Friday, 27 November 2020

Black Prince

The British military had strange ideas about what a tank should look like in WWII, which led British tank building into a dead end. It's not surprising that the American Stuart tank became the most common light tank in the British army and the most common medium tank was the Sherman. The British were on their own when it came to heavy tanks, as there was no foreign alternative to the Churchill. That didn't stop the British from making several attempts to replace it throughout the war. The Black Prince I was one such attempt. This was a direct descendant of the Churchill tank that came up short compared to its ancestor.

A big chassis for the 17-pounder

Formally, the UK had no heavy tanks. A new system of armament was developed in the 1930 that separated tanks into light, cruiser, and infantry categories. The Churchill was launched in 1941 as a heavy infantry tank. This was a typical heavy tank for the era and not a bad one at all, despite some growing pains. As combat experience showed, including on the Eastern Front, this tank was a viable heavy breakthrough tank, if lacking in the armament and mobility departments. The British first thought of replacing the Churchill in 1942, but the potential alternatives were even worse. Since there was no luck with replacements the Churchill remained in production and ended up becoming the most numerous heavy tank in history.

The Sherman VC ended up being the most numerous tank armed with a 17-pounder gun. 

One of the issues that British designers fought with for the whole war was armament. The 2-pounder (40 mm) gun developed shortly before the war was a very modern weapon until early 1941. After the appearance of Rommel's forces in North Africa it became clear that this gun was not enough to deal with the German tanks that had either 50 mm of front armour or applique plates. Work on the 6-pounder (57 mm) gun began before the Africa Corps landed in Libya, but vehicles with this gun did not reach the battlefield until mid-1942. The Churchill tank was among them. It was relatively easy to put the new gun into this tank. Meanwhile, the British were working on an even more powerful 76 mm gun as of late 1941. In British tradition, it was named 17-pounder after the mass of its shot. This gun was powerful, but also big and heavy. It was impossible to install in any British tank available at the time.

This was the official name of the A43 Infantry Tank.

The issue was partially resolved by Sherman tanks and Achilles tank destroyers, which had large enough turrets to fit the 17-pounder gun. Work on these vehicles took a long time, but the Sherman VC and Achilles IIC became powerful and numerous weapons in the summer of 1944. As for British tanks, they were equipped with 75 mm gun with the same ballistics as the American M3 gun. This also applied to the Churchill. This weapon was used on the Churchill VII and earlier variants were also re-armed with it. This was the most powerful gun used on this chassis. The turret was too small to allow a larger and more powerful gun to be installed. This was true not just for the Churchill, but for any British tank of the time. This was not news to British designers, who began working on the A30 Cruiser Tank back in 1942. A prototype was built in the fall of 1942. The British did not reinvent the wheel and simply put a new turret on a lengthened Cromwell chassis. 

The tank could fit a 17-pounder gun with no issues thanks to the enlarged 1880 mm turret ring.

These tricks weren't tried with the Churchill. There was an unfortunate attempt with the Churchill Gun Carrier, but that was still an SPG rather than a tank. Infantry tank chassis were not considered a good match for the 17-pounder gun, with the exception of the Valentine, but the Archer I tank destroyer illustrates that the initial design was rather ill suited for this gun. As for the Churchill, it was not considered as a carrier for the 17-pounder gun at all. It was too slow and heavy to be a tank destroyer and too many changes would be required to install a 17-pounder gun on it. As a result, discussion of the Churchill's replacement began again in the second half of 1943. This became possible due to the first steps in the design of the A41 tank, later named Centurion, that were made in September of 1943. A whole new turret was developed for it, and unlike the turret developed for the A43 Comet it could fit a full fledged 17-pounder. The A41's turret was lower than the A30's, and the designers made it future proof. The 1880 mm wide turret ring allowed it to carry even larger guns. The Churchill's replacement was not meant to have a direct copy of the A41's turret, but nevertheless Vauxhall received a full set of documentation on the turret in December of 1943.

The new tank was nearly 10 tons heavier than the Churchill VII, but still had the same Bedford Twin Six engine.

The newly indexed A43 inherited more than the turret layout from the A41. The tank was also going to have much stronger front armour. Even increasing the armour of the Churchill VII to 152 mm did not provide complete protection. After studying a Panther Ausf.D helpfully provided by the USSR the British suddenly realized that the use of sloped armour could radically improve protection. However, there was one problem. Sloped armour could only be used at the cost of removing the BESA machine gun in the hull and the driver's vision port. These factors were decisive, and the A43 retained the same configuration as the Churchill VII. This decision seems strange, but the British had their reasons. The A43 was supposed to double as a flamethrower tank, and with a sloped front plate such a conversion would be very difficult, if not impossible. As such, the new infantry tank was hardly revolutionary. It was named Black Prince after Edward, Duke of Cornwall, a famous commander in the 100 Year War. Many ships carried this honourable if not always lucky name, but that hardly bothered anyone in 1944.

A giant with a weak heart

The A43 finally took shape towards the summer of 1944. By this time the requirements of the General Staff were completely changed. All they wanted was an enlarged Churchill with a new turret and 17-pounder gun. The armour remained the same as the Churchill VII: 152 mm in the front and 95 mm in the sides was considered enough for a new generation infantry tank.

One of the first A43 prototypes on trials, early 1945.

Not only did the new tank retain the armour configuration of its predecessor, it retained the engine and transmission as well. There is a Russian saying that describes this situation: the old horse won't ruin the furrow, but won't plow very deep. The new tank used the same old Bedford Twin Six engine that was supercharged to 350 hp for the Churchill VII. In this case it was not supercharged any further, giving just above 7 hp/ton. This was not quite at the level of the Infantry Tank Mk.I that had a power to weight ratio of a paltry 6 hp/ton, but not far from it. Due to the increased mass the transmission was swapped out for the reinforced Merritt Brown H 52, but it was not much different from the gearbox on the Churchill VII.

Unlike the hull, the turret was completely new.

The running gear was also nothing new. The suspension and road wheels were taken from the Churchill VII, but there were now 12 wheels per side. This was because the hull was slightly lengthened. The design of the drive sprockets and idlers changed, but not much. The track links, however, were radically different. They were now 609 mm wide and had a new design. It was based on the Churchill VII links, but there were many differences. A further development of this design was used on the A39 Tortoise. The fenders were also an evolution from the Churchill VII. They were similar, but had many distinctions. The large front mudguards that were often the source of problems were done away with. They protected the driver from mud, but as soon as the shooting started they tended to get damaged by the tank's own gun. Since the idlers were no longer sticking out as far forward, the mudguards became a lot smaller and the top section was sloped. This improved the driver's vision, allowing him to look to the side with his Mk.IV periscope.

The gun was turned backwards for marches.

The hull of the A43 was also based on the Churchill VII. By time time welding finally replaced rivets and bolts. The A43's hull was also wider and longer. Work on improving protection continued. The evacuation hatches were still present, but they were strengthened. The air intakes were moved from the sides of the hull to the engine deck. This not only improved protection, but helped with the width of the tank, which grew to 4442 mm, close to the railway limit. Protection of the engine deck was also improved. The rear plate was thinned out to 51 mm to help with the weight, but it was also installed on a slope. Since the frontal protection of the Churchill VII was considered sufficient, the front of the A43 did not change much. There were still differences in assembly, for instance the joint between the central and upper rear plates was hidden behind a protrusion to protect it from direct hits.

Not only the turret but also the engine deck were redesigned. The protection of the latter greatly improved.

The most noticeable change was the turret. As mentioned above, Vauxhall received the full set of documents for the A41 turret in December of 1943. However, it was quite clear that the A43's turret was not a copy. The two tanks had the same turret ring diameter and design of the front turret part, influenced by the A34 Comet. There were also some common elements on the roof, for instance the 2" bomb thrower mount. The commander's cupolas were also similar. Difference started at the gun mount. The designers of the A41 experimented with coaxial armament, but there were no alternatives for the BESA in the A43. As per tradition it was installed to the left of the gun. Like on the A41, the commander and loader switched places. The gunner was also now on the right. Like the A41, the turret was largely welded. However, it didn't have the turret bustle and its shape was closer to that of the Churchill. The loader's hatch and stowage bin migrated from the A43's predecessor unchanged. Overall, the turret was clearly an original design.

The driver's vision improved due to the sloped fenders.

The ammunition capacity of the A43 surpassed expectations. Tanks armed with the 17-pounder gun struggled in this department. For instance, the Challenger carried only 48 rounds. The A41 carried 75 rounds, but the A43 left it in the dust with 89 rounds (although the requirements asked for 90) plus 8125 rounds for the BESA and 20 for the bomb thrower. This tank deserved the title of infantry tank. This impressive ammunition capacity would allow it to fight for a long time in support of infantry. The issue was that as with any tank, effectiveness on the battlefield is determined by many characteristics. The future showed that some of them left much to be desired.

A tank for a different war

The decision to build experimental A43 prototypes was made in May of 1944, before the Normandy landings. According to the contract with Vauxhall a batch of 6 pilot vehicles would be built with registration numbers T.353280-T.353285. Two tanks would remain at Vauxhall for trials, one would go to gunnery trials, one would be used up in penetration trials, one was saved for extended usage trials, one would be used for deep water wading trials. Changes were still being made to the project that were only partially implemented. These changes included carrying 90 rounds of ammunition for the main gun (the tank fit just 89) and a fully rotating mount for the 2" bomb thrower. Some ideas were not implemented at all, such as the idea to install the 32-pounder (94 mm) tank gun based on the 3.7" AA gun. It turned out that such a gun would not fit into the A43's turret. There was also a proposal to install a more powerful engine. This engine existed: the 600 hp 12-cylinder Rolls Royce Meteor was successfully used on Cromwell, Comet, and Challenger tanks. It was also used in the A41. For unknown reasons this engine was not installed in the A43. This was a strange decision, as this engine was later used in production Centurions that eventually reached the weight of 50 tons.

The air intakes were removed from the sides of the hull, which improved protection.

The War Department began thinking about mass production of the A43 or Black Prince I even before the pilots were built. A second contract for 300 vehicles was prepared on June 30th, 1944. However, pilot tanks would have to be built before the large batch, and there were some problems with that. The full sized model of the Black Prince I was shown in September of 1944. Vauxhall expected production to begin soon, but capabilities fell short of their wishes. Various delays (including the arrival of a 17-pounder Mk.III gun instead of a Mk.VI) resulted in the first pilot being finished only by January of 1945.

The first trials showed that the tank could reach a top speed of 17.5 kph on a highway or 12 kph off-road. The situation with overloading was not too bad. The tank drove well in difficult terrain. It was also easy to steer and turned out to be a stable gunnery platform. The problems lay in the gearbox. Issues with this component nearly killed the Churchill tank in its infancy and an increase in mass of more than 10 tons was not easy on the transmission. 

Tank #3 was sent for military trials, which ended unsuccessfully.

Pilot tanks began leaving Vauxhall in early 1945. The tank earned mixed reactions during trials. On one hand, it was a stable gunnery platform, the ventilation was effective, and vision was good. On the other hand, the design of the hull was criticized. The desire to preserve the BESA in the hull resulted in a disappointingly primitive front hull design.

This photo was supposed to show progress, but makes for an effective epitaph: Britain's first and last infantry tanks.

There are claims that these tanks were sent to the front lines but didn't arrive in time. This was not the case. Unlike the A41 that was indeed sent for front line trials (that it was too late for), the Black Prince I was not. Transporting this tank was a difficult task, as 40 ton trailers used to transport British tanks were too weak for this 50 ton giant. Periodic issues with gearboxes kept this tank from getting a green light from the army. There was no chance for large scale production. The end of the war in Europe heralded a stop to large scale production of tanks and SPGs altogether. The Black Prince's turn came on May 30th, 1945, when the contract for 300 tanks was cancelled.

Trials of tank #4, the only prototype to survive to this day.

Work on heavy tanks did not end with this. By the time the A43 was cancelled the British were working on the A45, which was based on the Centurion. Although the A45 was unsuccessful, it led to the FV214 Conqueror, the first and last mass produced British heavy tank. Of the six Black Princes that were built #4 got lucky. Today it can be seen at the Bovington Tank Museum. This tank is technically a runner, but photos suggest that the gearbox routinely gives trouble.

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