Sunday 14 October 2018

Porsche's Tiger: A Victim of Dirty Competition

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 let 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.

A diagram of the Typ 100 from a British handbook on German tanks composed in 1947.

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.

Specifications for the VK 45.01(P) as of March of 1942. As further development showed, the estimate of 52.5 tons of mass was quite optimistic.

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.

A diagram of the Typ 101 engine group. The electric motors and drive sprockets moved to the rear.

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.

Siemens-Schuckertwerke D1495a motors in the transmission compartment.

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.

Design of the rear of the second VK 45.01(P) built.

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.

The same hull from the front.

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.

New design of the suspension and road wheels of the Typ 101.

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.


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.

Firing on the front armour with 7.5 cm FK 16 n.A. As you can see, the sloped plates were not penetrated, unlike the upper plate.

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.

Typ 102 transmission layout.

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.

Voith hydromechanical transmission.

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.

Design for installation of the 10.5 cm KwK 16/775.

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 first VK 45.01(P). This is a production vehicle, not a prototype.

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 digit 1 marks the first turret.

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 same vehicle from the rear. This was the only one of its kind to use 500 mm wide tracks.

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.

Ferdinand Porsche examines the second mass produced Pz.Kpfw.VI(P1), early June 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 second vehicle was significantly different from the first.

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.

The modernized Typ101/2. Some historians confused the fan belt for the engine drive belt.

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.

Assembly of the Pz.Kpfw.VI P at Nibelungenwerk. A full size model of the VK 30.01(P) can be seen in the top corner.

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.

Evidence of the Pz.Kpfw.VI P's adoption into service. Take note of the publishing date.

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 plane crash. 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.

A tank that was used as a test chassis. This is an August-September production vehicle with wide fenders.

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.

During trials in the 503rd Heavy Tank Battalion.

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 Bad Berka. 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 could.

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. 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.

Crossing swampy terrain. Meanwhile, the Pz.Kpfw.VI H was being dug out of a swamp somewhere near Mga.

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.

Pz.Bef.Wg.VI (P), Ferdinand Porsche's only tank that saw combat.

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.

New track links and additional front armour can be seen.

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.


  1. I can't help but think that somewhere along the line the possibility of giving the Porsche tank thinner armor must of come up. Someone must of noticed during trials that it was too heavy to go up hill.

  2. One of the problems with the electrical transmission was that it used a lot of copper, a strategic metal already in short supply and badly needed for construction of U-Boats.

    1. ...and any number of other purposes, notably virtually anything involving electricity in some fashion. I vaguely recall once seeing a discussion on the German surface warships and a passing mention that an overhaul of, IIRC, one heavy cruiser included replacing nearly ten kilometers of electrical cabling...

      Porsche's enduring fascination with petrol-electric drivetrains was going up against some very formidable economic maths. Small wonder the powers that be invariably ended up choosing the purely mechanical alternatives.

    2. Kellomies. In Porsche's defense every vehicle built with some form of trick transmission which bypassed using brakes to steer tanks, had suffered heavy breakdown rates. From a simple engineering viewpoint the petrol-electric appears to be obvious. Don't get me wrong, you are 100% correct that Germany simply could not spare all the copper. Sort of like modern day environmentalist never take into account the need for copper and rare Earth materials to electrify our transportation systems. In their minds it's as simple as buying Tesla's.

    3. I know of the arguments for the setup, it's great for heavy vehicles (which is why variations of the theme were and still are used in eg. locomotives). But it's frankly baffling that Porsche apparently simply ignored, and nobody from the strategic/industrial planning office side seems to have pointed out to him, the very relevant raw-materials supply concerns involved.

    4. It's pretty simple, Porsche started his life as an electrical engineer, and basically made the backbone of his entire career in electrical transmissions. It was a concept he was extremely familiar with, and greatly believed in.

      He also had the feeling that as a engineer, it was not his job to determine what is economical, that was for his superiors to decide. It was his job to deliver technically. (Professor Porsche's Wars goes over this quite nicely)

    5. Kellomies Agreed! Most likely Porsche assumed that market economics would prevail and folks would just mine more copper and other strategic materials. To be fair Hitler liked Porsche and this most likely went to his head. But yes they should of canceled his tank before the first one was finished. That or build just one without armor and use it as a utility vehicle.

    6. This happens a lot in engineering, the customer will make bad requirements and then blame you ;) If the economy couldn't shoulder the weight of the extra copper, that fact should have been communicated in the requirements or soon after the customer learned about the fact that such an unacceptable transmission was used. There were reserved variants without electric motors, and yet those were not prioritized.

    7. The Germans were rationing comparatively plentiful steel already before the war, Porsche could not *possibly* have been unaware of the copper supply issues. That he forged on with his petrol-electric concepts anyway implies wilful disregard of such matters; in a sense perhaps admirable integrity of an "auteur" who refuses to compromise his vision but casting some real doubts on his skills as an industrialist and businessman.

      Why the prospective customer didn't hit the brakes far earlier I have no idea, though from what I know of the general internal workings of the Reich at those levels I'd be willing to bet money that rank cronyism and string-pulling were involved...

    8. Kellomies, Porsche had willfully ignored practicality several times in his career in favor of what he thought was the technically best solution (which being Porsche, was usually electrical in some way). This is the biggest reason he kept getting hired and then fired by a wide array of firms. He would be hired for his technical brilliance, and then fired when his developments proved industrially or economically infeasible.

      I can only assume that Hitler's infatuation with Porsche is why Porsche was entertained for so long. Amusingly, Albert Speer was greatly disenchanted with Porsche and got in arguments with Hitler on a few occasions for Porsche's pet projects (again because of his 'screw economics' mentality).

    9. He's sounding more and more like a less dysfunctional version of Tesla tbh.

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  4. The USA fooled around with the T 23 electric tank at the same time, and couldn’t make it work.