Saturday, 21 October 2017

Pz.Kpfw. Löwe: The German Lion

During the Third Reich, the German tank building school was defined, in part, by monsters such as the Maus and E-100. However, the German system of armament from the 1930s had no superheavy monsters like these, and no heavy tanks at all. In the second half of the 1930s, the plan was to have two types of light tanks and two types of medium tanks. How did Germany end up with monsters like the Pz.Kpfw. Löwe, and how were they developed?

Bigger and fatter support tanks

The German heavy tanks program began in January of 1936. Heinrich Kniepkamp approved the development of a B.W. (verstärkt) (support tank, reinforced) 30-ton class tank. Henschel was chosen to develop the chassis, with Erwin Aders at the helm. Partially, the tank was designed by Kniepkamp himself, as he personally designed the suspension layout.

This project was unlucky from the very beginning. The development of the German heavy tank program did not go according to plan. On March 12th, it was renamed I.W. (Infanteriewagen, infantry tank). On April 28th, the more familiar index D.W. (Durchbruchswagen, breakthrough tank) was set. In September of 1938, the D.W. evolved into the VK 30.01, keeping its hull design, but receiving a new suspension with interleaved wheels.

Initially, the heavy tank would have a 600 hp engine, which would leave its mobility at the level of a medium tank. In reality, the D.W. received a 280 hp Maybach HL 120 TR engine, and the VK 30.01 received a 300 hp Maybach HL 116. This was just the beginning of the metamorphosis of the tank, which had some unexpected branches.

One of these branches was a tank that could have become the first superheavy vehicle of the Third Reich. Its godfather was General Walther von Brauchitsch, who was appointed to the post of the commander in chief of the Wehrmacht's land forces on February 4th, 1938. On November 24th, 1939, he gave the order to design maximally protected La.S. (PzI), La.S.100 (PzII), and B.W. (PzIV) tanks. They were designed to break through powerful fortifications in Europe, which were in no short supply. In January, Henschel received an order for another reinforced PzIV variant. The tactical-technical requirements described a tank with the dimensions of a PzIV, but with a mass of 65 tons and 80 mm of armour, capable of reliably protecting from the Pak 38 anti-tank gun. The tank's top speed would be 20-25 kph.

Jentz and Doyle's research also mentions the A.W. (Artilleriewagen, artillery tank) project. Little is known about this vehicle, but the superheavy tank would have 100 mm of armour, which would protect it from the 88 mm Flak 18. Data on its mass ranges from 80 to 100 tons. Its armament would consist of a 105 mm howitzer with a barrel length from 20 to 28 calibers.

This is what the S.W. was intended to look like originally. This reconstruction by Hilary Doyle shows how the hull would be disassembled for transport. The turret is a placeholder, in reality the tank would have received a new turret made from scratch.

Initially, the project was indexed S.W. According to the requirements, Krupp engineers planned for three kinds of armament. The S.W. turret model presented in April if 1939 had room for a more powerful gun than the 7.5 cm KwK L/24. The first alternative was the 75 mm KwK L/40, with a muzzle velocity of 685 m/s. This gun was developed for the heavy 30-ton tank, and was supposed to be able to confidently defeat French FCM 2C family heavy tanks. It was eventually discarded, as it was decided that a 24 caliber long gun was good enough to defeat enemy fortifications.

The second alternative was a 105 mm gun with a 20 caliber barrel and a muzzle velocity of 420 m/s. This weapon was more powerful than the 7.5 cm KwK L/24, but had its drawbacks. The ammunition would consist of one piece, which would make the loader's life in the small turret difficult. In addition, racks for the large rounds were harder to position in the hull. Krupp's engineers didn't think of adding a large turret bustle.

VK 30.01 turret in a fortification, summer of 1944. The VK 65.01 would have had a similar turret, but with 80 mm thick armour.

After deliberations, the 6th Department of the Armament Directorate settled on the 7.5 cm KwK L/24. This happened in late June. Earlier, in April, Krupp received an order to produce a S.W. turret from mild steel. The turret was supposed to have a hydraulic traverse mechanism.

As for the chassis, Henschel's engineers came up with a strange design. The 30 ton weight limit was not arbitrary. There were very harsh limits, which came from, in part, the need to transport the tank by rail. As a result, the designers had to come up with a system where the tank would be transported in three pieces. The chassis was a further development of ideas used in the D.W. and VK 30.01. The shape of the hull was similar to that of the 30 ton tanks, but it was longer, and a machinegun turret was added to the front.

The suspension was similar, but changes were made here as well. The number of road wheels grew to 10 per side, and their diameter decreased. This was done to better spread out the weight of the tank. As with the D.W. and VK 30.01, a torsion bar suspension was used. A 600 hp Maybach HL 224 engine, designed in 1938, would be used in the tank.

Final design of the VK 65.01. According to documents, it was made from mild steel.

On September 1st, 1939, the Inspection of Motorized Forces issued the order for a pilot batch of the VK 65.01 heavy tank. Another index was used to refer to this tank: Pz.Kpfw.VII. 8 pilot tanks would be built, with armour supplied by Krupp. The VK 65.01 project continued to develop: according to a contract signed in March of 1940, the final variant of the turret looked like the VK 30.01 turret, but with thicker armour.

Work continued actively in the summer of 1940, but the project was at risk. First of all, there was nothing to assault. Czech, French, and Belgian fortifications were defeated without any assault tanks. In addition, experience from the French campaign showed that tanks heavier than 30 tons should be avoided, since bridges would not be able to hold them.

As a result, work on the VK 65.01 began to wind down starting in August of 1940. The first German superheavy tank only reached the stage of assembly of the hull from mild steel, which was done in mid-1941. Work on the turret stopped even earlier: in October of 1940. As for the A.W., the tank shrank down to the VK 36.01 in July of 1940. The VK 65.01 died, only to be reborn as an even more monstrous project.

Superheavy King of the Beasts

The first information that the development of German superheavy tanks restarted came from a Soviet intelligence memo, issued on March 11th, 1941. The memo was dedicated to "the direction of development of the German armed forces and changes in its composition". Among other information, it contained the following section :

"3. Heavy tanks.

According to information, which still needs to be confirmed, the Germans are starting to build new heavy tanks.

Type V
36 tons
75 mm gun and 2 machineguns
Up to 60 mm
Type VI
45 tons
75 mm gun, 20 mm gun, and 3 machineguns
Up to 70 mm
Type VII
90 tons
105 mm gun, 2 20 mm guns, and 4 machineguns

In addition, the Renault factories are repairing 72 ton French tanks, used in the war in the West. According to information received in March of this year, which still requires confirmation, Skoda and Krupp factories are starting production of 60 and 80 ton tanks."

Of course, the information in the report is somewhat skewed. However, it was not completely wrong. The Type V and VI were the VK 30.01 and 36.01, which were also sometimes called Pz.Kpfw.VI. As for the 90 ton Type VII, recall that the VK 65.01 had that index. The 90 ton mass didn't appear from nowhere. According to documents dated April 4th, 1941, Krupp was working on a chassis that was only called "Sfl". No reliable data survives about this chassis, but it was supposed to carry a 149 mm L/40 gun.

This document, dated April 4th, 1941, makes one of the first mentions of the future VK 70.01.

It was clear what kind of chassis this was in November of 1941, when a new index appeared as the gun carrier: VK 70.01. The new heavy tank was first discussed at a meeting on October 4th, 1941, with the participation of Erich Wolfert, Krupp's chief engineer. The mass of the tank was estimated at 75 tons. It also was sometimes called Pz.Kpfw.VII.

Daimler-Benz MB.507 diesel engine, initially planned for installation into the tank.

The requirements for the VK 70.01 were ready for November 1st, 1941. According to them, the combat mass was set at 73 tons. The hull and turret armour would be 140 mm thick, and the sides would be 100 mm thick. The crew would consist of 5 men, three of which would be in the turret. the Daimler-Benz MB.507 engine, designed for LS torpedo boats, would propel the tank. Compared to the marine version, its power was slightly reduced. At 2200 RPM, it output 800 hp, and at 2400 RPM, 1000 hp. In the first case, the expected top speed was 40 kph, in the second, 43.6 kph.

The most powerful tank gun to be considered for installation in a German tank. No work was done past calculations.

The armament is worthy of additional discussion. As mentioned above, the initial plan was to use a 149 mm L/40 gun. According to correspondence, it would use separate ammunition, but single piece ammunition was originally planned. The weight of one round ranged from 43 to 50 kg. The expected muzzle velocity was 750 m/s. 

On November 8th, the issue of an even more monstrous gun was raised. The length of its barrel increased to 52 calibers, and the muzzle velocity increased to 890 m/s. We can only guess what kind of tank this gun was supposed to fight against. For some reason, this gun was later assumed to be the armament for a tank destroyer on the E-75 platform. In reality, the weapon is older than the chassis by 2.5 years, and this tank destroyer only existed in the form of approximations of the chassis's mass reserves.

Aside from a 149 mm gun, Krupp began working on a slightly less monstrous 128 mm gun. According to requirements issued on November 11th, 1941, the VK 70.01 had to be able to penetrate 180 mm at 60 degrees from 1000 meters. Two variants of ammunition were prepared for the prospective 128 mm gun by late December. The first was 1313 mm long, the second was 1593 mm long. The muzzle velocity was the same for both: 840 m/s.

The 105 mm L/70 gun was the main weapon of the VK 70.01 by the spring of 1942.

While the armament was being discussed, the VK 70.01 continued to evolve. By mid-December, the mass of the tank grew to 90 tons. This was a hard limit, since it was set by the weight capacity of railroad platforms. The first draft of the VK 70.01 (blueprint W 1648) was presented at a meeting on January 21st, 1942, to the Krupp technical director Erich Muller, Wolfert, and Sebastian Fichner, the chief of the 6th Department of the Armament Directorate, among others.

The presented project was slightly different from the initial requirements. The mass was 82 tons, and the top speed decreased to 35 kph. The thickness of the armour also decreased: the front was 120 mm thick, and the sides were 100 mm thick. Finally, the armament changed: the 128 mm gun vanished temporarily, the 149 mm gun was still under discussion, and the draft had a 105 mm L/70 gun. Like the 128 mm gun, it originated from an AA gun. The muzzle velocity was 965 m/s. During the discussion of the project, the engine was replaced: now the 800 hp Maybach HL 230 would be used, which was to enter production at the start of 1943.

The VK 72.01 was an attempt to create a lighter VK 70.01. As you can see by the numerous corrections, there was no consensus regarding the armament of the tank, or even its name. This document contains both "Pz.Kpfw. Löwe" and "Pz.Kpfw. VII"

Turbulent discussion of further development continued through February and March. The 128 mm gun returned, but now with a barrel length of 50 calibers. Nevertheless, the 105 mm gun was still considered optimal. The military was inclined to reduce the weight of the tank by thinning out the armour in the front to 100 mm and the sides to 80 mm, the same as on the VK 45.01.

This rush was triggered by German fears that, after the KV-2, even more powerful Soviet tanks would come from the East. German reports that 100 ton tanks are being built in the Urals were picked up by Soviet intelligence. The Germans were in the same state of panic as the Soviet military brass in the spring of 1941 after hearing about the 90 ton Type VII heavy tank. Based on plans made in late January-early February, the VK 70.01 would enter production by April.

The canonical Pz.Kpfw. Löwe, blueprint W 1661, dated April 7th, 1942. The front of the hull is formed from one curved plate.

The idea to reduce the weight of the tank evolved into the VK 72.01, which was finalized on March 5th, 1942. The 72 ton tank had "lighter" armour. Initially, it was supposed to carry either a 128 or a 149 mm gun. Later, the armament was changed to a 105 mm L/70 and 149 mm L/37. No data on the engine was specified, but the crew was increased to 6 men. Later, the data on the VK 72.01 was repeatedly changed. This is when the name Pz.Kpfw. Löwe was used, as well as Pz.Kpfw. VII. The VK 70.01 and related projects had a whole litany of indexes. Documents continued to refer to it by different names.

Hilary Doyle's reconstruction of the Pz.Kpfw. Löwe, viewed from the front. As with the VK 30.01, there are many questions regarding the commander's placement in the turret.

The situation with the "canonical" Pz.Kpfw. Löwe looks just as curious. It became so just because blueprint W 1661 is the only one that is still available in graphical form. It's dated April 9th, 1942. The 90 ton tank was still equipped with the Maybach HL 230, but its top speed was reduced further, to 23 kph. The armour and armament was the same as on the W 1648 project. There was also a lighter variant of the tank with 80-100 mm of armour that weighed 76 tons. The top speed increased to 26.8 kph.

Several features of the tank give cause for interest. For starters, the turret would be cast, a rarity for German tanks. The placement of the commander's cupola raises many questions. According to the draft, the commander would be sitting on top of the gun breech. Finally, the front plate was curved. Krupp's engineers planned on making the front of the tank in one part, just like on early T-34s. This was a common solution for Krupp at the time: the first (120 ton) Typ 205 Maus, as well as both variants of the Typ 180, had curved front plates.

The mouse that killed a lion

This was not the end of the Pz.Kpfw. Löwe's transformations. From March of 1942, a new player entered the superheavy tank develoment game, Porsche K.G. Ferdinand Porsche's team received an order for a 100 ton weight class tank. Like his competitors from Krupp, Porsche's engineers selected the 40 caliber 149 mm gun as the tank's main weapon. One alternative was a 128 mm L/50 gun.

One of the variants of the Pz.Kpfw. Löwe, dated April-May 1942. This tank has a 105 mm gun and a rear turret. As you can see, the front plate of the hull is curved.

Despite the competition between Krupp and Porsche K.G., there was cooperation on a number of issues. In either case, the contract for producing hulls and turrets would go to Krupp. Turrets for Porsche's tanks were also designed in Essen.

In turn, Porsche's design bureau designed engines, among other things. Draft W 1662 appeared on April 23rd, which listed Porsche K.G.'s engines are alternatives for the tank's power plant. A pair of diesel engines would produce 840 hp.

A turret designed by Krupp in May of 1942 for the 15 cm KwK L/40. It would likely have been installed on the Pz.Kpfw. Löwe if a decision was made to use a gun this powerful.

Several more variants of the Pz.Kpfw. Löwe were presented by Krupp in May-June of 1942. At least one had its turret in the rear. Until recently, that tank was assumed to have the 149 mm L/40 gun, but later it was discovered that this model was armed with a 105 mm gun. As for the 149 mm gun, it was only finally settled on in the second half of May. The issue was that it would not have fit into the stock turret. Given the 1.5 meter long cartridges, it would be impossible to load it.

Sadly, the final blueprints, including W 1670, have not been discovered yet, but it is likely that the turret was the same as on the first variant of the Maus. The similarity is expected, since the designer was the same. This turret had a turret bustle that solved some loading issues. Either way, by June of 1942 it was clear that the days of the Pz.Kpfw. Löwe are numbered. Porsche's project was clearly better and had a clearer future. On July 20th, 1942, the Lowe project was closed. Nevertheless, Krupp did not give up, and so the Tiger-Maus project was born. However, that is a whole different story.

1 comment:

  1. 10.5cm L/70 KWK

    This guns muzzle velocity was indeed given with 965m/s in some sources. However, this velocity was for a non-standart AP-shell, which in the primary sources is reported as Pzgr L/4.3 as of 18.0kg weight.
    The standart AP shell was the lighter, 15.6kg 10.5cm Pzgr rot, for which the primary sources give a muzzle velocity of 1025m/s when fired by the 10.5cm L/70 KWK. It occurs in primary sources together with the 18kg shell and 965m/s. No decision was made which projectile was to be used.