Saturday, 22 February 2020

The Last Cruiser

The stagnation of British tank building in the 1930s cost the country dearly in WWII. Nearly the entire war was spent playing catch-up. There were some minor successes such as the Matilda tank, but the most common type of tank was the cruiser. Having started the war with tanks that had similar characteristics to the Soviet BT-7 tank, British tankers continued to receive new vehicles that were half a step behind their German counterparts. The British only received a tank that had more or less caught up to the enemy towards the end of the war. This was the Comet, the last cruiser tank put into mass production.

A better Cromwell

The A24 program had a good chance at making up the distance between British and German medium tanks. Theoretically, this tank was a match for the German Pz.Kpfw.III Ausf.J, exceeding it in mobility and armament. The problem was that the A24 turned out very unrefined and suffered from growing pains. The result was the Cruiser Tank Mk.VIII, aka A27M, aka Cromwell. These tanks  still missed the battle of North Africa and the landings in Italy. By the Normandy landings the Cromwell was obsolete. It was a match for the late PzIV variants with somewhat poorer protection and armament, but significantly higher mobility. The problem was that the German Panther tanks, surpassing the Cromwell in all parameters, reached the front lines a year prior.

A cutaway drawing of the Comet I. A less powerful gun allowed the creation of a smaller turret than the Challenger had.

Despite the growing pains, the Cromwell chassis was a good design. The Cruiser Tank A30 or Challenger on the Cromwell chassis began development in early 1942. In addition to a longer chassis and larger turret, the Challenger had a more powerful 17-pounder (76 mm) gun. There were two significant drawbacks: the greater mass and greater size (mostly the turret). The A30 was also a prolonged project: the first prototype was built in the summer of 1942, and mass production began only in March of 1944. The General Staff and War Department changed production plans several times over this period and also developed alternatives (for instance, the Avenger tank destroyer). Oliver Lucas from the Ministry of Supply played a key role in creating requirements for the new designs.

A pilot tank, 20 were made in all.

One of the requirements was developed in the spring of 1943. The British had already encountered the German Tiger tank. It turned out that the front armour could be penetrated by the 6-pounder only at close range. On the other hand, the 17-pounder anti-tank gun (only a towed variant at that time) did very well. An analysis of the situation suggested that the armament of the Cromwell was obsolete and the Challenger in its current form was ill-suited for the role of a cruiser tank. A logical decision was an intermediate design: something larger than a Cromwell but smaller than a Challenger. The 17-pounder gun could not be used: it  needed a 1778 mm turret ring.

The solution was to use a barrel shortened from 4581 mm to 4204 mm (full length including muzzle brake). Not only the barrel was shortened: the breech was shortened from 583 to 420 mm, as was the propellant casing. The gun was indexed QF 77 mm or 77 mm HV. In reality, the caliber was the same: 76 mm. The muzzle velocity decreased, but the gun still retained very high penetration power.

The driver's observation port and entrance hatch.

Work on a new tank began in parallel with work on the new gun. According to requirements, the new A34 cruiser tank received a turret with a 1626 mm turret ring (the same as the Challenger) on the Cromwell chassis. Unlike the longer A30, the vehicle retained five doubled up road wheels per side, but the tracks were widened to 457 mm (the Cromwell's tracks were 355 mm wide, the Challenger's were 394 mm). The mass increased to 32-33 tons. However, the Ministry of Supply was still thinking about alternatives. Specification A35 was discussed at a meeting on July 13th, 1943: the same A34, but with a longer hull, six wheels per side, and a 1778 mm wide turret ring mounting a full sized 17-pounder. The idea was rejected, but returned to at least once in the A44 project (a similar concept as the A35 but with thicker armour). Like the A35, it did not move past the concept stage.

First production Comet I, fall of 1944.

A wooden model of the A34 was finished by the fall of 1943. In October, the General Staff made an order for three mild steel prototypes and a hull for trials. Like the A30, the A34 used the Cromwell chassis as a starting point, but the A34 was improved. Retaining the Type F hull, the designers switched to welding. This not only increased the hull's robustness but allowed for weight savings. The upper front armour was increased to 76 mm and the lower front to 64 mm. The Type F hull solved the problem of exiting the tank for the driver and hull gunner. Their hatches were not very large, but still better than the two-piece driver's hatch that was blocked by the turret at certain traverse angles.

There were no engine or transmission changes: the A34 retained the 600 hp Rolls Royce Meteor Mk.III in combination with the Merritt-Brown Z5 transmission. They were sufficient for necessary mobility.

The final configuration looked similar to a T-34-85, slightly surpassing it in mobility and armament.

Unlike the hull, the turret was designed from scratch. The Cromwell's turret was assembled with bolts, but the A34 had a fully welded turret. The front, including the gun mantlet, was cast. The other parts were rolled. The front armour was 102 mm thick, the sides were 64 mm. Of course, cast armour is weaker than rolled, but overall the turret had similar protection to the Panther. Thanks to the enlarged turret ring, it was not as cramped on the inside as the Cromwell. The new turret also had more observation devices, which helped with visibility.

The same tank seen from above.

The first A34 tanks made from mild steel were finished in February 1944. 4 were made in all. The experimental tanks were different from the later ones, largely in the running gear (it was inherited from the Cromwell, which led to some issues during trials). A decision was made at a later date to change the running gear. The biggest difference was the addition of four return rollers per side. The thickness of the road wheel tires increased to 146 mm. The suspension was reinforced: telescoping shock absorbers were altered and the attachment of the springs to the suspension arms was changed.

Overall view of the Comet I.

The War Department did not wait until the end of the trials to order a pilot batch of 20 tanks. Like the mild steel tanks, these vehicles did not receive registration numbers. They were equipped with the modernized running gear, which only showed that the A34 still needs improvements. The RAC training center was supposed to accept the pilot tanks on March 17th, 1944, but work on defects dragged on. As a result, plans to put the A34 into production slipped to the fall.

The armour diagram. The hull remained rectangular, making ricochet unlikely.

The first production tank with registration number T.334901 was ready in October of 1944. It was generally analogous to prior vehicles, but had some improvements. The biggest change was the turret. It was noticed that the commander's cupola was vulnerable to being shot from the front, and a special deflector was added. There were also some changes to internal equipment. The mass of the tank crept up to the 33 ton mark, but thanks to the powerful engine the tank retained a decent power to weight ratio: 18 hp/ton. The top speed was recorded at 51.2 kph, the average speed was 40 kph, which was enough for a cruiser tank. The A34 was accepted into service as the Comet I.

Tail end of WWII

The War Department knew how important the new tank was and took all measures to ensure rapid production. The registration number pool allocated to these tanks indicated the requirements: it was planned to make 3000 tanks with registration numbers T 334901-T 337900. However, the initial order was somewhat smaller: 2000 tanks. It was spread out between four factories. Oddly enough, Birmingham Railway Carriage and Wagon Company (BRC&W), the company that produced the Cromwell and vehicles on its chassis, was not among them.

Leyland was most involved in the design, and received the biggest piece of the pie. Contract M9707 was signed for 825 tanks with registration numbers T 334901-T 335725. 350 tanks with registration numbers T 335726-T 336075 produced by John Fowler & Co. followed, produced for contract M10536. Another 500 with registration numbers T 336076-T 336575 were built by English Electric for contract M10531. Finally, 325 tanks with registration numbers T 336576-T 336900 were built by Metropolitan Cammell for contract M10532.

Comet I production at the Leyland factory.

A significant delay in production meant that the Comet missed both the Normandy landings and the heavy fighting of the fall of 1944. Even production at four factories simultaneously did not mean that the tanks will appear on the front lines immediately. Improvements also continued. After production of 100 units another variant appeared, but it had the same index: Type A. Experience showed that the idler with a rubber tire had a limited lifespan. A fully metallic idler was designed, tested on one of the prototypes, and put into production. The ammunition racks, initially fitting 58 rounds, were changed starting with the 101st Comet to fit 61 rounds. The return rollers also changed during production.

Comet I during training exercises with the 29th Armoured Brigade, January 1945. The brigade had to urgently transfer back to Sherman V tanks soon after.

The first Comet I began to reach front line units in December of 1944. The description of the Comet's career is usually limited to "used in one division in 1945". Indeed, they fought only in the 11th Armoured Division, but there were more than just two dozen as with the Heavy Tank T26E3. 31 Comets had already arrived in France in December of 1944. They were assigned to units of the 11th Armoured Division: the 29th Armoured Brigade, 3rd Royal Tank Regiment, 23rd Hussars, and 2nd Fife and Forfar Yeomanry. Before that, the 11th Armoured was fully equipped with Sherman V tanks, the British designation for the Medium Tank M4A4.

The 29th Armoured Brigade was the first to be rearmed with these tanks. It was transferred to Belgium where training with Comets began, but the German counteroffensive in the Ardennes put a stop to it. The brigade was hurriedly put back into Shermans.

Comet I from the 3rd RTR, March 30th, 1945. Tankers of this regiment had the chance to fight Tigers in their new tanks.

The delay meant that the actual rearmament took place closer to late January of 1945. Tankers of the 23rd Hussars managed to redistribute their ammunition in such a way as to fit 12 additional rounds of ammunition. This system was soon adopted by other tankers of the 11th Armoured. The division was fully ready for combat in late February. The Comet finally saw battle in March.

Unlike the Cromwell, which did not receive much love from its crews, the new tank was met with enthusiasm. The Comet was more mobile than the Sherman V, and had greater firepower (but still not as high as the Sherman VC). The tankers did not like the rectangular hull inherited from the Cromwell. The thicker armour did not help much. Tankers asked for a sloped front plate. This meant that the hull machine gun disappeared, but it was better than having armour that could be penetrated by the majority of German tanks. A 25 mm plate was installed as an experiment, but this was not put into production. The tankers also complained about the thin floor plate. Hitting an anti-tank mine could have very dire consequences.

Tanks with new all-metal idlers also made it to the battlefield.

After crossing the Rhine the 11th Armoured continued its advance into Germany. While the Comet did not see much tank-on-tank action, there were some instances of it. On April 12th tanks from 1st platoon A squadron of the 3rd RTR encountered a Tiger tank from Major Schultz's battle group. The Tiger managed to immobilize and destroy one Comet, but Sergeant Harding's tank flanked it and penetrated the side from 100 meters. The Comet I could penetrate the Tiger from a much larger distance, and the front armour at that. The 11th Armoured lost 26 Comet tanks in all, clear evidence that the tanks did not remain in reserve. The characteristics of these vehicles were largely the same and in some cases superior to the T-34-85 and Medium Tank M4 with the 76mm gun. This was a partial repeat of the situation with the Challenger I: the designers came up with a tank that did well in battle, but due to production issues it could not fully show itself on the battlefield.

Comet I at the NIBT proving grounds, summer of 1945.

Improvements continued in parallel with production. A new exhaust system was developed by spring with the exhaust pipes in the rear. It was not installed immediately, and the openings were welded up until a certain point. A tank of this type with registration number T.335159, produced in March of 1945, was sent to the USSR. The vehicle ended up at the NIBT proving grounds and went through a trials program including a 1000 km drive. The tank also took part in comparative trials to measure driving effort. It turned out that thanks to hydraulic servos the effort to drive the tank ranged from 12 to 20 kg depending on the conditions.

Overall, the tank did not impress Soviet testers. Of course, the move to welding and other improvements raised its effectiveness compared to the Cromwell, but the shape of the hull and turret were still poor. The British tank paled in comparison to the T-44. Today the vehicle that went through trials can be seen in the Kubinka tank museum.

Comet I from the 7th Armoured Division at the Victory Parade in Berlin, September 7th, 1945.

The War Department had no illusions about the Comet. It was clear in 1944 that this tank was only a temporary solution. The Comet was superior to the PzIV, but not quite a match for the Panther, especially in protection. The real answer to the Panther was the A41 heavy cruiser, the future Centurion. It turned out to be a much better tank, and the Comet's fate was sealed by the spring of 1945. The War Department radically decreased the orders for this tank after the end of the war. Leyland delivered 610 of them, Fowler 150, English Electric 276, Metropolitan-Cammel - 150. Not counting pre-production prototypes, 1186 tanks were made.

Comet at a demonstration, 1951. The tank already has new smoke launchers.

The end of production did not mean that the vehicle would disappear from service. The Centurion still had a ways to go, and the Comet was not a bad tank after all. After the end of fighting in Europe the 7th Armoured division was rearmed with these tanks. They took part in the Victory Parade in Berlin on September 7th, 1945. Some of these tanks had the new exhaust pipes. These tanks were called Comet I Type B.

The smoke launchers were changed afterwards. Initially, a bomb thrower was installed in the turret. It was deemed ineffective, and later 6-shot No.80 smoke launchers were installed on the sides of the turret, which were more effective in putting up smokescreens. These modernized Comets served in the BAOR (British Army on the Rhine) until 1957 and in Hong Kong until 1959. Their service in training units was even longer. The tanks were only written off in 1969. Not a bad result for a tank that was a middle ground between the Cromwell and Centurion.

Comet in the Irish army. Ireland bought 8 tanks of this type, 6 of them survived until this day.

Unlike the Cromwell, which was given to Polish and Czechoslovakian units, the Comet was never given to Britain's allies. The only tank sent abroad for a very long time was the one sent to the USSR. The tanks were exported only later, in the mid-50s, when they began to be written off. The first buyer was South Africa: 26 Comets were purchased at a cost of 20,000 pounds each in 1954. Libya also showed interest in the Comet in that same year, but the deal was not made (the Centurions were much more interesting). In 1957 Batista's government in Cuba acquired 15 tanks. They soon fell into the hands of the revolutionaries.

Ireland took an interest in the Comet in 1958. Until then, the country's armoured forces numbered only two Landsverk L-60 tanks and four Churchills. After negotiations held in 1959-1960 Ireland purchased 8 tanks at the cost of 22,000 pounds each. They remained in use until 1973, and 6 of the tanks survive to this day. The biggest order came from Finland. In 1960 the Finns acquired 41 Comets at a steeply discounted price of 2500 pounds apiece. These tanks served in the Finnish army until 1970.

A Finnish Comet, showing new exhaust pipes that were introduced on the Type B hull. Finland was the biggest buyer of Comet tanks, 41 in all.

The Comet had the best post-war career of all wartime British tanks and SPGs. The tank saw only a few months of combat, but its career after that was very long. British designers managed to catch up to tank designers from other nations and produced a modern tank. However, tanks become obsolete quickly during war, and by 1945 the Comet had insufficient protection from the front. The shortfall was only made up with the Centurion, which without exaggeration became a game changing tank.


4 comments:

  1. Just two quick questions/corrections:

    "The registration number pool allocated to these tanks indicated the requirements: it was planned to make 30000 tanks with registration numbers T 334901-T 337900."

    Wouldn't that be 3,000 tanks, rather than 30,000?

    "The first production tank with registration number T.334901 was ready in October of 1941."

    Shouldn't it be 1944?


    On a complete side-note, do you happen to have any info on why Austria got the Charioteer? Were they also offered Comets?

    ReplyDelete
    Replies
    1. Good catch, thank you. No idea about Australia, perhaps they managed to get Centurions instead?

      Delete
  2. Similar to the above typo:

    However, the initial order was somewhat smaller: 2000 tons. It was spread out between four factories.

    That should be tanks, not tons, right?

    ReplyDelete