Cruiser Mk VIII Challenger

The Tank, Cruiser, Challenger (A30) was a British tank of World War II. It mounted the QF 17-pounder anti-tank gun on a chassis derived from the Cromwell tank to add heavier anti-tank firepower to the cruiser tank units.

The design compromises made in fitting the large gun onto the Cromwell chassis resulted in a tank with a powerful weapon, but with less armour. The extemporised Sherman Firefly conversion of the US-supplied Sherman was easier to produce and, combined with delays in production, meant that only 200 Challengers were built. However, it was able to keep up with the fast Cromwell tank and was used alongside them.

History

The driving force in the development of Challenger was W. A. Robotham. Roy Robotham had been a Rolls-Royce executive in the car division who, with no work to do, had led a team to develop a tank powerplant from the Rolls-Royce Merlin aircraft engine. The Rolls-Royce Meteor gave the British a powerful, reliable engine, which would power the A27M Cruiser Mk VIII Cromwell tank. Robotham's contributions gained him a place in the Ministry of Supply and on the Tank Board, despite his lack of experience in tank design.^[5]

The General Staff brought forward specification A29 for a 45-ton 17-pounder-armed cruiser tank based on needs identified in the African desert campaign. However, the design weight of this vehicle was too heavy and, prior to manufacture, the specification was passed over in favour of the alternate specification, A30, which was 10 tons lighter.^[6]

In 1942, an order for an A30 based tank was placed with Birmingham Railway Carriage and Wagon Company (BRC&W) expecting it to be based on the Cromwell components also being manufactured by BRC&W. Turret and gun mounting was in the hands of Stothert & Pitt. Birmingham Carriage had to modify the Cromwell hull to take a bigger turret.

The design received additional emphasis when it was found in May 1943 that the Cromwell was not going to be able to fit its intended armament. Vickers had been developing a 50-calibre-long 75mm "High Velocity" tank gun. It was realised late in the design process that the Cromwell's turret ring was too small to mount this 75 mm (3.0 in) gun.^[7] Thus, the Challenger would be the only British cruiser tank to mount a weapon that could tackle heavier German armour until the arrival of the A34 Comet.

British tank production was a limited resource, however, and insufficient numbers could be made. In the lead-up to D-Day, Sherman tanks were upgraded with the 17-pounder creating the interim Sherman Firefly. Converting Sherman tanks to Fireflys was simpler than producing Challengers, and the A30 order was cancelled after about 200 had been built, allowing BRC&W to focus on production of the Cromwell.

The tank was rendered obsolete when the Vickers HV 75 mm gun was developed to become the 77mm HV (actually 76.2 mm calibre) to arm the Comet tank. The 77mm HV used the same projectiles as the 17-pounder, although with a reduced propellent charge compared to the 17-pdr. The 17-pdr was reintroduced briefly on earlier marks of the Comet's successor - the Centurion tank.

Design

Cruiser tank Challenger (A30)

The turret mounted the Ordnance QF 17-pounder gun required in the Tank Board specification. The hull machine gun was removed to provide stowage space for the long 17 pounder cartridges. The War Office expected that this larger ammunition, together with its stowage forward, would require two loaders. This raised the turret crew to four - Commander, Gunner, Loader 1 & Loader 2.

To accommodate the larger weapon and additional crewman in the turret a much larger turret than that of the Cromwell was specified, developed separately. This impacted significantly on the design, and was not resolved until later development of Avenger.

To accommodate the weight of the 17-pounder and ammunition an extra wheel station and suspension arm was needed, lengthening the hull. This change in length, without a corresponding change in width across the tracks, reduced mobility compared to the Cromwell, although speed remained high at 25 mph.

To limit the weight, the amount of armouring also had to be reduced. This was not possible on the hull, so it was reduced on the turret - 63 mm on the front and 40 mm on the side compared to 75 mm and 60 mm on the Cromwell. As the base of the turret was unprotected, a jacking feature was fitted to clear any jam resulting from enemy action.

The additional length allowed larger hatches to be fitted in the hull while still clearing the turret, providing easier access than Cromwell.

The first Challenger was completed in September 1942, only 8 months after development had commenced. When the second was tested at Lulworth, it was criticised that, although it would be effective at long range against the current best-gunned tank in German service (the Panzer IV "Special" with the long 75 mm gun), at shorter ranges it would be at a disadvantage due to slow firing rate and thin armour.

Challenger had been developed in anticipation of more heavily armoured Axis tanks however, following a strong trend in Nazi German tank design. At roughly the same time the Tiger 1 entered service with the opposing forces, placing an immediate need for a 17 pounder armed tank in response.^[8]

Design approvals took 5 months. Although changes to the design were minor, a committee met to determine whether a requirement for a 17 pounder tank existed. An order for a small production run of 200 was placed in February 1943, but production capacity was limited alongside continuing Cromwell tank production. In November, it was announced that no more would be ordered. Production efforts moved to the Sherman Firefly to more rapidly meet the immediate needs, while design efforts re-focused on the A34 Comet. Comet replaced Cromwell, Firefly and Challenger with a common design.

Controversy

Upon Robotham's appointment as Chief Engineer to the Department of Tank Design, the lack of progress on an (A29) 17-pounder armed tank could not adequately be explained. Robothams memoirs indicate a lack of awareness that any such requirement exsted within the department, and military users were still reviewing whether the tank was required at the point when the rushed A30 design had been completed and prototype vehicles run.^[9] As such Challenger was raced into service alongside Cromwell production, limiting the number of tanks that could be produced.

Previous reliability issues with British tank design, along with limited manufacturing capacity, led to a joint mission to the US to explore US tank options and share design experiences learned from action. This led the British and Comonwealth forces to introduce a much larger contingent of US-made vehicles, each using dual purpose 75mm weapony with reduced anti-armour capability (US doctrine placed artillery in the primary anti-armour role, while tanks used the dual purpose capability of the gun to fire high-explosive shells at unarmoured targets).

Cromwell with 6-pounder had been delayed in design, and the move to cancel Challenger while switching Cromwell to the dual purpose 75mm gun (with a corresponding drop in anti-armour performance) left British and Commonwealth forces without a main-force tank weapon capable of taking on the equivalent generation of Axis tanks on an equal basis. This lack of firepower was keenly felt by tank crews fighting heavier armed, and sometimes more heavily armoured Axis tanks. This became known as "the great tank scandal".

Firefly was used as a stop-gap measure. The situation was only resolved, much later, with the introduction of the A34 Comet. While Comet improved significantly upon both Cromwell and Challenger designs, its design and production followed that of the Cromwell tank and thus was delayed much longer than an equivalent production (and evolution) of Challenger.

Performance

In comparison with Tiger 1, Challenger had sufficient gun performance against its intended targets, a much higher top speed and cross country mobility, but substantially less armour. This was driven by doctrine. Challenger was designed as a fast cruiser tank for British crews trained to fire on the move, and much of its protection was expected to come from its ability to move faster than Axis crews were able to effectively sight. This rendered it vulnerable to perforation or penetration by enemy rounds when hit.

Challenger was an extremely reliable tank, built at a major transition point in British tank design (vehicles prior to Cromwell having been notably unreliable). A problem was experienced with track throwing caused by mud build-up in the wheels, but this was resolved in-service.^[10] Spares logistics and maintenance were vastly simplified through the use of common parts with Cromwell. This proved a significant advantage.

In comparison with Firefly the tank lacked the sloping forward armour, but presented a lower profile to the enemy, and avoided the Firefly's constraint on gun depression. Challenger provided 10° of gun depression while Firefly was limited to 5°. This provided significant advantage in combat.^[11]

Despite operating to a lower design weight than the earlier A29 specification, Challenger itself proved a challenge for logistics, and required dockyard equipment to ship. As such it could not be used in amphibious assaults, such as the D-day landings. While easier to transport than its Axis counterparts, they did not suffer the same transport problems in defensive actions in the latter phase of the war.

Service

A Challenger tank crosses a Bailey bridge near Esch, Netherlands. 27 October 1944

The vehicle entered front-line service with the allied invasion of Normandy. No provision had been made for deep wading trunking and the A30 was unable to participate in the Normandy landings. Challenger crews had to wait until the Mulberry harbours were built and ports captured.

Challenger and Firefly, both equipped with 17-pounder, were added to tank squadrons to deal with opposing heavy tanks. Many Challengers were issued to units using Cromwells, simplifying maintenance as they shared many parts.

It was initially unpopular, with crews complaining about the lack of armour, the high silhouette and of the tracks being thrown.^[12] Troops used to the low profile of the Crusader and Cromwell found the high-profile a major problem, although it was still shorter than the comparable Sherman Firefly.

As service continued confidence in the vehicle grew. Challenger was preferred by its crews over Firefly, through being lower, faster and more manoeuvrable. Unfortunately, however, the early bad reputation persisted with others.^[13]

Other allied forces were also issued with the Challenger, the 1st Polish Armoured Division receiving several in mid-1945 and the 1st Czechoslovak Armoured Brigade used it during the siege of Dunkirk in late 1944.^[14][15]

After the war, the Czechoslovak government purchased 22 Challengers from the brigade inventory, which served in the Czechoslovak army (first with the 11th, later 23rd, Tank Brigade and then with the 13th Independent Tank Battalion) until they were put in reserve in 1951 and scrapped in 1959.^[16]

Variants

A30 Avenger SP2 or SP 17pdr, A30 (Avenger) was a development of Challenger to be used in an artillery role. It removed the second loaders position and featured a much lower profile turret and lower superstructure on the hull. An additional stowage bin was provided on the glacis plate for a large camo net. Return rollers were added to the tracks.^[17]

Avenger featured a permanent opening in the turret roof covered with an armoured cover supported a few inches above. This provided the commander and loader with full 360 degree visibility.^[18]

As many as 500 vehicles appear to have been planned, and 230 vehicles were ordered from BRC&W, but this dropped to 80 with the end of the war. It is not known how many were actually built. The SP2 nomenclature indicates its production alongside the Valentine Archer (SP1) and Alecto (SP3).^[19]

Avenger suffered in trials as the engine had to remain running to power the tank's turret traverse motor. The noise and exhaust could give the vehicle's position away. Winter trials involving a prolonged stationary position also failed in comparison with Archer, when Avenger's steering failed. Both had problems with camouflage. The vehicle was dropped from trials in 1950, along with removal of its US derived equivalent, the Achilles.^[20]

While Avenger was only used for trials, and was ultimately unsuccessful as a self-propelled artillery piece in comparison with the purpose built vehicles, it provides an interesting example of what could have been possible for the Challenger tank had it not been forced to accommodate the second loader and larger turret during the tank design. This is highlighted within designer WA Robotham's memoirs, indicating that it may have been corrected had design efforts not moved to the Comet.^[21]

Survivors

A30 Challenger, Overloon War Museum

Two vehicles survive. One is at the Overloon War Museum in the Netherlands. The other was awaiting restoration at the Isle of Wight Military Museum in the United Kingdom until its closure. Once restored, it will be displayed at the Bovington Tank Museum.^[22]

References

Bibliography

• Bingham, James (1971). AFV Profile No. 25 Cromwell and Comet. Profile Publishing. 
• Boyd, David. "The Challenger Tank (A.30)". wwiiequipment.com. 
• Evans; McWilliams; Whitworth; Birch (2004). The Rolls Royce Meteor. Rolls-Royce Heritage Trust. ISBN 1-872922-24-4. 
• Fletcher, David (1993). The Universal Tank. HMSO. ISBN 0-11-290534-X. 
• Fletcher, David (2006). Cromwell Cruiser Tank 1942-1950. Osprey Publishing. ISBN 1841768146. 
• Hayward, M. "The Other Challenger". Shermanic Firefly. 
• White, B T (1963). British Tanks 1915-1945. Ian Allan. 
• Royall, Tim (2000). Wheels & Tracks number 70. After the Battle. 
• Robotham, WA (1970). Silver Ghosts and Silver Dawn. Constable. ISBN 0-09-456690-9. 

External links

Wikimedia Commons has media related to Challenger A30 tank.

• OnWar
• whatifmodellers.com