Thursday 22 December 2022

All the King's Horses

The heaviest mass produced tank of WWII appeared on the Eastern and Western Fronts almost simultaneously. Unlike the Tiger, which the Western Allies had a taste of in Africa, and the Panther, information on which was available from the USSR, the forces that landed in Normandy on D-Day had to go into battle against the “King Tiger” blind. How did the Western Allies learn about the last member of the German “Big Cats”?

Bits and pieces

The Panzerkampfwagen Tiger Ausf. B saw its first battle on July 18th, 1944, in France. Two tanks from the first company of the 503rd Heavy Tank Regiment were knocked out. In addition, one tank fell into a bomb crater and got stuck there. Despite being aware of a “new mark of Tiger … having a sloping sided turret and hull” as early as May of 1944, the British learned very little from these knocked out vehicles, if anything at all. Judging by the somewhat inaccurate description of a new 66.4 ton Tiger tank with the 8.8 cm KwK 43 cannon described in the September 1944 edition of the A.F.V. School Gunnery Wing Information Bulletin, any available information was collected from intelligence sources rather than from the knocked out tanks. Even this limited information was more than what the Americans obtained. The head of the American military mission in the USSR, Major General John R. Deane, sent a request to Lieutenant General Lebedev, the head of the Red Army Main Directorate of Armoured Vehicles (GBTU) on October 4th, wishing to know more about the new enemy tank. Judging by the fact that Deane used neither the official index of the tank nor its commonly used nickname, but the term “Tiger Imperial”, the Americans had precious little information about the vehicle.

Photograph of the King Tiger tank from the January 1945 issue of the Intelligence Bulletin magazine. The photograph is annotated with the thickness of the tank’s armour plates.

Looks like the GBTU was not inclined to share too much information, as the article on new German tanks published in the January 1945 issue of the Intelligence Bulletin magazine had very few new details about the tank. According to the article, the King Tiger tank has been fighting on the Eastern Front since the winter of 1943-44. The improved Tiger weighed 75 short tons (68 metric tons) and reached a top speed of 24 mph (38 kph), with an average off-road speed of 9-12 mph (15-19 kph). Its 2’8 ½” wide tracks (650 mm) were highly resistant to anti-tank mines.

Despite the scarce information on the tank, the article praises its gun. According to the author, the gun’s high muzzle velocity allowed the tank to effectively engage targets at long range. However, it had its drawbacks. The high muzzle velocity came at a cost of a low barrel lifespan: only some 500 rounds. In an effort to reduce wear, a low velocity high explosive shell was produced, which reduced the maximum range. The article mentions that the same gun was used on Elephant, Jagdpanther, and Nashorn tank destroyers.

This data does not fully match up with the newsreel dedicated to trophies of the 1st Army captured at Düren in late 1944. Here, the width of the tracks is recorded as 34” (863 mm), the mass as 72 short tons (65 metric tons), and the top speed as 20 mph (32 kph). It’s likely that the data in the magazine came from a captured instruction manual, whereas the data in the newsreel was obtained experimentally. The speed obtained in Soviet trials of a captured King Tiger tank was noticeably lower than claimed in the manual as well.

King Tiger tank captured by the 1st Army at Düren.

Judging by the footage, the tank was disabled when a shell jammed its turret ring, and the Americans were able to capture it intact. The British were not as lucky. The situation with the original Tiger tank repeated itself, and obtaining a sample in running order for experiments proved a difficult task. Fortune eventually smiled upon the British forces, at least partially. On September 20th, 1944, a King Tiger tank turret was captured at Plessis. The tank that it came from burned up, but lab analysis showed that the heat was not enough to affect the condition of the turret armour. The turret was recovered and sent back to England for analysis.

A King Tiger tank knocked out at Plessis. A mortar shell struck a nearby ammunition truck, and the resulting explosion disabled the tank. The turret was later recovered for experiments.

Unlike the armour of other German heavy tanks, the King Tiger’s turret was surface hardened, but not on all plates. The hardness of the outer surface of the right side of the turret was 535-565 BHN, but the hardness of the outer surface of the left side was only 305-330. The hardness of the inner surface of both plates was comparable (325 and 296). The left side had another quick: its thickness varied from 80 to 88 mm. The thickness of the right side was a constant 82 mm. Like the right side, the front of the turret was also surface hardened. The roof, on the other hand, was softer than expected. A previous analysis of a Panther Ausf. G led to a theory that the Germans were reducing the hardness of armour in the 40 mm range, and this observation was consistent with this hypothesis. A lab analysis revealed a higher carbon content than expected. The Department of Tank Design theorized that this was done to retain the possibility of surface hardening the armour if it was required. This theory was supported by the fact that, out of four Panthers examined on the Western Front, none of them had surface hardened armour, but one such Panther was found on the Eastern Front. However, this attempt was futile. According to the author of the report, the surface hardening did little to affect the penetration of British capped armour piercing shells.

The lab analysis also showed that the quality of German armour varied wildly in comparison to British armour. When hit at normal, the performance of the armour was comparable, but the German plates performed much more poorly when angled.

Turret diagram with a likely placement of the gun mantlet. The British called this turret type “Plessis”, in honour of the village where it was found.

The gun mantlet was missing from the turret, but the report author was certain that neither the 57 mm 6-pounder nor the 76 mm 17-pounder would be able to penetrate it. The front armour not covered by the gun mantlet was split up into two sections: the most vulnerable (two 305×203 mm surfaces), where the 100 mm armour was exposed at almost a 90 degree angle, and the rest (1219×610 mm), where the armour was presented at a high angle.

The most vulnerable part of the turret could be penetrated by the 17-pounder at any range with an ordinary APCBC shell. The same gun could also penetrate this armour at an angle of up to 20 degrees when firing from 100 yards. The APDS round could have penetrated the armour from 1000 yards at an angle of up to 55 degrees.

The 6-pounder APCBC shell could have penetrated the most vulnerable part of the front of the turret from 1000 yards and the side from 750 yards. Other areas were too tough to handle. The APDS shell improved its chances: the most vulnerable area could be penetrated from 2500 yards, the most well protected area from 1700, and the side was vulnerable from 2300 yards.

The 2-pounder gun equipped with the Littlejohn Adapter could have penetrated the most vulnerable part of the turret or the side from 650 yards. 75 mm HEAT shells were also deemed as a possible effective weapon against the most vulnerable areas of the turret. A standard M61 75 mm round could only hope to defeat the side of the turret side at 400 yards, given a favourable angle.

The joints between turret plates piqued the interest of the British specialists. The author noted that this kind of connection improves the turret’s resilience under fire, but using this technique in production would have been expensive and time consuming.

Diagram of the “Plessis” turret armour. The shaded parts are vulnerable to even 57 mm APCBC shells.

While the report was being written, examinations of other knocked out King Tiger tanks revealed that the “Plessis” turret was among the minority, and other tanks carried an improved design. A sample was obtained and shipped to the proving grounds. This time, the entire tank was sent along with the turret. The tank was not in running order, and could not fire due to damage to the return gear, but at least it could be used to establish the protective qualities of the King Tiger.

The new turret, especially the new gun mantlet, removed a weakness that has been especially prevalent in the Panther tanks. It was now much more difficult to penetrate the roof of the driver’s compartment by ricocheting a shell off the gun mantlet. The gun mantlet armour was also significantly harder than that of the Panther or Jagdpanther gun mantlets. The hardness of other plates was comparable with the hardness of British plates of the same thickness, aside from the very thickest plates. According to the British, this degree of hardening was not enough to achieve optimal resistance. The amount of carbon in the steel decreased compared to previous samples, but was still enough for surface hardening.

King Tiger chassis #280093, turret #280124, produced in June of 1944, captured near Beauvais.

Same as in the previous report, the vulnerability data comes from calculations. However, as the report author notes, the quality of German armour was, at best, equivalent to that of British armour, and in many cases it was much worse. If anything, the numbers in the report underestimate the performance of British weapons.

A weak spot uncovered by the tank’s gun mantlet was found on the front of the turret once again. This spot could be penetrated by an APDS shell from the 17-pounder at 30 degrees from ranges of up to 1000 yards. The lower front plate could be penetrated from 1200 yards at normal or at 500 yards at a 20 degree angle. An APDS shell from the 77 mm gun could have penetrated that plate from 550 yards. The upper front plate was invulnerable to British anti-tank artillery. To penetrate it, a weapon 25% more powerful than the 17-pounder was needed. The report suggests that it is better to fire at the sides of the tank’s turret due to its rhomboid shape.

Firing at the sides of the tank’s turret, even at a sharp angle, would yield more results than firing at the front armour.

For instance, firing an APBC shell from the 6-pounder at the tank’s turret would yield results from 750 yards when ∠GAT was greater than 47 degrees. The tank’s hull was vulnerable at 58 degrees, and the upper side with angled armour was vulnerable at 70 degrees. When an APDS shell was used, these angles decreased to 33, 47, and 55 degrees, respectively. The side of the turret could be penetrated by an APCBC shell from the 17-pounder from 500-1000 yards at a sharp angle (25-30 degrees).

Armour diagram of the Beauvais King Tiger.

15 mm bullets could have an effect, since the gun mantlet offered poor protection from the right side at low depression angles. Armour piercing 15 mm bullets could also jam the turret.

25-pounder HE shells would have yielded the same results as against the Panther, as would fire from 20 mm aircraft cannons: damage to the radiators would be sufficient for the tank to quickly overheat and stop. An HE shell that hit above the tracks would also blow out the bottom of the pannier and detonate the ammunition stored inside. Since the internal equipment was not directly attached to the sides of the hull and turret, it would be difficult to dislodge by firing HE shells at the tank’s armour. The design of the tank’s hatches also made it impossible to penetrate the liner with shell fragments or bullets.

PIAT grenades could have penetrated the side of the hull or turret at an angle of up to 60 degrees. To guarantee the destruction of the tank’s tracks, at least two Mk.V anti-tank mines had to be used. One mine would only sever the track in ideal circumstances.

The inspection showed that the King Tiger was the most formidable tank of the German arsenal. Not only was penetration of the tank’s front armour unlikely, but several tried and true measures that were successfully used against the Panther no longer worked.

American 90 mm T30E16 HVAP round for use against heavily armoured targets

American anti-tank artillery was not as helpless against this newcomer as its British counterpart. The Heavy Tank T26E3 and Gun Motor Carriage M36 had an ace up their sleeve: the T30E16 HVAP round for their 90 mm M3 guns. Its shot could penetrate the upper front plate of the King Tiger from 100 yards, or the gun mantlet from 800 yards. The manual that came with the shell reminded the user that tungsten was an expensive and strategically vital element. These shells were only to be used at short ranges. For all other cases, the APC-T M82 shell was used, which could penetrate any other armour plate of the King Tiger.

A fully assembled T30E16 HVAP round.

Belly of the beast

Satisfied with their inspection of the King Tiger from the outside, the British climbed inside to evaluate the crew conditions. The commander’s station was the first to be examined. The tank commander had three positions: sitting, standing on the turret basket floor, or standing on the armrests of his seat. Unlike the tank’s predecessor, the commander’s seat had a back, but this came with a brand new problem: the back was positioned too far forward, and was liable to shove the commander off his seat, especially in motion. It was much more comfortable to stand while commanding the tank. The commander’s cupola of the King Tiger was judged to be superior to the one used on the original Tiger, but it was difficult to use for a man of medium height while standing on the turret basket floor.

The commander’s cupola of a King Tiger tank

The gunner’s seat was also comfortable, but his workspace was no better than that of other German heavy tanks. The position of the traverse mechanism handwheel prevented him from bringing his knees together. The cramped turret did not allow him to fully spread them either, which meant that it was impossible to sit comfortably, and the gunner quickly became fatigued. Using the handwheel was also difficult. Its angle could be adjusted, but no angle offered comfortable usage, as the gunner’s wrist chafed against the edge. This design was deemed “very unsatisfactory” by the British.

The gunner could also traverse the turret with floor pedals, but they were also difficult to use. The pedals were positioned too far to the right. When traversing the turret to the left, the gunner’s leg hit the handwheel gearbox. When traversing to the right, his leg was liable to slip into the opening in the turret basket floor. In addition, the pedals were very stiff to operate. It looks like the German engineers knew this, as they added an auxiliary traverse lever to the left of the gunner’s seat. This was better than nothing, but, according to the testers, even the combined operation of the pedals and lever did not allow for satisfactory turret control. In addition, the gunner hit his elbow against the commander’s footrest when pulling the lever back (traversing to the right).

The elevation handwheel also had its issues. The handle was too short, and the gunner’s hand hit the turret traverse lever when rotating it. The electric firing mechanism button was located on the handwheel handle, but no backup manual trigger was found.

The TFZ 9d sight was positioned too far to the right, and the gunner had to twist his body to look into it. The rubber liner was so hard, that using it in motion was an easy way to injure your nose. Aside from this sight, the gunner had no other observation equipment.

The rear turret hatch. According to the British, it was unsuitable for evacuation.

The driver’s seat was also uncomfortable. Unlike the commander, the back of his seat was well designed. The British liked the idea of a steering wheel, but not the design of the levers. The levers could only be operated from the lower seat position, and the driver’s hand hit the stick shift when using the right steering lever. It took both hands to operate the handbrake. The British found the design of the pedals satisfactory, except for the gas pedal. In the lower seat position, the gas pedal was positioned nearly vertically and was hard to press. The pedal for the upper position was very small, and it was hard to find by feel alone. The driver only had one episcope to look through. It could turn, but the driver’s sight was still very limited. The British came to the conclusion that even an experienced driver would have to rely on instructions from his commander when driving along a complicated road.

As the radio operator’s seat was absent, the testers could not reach any conclusions about this crew member’s comfort level.

The loader’s hatch in the turret roof. The British thought that it was copied from the Soviet KV-1 tank.

The loader’s seat was removable, and was also missing. However, it was still possible to evaluate his workspace while standing. The height of the fighting compartment was only 5’7” (170 cm), but the loader’s hatch ate up 3” (7.6 cm) when closed. Even a 5’4” (162 cm) tall loader could not work well in this space, since then he was not tall enough to reach the top two rounds of the ready rack.

Unlike the original Tiger, the loader also had access to the auxiliary turret traverse handwheel, but it was poorly positioned. Working with it was characterized as “uncomfortable and tedious”. The handwheel handle was also deemed too short.

The presence of one episcope was considered enough for the loader. However, this did not help the loader any when trying to see his ammunition. Since there was no lighting in the turret bustle, the ready racks were hard to see, as was the evacuation hatch. The shells in the ready racks also made it very difficult to climb through this hatch. Even with the shells removed, the hatch was only usable by an extremely skinny man. Testers decided that it would be easier to exit through the hatches in the roof of the turret than to risk getting caught on many protruding items on the way through the rear. During an attempt to climb out of the rear hatch, one tester became stuck, with two others taking 13.5 and 15 seconds to exit the tank. The faster tanker tore his clothes in the process. To compare, evacuation through the roof took up to 14.1 seconds (for the gunner), so there was no reason to risk climbing through the rear hatch.

Ammunition stowage in the King Tiger tank.

It took 8 seconds to load the gun from rack A and 9.6 seconds from rack B (8.2 seconds if the gun was elevated as far as possible). An issue arose when loading the gun at maximum depression. The guard rail around the breech blocked access to it, which made loading difficult and increased chances of dropping the heavy 51 lbs (23 kg) round. In this situation, loading the gun from racks A and B took 9.3-10.1 seconds. Loading from other racks took even more time. For instance, the loader needed 17.8 seconds to retrieve a shell from rack G. Refilling racks A and B from rack G or H was a very difficult and exhausting task. Accessing racks C and F was also difficult, as the MG 34 ammunition storage got in the way of retrieving the rounds. Disposal of a spent shell casing took 2.4 seconds.

Here, practice and theory were at odds once again. On paper, the rate of fire of the 8.8 cm KwK 43 L/71 was claimed to be 6-10 RPM. According to British experiments, this rate of fire was simply impossible. In general, the British did not like the bulky and heavy rounds, the design of the ammunition racks, and the necessity of throwing away the spent shell casing before the gun could be loaded again.

The gun itself drew more criticisms from the British. One of the complaints was that the gun was not maneuverable enough. Citing Soviet experience in fighting powerful but clumsy Ferdinands and Tigers, the British expressed that they would rather employ a maneuverable 76 mm gun than a heavier larger caliber gun. The mass of the 8.8 cm KwK 43 was 3563 lbs (1616 kg), which the British found excessive when compared to 2063 lbs (936 kg) of the 17-pounder. Experience in Normandy backed up the conclusions made from operational research on the Eastern Front.

On the other hand, the gas ejection system was found to be quite effective. Footage taken by a high speed camera showed that a significant amount of gun fumes, although not all, were ejected from the gun tube after firing. The compressor took about 30 seconds to recover the original pressure in the system after firing when operating at 1000 RPM, and 21 seconds at 1500 RPM.

 A King Tiger tank on its way overseas. The Americans performed their own evaluation of the vehicle.

The Americans decided to work with the uncomfortable turret traverse pedals and calculate the speed of the traverse. It took 700 rotations of the handwheel to fully rotate the turret by hand. With the engine working at 500 RPM, a full turn took 68-69 seconds in high gear. With the engine at 1000 RPM, turning the turret in high gear took 35-37 seconds, 25 seconds at 1500 RPM, and 18-19 seconds at 2000 RPM. In low gear, it took 75-77 seconds to turn the turret in a full circle at 1000 RPM, 50-52 seconds at 1500 RPM, and 40 seconds at 2000 RPM. No attempt to test traverse at a higher RPM was made, as the Americans were afraid of breaking the engine.

A colossus’ legacy

Despite the tank’s current day reputation, post-war inspection of German factories where King Tiger tanks were produced did not impress the British. The quality of the work and setup of production were judged to be poor. G were left in between plates due to loose tolerances, and welding seams cracked. Re-welding of defective hulls and turrets slowed down the already time consuming assembly process. Some gaps were large enough to require metal wedges to be hammered into them, which weakened the structure. The report’s author compared the German tank armour to a poorly built brick wall: they looked impressive, but this impression was misleading due to bad application of mortar.

A King Tiger hull at a Krupp factory. The arrow points to a crack in the welding seam.

Interestingly enough, “Tiger panic” did not die out with the end of the war. Post-war CIA reports claim the presence of King Tiger tanks in the hands of America’s new enemies. On paper, hordes of former German tanks wandered through Eastern Europe. According to CIA information, these were not just captured tanks, but newly produced ones as well. German specialists were allegedly hard at work in Chelyabinsk, producing known German tanks and designing new models. These ghosts did not only haunt the Americans. British specialists decided that the Soviets could install the 8.8 cm KwK 43 in the IS-3 in an attempt to improve its rate of fire.

However, when it came to “taming” the German King Tiger, the former Allies were not interested. For example, a King Tiger is listed among the trophies offered to the Canadians for study on February 5th, 1945. The Canadians declined to receive this tank.

According to CIA informants, a King Tiger tank was observed at a rocket test facility in Lyublino.

The King Tiger was a powerful enemy, not only almost invulnerable from the front against Allied anti-tank artillery, but also lacking several drawbacks of its predecessors. However, it still had many of the drawbacks common to all German “Big Cats”. Poor quality armour and welding, low speed, and uncomfortable working conditions for the gunner and loader reduced the tank’s value on the battlefield. Despite all of these drawbacks, the tank left its mark in the hearts and minds of specialists and the general public alike.

  • W. Schneider, Tigers in Combat I
  • Documents from the Central Archive of the Ministry of Defense of the Russian Federation
  • Documents from the archive of the Canadian Military Headquarters, London (1939-1947) RG 24 C 2
  • Intelligence Bulletin Vol 3 No 5 January 1945
  • IUCAT World War II films. Volume 16 Activities in the European Theatre of operations: 1st Army: Duren.
  • Armour Branch Report on Armour Quality & Vulnerability of “Tiger” II Turret
  • Armour Branch Report on Armour Quality & Vulnerability of Royal Tiger
  • Armor Piercing Ammunition for Gun, 90-mm, M3
  • Dokumentation W 127: Datenblätter für Heeres-Waffen, Fahrzeuge, Gerät
  • CIA Documents: CIA-RDP80–00810A007500350009–5, CIA-RDP82–00457R000100500009–0, CIA-RDP83–00415R002200080001–7
  • Army Operational Research Group Report No.11/51 Assessment of Forms of Anti-Tank Defense, Effectiveness of British and Russian Tanks
  • BIOS Final Report No. 614 Item No. 18 Welding Design & Fabrication of German Tank Hulls and Turrets

1 comment:

  1. "The front armour not covered by the gun mantlet was split up into two sections: the most vulnerable (two 305×203 mm surfaces), where the 100 mm armour was exposed at almost a 90 degree angle, and the rest (1219×610 mm), where the armour was presented at a high angle."

    I assume these are 'width x height" dimensions for both sets of figures? (I say this as the turret front appears to be wider than it is tall).

    I also don't know if the 1219 x 610 mm figure represents the entire turret front facing, or just the less-vulnerable area. Even if one assumes its the total facing, the vulnerable areas represent less than 20 % of the total surface area, and one-third of the total height of the turret facing. Moreover, even if one assumes the 50 % test-firing dispersion data for the Kwk43 as being representative (a 30 cm x 50 cm tall ellipse at 1000 meters) the vulnerable areas are un-targetable at 1000 meters; if you use the more realistic combat figure of 2 or 3 times that metric (3 times being the 95 % criteria) then it's 'yeah, you have a good chance of hitting somewhere on the turret, but not a lot of control where'. Once again, like a lot of other examples of 'weak spots' cited, this 'weak spot' doesn't have much practical value.

    "Interestingly enough, “Tiger panic” did not die out with the end of the war. Post-war CIA reports claim the presence of King Tiger tanks in the hands of America’s new enemies. On paper, hordes of former German tanks wandered through Eastern Europe. According to CIA information, these were not just captured tanks, but newly produced ones as well. German specialists were allegedly hard at work in Chelyabinsk, producing known German tanks and designing new models. These ghosts did not only haunt the Americans. British specialists decided that the Soviets could install the 8.8 cm KwK 43 in the IS-3 in an attempt to improve its rate of fire."

    I wonder if this perception was due to the CIA acquiring former Wehrmacht "experts" who, among other things, thought the Kwk43 was superior to the D-25T in armor penetration (by Soviet tests, it wasn't) or that the German King Tiger's armor was superior to that of the IS-3 (again, it wasn't). Soviet design criteria by war's end required that their medium tanks had to resist the Kwk43; but their heavy tanks had to resist the D-25T. So why would anyone want to make a King Tiger when you had the IS-3 with a better gun and superior armor protection in a lighter package? And the IS-4 has much superior armor and still is like 10 tons lighter.

    I say this because in generation after WWII's perception of the conflict, particularly in the East, was very much distorted by the German "experts" and generals either the CIA hired or who wrote memoirs after the war.