Monday 1 November 2021

The Third Reich's Last Tanks

German tank building was in a difficult state towards the end of WW2. The issue wasn't just in factories damaged by bombers, loss of significant territories, and shortages of resources. The consequences of mistakes in planning and production as well as unscrupulous competition began to crop up. Let's take a look at how the new head of the Panzerkommission tried to bring order back to German tank building and what came of it.

God helps those who help themselves

German tank building was in a tough spot by 1944. Production of light tanks failed completely. An official order for a new reconnaissance tank was made on September 15th, 1939, and MAN presented the vehicle known as the VK 13.03, Pz.Kpfw.II Ausf.L Luchs, or Pz.Sp.Wg.II Ausf.MAN (Panzerspähwagen - armoured reconnaissance vehicle) in early 1942. 

Pz.Kpfw.II Ausf.L Luchs with a 50 mm gun in a lightened VK 16.02 turret.

The plan was to build 800 Luchs tanks with the first 100 due by April 1943. Instead, it took until January of 1944 to complete this batch, and that was the full run of production. This was a truly catastrophic result. Even though Skoda and BMM received similar orders later, they presented their bids earlier. The Pz.Kpfw.38 n.A. turned out to be more than a match for the Pz.Kpfw.II Ausf.L. 

German companies pulled some strings with the Ordnance Directorate to get rid of their Czech rivals, but they could not meet the demand for reconnaissance tanks, and so the German army was left without them. There was no prospective light tank chassis by the end of the war. This result was obtained by Germany on its own, without any foreign saboteurs.

There were also serious missteps in the 20 ton tank class. The unified medium tank was envisioned in 1937, but the Germans continued to build armoured vehicles on separate Pz.Kpfw.III and Pz.Kpfw.IV chassis for the duration of the war. The tanks had similar characteristics, but very different designs. Both platforms reached their limit by 1943. Even with the Tiger and Panther on hand, the Germans couldn't abandon the 20 ton class chassis, as it was needed for mass produced tank destroyers, SPAAGs, SPGs, etc. Work was conducted to replace the ageing Pz.Kpfw.III and IV, but for various reasons the VK 28.01, Porsche's Typ 245, 250, and schwerer kleiner Panzerkampfwagen (small heavy tank) remained on paper.

As for the Panther and King Tiger, these were quite fiddly tanks with low reliability. This is often excused as growing pains or necessary wartime compromises. This is partially correct, but the Ordnance Directorate started affecting the process even before the war. For instance, when developing a gearbox for the 700 hp engine the Germans ignored planetary and three-shaft schemes and focused on expensive and exotic shaftless designs. A three-shaft gearbox had to be hurriedly developed to make the Panther cheaper to produce, and its reliability suffered as a result. The planetary gearbox was not even tested on a Tiger tank before Germany lost the war.

Schwerer kleiner Panzerkampfwagen with the 105 mm PAW cannon.

The looming catastrophic end of the war made it clear that the German army needed lots of cheap and easy to produce armoured vehicles. Unification and rationalization would have made production and service easier, but the German industry continued to deliver Tigers and Panthers as well as a whole zoo of vehicles in the light and 20 ton classes. It was necessary to improve the design of prospective tanks and catch up on unification. These were the most pressing issues for German tank designers in the last months of the war.

A unified chassis

Gerd Stieler von Heydekampf, director of the Henschel factory in Kassel, replaced Ferdinand Porsche as the head of the Panzerkommission in December of 1943. As an experienced manager, it was clear to von Heydekampf that the German tank program was a mess. In his words, heavy industry did not have necessary experience of mass production that automotive plants did. New designs were developed in an irrational manner, which resulted in a large number of distinct designs, many of which were needlessly complex. With von Heydekampf at the help the Panzerkommission no longer had an independent competitor and generator of new ideas, but tank development began to evolve in a less disjointed way. The Germans could finally deal with their zoo. 

Pz.Kpfw.III/IV, a tank on a single unified chassis.

Requirements for the Pz.Kpfw.III/IV medium tank were approved at a meeting of the Panzerkommission held on January 4th, 1944. As the name implies, this was a new vehicle on a unified chassis that combined successful solutions from both the Pz.Kpfw.III and IV. The Pz.Kpfw.IV donated its turret, gun, and cooling system. The ZF SSG 77 gearbox and turning mechanism were taken from the Pz.Kpfw.III. The engine remained the same HL 120 TRM. The Pz.Kpfw.III style final drives were reinforced. The running gear was brand new, composed of six steel rimmed 660 mm wheels per side.

The bogey suspension with leaf springs was taken from the Pz.Kpfw.IV tank, but the 540 mm wide tracks were inspired by the Tiger II. The clearance was raised to 520 mm. The new hull had good sloped armour. The upper front plate was 80 mm thick at an angle of 50 degrees. The upper side was 30 mm thick at 36 degrees. To simplify the design, the turret traverse was powered by a flexible electric cable meaning that the traverse was limited to 270 degrees in each direction. The ammunition capacity increased to 100 rounds.

Fragment of a Sturmgeschütz auf Pz.IV blueprint dated January 17th, 1944. 540 mm wide tracks, new road wheels, and sloped sides can be seen. All air intakes were moved to the roof. The same solutions were used on the new III/IV chassis.

The leichter Panzerjäger III/IV light tank destroyer was also designed on this chassis. It owed its light classification to the fact that Germany only split its tank destroyers into light and heavy classes. The unified chassis used the Jagdpanzer IV casemate with the 75 mm Pak 42 L/70 gun and 80 mm of front armour angled at 50 degrees. 

Department #6 of the Ordnance Directorate signed contracts for three experimental chassis in March of 1944. Production of the Pz.Kpfw.III/IV as soon as February of 1945 was discussed in June, but it was quickly decided to put all efforts behind production of the Panzerjager III/IV or Panzer IV lang (E) tank destroyer. The plan was to switch over Alkett and MIAG to the new vehicle in November of 1944, Krupp in January of 1945, and VOMAG and Nibelungenwerke in March. This move replaced the StuG III, StuG IV, Jagdpanzer IV, Panzer IV/70 (V) and Panzer IV/70 (A) with one vehicle. This was a good solution, as the new tank destroyer would have the powerful 75 mm Pak 42 gun without the overloaded suspension and issues with final drives of the Panzer IV/70 (A) and (V).

The prospective Panzer IV lang (E) was supposed to replace several existing designs.

The Germans tested several different suspensions for the prospective chassis. In September of 1944 Deutsche Edelstahl even assembled a Panzer IV lang (E) hull, but a month later the unified tank destroyer program was stopped for an even simpler and cheaper alternative.

The 38 D family

American aircraft pushed the Germans towards a new decision on unification. Alkett was bombed heavily in November of 1943, resulting in a significant drop in StuG III production. That is when the Germans decided to spin up production of an analogue at Czech factories. BMM had no equipment for working on 20 ton class vehicles, and so it rapidly developed the  leichten Sturmgeschütz auf 38(t), an SPG based on the Pz.Kpfw.38(t) and Pz.Kpfw.38 n.A. chassis. Later, Guderian insisted that it be renamed Jagdpanzer 38(t). The armament and thickness of the front armour were about the same as those of the StuG III and Jagdpanzer IV, but it was much simpler and cheaper. The Jagdpanzer 38(t) was cramped, unreliable, blind, and slow, but it had one significant advantage: it was ready for production immediately.

Comparison of the 38(t) and 38 D chassis showing different layout variants.

On September 26th, 1944, OKH announced the decision to spin up Jagdpanzer 38(t) production with the Tatra diesel engine at Alkett. This seems like a strange decision, since both the StuG III and Panzerjager III/IV that was supposed to replace it were better than the Jagdpanzer 38(t). Unfortunately, the army needed as many armoured vehicles as possible from Alkett, up to 1000 units monthly, and the factory never managed to produce more than 500 StuGs per month.

The Jagdpanzer 38(t) was the simplest, cheapest, and most mass producible alternative. On October 4th the Panzerkommission decided to keep just three types of chassis in production: the light 38(t), medium Panther, and heavy Tiger II. All SPGs, reconnaissance tanks, and ARVs would be built on these chassis. Any other vehicles would be phased out of production. The Pz.Kpfw.III/IV program was cancelled.

Jagdpanzer 38 D tank destroyer with the 75 mm Pak 42 L/70.

Department #6 of the Ordnance Directorate responded by saying that the 38(t) chassis is unsuitable for production at German factories due to differences in equipment. The Czechs also used planetary gearboxes, while the Germans traditionally preferred three shaft and shaftless designs. Alkett's design bureau led by Chief Engineer Michaels immediately began to convert the Jagdpanzer 38(t) to German standards, also correcting its many defects.

The new Jagdpanzer 38 D tank destroyer had a reinforced suspension, final drives, and turning mechanism. The lower side armour was no longer sloped, but the hull was wider. The 220 hp Tatra 103 air cooled diesel engine was linked to the ZF AK 5-80 gearbox via a reductor gear and a driveshaft. The top speed was 40 kph. The vehicle carried 380 L of fuel, enough to cover 500 km on good roads or 300 km cross-country. It was possible to widen the tracks from 350 to 460 mm and a new suspension on volute springs allowed the maximum weight to grow from 16.7 to 20 tons. Three types of armament were proposed: a 75 mm Pak 39 L/48, Pak 42 L/70, and 105 mm Sturmhaubitze 42/2.

Aufklarer 38 D reconnaissance tank with a 20 mm autocannon in an open topped turret.

The Aufklarer 38 D reconnaissance tank was designed on the 38 D chassis. The hull was longer and lower, the front armour was 30 mm instead of 60. The mass decreased to 14 tons. The gear ratio was changed to give it a top speed of 52 kph. There were two variants of armament: an open topped turret with a 20 mm autocannon and a machine gun and a 75 mm L/48 AK 7 B 84 mount without a muzzle brake. The turret, gun mount, and diesel engine were unified with the same components used on armoured cars. The result was a speedy light tank just 1.64 m tall with 500 mm of clearance. Its chassis would be used for the Bergepanzer 38 D ARV, Kugelblitz 38 D SPAAG, APC, and 120 mm mortar carrier.

The 38 D program solved a number of issues for the Germans. The army received its long awaited reconnaissance tank, five different 75 mm SPGs were replaced with one, and obsolete chassis were finally removed from production.

In January of 1945, the Germans planned to produce the first five Jagdpanzer 38 D at Alkett in march, then ramp up production until 800 vehicles monthly starting with December. VOMAG would build its first five Jagdpanzer 38 D in June and reach a rate of 300 vehicles monthly by December. The plans were corrected in March. Alkett was now expected to deliver two prototypes by April and begin mass production in June.  Zahnradfabrik send Alkett gearboxes for final assembly on April 5th, but the subsequent face of the Jagdpanzer 38 D is unknown. Preparations for production ended with the war, factory documentation was lost in a fire, and if any prototypes were captured they were likely confused for regular Jagdpanzer 38(t)s and scrapped.

Aufklarer 38D with a 75 mm gun in a casemate.

As for the Aufklarer 38 D, production would be set up at MIAG. In January of 1945 plans were made to receive the first five tanks in March with production growing to 300 units per month by December. The plans were also revised in March. The chassis would be used for tank destroyers and ARVs instead. The AK 7 B 84 gun mount was tested at Kummersdorf in February, but work on it would be completed only in April of 1945.

German tank builders spent a large amount of effort to create a new universal chassis, but the war ended just as they were about to reap the fruit of their labour.

Development of the Tiger II

The Tiger II would remain in production. No one considered replacing it, although the raw resign needed a serious refinement.

There were no complaints about the armament and armour, but reliability was a different case. Trials of a captured vehicle in the USSR revealed a multitude of issues. A tank that had driven just 444 km was leaking oil from the right cooling fan drive, its track links and pins were crumbling, final drives and drive sprockets broke twice, and wear of the engine resulted in fuel expenditure of 971 L per 100 km of driving on a country road. This is not even the full list of defects! Full trials could not be carried out due to a lack of spare parts.

A new engine deck for the Tiger II. This blueprint is dated November 24th, 1944.

Henschel's engineers slowly mitigated the drawbacks of their creation. The linkages in the cooling system were improved in June of 1944. Composite track links showed themselves poorly both from the point of view of their own lifespans and wear on the drive sprocket, and so starting in March of 1945 regular Kgs 73/800/152 tracks and drive sprockets with 18 teeth were introduced. A new engine deck was designed with the engine maintenance hatch enlarged and its flap split into three sections as well as new grilles. Erwin Aders reported that the new deck would be used starting with approximately the 700th production tank, but this never took place.

The OG 40 12 16 B gearbox could take the necessary load, but there were still questions due to its high complexity. The Germans were worried about production issues and considered the possibility of moving to the AK 7-200 gearbox used on the Panther. However, this gearbox was weak even for a 45 ton tank and suffered from breakdowns of the third gear. The PP33 planetary gearbox offered by the Pulsgetriebe company, designed under the guidance of planetary gearbox expert Erich Puls. This was a very simple design with eight gears forward and backwards with an excellent range of speeds of 18.63. The PP33 passed bench trials. Installation into a Tiger II tank was planned, but never took place.

Trials of the PP33 gearbox (right) on the PP37 bench (left) took place in Leipzig from January 5th to June 19th, 1944.

The engine was a whole different story. The Germans never managed to polish the HL 230 engine. Its output was capped at 600 hp at 2500 RPM (compared to the initial target of 700 hp at 3000 RPM) as of November 1943. The compression ratio was reduced from 1:6.8 to 1:6.4 in March of 1944. The 600 hp engine was clearly not enough for the 70 ton Tiger II, and so a replacement was needed. Several alternatives were discussed at a meeting involving von Heydekampf and Colonel Holzhauer from Department #6 held on January 23rd, 1945.

Maybach was working on a new 800-900 hp direct injection HL 234 engine. Its size was about the same as the HL 230, and the engines were interchangeable. The issue of unreliable carburettors that cropped up two years prior would also be resolved. The HL 234 was a favourite, but Maybach never got it to working condition. 

Drawing of the Sla 16 engine dated November 29th, 1944.

The main competitor was the air cooled Sla 16 diesel engine designed by Porsche and Zimmering. It was more fuel efficient and more powerful than the HL 230 (750-770 hp compared to 600), but Henschel chief engineer Erwin Aders argued that the X-shaped layout required a full change of the engine compartment, hull, and track tensioning mechanism.

An experimental Sla 16 was installed into a Jagdtiger at Nibelungenwerke after successful bench trials. The stock cooling system bulkheads had to be removed, the rear plate altered to fit new exhaust pipes, and new engine mount and engine deck had to be installed. Unfortunately, it is impossible to say what it looked like based on surviving information. There were three fuel tanks instead of seven, but the total volume was the same as on the production vehicle. The Germans could very well have introduced this engine into production for new vehicles, but replacing it on existing tank and SPGs would have been hard, unlike with the HL 234. There was also a second reason to reject it. Production of the first 100 unit batch was supposed to start at the Steyr factory instead of DB 605 aircraft engines, but the factory was also needed to build Tatra engines, and it would not be possible to retool it twice.

Two more engines were discussed in addition to the HL 234 and Sla 16. The Klöckner-Humboldt-Deutz company was working on the water cooled 800 hp T8 M118 V-8 diesel. The engine was simple, powerful, and could easily fit into the engine compartments of either the Panther or Tiger, but mass production was a long way off. MAN and Argus also designed a 700 hp H-16 air cooled LD 220 diesel engine. This engine was considered a backup plan in case the Sla 16 failed. Note that out of the four prospective Tiger II replacement engines, three were diesels.

Draft of a 105 mm gun installed in a Tiger II.

As for armament, the Germans were planning on fitting a stabilized sight, gun stabilizer, and rangefinder, as well as replacement of the MG 34 with the MG 42. This required considerable changes to the turret. Kreiselgeräte was tasked with development of the gun stabilizer, Karl Zeiss and Ernst Leitz worked on satbilized sights and rangefinders. Krupp also presented a draft project of a Tiger II with a 105 mm L/68 gun in late November of 1944. The Ordnance Directorate rejected this proposal since the gun was not accepted into service and separate loading would have reduced the rate of fire.

The expedited tank development program would have given the Tiger II a rangefinder and stabilized sight in April of 1945 and the HL 234 engine in August. The Sla 16 and T8 M118 diesels, gun stabilizer, and poison gas protection came after.

Panther Ausf.F

The Panther remained an unreliable tank until the end of the war. It could not cover long distances on its own due to its unreliable final drives, weak turning mechanism, and problems with the engine and gearbox. This happened for two reasons. One was that the Panther was a very numerous vehicle by German standards and any serious changes threatened production volumes. The second was that MAN was distracted by work on the Panther II, a project which started to slip in May of 1943. The only thing left to do was migrate solutions developed for the Panther II onto the Panther.

The final drive was the weakest part of the Panther.

The decision to accept new final drives developed by MAN and prepare equipment to produce them was made at the meeting held on January 4th, 1944, the same one that defined requirements for the Pz.Kpfw.III/IV. There were great difficulties with this. Despite all effort, it was impossible to improve reliability of the mass produced final drives since the size of gears and bearings was limited by the position of the track, drive sprocket, and brakes. Planetary final drives showed themselves well in trials, but production was harder and more expensive, plus the Heerestechnisches Büro (Army Technical Bureau) opposed them. Discussion lasted for a year and a half and led to nothing. The Panthers continued to break down.

Production of the Panther Ausf.G with a Panther II style hull began in March of 1944. Meanwhile, Rheinmetall continued to work on a new turret initially meant for the Panther II. The Turm Panther (schmale Blende) (Panther turret, narrow mantlet) was presented on March 1st, 1944. The order was given to Daimler Benz, who developed the Schmalturm turret jointly with Skoda. This turret was easier to produce, better armoured despite similar weight (120 mm thick front, 60 mm sides and rear), and equipped with a rangefinder. Its compact mantlet reduced the likelihood of a ricochet into the hull roof. An MG 42 machine gun and stabilized sight were planned, just like for the Tiger II.

A Panther Ausf.G with a Schmalturm turret. Mass production Panther Ausf.F tanks would have looked similar to this.

Production was supposed to shift to the Panther Ausf.F with the Schmalturm turret by May of 1945. This tank had thicker hull roof armour, new driver and radio operator's hatches, and an StG 44 assault rifle instead of the bow machine gun. The Panther would also use the HL 234 engine as of August 1945, same as the Tiger II. A simplified AK 5-200 5-speed gearbox, new turning mechanisms, and diesel engines were also considered. The Germans had time to produce only a few Schmalturm turrets and Panther Ausf.F hulls before the end of the war. It was considered that assembly never took place, but photos of Panther Ausf.F tanks with Ausf.G turrets have been found.

One cannot avoid mentioning the 88 mm KwK 43 L/71 gun in the Schmalturm turret. This idea was pitched by Krupp in the fall of 1944. Minimal changes were made to the turret. The trunnions were moved 350 mm forward to fit the breech. Instead, Daimler-Benz suggested increasing the turret ring diameter by 100 mm to 1750 mm, and also installing the rear plate vertically to increase internal volume.

Sketch of a Panther with an 88 mm gun.

The decision to combine the two projects was made at an Ordnance Directorate meeting held on February 20th. Daimler-Benz would develop a Schmalturm turret with a 1750 mm wide turret ring and sloped rear plate, Krupp would work on the 88 mm gun and its mount. Overall, the weight of the Panther would grow by a ton. Inspector General Wolfgang Thomale considered it necessary to use planetary final drives on these tanks. The Germans expected to build a mild steel prototype of a Panther with an 88 mm gun in June. In case of success, mass production would begin in Q4 of 1945.

Panzerwaffe '46

One article is not enough to cover all late war development programs. For instance, rigidly mounted guns and night vision devices were omitted. However, the above is enough to understand how German vehicles developed in 1944-45 and what tanks and SPGs would go into battle in the event that the war continued past the spring of 1945. Fans of Teutonic genius will be disappointed to learn that neither the Panther II nor the E-series would ever see the light of day. Work on the former stalled in the spring of 1943, and the E-50 and E-75 were never completed.

Plans for production in 1945 that von Heydekampf revealed during interrogation.

Instead, the Germans aimed to finally phase out vehicles on old chassis and replace it with light vehicles on the 38(t) and 38 D chassis, in parallel improving the designs of the Panther and Tiger II. According to von Heydekampf, the plan was to build 2000 light, 450 medium, and 200 heavy vehicles monthly by the middle of 1945. The implementation details of this plan remain a mystery. Von Heydekampf also listed the following as high priority topics:
  • Rigidly mounted guns (the recoil would be absorbed by the hull).
  • Further development of the 38(t) and 38 D programs.
  • Improvements of the Panther and Tiger designs.
  • Development of new engines.
  • Introduction of stabilized sights.
  • Development of the Kugelblitz SPAAG.
  • Introduction of night vision devices.
Overall, the German tank industry began to develop along more rational lines, producing tanks that would be a match for Allied vehicles. The problem was that the Centurion, Pershing, IS-3, T-44, and T-54 were already on their way. The Germans were hopelessly falling behind with no sign of their former supremacy.

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