in neutral the tank could be pivoted on its axis. The Churchill utilized hydraulics in the steering and clutch controls, which reduced driver fatigue. Its 22 bogie wheels gave a somewhat rough ride, but a number of them could be shot off and the remainder could continue to support the tread. Its roomy interior allowed it to carry 58 rounds of ammunition for the 76mm gun and 150 for the 40mm. The Churchill Mark III, which mounted the 6-pounder (57mm) gun, first saw action in the August 1942 Dieppe Raid, where it gave an indifferent performance. From that point on Churchills were in almost constant action.

Early mechanical problems were overcome, and the Churchill turned out to be a reliable AFV. Changing tactical requirements led to changes in armament and upgrades in armor. The Mark III was the first Churchill to mount a 6-pounder gun in the turret, necessitating a new, welded turret; the Marks V and VIII, intended for a close-support role, mounted a 95mm howitzer. About 10 percent of the 5,640 total Churchills produced throughout the war mounted the 95mm howitzer. Produced in Marks I through XI and in many specialist versions, Churchills continued in service with the British Army into the 1960s.

CRUISER TANK, MK I AND MK ICS (A9)

17 Wednesday Dec 2008

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The main British tank strength in the twenties and early thirties was the Vickers Medium Mk II with the various light tank types introduced for the “scouting” role. Proposed replacements for the Medium Mk II, the Medium Mk III (” 16 tonner”) and the “Independent” were abandoned on the grounds of expense during the financial cut-backs of the thirties. Similarly the A7 and A8, built by the Royal Ordnance Factory, Woolwich, as medium tanks, never went beyond prototype stage, again largely for financial reasons. In 1934, however, Sir John Carden of Vickers Armstrong (the firm which built the Medium Mk III), designed a new medium tank, designated A9, to meet General Staff requirements resulting from the proposals offered to the General Staff’s Research Committee by the Inspector-General of the Royal Tank Corps. It incorporated the best features of the discontinued Medium Mk III, but was much lighter so that it could be powered by a standard commercially-made engine and thus be produced more cheaply. Designed weight was about 10 tons, though production vehicles exceeded this. The pilot model was to be powered by a single Rolls-Royce Phantom II engine of 7·67 litres, but this proved unable to provide the specified performance, so a 9·64 litres AEC bus engine was adopted instead.

An alternative 2pdr gun or 3·7in howitzer (CS) armament could be fitted and there were two auxiliary machine gun turrets as in the Medium Mk III. A 3pdr instead of 2pdr was initially proposed, but the latter weapon had become the new standard tank gun when production started in 1937. Two types of tank “cruiser” (essentially the old “medium” class) and “infantry” had been decided upon by the British War Office when considering future requirements in 1936. The A9, which originally had been rated a “medium” tank, thus became the Cruiser Tank Mk I. Trials of the pilot model started in July 1936 and production of 125 vehicles commenced a year later, 50 of them built by Vickers and 75 by Harland and Wolff, Belfast. A9s equipped some regiments of the 1st Armoured Division in France until the time of the Dunkirk withdrawal in June 1940. They were also used by regiments in the Western Desert until 1941. The A9 had inadequate armour and too Iowa speed for the “cruiser” role. Interesting design features were the external steering brakes on the rear sprockets (good for cooling), power turret traverse, and “slow motion” suspension-later used essentially unchanged on the Valentine.

SPECIFICATION

Designation: Tank, Cruiser, Mk I (A9)

Crew: 6 (commander, gunner, loader, driver, MG gunner (2))

Battle weight: 28,7281b

Dimensions:

Length 19ft:

Height 8ft 8tin

Width 8ft 2tin

Armament: Main: 1x 2pdr OQF

(1 x 3·7in howitzer in Mk ICS)

Secondary:3 x Vickers’ 303 cal MG (one co-axial)

Armour thickness: Maximum 14mm

Minimum 6mm

Traverse: 3600 Elevation limits:-

Engine: AEC Type A179 6 cylinder gasoline (petrol) 150hp

Maximum speed: 25mph

Maximum cross-country speed: 15mph (approx)

Suspension type: Triple-wheel bogies on springs with Newton hydraulic shock absorbers (“Slow motion” type)

Road radius: 150 miles

Fording depth:-

Vertical obstacle: 3ft

Trench crossing: 8ft

Ammunition stowage: 100 rounds 2pdr

3,000 rounds’ 303 cal MG

Special features/remarks: First British tank with hydraulic power traverse. Boat-shaped hull offering no external vertical faces. Riveted construction.

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