The German heavy tank program began in 1937, but work dragged on. Changes were being introduced into the design of tanks that hadn't even been built yet. Because of this, Porsche K.G. began working on a new Typ 100 heavy tank, known also as the VK 30.01(P), in December of 1939. Work on this project led to the creation of another tank, the VK 45.01(P), or Pz.Kpfw. Tiger (P), the main subject of today's article. This vehicle, often called the Porsche Tiger, was accepted for service and could have become the main German heavy tank of the war, had the situation developed a little differently.
Heavier weight with same dimensions
The VK 30.01(P) became the first German tank to combine thick armour with powerful armament that allowed it to combat vehicles of the same class. However, in March of 1941, when the armament of this pioneer was still being approved, the issue of even more powerful weapons arose. Germany was preparing for war against the USSR, and the Germans did not have verified information regarding the types of tanks used by the Red Army. Information that came in was sparse and contradictory, featuring tanks weighing over 100 tons.
It's not surprising that the creators of the German heavy tank examined more powerful weapons than the 8.8 cm Flak 18. These weapons included the 10.5 cm KwK L/47 and the 8.8 cm KwK L/56 with an increased muzzle velocity. A third weapon was considered in May: the 8.8 cm KwK L/71, based on the ballistics of the Flak 41 AA gun.
The future direction of German heavy tank development was confirmed during a meeting with Hitler on May 26th, 1941. The requirement for a gun that could penetrate 100 mm of armour from 1.5 km away was raised once more. In addition to that, the requirements for protection were increased. The thickness of the sides remained at 80 mm, but the front of the hull and turret had to be 100 mm thick. These changes applied to both the VK 30.01(P) and the vehicles designed by Henschel.
Since the VK 30.01(H) and VK 36.01 did not satisfy these new requirements, Henschel's engineers began work on a new tank. This tank, the VK 45.01(H), used the experience gained from the VK 36.01. The turret was taken from the VK 30.01(P). The development of the VK 30.01(H) and VK 36.01 continued, and so Henschel was working on three heavy tanks at the same time.
As for Porsche, initially the aim was to rework the Typ 100 to satisfy new requirements. The idea of improving the gun was quickly dropped. It is often claimed that the Tiger Ausf. E allegedly could have had the 8.8 cm KwK L/71 installed during modernization. In reality, this gun was considered from the very beginning. However, the gun demanded by Hitler was a victim of the turret. It was impossible to fit this gun into the turret that Krupp designed. Porsche himself wrote about it. THe idea of using the 8.8 cm KwK L/71 in the VK 45.01 turret is nothing more than an impossible wish.
The design of the Typ 100 with improved armour led to an unsatisfying conclusion. The vehicle's mass crossed the 50 ton mark. The existing engine was no longer sufficient. New, more powerful engines were needed, which in turn made it necessary to redesign the engine compartment. Instead of a modernization, the engineers ended up with a whole new tank. Its development began in July of 1941.
The vehicle was indexed Typ 101. Porsche's design bureau used the index Sonderfahrzeug II. The index VK 45.01(P), which was also used to refer to the VK 30.01(P) towards the end of its development, was also used in regards to this vehicle. However, it was clear from the start that the 45 ton weight class had little to do with reality.
Unlike Henschel, Porsche's engineers did not radically rework the initial design. The dimensions of the vehicle and the turret remained the same. However, the layout of the vehicle changed radically. The idea of a front drive sprocket was admittedly not the greatest. One of the drawbacks of this layout was that it was incredibly difficult to service the electric motors. A hatch in the front was needed to remove them, which hardly improved the resistance of the armour. The motors and drive sprockets were moved to the rear.
The increased mass forced Porsche K.G. to design a new gasoline engine, an air cooled V10. The index was the same as the tank: Typ 101. Its volume increased to 15 L and power to 310 hp at 2500 RPM. Two engines installed in the tank would have a combined power output of 620 hp. Each engine was connected to a Siemens-Schuckertwerke aGV 275/24 generator located to the front of the engine. Redesigned sponsons housed the cooling fans that took in air for the engine and transmission compartments. Current from the generators went to two Siemens-Schuckertwerke D1495a motors.
The hull had to be redesigned as a result of this change in layout. The length and shape remained almost the same, but the rear underwent a number of changes. The front also somewhat changed shape. The thickness of the front armour increased to 100 mm, and the sides and rear to 80 mm. The engine compartment also changed to accommodate the transmission. The sponsons also increased in height. To improve visibility, observation devices were installed into the corners of the front hull.
Evacuation hatches were included in the sides of the hull in the initial design. They appeared here thanks to the 6th Department of the Armament Directorate. Recall that the same hatches were used in the PzI Ausf. F, PzII Ausf. J, and VK 36.01, which were all designed with the direct involvement of the 6th Department. The fact that the hatch weakened the side armour and was nearly impossible to use didn't matter. The VK 45.01(P) hulls were built with openings for the hatch, but the idea was quickly discarded. Not one tank with these hatches was built, and the openings were welded shut at the factory.
Another archaic solution remained, however. The new heavy tank inherited the characteristic stepped front hull. Including the truncated corners, it consisted of 6 parts. Areas weakened by the driver's observation device and machinegun mount were weaker still due to the nearly vertical front plate, positioned at only a 9 degree slope.
Unlike the hull, the suspension changed quite a bit. The support rollers were discarded, and the road wheels received internal shock absorption. The design of the drive sprockets and idlers changed completely. Only the track links remained unchanged, but not for long.
Metamorphosis
Hitler ordered that six prototypes of the VK 45.01(P) and VK 45.01(H) be built, all with identical turrets. However, the decision to build 100 VK 45.01(P) immediately without any prototypes was quickly made. At this point, Porsche's brainchild had a high priority. This was not because of Porsche's friendship with Hitler, Todt, and other industry figures. Unlike Henschel, which was on its fifth year of designing a heavy tank, Porsche K.G. completed its task quickly. Porsche's vehicle was also more promising. As for the potential subcontractors, such a Krupp, it didn't matter whose tank won. Either way, they would get the contracts for production.
On July 22nd, 1941, contract SS-2105803/41 was signed with Krupp for 100 sets of armour. Contract SS-210–5905/41 for the production of 100 turrets with armament was signed the next day. The guns were supplied by Wolf Buchau. The engines came from Simmering-Graz-Pauker AG. Electric equipment, including generators and electric motors came from Siemens-Schuckertwerke. The suspension was produced by Skoda. Final assembly was performed at Nibelungenwerk in Austria.
Krupp was finished first. The first four VK 45.01(P) hulls were completed in December of 1941, then 3 more in January of 1942, 12 in February, and 9 in March. 64 hulls were built before July of 1942.
An incident happened with the hulls in the spring of 1942. A hull was tested against the 7.5 cm FK 16 n.A. at Kummersdorf at a distance of 100 meters. The lower front plate was not penetrated, but the upper plate had no shortage of holes. At a meeting on May 7th it was decided that front armour should be surface hardened. These parts were introduced partially starting with vehicle #150050 and entirely from #150060. Trials in July showed that the situation improved. Nevertheless, all tanks built at Nibelungenwerk had old hulls.
The changes did not end with surface hardening. A decision was made in March of 1942 to built half of Pz.Kpfw.VI Ausf.P (that was the designation used) in the Typ 102 variant, factory index Sonderfahrzeug II HA. The Typ 101 was referred to as Sonderfahrzeug II EA. The E meant electrical transmission, while H meant hydromechanical, designed by Voith. The total mass of the electric transmission was 4.6 tons. The hydromechanical transmission, while half as heavy, was rather bulky, and only had a two speed gearbox.
On March 23rd, Krupp received the order to prepare 50 hulls for the Voith transmission. 10 hulls were ready by May. Voith received an order for the transmissions. According to CIOS data, 20 sets were built. However, they were not installed on any tanks. Orders were given to install just one transmission, and convert the rest of the hulls back. Later this transmission was installed on the Ferdinand tank destroyer. The vehicle travelled for 2000 km, but results showed that this transmission worked worse than the stock Tiger Ausf. E transmission.
Another alternative that never made it into production was a new gun. On October 30th, 1941, the Skoda design bureau prepared a project for the 10.5 cm KwK 16/775 gun. The 105 mm L/40.6 cannon could be installed in the Krupp turret with some changes in the mantlet and a new commander's cupola. The work did not progress past the draft stage. The characteristics of this weapon were not impressive compared to the 8.8 cm KwK 36.
The biggest problem with the VK 45.01(P) was the rush to get it into production. The reason why German command wanted to push it into production without waiting for a prototype is not hard to grasp. Very soon after the invasion of the USSR, the Germans understood that they underestimated the Red Army, including its T-34 and KV tanks. The Wehrmacht needed a heavy tank like a fish needs water.
The bottleneck in production was the engine, produced at Simmering-Graz-Pauker. The first prototype was built in December of 1941, and broke several minutes after it was started. Porsche and Simmering worked on correction of defects for several months. On March 9th, 1942, a second engine was delivered, which functioned like clockwork. Two days later a third engine arrived, also without issues. Both were sent to Nibelungenwerk on April 10th. Krupp delivered its first turret on that day.
The tank was completed on April 18th and sent to Hitler's HQ. This vehicle had large fenders, which protruded outside of the hull. The demonstration held on April 20th, Hitler's birthday, was generally successful, but not trouble-free. Issues with the engine did not disappear entirely, including cooling. In addition, 500 mm wide tracks proved insufficient for such a heavy tank. Changes were needed, and quickly. Nibelungenwerk was due to deliver the first 10 tanks in May of 1942.
By this point, Henschel caught up to its competitor after running in circles. On April 20th the first VK 45.01(H) was presented to Hitler along with the VK 45.01(P). Henschel's tank was lighter and used nearly the same turret as the Porsche tank.
Fighting with defects and bureaucrats
Defects discovered during testing resulted in postponement of the 10 tanks due in May of 1942. Meanwhile, Krupp delivered 2 turrets in April and 8 more in May. No turrets were delivered in June. The shape of the turrets was then changed, this was especially noticeable by looking at the roof. The earlier version had an indentation in the roof for the gun. Now the indentation was enlarged to cover the entire width of the turret. This allowed the size of the fighting compartment to be somewhat increased. These changes were introduced starting with turret #11 (this was the ninth turret meant for Porsche's tanks). The gun mantlet also changed. The first two altered turrets were finished in July of 1942.
The second tank, at this point named Pz.Kpfw.VI(P1), was completed in early June of 1942. It was somewhat different from the first production tank. The protruding fenders were replaced with individual front and rear ones. The width of the track links increased to 600 mm. This change was necessary, since the mass was significantly higher than planned and nearly reached 60 tons. The tank was equipped with a storage box from the PzIV. Finally, the vehicle received a full set of instruments, largely stored along the sides and on the rear fenders.
The tank was sent to Kummersdorf where it went through trials. Issues with the engine and cooling system cropped up again. However, these issues were already known. A production engine was tested in June of 1942. It put out 311 hp, but then the problems started. Karl Rabe, Ferdinand Porsche's right hand man, discovered the main cause of the issue. Due to a small cooling surface and bubbling of the oil, which played the role of the coolant, the distributer shaft overheated. As a result, the engine began to rapidly lose power and break down after 50 hours of service.
A modernization was proposed to resolve the issue. The engine with two additional fans placed over the generator was indexed Typ 101/2. It had similar dimensions to the Typ 101, but the engine compartment still had to be enlarged to house it. The contract changed once more on July 23rd. Now 30 vehicles were to be built in the Typ 101 variant, 10 more in Typ 102, and the 60 remaining tanks with the Typ 101/2 engine would be called Typ 103. Since these modifications differed little from the original, they all retained the Sonderfahrzeug II EA factory designation.
Delivery of hulls stopped pending modifications. The deliveries were scheduled to resume on October 5th, 1942, and 45 chassis would be ready between February and March of 1943.
There was also a reserve variant, first mentioned on March 23rd, 1942. These were the Typ 130 and Typ 131 tanks, with factory names Sonderfahrzeug 101 WE and Sonderfahrzeug 101 WH respectively. Their special feature would be liquid cooled engines. The Typ 131 was more of a backup plan. In practice, only the vehicle with an electric transmission, the Sonderfahrzeug 101 WE, would be built.
Some historians claim that after the demonstration held on April 20th the Nazi leadership made the choice to go with the Pz.Kpfw.VI(H1) over the problematic vehicle. That is not the case. Yes, Porsche's tank had plenty of growing pains. However, that was normal for entirely new tanks, especially ones put into production without a prototype. The electric transmission that is often ridiculed worked fine, unlike the transmission on the Henschel tank.
Do not be fooled into thinking that everything was going smoothly with Henschel's production, either. The first tanks were only delivered in August of 1942, a meagre 8 units. Nibelungenwerk completed 4 tanks in that time. In September, 3 and 4 tanks were built, respectively.
On August 15th, 1942, Porsche's tank received the name Pz.Kpfw.VI P and the index Sd.Kfz.181. The same index applied to the Pz.Kpfw.VI H. In other words, both tanks were accepted into service.
It's not a secret that Henschel's Tiger had a higher priority at this point. This vehicle was designed under the direct control of the 6th Department of the Armament Directorate and Heinrich Kniepkamp personally. In April of 1942, even before the demonstration, Henschel had received a contract for 200 tanks. 124 were awarded in August of 1942. On February 8th, 1942, Fritz Todt, one of the supporters of Porsche and the Tank Commission, died in a car accident. Nevertheless, the Armament Directorate waited. 5 of the completed Pz.Kpfw.VI P went to Döllersheim, where they were assigned to the 503rd Heavy Tank Battalion. This implies that Porsche's tanks were still considered a viable alternative in the fall of 1942.
Starting with the sixth tank, the Pz.Kpfw.VI P changed. Trials showed that the idea with trimmed fenders was not the greatest, and expanded fenders that ran along the length of the tank returned. Design changes were made, the reliability of the engine increased. Not all issues were resolved, but recall that the Typ 103 was to enter production, which had an improved cooling system. In addition, the Typ 130 with liquid cooling was held in reserve.
Of the 9 tanks built from April to September, 4 were used as test chassis for various components. In October of 1942, the final tenth tank was completed. The vehicle was built as a commander's tank, and received the serial number 150013.
The Armament Directorate found itself in a sticky situation in October of 1942. Two tanks with identical armament, nearly identical armour, and each their own advantages and drawbacks were in production simultaneously. It was decided to perform comparative trials. Production of the Pz.Kpfw.VI P was paused on October 14th. On November 8th, two Pz.Kpfw.VI P and two Pz.Kpfw.VI H arrived in Berke. In climbing trials, both of Porsche's tanks managed to climb over an obstacle that neither the Pz.Kpfw.VI H nor the VK 36.01 cold.
During the trials it became more and more clear that they were staged as an excuse to limit the volume of Pz.Kpfw.VI P production. It was already decided what would happen with the 91 chassis that were produced already. They would be used to make the 8.8 cm StuK 43 Sfl L/71 Panzerjäger Tiger (P), better known as the Ferdinand. 90 turrets were converted by Wegmann for installation on the Pz.Kpfw.VI H (known as the Pz.Kpfw. Tiger Ausf.E as of December 1942). Henschel began to ramp up production, delivering 17 tanks in November and 38 in December.
The competition was dirty, but war is war. German command had to make a decision regarding which of the two similar tanks would remain in production.
One Pz.Kpfw.VI P made it to the front lines. This was the Pz.Bef.Wg.VI (P), the last tank that was built. It took part in trials in November of 1942, and later the tank ended up in Kummersdorf. In 1943 the tank was used for various trials. In early 1944, the vehicle returned to Nibelungenwerk, where it was converted. Instead of Typ 101 engines two Maybach HL 120 TRM engines were installed. The front hull armour was thickened to 200 mm. The Ferdinand SPGs were also modernized at this time, and renamed to Elefant. Since the Pz.Bef.Wg.VI (P) became heavier, it received the same 640 mm wide track links as the Ferdinand/Elefant. The tank also received a Zimmerit coating.
The converted commander's tank was sent to the front as a part of the 653rd Tank Destroyer Battalion. The tank was among its relatives: the battalion was armed with Elefant tank destroyers. There were three more vehicles on the Pz.Bef.Wg.VI (P) chassis here: the Bergepanzer VI ARV. The fate of all of these vehicles was the same. The Lvov-Sandomierz offensive began on July 13th. No records of the first and last battle of the Pz.Bef.Wg.VI (P) remain. One can only assume that the tank was lost under the steamroller of the Soviet offensive. On July 18th it was listed in the battalion, but by July 22nd it was missing, along with two of the Bergepanzer VI.
The real story of the Porsche Tiger is different from what some historians tell. There was no complex and constantly breaking transmission, nor was there 100 chassis built before the decision to stop production, nor a total victory of Henschel's Tiger over the Porsche variant. There was, however, a rush and a dirty contest.
After the end of the war there was no longer the 6th Department, nor the Armament Directorate, no Hitler, no Third Reich. However, a large part of the German companies remained. When work on a 30 ton class tank known as the Standardpanzer began in the late 1950s, the design submitted by Group A won. The developer of the chassis was the Porsche company, with Wegmann responsible for the turret. In 1965, the tank was accepted into service as the Leopard. Over two decades before that, Porsche K.G.'s first tank bore that name.
Translated by Peter Samsonov. Read more interesting tank articles on his blog Tank Archives.
Sources:
- BAMA (Bundesarchiv)
- NARA
- VHU Prahan (Vojenský historický archiv)
- Archive Jiri Tintera
- Panzerkampfwagen VI P (Sd.Kfz.181): The history of the Porsche Typ 100 and 101 also known as the Leopard and Tiger (P ), Thomas L. Jentz, Hilary L. Doyle, 1997, Darlington Productions, Inc, 1–892848–03–1
- Panzer Tracts No. 6 — Schwere-Panzerkampfwagen D.W to E-100, Thomas L. Jentz, Hilary L. Doyle, Panzer Tracts, 2001, ISBN 0–9708407–1–3
- Germany’s Tiger tanks, D.W. to Tiger I: design, production & modifications, Thomas L. Jentz, Hilary L. Doyle, Schiffer Publishing, 2000, ISBN 0–7643–1038–0
- Der Panzer-Kampfwagen Tiger und seine Abarten, Walter J. Spielberger Motorbuch verlag, 1987, ISBN 3–87943–456–5
- Professor Porsche’s Wars: The Secret Life of Legendary Engineer Ferdinand Porsche Who Armed Two Belligerents Through Four Decades, Karl Ludvigsen, Pen and Sword, 2015, ISBN 978–1783030194
