Nazi Germany (1943)

Assault Gun – Design Only

The Jagdtiger (Hunting Tiger) is a highly recognizable vehicle consisting of a huge flat-sided casemate built on the hull of the Tiger II Heavy Tank. What is less well known is that the Jagdtiger as we know it (design started in early 1943), was not the vehicle originally requested and that, by tracking that design philosophy and evidence, it is possible to see a completely different Jagdtiger; one which was never built yet still offers a fuller picture of the evolution of German heavy armor in the Second World War.

Conception

In the spring of 1942, the Army General Staff was requesting a 12.8 cm gun mounted on a self-propelled chassis capable of supporting the infantry and of destroying unarmored as well as armored targets at distances up to 3,000 m. Armor and firepower were the priority, not speed and maneuverability.

By 2nd February 1943, this demand became an official request in the form of a letter sent from Wa Prüf 4 (the Army High Command design office for artillery) to Friedrich Krupp of Essen, setting out the requirement to mount a 12.8 cm Sturmkanone (Eng: Assault Gun abbreviated to ‘Stu.K’) on a modified Tiger H3. The ‘Tiger H3’ concerned was what we now know as the Tiger II, which was not named as such until March 1943 following the abandonment of the VK45.02(H), which was at the time known as Tiger II.

The requirements from Wa Prüf 4 for the modifications meant moving the engine forward on the chassis, with the gun being mounted in a casemate at the rear. This philosophy was felt to have the advantage of keeping the barrel overhang for the tank to a minimum and allowing for a better distribution of weight, although it was not without problems, as would soon become apparent.

The firm of Henschel und Sohn of Kassel would be responsible for the design of the hull modifications to fulfill this project and was contracted to produce designs. The gun desired was a 12.8 cm Stu.K, and the intention was to simply take the 12.8 cm Kw.K. L/55 gun unchanged, in its entirety, along with mounts, breech, brake, and recuperator from the Pz.Kpfw. Maus, although there was a strong emphasis placed by the High Command on the removal of the muzzle brake, as this allowed the use of Triebspiegel shells for heavy anti-armor work. The design, therefore, was not simply an assault gun, but also a tank-destroyer too, the difference between the two being blurred in this regard.

Further requirements set out in this letter were the use of as simple a design as possible with an elevation of -8 to +15 and 15 degrees of traverse. The sighting for the gun consisted of the Sfl.Z.F.5 and Rbl.F.36 telescopes to allow for both direct and also indirect fire.

Panzerjäger Panther design

By the start of 1943, the attempts to mount a 12.8 cm gun on a chassis were focused on using either the Panther or Tiger II as a basis. The Panther design to mount this 12.8 cm gun followed the design request closely. The engine, cooling, and ancillaries were moved to the front of the hull, behind the driver and radio operator, with the fighting compartment at the back.

The 12.8cm L/55 gun was mounted in the front of a well-sloped casemate with sloping sides, a flat roof, and a sloping rear, rather akin to the design of the back of the Ferdinand. Elevation limits for this gun were just +15 degrees to -6.5 degrees which did not meet the -8 degrees desired. Further, the rather small space of the casemate for the breech of this huge gun likely restricted the traverse to below the required 15 degrees each way.

The advantages of the design, such as the less complex and expensive Panther chassis compared to the Tiger II chassis, and the reduced length, just 8.5 m long from the muzzle to the rear, were offset by its deficiencies, such as the gun placement complicating maintenance of the engine and transmission. It is also possible that the armor which could be carried was not felt to be sufficient on the Panther chassis but, regardless of why the design was dropped, the attention was switched to the Tiger II chassis instead.

Enter the Tigerjäger

The Panzerjäger Panther design was dropped at some point, but Dr. Erwin Aders, the design lead at Henschel und Sohn, was working on two alternative designs for a Panzerjager based on the new Tiger II design. By March 1943, Aders was actively considering armor for the design up to 200 mm thick on the front and up to 100 mm on the sides, although this was subject to change in order to keep the weight to 70-tonnes (77.16 tons) or less. The goal was to provide a finished design by June 1943.

On 12th April 1943, Aders’ designs for Henschel were ready and the name being used at the time was Tigerjäger (Hunting Tiger). Designs plural, because Aders presented not one design but two: Tigerjäger Design A and Tigerjäger Design B.

Competing Designs

Design A had completely disregarded the requirement of the initial design brief to move the engine to the front of the hull. Instead, this design kept the engine at the back, with the transmission at the front as it was already arranged on the Tiger II. Despite this, the hull still had to be lengthened by 300 mm. Spielberger, Jentz, and Doyle (2007) describe the frontal armor of this design as being 150 mm at 40 degrees on the glacis and 200 mm thick on the 60-degree sloping part on the front of the casemate. However, the side armor had been reduced from the 100 mm desired in March to just 80 mm in order to keep the weight down. In other words, the frontal armor was now effectively double or more than the Tiger I but with the same side armor as the Tiger II.

Construction of a casemate with the armor desired and enough room for the breech of the huge 12.8 cm gun created a major problem and the height of Design A had to be reduced by 40 mm to allow it to fit inside the German rail gauge height limits for transportation. This had the effect of reducing gun depression from the -8 desired to -7 but, other than that, the design had met almost all of the requirements desired in the original letter from Wa Prüf 4 in February.

Design B, on the other hand, was significantly more problematic. In order to meet the requirements of Wa Prüf 4’s request to move the engine to the front, the hull roof had to be raised. Further, the cooling system of fans and radiators would not fit and would require a total redesign but even so, the engine was put in the middle of the hull. This, in turn, created additional problems with the transmission of power from the engine to the transmission at the front and to resolve that dilemma would mean designing new intermediate gearing. If that was not bad enough, Dr. Aders had not managed to design an effective system for exhaust from the engine and ventilation as the new arrangement had created so many difficulties for the design, and that was just the automotive problems.

Along with this total redesign of the Tiger II to accommodate this new automotive arrangement and the casemate at the back, the vehicle was too large for the rail gauge. Altering the design in order to meet this limitation would further reduce the movement of the gun which was already reduced by the height of the hull in front of the casemate. Assuming for a moment that the height could be amended in the same manner as Design A, reducing the -8 depression to just -7, then we can only surmise that the figure of -7 would be yet further reduced by this engine deck-height issue to -6 or less. Significant benefits of this gun mounting which should not be forgotten, however, were that it kept the center-of-gravity of the vehicle further back and meant there was very little overhang of the gun over the front of the hull.

One more problem to add to this litany of issues was maintenance. Not only would Design B require parts unique to it which were not compatible with the Tiger II, such as the gearing and cooling systems, but access to these parts was hard too. The 12.8 cm gun and mantlet would overhang the engine deck and, with limited traverse and elevation, there was no means to remove the engine or transmission without first removing the gun. This would also have to be done anyway for the Design A option but only for a change of the transmission and not for the engine. A short note here is that, at this time, the only engine being considered for the Tigerjäger was the same as that of the Tiger II, the Maybach HL 230 TRM producing 700 hp.

When Design A was amended with the casemate 200 mm further back due to a design change over the gun mounting, it resolved the centre-of-gravity issues and also reduced the gun overhang at the front. Design B, therefore, offered little in the way of advantages over Design A and a whole slew of major and unresolved problems. With an urgency to get this heavy 12.8 cm assault gun platform into service, there was only one logical choice and Design A, despite not being the engine-forward design requested, was selected instead. Design A went on to be the Jagdtiger and Design B was dropped.

The Duplicate

The first ‘Tigerjäger Design B’, as previously described, dates to the first half of April 1944 and the creative mind of Dr. Aders at Henschel und Sohn. Just to be confusing for historians, there is another Tigerjäger Design B. In fact, it is actually written as ‘Tiger-Jäger B’ and also emerges from Henschel just a month after the first Tigerjäger Design B. This means it is almost certainly from Dr. Aders as well, as he was the chief designer at Henschel.

Given the fact it was almost certainly proposed by the same designer responsible for Tigerjäger Design A and Tigerjäger Design B, from the same firm and only separated by a month, it would be easy to assume that there may be an error and that there was, in fact, only 1 Tigerjäger Design B. Here though there is a lucky break for the curious, as the plans for the May 1944 Tigerjäger Design B, unlike the April 1944 Tigerjäger Design B, actually survive.

Looking at the plans for the May Tigerjäger Design B and comparing it to the description known for the April design, it becomes very apparent that they are not the same vehicle which have been confused. The April vehicle was an engine-forward, rear casemate design with the 12.8cm gun over the engine with a small projection, whereas the May vehicle is the engine-rearward center-casemate design just like that known for Tigerjäger Design A from April, mounting the same gun but only over the front of the hull and projecting forwards.

The May Tigerjäger Design B initially looks like Design A, but there is one key visual difference that is easy to overlook; a cut-away portion on the top edge of the glacis. This cut-away reduced the point at which the gun would foul on the hull during depression.

The armor listed on the plan for the May Tigerjäger Design B also matches the armor described for the April Tigerjäger Design A, namely 200 mm on the front of the casemate, 150 mm on the glacis, and 80 mm on the sides. As these armor figures both pre- and post-date the April Tigerjäger Design B, it can be reasonably assumed even without the plans that the armor would be the same.

Resurrection: September 1943

Design B might have failed but the idea of sticking the 12.8 cm gun is a rear-casemate engine-forward design certainly had one last surprise. This time it was not from Henschel but from Krupp.

On 24th September 1943, Colonel Crohn (Wa Prüf 6) wrote to Krupp about improving the armament for the Tigerjäger, which was now the Henschel Design A type vehicle. There had been problems with the 12.8cm L/55 from Krupp which was, as yet, still unfinished. The gun suggested by Colonel Crohn was the 12.8cm L/70 version of the gun which used the same two-piece ammunition as the shorter gun but would deliver a higher muzzle velocity for armor-piercing rounds.

Krupp set to work and on 21st October replied that they had altered the design (the current Design-A type vehicle) to take the L/70 instead of the L/55. The gun could still fit in the same mounts as the L/55 gun but caused serious problems. The extremely long barrel now projected nearly 5 m beyond the front of the tank, bringing the center of gravity much further forwards, leaving a great strain on the front suspension.

The solution, in one way, was obvious – put the gun further back. In fact, mount the gun in a casemate at the back of the hull and, in doing so, move the engine forwards. This was then unsurprisingly exactly what Krupp suggested. At the same time, they outlined what effect the use of an L/70 would have on the primary design they suggested, and outlined this exact alternative, namely moving the engine forwards and the gun backward. This would reduce the overhang at the front to just 2 m or so and bring the center-of-gravity further back too. The drawbacks though, would be the same as before on the Design B and, on top of this, Krupp foresaw an increase in weight too on top of the weight of the heavier gun. Krupp said that it would consult with Henschel on the matter but, as Henschel had already considered this problem, it is no surprise that this idea died as quickly as it started.

By the end of October 1943 then it can be said that the rear-casemate engine-forward Tigerjäger was well and truly dead as an idea.

Clues

Because the designs were both rejected,k as both had so many faults and neither drawing has survived, it is perhaps no surprise that the descriptions provided, along with a knowledge of the development of the 12.8 cm Panzerjager and Tiger II programs, only allow for an approximation or surmised layout to be offered.

Looking at all of the other Panzerjägers following this engine-forward principle, such as the Panzerjäger IV mit 8.8 cm L/71, the Elefant/Ferdinand with the 8.8 cm L/71, and the Panzerjäger Panther with the 12.8 cm L/55, they all share the same core elements of sloping casemate sides, flat roof, and a rear which slopes both out from the floor to about the midpoint before sloping back to meet the casemate roof.

It is also worth considering that rear-mounted guns were actually installed on the Tiger II chassis, such as the 17 cm Selsfahrlafette 17/21, better known as the ‘Grille’ (Cricket). For that design, the engine was brought forward and the gun taken to the rear. A look at the engine position in the Grille, therefore, provides a view of what the front section of Design B might have looked like with the engine brought forwards. Why was it not a problem for the Grille when this layout was such a problem for the Tigerjäger? Simple: the Grille’s 17cm gun could be elevated far enough that access to the engine and transmission was relatively easy, as the gun did not need to be removed first.

Without seeing the original design, it is not possible to know for sure what Tigerjäger Design B looked like and the ‘invention’ of a tank, however reasonable it may look, is avoided by serious historians, which is why the artist’s impression shown here by the author is offered with the warning that it is exactly that, a rough impression of what it might have looked like based only on the little information available and from contemporary designs. Only if, and when, the original drawings are found can it be known for sure how close this impression is to reality.

Conclusion

The Tigerjäger Design B was literally a ‘paper panzer’ – it never left the drawing board. Designed by Henschel exactly as was actually demanded, it was simply surpassed by the alternative design (Design A), the design which went on to be the Jagdtiger. Using a rear casemate design with the engine forward would have allowed the use of the 12.8cm L/55 (April/May 1943) or even L/70 (September/October 1943) without the otherwise enormous overhang and without the excessive weight on the front suspension. Nonetheless, the design caused other problems relating to maintenance, the need for new component parts and really was not needed. There had been serious delays already in the Jagdtiger program at the time and 12.8cm L/55 production was behind schedule; switching to a longer gun would simply have slowed things down even more and the L/70 was simply not necessary to deal with its intended targets.

Krupp’s ideas for mounting the L/70 in the Design A never came about either and its ideas about moving the casemate to the rear were equally impractical given the problems of engine access. As it was, the Jagdtiger would follow a more conventional layout and the Design B of April 1943 was dropped. Together, the discussions over the Tigerjäger come together to provide a fuller picture of the small, but important steps in the evolutionary process for the Germans’ heavy Jagdtiger program.



Illustration of the Tigerjäger Design B produced by Mr. C. Ryan, funded by our Patreon Campaign

Tigerjäger Design B (April – March 1943) Total weight, battle-ready est. 75 tonnes Crew 6 Propulsion Maybach HL 230 TRM petrol producing 700hp Armament 12.8cm Kw.K. L/55 plus hull mounted machine gun Armor Up to 200 mm frontal, 80 mm sides and rear. 40-50 mm roof

Tigerjäger Design B (September-October 1943) Total weight, battle-ready est. 70 – 75 tonnes Crew 6 Propulsion Maybach HL 230 TRM petrol producing 700hp Armament 12.8cm Kw.K. L/70 plus hull mounted machine gun Armor Up to 200 mm frontal, 80 mm sides and rear. 40-50 mm roof

Sources

Spielberger, W., Doyle, H., Jentz, T. (2007). Heavy Jagdpanzer: Development, Production, Operations. Schiffer Military History, PA, USA

Hoffschmidt, E., Tantum, W. (1988). German Tank and Antitank. WE Inc., CT, USA