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Oscillating Turrets

Oscillating turrets were one of the latest trends in tank design in the early years of the Cold War, in the 1950s. The original intention of this type of turret was to make it easier to employ an automatic gun loader in the turret of a tank.
As well as the ability to fit an autoloader, there were other benefits. These included the ability to mount a big gun on a small chassis, have fewer crew members by the omission of the Loader crew member, and have a smaller turret. It also generally allows for a better front profile ballistically.

An AMX-13 90. The AMX-13s is perhaps the most famous and most successful tanks to use oscillating turrets. Photo: The Modeling News.

Design

Oscillating turrets consist of two parts that move on a separate axis. These are the top ‘roof’ section which holds the rigidly mounted main armament which moves up and down. In a conventional turret, the gun moves separately from the turret body, on its own trunnions.
The bottom ‘collar’ part is attached to the ‘roof’ via pivot joints and is fixed directly to the turret ring, allowing conventional 360-degree traverse.

History

Though it seems a relatively modern idea, the oscillating turret design actually goes back as far as the First World War, to a designer by the name of Arnold H. S. Landor. Landor, a British inventor living in Italy, who designed a new armored car in 1915. It featured possibly the first ever oscillating turret, which was armed with 65 or 75mm gun (specifics unknown) mounted on the vehicle’s roof. This was closely followed by an Armored car designed by Joseph Gonsior, Friedrich Opp, and William Frank. A joint project between the USA and Austro-Hungary from 1916, it had a machine gun in an oscillating turret. The elevation/depression was controlled via hand-cranks.
The next time such a component would appear would be in the early 1940s on the French armored car prototype, the Panhard 201. After the German invasion of France, the prototype was evacuated to northern Africa. This armored car was topped off with an oscillating turret that was manually operated and armed with an SA35 25mm gun.

The Panhard 201 with a simple oscillating turret. Photo: SOURCE
Late in the in the Second World War, the turret type was used again, this time as part of the German prototype Self-Propelled Anti-Aircraft Gun, the Flakpanzer IV Kugelblitz. This prototype was named after its turret; the name translates to “Lightning Ball”. It consisted of an armored ball mounted on an armored collar connected to the turret ring. The ball, mounting dual 30mm MK 103 cannons, moved independently in elevation, allowing it to target aircraft.
Post Second World War and during the early stages of the Cold War, the French began to lead the way in the development of this type of turret. They invested a great deal of time and money in designing such turrets for light tanks like the AMX-13 and armored cars such as the Panhard EBR (descendant of the 201). The French became the leaders in this technology and was the first (also one of the few) nation to employ this type of turret on a vehicle that saw active service.
Though they were never used on a serial production vehicle, the United States of America also began experimenting with oscillating turret designs in the late 1950s. Such turrets were developed for Light, Medium, and Heavy Tanks. Several prototypes were built to test these turrets, but they were never adopted. This was largely due to the fact that the Americans found no real advantage in using these turrets over the conventional format.

A scale model of the Kugelblitz produced by the designers. Photo: panzernet.net

Advantages

The major advantage of this type of turret was that it made the addition of an autoloader far easier becasue the loading system moves with the gun. In a conventional, rotating turret, an autoloader would have to follow the gun in elevation and depression to align the shell with the breech, and then ram it in. This method was used in the T37, an experimental American light tank. In other cases, such as with the Soviet IS-7 heavy tank, the gun had to be brought back to a neutral elevation after every shot, making engaging a target with multiple shots much slower. This is called the ‘index position’ and its an issue that remains to this day.
Oscillating turrets eliminated the hassle of both of these methods. As the gun was rigidly placed in the upper part of the turret, the autoloader, attached to the upper ‘roof’ section was free to ram shells in whatever the elevation angle the gun. Not only does this system speed up reloading but it allows the gun to stay on target during reloading which improves the speed of second and subsequent shots on target.
In a conventional turret, the breech of the gun sinks into the basket when elevated, meaning that the turret ring has to be of large enough diameter to accommodate this motion. With an oscillating design, the breach remains above the turret ring whatever the angle, meaning that the turret ring can be smaller, ergo, the hull can be smaller allowing for a bigger gun proportionally on a smaller vehicle. However, in this case, the maximum elevation angle is defined by the space between the rear of the turret and the deck of the hull, which may be less than the angles possible in a conventional design where the breach can fall into the hull.

Disadvantages

In this type of turret, the gun is often mounted high-up to grant as much room for elevation and depression as possible. Angles of fire though, were still rather limited when compared to traditional gun mounts. In elevation, the turret bustle would often be mere inches above the engine deck. Mounting the gun high in the turret gives a larger silhouette and easier to spot at distance than the lower-profile conventional turret. This is somewhat offset, however, due to the fact that in a hull-down position less of the turret would be exposed due the height of the gun mount and the improved ballistic shape of the turret
One of the biggest issues with oscillating turrets is that they could not be made safe against NBC (Nuclear, Biological, Chemical) attacks. Due to the to their design, there was a gap between the two moving sections of the turret. This was usually covered by waterproof canvas or rubber bellows that shrank and extended with the motion of the turret, but it was not an air-tight seal.

Outcome

The complexity of their design was the downfall of the oscillating turret, with most work on such designs coming to an end in the mid-1980s. To most military bodies, the opinion was shared that the turrets provided ‘no real advantage’ over the traditional format.
Autoloader technology had improved to the point of being compatible with a regular gun and turret layouts, removing the need for such turrets and the disadvantage of not being able to be sealed against NBC had remained a major and unresolved problem.
In 2013, however, a new vehicle with an oscillating turret entered service with the US Military. This is the M1128 Mobile Gun System (MGS). It consists of an unmanned, remote-controlled turret on the hull of the Stryker ICV (Infantry Combat Vehicle). The vehicle is armed with a 105mm M68A2 rifled gun, and is fed by an 8-round autoloader. It is currently one of the only vehicles with an Oscillating turret serving in an active Military.

The M1128 MGS with turret eleveated. Photo: WBS


French AMX-13 75.

Austrian SK-105 Kürassier

American 90mm Gun Tank T69

American Stryker based M1128 Mobile Gun System
Illustrations by Tank Encyclopedia’s own David Bocquelet

Tanks & AFVs with Oscillating Turrets

France

Panhard EBR: Armored car. In 1940, one of the pilot vehicles, the Panhard 201, was used in testing one of the earliest examples of an oscillating turret. Later models shared turret types and weaponry with the AMX-13. 1954, in service in France until 1981
AMX-13: A series of light tanks. Started out with a cylindrical oscillating turret with non-autoloading 75mm. This progressed to a longer, squarer turret with an autoloading system known as the FL-10. It is perhaps the most successful type of oscillating turret. Armaments progressed from a 75mm gun, to a 90mm and finally a 105mm gun. Entered service in 1952, in service with France until the 1970s, also in the arsenal of countries like Israel, Mexico and Singapore. Singapore only began to retire the tank in 2012.
Char Leger De 12 Tons: Competing design for a light tank, utilising a similar (if not the same) turret as the AMX-13. The major difference was with the running gear based on the classic German interleaved design. Early 1950s, no serial production.
AMX ELC EVEN series: A series of light tanks with various weapons including 30mm, 90mm and 120mm guns. The oscillating turret , consisted of a flat upper part on top of a ‘neck’ joint which was protected behind a truncated material cover. The weapons were often mounted off the center line at the extreme right or left of the turret. 1955, no serial production.
Batignolles-Châtillon Char 25t: Medium tank prototype designed along the same lines as the AMX-13s. It was armed with a 90mm gun and auto-loader. 1954, no serial production.
Lorraine 40t: Medium tank prototype with a unique suspension consisting of pneumatic road-wheels. It was armed with a powerful 100mm gun and autoloader. 1952, no serial production
AMX-50: A series of heavy tank prototypes. The earliest version borrowed much from the Lorraine 40t using a similar turret and the same 100mm gun and autoloading system. The later version incorporated a newer, larger turret design similar to that of the AMX-13’s known as the ‘Tourelle D’ and was armed with a 120mm gun. The AMX-50s borrowed the German style suspension with interleaved road-wheels. Early 1950s, no serial production.
Somua SM: A heavy tank design that competed with the AMX-50. It featured the same turret as the early AMX-50 prototype, armed with a 100mm gun fed by an autoloader. The hull design was heavily inspired by the Tiger II, but used a different individual wheel suspension instead of the famous interleaved type. Early 1950s, no serial production
Medium Tank M4 with FL-10: A number of surplus Sherman tanks were updated by adding the AMX-13’s 75mm armed FL-10 turret. Various models of Sherman were updated, including M4A1s and M4A2s. M4A2s with the turret were used by the Egyptian army in the Six-Day War. Mid-1950s, limited production.
Light Tank M24 with FL-10: A project to modernize M24s in France’s inventory by replacing the standard turret with the 75mm armed FL-10 of the AMX-13. 1956, no serial production

United States of America

Gonsior, Opp, and Frank War Automobile: A joint armored car project designed by Joseph Gonsior, Friedrich Opp, and William Frank. A joint project between the USA and Austro-Hungary from 1916, it had a machine gun in an oscillating turret. The elevation/depression was controlled via hand-cranks. Never left blueprint stages. 1916, no serial production.
76mm Gun Tank T71: A light tank design by two competitors. These were Detroit Arsenal (DA) and Cadillac Motor Car Division (CMCD). DA’s design utilised an oscillating turret and autoloader feeding a 76mm gun. The vehicle was never built and never left blueprint stages. Early-1950s, no serial production
90mm Gun Tank T69: Medium Tank prototype with an oscillating turret mounted on the hull of the failed T42 medium tank project. The turret contained an 8-shot cylinder, not unlike a giant version of one you would find on a handgun. Only one was ever built as the turret was not thought to provide “any real advantage” over the traditional type. Mid-1950s, no serial production.
105mm Gun Tank T54E1: Medium tank prototype produced for series of trials to find the best way to mount a 105mm gun on the hull of the M48 Patton III. An autoloader system was also utilised inside the turret. Mid-1950s, no serial production.
155mm Gun Tank T58: A heavy tank design utilising an oscillating turret with autoloader, mounted on the hull of the T43/M103 hull. Had the tank left the drawing board, it would’ve been armed with a 155mm gun, the largest gun to be mounted in an oscillating turret. Mid-1950s, no serial production.
120mm Gun Tank T57: A heavy tank design similar to the T58 but armed instead with a 120mm gun. Mid-1950s, no serial production.
120mm Gun Tank T77: A heavy tank project to mounting the T57’s turret on the hull of the M48 Patton III. Mid-1950s, no serial production.
M1128 Mobile Gun System: The latest American vehicle to use this turret type. It consists of an unmanned, remote turret on the hull of the Stryker ICV (Infantry Combat Vehicle). The vehicle is armed with a 105mm M68A2 rifled gun, and is fed by an 8-round autoloader. 2013, currently serving.

Austria

SK-105 Kürassier: Austrian light tank. The hull was an indigenous design, but it utilized the turret of the AMX-13 bought from France. They were armed with 105mm guns. Early 1970s, in service with Austria until the 1990s, remains in service countries such as Argentina and Botswana.

Sweden

EMIL Project: A series of heavy tank designs with heavily armored oscillating turrets. They were designed with autoloaders and guns from 105mm to 150mm. Two chassis, codenamed “Kranvagn” (English: Crane vehicle) were constructed before the project’s cancellation. Early 1950s, no serial production.
Strv m/42-57 Alt. A.2.
In an effort to up-gun their already vastly outdated Stridsvagn m/42. A meeting was held on February 15th, 1952 on possible improvements. One solution was to mount a new oscillating turret design on to the m/42’s hull. This idea never came to fruition, however.

Germany

Flakpanzer IV Kugelblitz: Anti-aircraft tank built on the chassis of the Panzer IV. The tank was named after its turret, the name meaning “Ball Lightning”. It was armed with two 30mm MK 103 auto-cannons. 1943, no serial production.
DF 105 Combat Tank: A cooperative project between France and Germany combining the Marder I chassis with an updated AMX-13 turret with a 105 mm main gun. It was called the DF 105 Combat Tank. Early-mid 1980s, not serialized. Mid-1980s, no serial production.
CLOVIS, FL-20, 105mm: A follow up project of the DF 105. The Marder chassis remained the basis, but a completely new oscillating turret was added. It was possibly one of the last turrets of the type to be developed. 1985, no serial production.

Great Britain

COBRA: A design for a 30-ton tank to carrying a 120mm gun. It was extremely lightweight for a tank with such a gun, but retained excellent armor protection over the entire frontal arc. Side and rear armor were sacrificed, however. 1954, no serial production.

Italy

AMX-13/60: An update program that replaced the existing gun of the French Light Tanks with a high-velocity 60mm gun.

Links, Resources & Further Reading

www.chars-francais.net
www.armchairgeneral.com
Panzer Tracts issue 12–1: Flakpanzerkampfwagen IV and other Flakpanzer projects development and production from 1942 to 1945, Thomas Jentz & Hilary L. Doyle.
Presidio Press, Patton: A History of the American Main Battle Tank, Volume 1, R. P. Hunnicutt
Presidio Press, Firepower: A History of the American Heavy Tank, R. P. Hunnicutt
Rock Publications, the AMX-13 Light Tank. Volume 2: Turret, Peter Lau
The Tank Museum, Bovington, UK
The National Armor and Cavalry Museum (NACM), USA
Musée des Blindés, Saumur, France

Categories
articles German tech

Schmalturm Turret

This turret had been associated with the planned Panther II. For a while it was thought to have been designed solely for it. The new turret was actually developed independently and was considered as an upgrade for both the ageing Panzer IV which was in its Ausf. J model at the time, and the Ausf. F of the fearsome Panther.
The Schmalturm (English: ‘narrow turret’) takes its root from the armaments manufacturer Rheinmetall. After their attempt failed somewhat, the project moved to Daimler-Benz in February 1944. This is where the name “Schmalturm” was born.
It followed specific design requirements, these were:
– Elimination of the shot trap under the mantlet
– An increase of protection while keeping the weight of the turret as low as possible.
– A decrease in the overall size of the turret, while still leaving the crew room to work efficiently.
– Addition of a stereoscopic rangefinder (The lack of this was one of the reasons Rheinmetall’s wasn’t approved).
– The replacement of the MG34 machine gun with the newer MG42. Make it easy for conversion into a command tank version (Befehlpanzerausführung).
– Make it compatible with possible IR device installation.
– It should Keep the standard Panther turret ring diameter (1650mm).
– Finally, Make the whole thing easier, faster and cheaper to produce.

Daimler-Benz’s Schmalturm

turret close up
Daimler-Benz’s prototype of the Turret, off-tank. (Photo – Achtungpanzer.com)
The turret granted increased armor protection in the shape of a 150mm conical mantlet leading to the 120mm front plate. The turret sides were 80mm thick outwardly angled to increase the effective protection. Despite the increased armor and narrower shape of the turm, the internal volume of the structure remained the same.

Armament Modifications

pzpantherf-bk
The KwK 44/1 in a special mount used for firing tests. Source:- https://www.oocities.org/
The Schmalturm turret was designed to carry a derivative of the deadly 7.5cm Kw.K.42 L/70 tank gun. In order to accommodate this powerful cannon, modifications had to be made to the recoil system. Škoda of Pilsen, Protektorat Böhmen und Mähren (English: ‘Protectorate of Bohemia and Moravia’) (German-occupied Czechoslovakia) with assistance from Krupp managed to create a new version of the canon with a more compact recoil system mounted on top of the gun. This was designated as the 7.5cm Kw.K.44/1 L/70. This allowed the gun to have +20/-8 elevation/depression. The usual muzzle brake was also removed from the barrel.

Panzers Considered for Upgrades

Panther Ausf. G and F

The Panzerkampfwagen Panther Ausf. G of the Panther were the test beds for the ‘Versuchs-Schmalturm’ (English: ‘experimental narrow turret’). The production version was to be named Panzerkampfwagen Panther Ausf.F and include several other changes. The tank needed little in the way of modification to accommodate the new turret. Several Ausf. Fs hulls and turrets were under construction near the end of the Second World War and at least one Panther Ausf. F hull mounting an Ausf G turret was known to be completed and see service defending Berlin in 1945.

Panzerkampfwagen Panther with 8.8cm Kw.K.43 L/71

Schmalturm-88
A diagram of the possible inclusion of the 88mm cannon, note just how little space is left in the turret. (Source – ftr-wot.blogspot.co.uk)
A further planned development of the turret, designed by Krupp in 1944, was the inclusion of the 88mm L/71 cannon, thus creating the Panzerkampfwagen Panther with 8.8cm Kw.K.43 L/71. The project was later taken over by Daimler-Benz in early 1945.
In Krupp’s design, in order to mount this larger gun, the trunnions of 8.8cm Kw.K.43 L/71 the was moved forward and protected by a bulbous housing, in front of which was the conical mantlet. Additionally, the trunnions on the 8,8cm Kw.K.43 L/71´s gun carriage were moved 350mm rearwards or the gun itself was moved 350mm forwards depending on how it is interpreted. This upgrade, however, would have necessitated the enlargement of the turret ring by 10cm.

Panzer IV mit Schmalturm

Pz IV Schmalturm
It is very unlikely that this mating would’ve been a success. The already overloaded Panzer IV Ausf. J chassis would have never been able to carry the added 7,5tons of the turm. The vehicle was already at its limit with 80mm frontal armour and 7,5cm L/48 main-gun, a weight which caused bending frontal springs and forced an enormous tension on the final drives. Also, the Ausf. J had no electrical turret traverse and used a simple mechanic turret traverse with a gearing for the gunner.
Early in September 1943 another concept was penned. Wa. Pref. 6 asked Krupp if it would be possible to squeeze the Panthers 7,5cm L/70 in the standard Panzer-IV turret. Krupp’s reply was as simple as “No”. Another order from April 12th 1944 demanded to equip a modernised Panzer-IV chassis with 7,5cm KwK-42 in a modernized turret, but this turret had only 50/30mm of armour and had a weight of 4,5tons.
The Panzer IV mit Schmalturm would’ve been the final and most powerful form of the Panzer IV model of tank, which at the time of the turret’s development was starting to be phased out.
Armed with the L/70 canon, this would have definitely been the case, and it would have improved its chances against tanks such as the T-34/85 and late-war 76mm cannon armed M4s.


Tank Encyclopedia’s own rendition of a Panther Ausf. G mounting the Schmalturm turret.
panther g early proto turret
First Versuchs-Schmalturm on a Panzerkampfwagen Panther Ausf. G chassis. Note the muzzle brake still on the gun. (Photo – Panzer Tracts)
pzpantherf-2
The same early test bed as above seen from the side. (Photo – Panzer Tracts)
panther g later turret
A second iteration of the Versuchs-Schmalturm mounted of a Pantherkampfwagen Panther Ausf. G chassis. (Photo – Panzer Tracts)

Bovington’s surviving Schmalturm, displaying the damage sustained in live-fire tests. (Photo – Author’s Photo)

Rheinmetall’s schmale Blende

pzpantherf-turettsk2
A diagram of Rheinmetall’s schmale Blende. Source:- www.oocities.org
Rheinmetall had been tasked with designing the Panther II turret. This new turret was named ‘Turm Panther 2 (schmale Blendenausführung)’ (English: ‘Turret Panther 2 (narrow mantlet variant)’). The cancellation of the Panther 2 project came in May 1943, but Rheinmetall continued their work, with their turret now destined for the original Panther.
Rheinmetall’s progress was sluggish, as 1 year later, they had not yet progressed beyond the drawing stages as evidenced by drawing H-Sk 88517 “Turm – Panther (schmale Blende)” (English: ‘Turret-Panther (narrow mantlet)’).
New requirements were drawn up for a new iteration of the regular Rheinmetall-designed Pantherkampfwagen V Panther turret. An Entfernungsmesser (English: ‘rangefinder’) was to be incorporated into the turret and the gunner’s sight was to be changed to a periscope in the roof. Rheinmetall’s design incorporated the Entfernungsmesser in the turret, but this created a huge hump in the turret roof.
It appears this design, combined with the long time already used with no practical results, prompted Wa. Prüf. 6 to move responsibility for designing a new turret from Rheinmetall to Daimler Benz. It seems about nothing from the Rheinmetall’s Turm – Panther (schmale Blende) design was used by Daimler Benz for their Schmalturm design. By 20 August 1944, the first Versuchs-Schmalturm was mounted on a Panther Ausf. G chassis.

Fate

A number of prototype turrets had been produced and tested on and off the Panther Ausf. G. However not a single Panzer IV would ever feel the power of this new armament, even though there were copious amounts Panzer IV hulls, no Schmalturm ever touched its turret ring. None of these projects left the prototype phase, and both the Pz. IV mit Schmalturm and Panther with 8.8cm Kw.K.43 L/71 never progressed further than pencil lines on paper.
Two of the production turrets were retrieved after the war by the Allies. The Americans took one while the British took the other and used it for ballistic tests. The remains of this turret can be found in the Bovington Tank Museum.

An article by Mark Nash

Links & Resources

Panzer-IV und seine Varianten (Panzer Iv and its variants) Spielberger and Doyle
Panzer Tracts issue No.5-4, Panzerkampfwagen Panther II and Panther Ausfuehrung F
Panzer Tracts issue No.20-1, Paper Panzers
The Author would like to thank Marcus Hock and Herbert Ackermans for additional information.

Categories
articles German tech Soviet tech

Zimmerit in Soviet and German tests

An unusual substance

The Soviets first encountered Zimmerit late in 1943 on Tiger tanks and Panzer IVs. Examining 5 Tiger and 15 Panzer IVs, the Soviets found that the Tigers were covered across the glacis, lower plate, hull sides, turret sides and even the track guards with this grey substance. Measuring it though they found it to be just 2-4mm thick. Of the 15 Panzer IVs captured with Zimmerit, two also had this material on the armored screens mounted on their turrets as well.
A well ‘zimmeritted’ Panzer IV on the Eastern Front, with Zimmerit on the hull and Schurzen as well as the turret screens
A well ‘zimmeritted’ Panzer IV on the Eastern Front, with Zimmerit on the hull and Schurzen as well as the turret screens
The Soviets were initially confused as to the purpose and make-up of the material, but quickly established that it would neither burn nor dissolve (although it would get softer in hot water). Far from thinking it to be a fire hazard, the Soviets initially suspected Zimmerit was some form of protection from incendiary bottles or camouflage, two things the British also considered later.
German records indicated that Zimmerit consisted of 40% Barium Sulphate, 25% Polyvinyl Acetate, 15% Ochre pigment, 10% Zinc Sulphide,
10% Sawdust. The Soviets examining both burned and unburned samples of Zimmerit in April 1944 (the samples provided to them from the front were rather small) found the material to have a melting point of 1100C and to consist of:

  • 53% Barite (Barite is another name for Barium Sulphate)
  • 16-17% Quartz
  • 27% Organic material
  • ~3% unidentified

The Soviet scientists did not receive very much Zimmerit to test but from what little they did have they made two assumptions. One was that the ridges may serve to concentrate the liquid and or heat from flammable liquids. This may melt the coating to extinguish the fire. The other one was that Zimmerit was some kind of winter camouflage due to the greyish color of the material.
Other vehicles found by the Soviets with it included the Panzer S35 and Panzer 38H, both of which were notable enough to be documented with at least one sent to Kubinka for trials, testing, or display.

Former German Army Panzer 38H(f) on show at the Kubinka testing ground in 1945, sporting a coat of either Zimmeritt or Cement
Former German Army Panzer S35 in Soviet hands, date unknown. Reportedly captured in Summer 1944 with a coating of either Zimmerit or Cement.
Former German Army Panzer S35 in Soviet hands, date unknown. Reportedly captured in Summer 1944 with a coating of either Zimmerit or Cement.
Whatever else they may have thought of it though the Soviets do not seem to have been either concerned or impressed by the material. It is possible they did some further testing with it, they probably had more pressing issues to deal with.

Somua_S35_zimmerit
Panzer S35 (Captured SOMUA S35) testing Zimmerit
Hotchkiss_H39-zimmerit
Panzer 38H(f) (Captured Hotchkiss H39) testing zimmerit
Germany 1945, this Panther Ausf A has suffered a significant fire resulting from enemy fire which has scorched off the Zimmerit coating from the hull and turret side.
Germany 1945, this Panther Ausf.A has suffered a significant fire resulting from enemy fire which has scorched off the Zimmerit coating from the hull and turret side.

Was it flammable?

One note of particular interest was the unusual application of Zimmerit to a couple of T-34s. In November 1944, the Germans conducted some limited trials of Zimmerit to test the veracity of the ‘flammability’ rumors. Two captured Soviet T-34 tanks were used for the tests.
T-34 number 1 had Zimmerit applied by the manufacturer, consisting of multiple layers which were properly hardened by means of a blowtorch. T-34 number 2 has just a single layer of Zimmerit applied by range staff in a single layer and left unhardened.
Tank number 2 was then left for 4 days and was completely cold (just 5 Celsius) before the armor was heated with a blow lamp and a welding torch for a period thirty seconds, which resulted in 3-4 seconds of small flames and a slight afterglow. The flames were probably a result of burning off of some of the residue which had not evaporated due to the cold weather, as it was reported that the smell of solvent could still be felt at this time.
The vehicle was left for another 2 days, after which it was heated by means of a camp fire made inside the vehicle. This raised its temperature to about 35 Celsius, and then the vehicle was again blowtorched.This time there were about 20 seconds of small flames and a slight afterglow. It is surmised that the preheating to 35 degrees released all the remaining solvents which were the cause of the flames.
This solvent flammability was found again during testing of ‘wet’, freshly applied, undried Zimmerit. Immediately after application, it was found to burn easily across the whole tank, but was also easily extinguished with just sand. The solvent in wet Zimmerit was, of course, flammable, so this is not a surprising result. Despite these tests and the resultant burning, it was found that the intermediate layer of Zimmerit still did not burn.
After these very elementary tests were finished, some firing trials were carried out on these vehicles with a variety of shells from both the 7.5cm PaK40 and the leFH18, at a range of 250 metres:

  • 7.5 cm Pzgr. 39, dud, no tracer (the shell is listed as being defective)
  • 7.5 cm Pzgr. 39, unmodified
  • 7.5 cm Pzgr. APC M61 Projectile with HE and tracer
  • 7.5 cm Pzgr. 38 Hl/C (?)
  • 7,5 cm PzGr 34
  • FH Gr. Phosphorus

At no time, from any of the impacts on either vehicle, did the Zimmerit catch fire. It was chipped off at the point of impact though and the overall conclusion of the testers was that Zimmerit was not the cause of fires in German tanks.
These German tests therefore sadly do not confirm the Soviet theory about how Zimmerit worked. The camouflaging element was essentially forgotten and the Soviets were winning anyway so wasting time on Zimmerit would have been nothing but a distraction for the Soviets. Despite the results of the tests proving Zimmerit wasn’t flammable, the Germans too dropped it.

An article by Andrew Hills

Other articles in this series

Part I: Zimmerit in German Use
Part III: British work on Zimmerit
Part IV: US work on anti-magnetic coatings

Links & Sources

The links and sources can be found in part I of the Zimmerit series

Categories
articles German tech

Zimmerit in German use

Origins

Probably one of the more unusual elements of German tanks of WW2 is the substance known as ‘Zimmerit’. This unusual material which many tank enthusiasts and modellers have heard of but do not really know much about is as interesting as it is complicated.
The substance known as Zimmerit is referred to as a non-magnetic coating designed to prevent magnetic mines from adhering to the armor of the tank. Zimmerit first appears in 1943. The DB and Alkett factories started applying it from about November 1943 and an order from the German High Command, OKH (Oberkommando des Heeres), dated the 29th December 1943, called for Zimmerit to be applied to tanks, albeit not on the turrets or track guards. A British wartime report from 1945 later confirmed that development of Zimmerit had begun in 1943 as a counter to Russian infantry assault teams using mines held in place by magnets against German tanks.
Tiger II at Bovington showing its hull and turret Zimmerit.
Tiger II at Bovington showing its hull and turret Zimmerit.

Application and composition

The original order was just to cover the hull of the tank. This is logical as the hull would be the easiest part to reach for enemy infantry armed with magnetic charges. In practice however, it was often applied all over parts of the vehicle, including track guards and turrets, in a wide variety of patterns often varying on a single vehicle.
Examples of different Zimmerit patterns
Examples of different Zimmerit patterns
Examples of different Zimmerit patterns
Different styles of Zimmerit application on the back of the turret of a Panther. Note that neither the cupola nor the roof are coated with Zimmerit. Different styles of Zimmerit application on the back of the turret of a Panther. Note that neither the cupola nor the roof are coated with Zimmerit.
Different styles of Zimmerit application on the back of the turret of a Panther. Note that neither the cupola nor the roof are coated with Zimmerit.
The actual substance was a mixture of materials almost certainly developed by the firm of C.W. Zimmer AG, Berlin (a well known manufacturer of paints) and is a mix of:

  • 40% Barium Sulphate: BaSO4, non-flammable non-water soluble, melting point 1345 C Refractive index 1.64. Main use is in paints and dyes
  • 25% Polyvinyl Acetate: C4H6O2, unbonded it is flammable at 104.4 C. Main use is in adhesives and paints (possible ‘Mowlith 20’ sold to the firm C.W.Zimmer in July 1943 by the firm of I.G. Farbenindustrie A.G. Hochst, Germany. Mowlith 20 was a 50% Benzene mixture)
  • 15% Ochre pigment: such as Goethite (FeO(OH)) and Limonite (Iron 3 Oxide, Fe2O3) is basically Iron Oxide, non-flammable non-water soluble. Main use is in paints and dyes. This ingredient is responsible for the natural yellow colour of unpainted Zimmerit.
  • 10% Zinc Sulphide: ZnS, melting (sublimation) point: 1185 C, non-flammable non-water soluble. Used extensively in infra-red optical materials
  • 10% Sawdust: Cellulose fibers, flammable but once bonded will char creating a thermal barrier.

Unusual application of Zimmerit to side ‘Schurzen’ on these PanthersUnusual application of Zimmerit to side ‘Schurzen’ on these Panthers
Unusual application of Zimmerit to side ‘Schurzen’ on these Panthers
An unusual Panzer IV with Zimmerit covering its Schurzen side plates
An unusual Panzer IV with Zimmerit covering its Schurzen side plates
The paste itself had an unpleasant smell of acetone, but was easy to handle and put onto the vehicle, requiring no preparation of the bare metal surface beforehand. In practice though, a non-corrosive primer was usually applied over the metal surface before the Zimmerit.
This mixture was pasted onto the surface of the vehicle in two applications. The first layer was to be 5mm thick and left to dry for 24 hours, marked out in squares with a metal trowel. A second coat was then applied over this and marked with a metal comb, in order to create a criss-cross pattern to improve adhesion to the first layer. The entire coating was then dried and hardened with a blowtorch. It took less than an hour with a blowtorch to evaporate off the solvents used in the paste and leave it dry, but the whole application, texturing and drying process took a couple of days per vehicle. Even if it were not blowtorch dried, the paste dried out anyway and reached normal hardness within eight days.
Applied correctly, this mixture created a rough hard raised textured surface. It provided not only a poor contact surface for mines, but the texturing also gave a good camouflage finish. Even a small distance between the magnet and the vehicle body reduces the effectiveness of a magnet. This combined with the irregular surface concerned and movement over terrain, was probably quite effective as protection against magnetic weapons.
Factory application of Zimmerit on a PantherFactory application of Zimmerit on a Panther
Factory application of Zimmerit on a Panther

The British investigate

In August 1945, a British team was investigating Zimmerit as a possible means of protection against the Japanese use of magnetic mines in the Pacific. Information had started to be gathered on the substance soon after it was discovered on captured and knocked out enemy vehicles, with samples scraped off and sent for analysis in 1944. Further to the intelligence work on captured samples of Zimmerit, German POW’s had also revealed some of the use of the substance, but it was not until the 14th August 1945 that the British team managed to get some substantive information on the development of Zimmerit and where it came from. That was the day that the British team finally got to the Henschel works in Kassel in Germany. Here the team interviewed the Director of Production about Zimmerit. He recounted that the paste itself was supplied to the Henschel works in drums directly from Chemische Werke Zimmer in Berlin (although other plants were also involved in the manufacture) and had the consistency of soft putty.
Detailed photo of the Saukopfblende gun mantlet from a Jagdpanzer IV showing Zimmerit
Detailed photo of the Saukopfblende gun mantlet from a Jagdpanzer IV showing Zimmerit
The Director of Production revealed that he had thought the order to discontinue the application of Zimmerit was due to the development by the enemy of better anti-tank weapons, rather than because of any safety, production or effectiveness concerns. The order in question had been issued by the OKH on the 9th September 1944 following rumors of Zimmerit causing fires or being flammable. Later German tests would show this to be completely false, but, in either case, there was a significant quantity of Zimmerit left at the Henschel works and the British liberated some 100 tons of it from there. Zimmerit was officially discontinued for factory application from the 9th of September 1944, however, there must have been quantities shipped out to units, as it was not ordered discontinued for field application (which would include foreign maintenance depots and even factories) until the 7th of October.
Panzer IV Ausf H of 26th Pz.Division Italy 1944 with locally applied Zimmerit coating
Panzer IV Ausf H of 26th Pz.Division Italy 1944 with locally applied Zimmerit coating

In use

It is possible that many vehicles got rushed through the application process. As a result some may only have received a single layer of the material due to the constraints on production, or supply. It’s also likely that many vehicles were partially through the process in the factory when the order to discontinue came in. Even at the factories, given the novelty of the material and quality control issues, it is also likely that many vehicles did not get a sufficiently thick two-layer coating. A thin single coating would dry faster so would have aided in speeding factory production. It’s also quite likely that tankers may have imitated Zimmerit on their vehicles using cement.
German soldier spray painting camouflage paint over Zimmerit
German soldier spray painting camouflage paint over Zimmerit
Once applied though, Zimmerit was surprisingly durable. Many vehicles have been dug up after having been buried for decades in rivers or swamps and still retain traces of it. Even battle damage didn’t blast it off the surface, as a shell would only cause localized loss of the material.
Battle damaged Tiger showing resilience of material to combat damage
Battle damaged Tiger showing resilience of material to combat damage
Despite the stated purpose of Zimmerit for protecting against magnetic mines, it’s not clear that it actually worked. Neither the British, Russians, nor the Americans made any notable use of magnetic mines to counter German tanks. Whether or not it actually worked for the stated purpose, it was certainly effective as camouflage and this may serve to explain why so many variations of it exist on a variety of vehicles.

An article by Andrew Hills

Equipment known to have had Zimmerit applied (click link for photo)

Elefant Pz.Kpfw.III N Pz.Kpfw.IV H
Pz.Kpfw.IV J Sd.Kfz.251/8 Ausf.D Wirbelwind
Ostwind Sturmhaubitze 42 Pz.IV L/70
Jagdpanzer IV Sturmgeschütz III G Sturmgeschütz IV
Panzersturmmörser ‘Sturmtiger’ Pz.Kpfw. Panther D Pz.Kpfw. Panther A
Pz.Kpfw. Panther G Bergepanther Tiger II – Henschel
Pz.Kpfw. Tiger Ausf. E Jagdpanther Sd.Kfz.166 ‘Brummbar’
Jagdtiger Tiger II – Porsche  T-34
Churchill Mk.IV Sherman M4A2

Equipment known to have had Zimmerit-like material applied (click link for photo)

Ram Sexton Cromwell 25Pdr gun
Panzer 38H(f) Panzer S35(f)

Other articles in this series

Part II: Zimmerit in Soviet and German tests
Part III: British work on Zimmerit
Part IV: US work on anti-magnetic coatings

Links&Sources

OKH Order 29th December 1943
WW2 Infantry Anti-tank Tactics, Gordon Rottman, Osprey Elite Series No.124
21 Army Group AFV Technical Report # 26, Amended
British “Zimmerit”, by Jeffrey D. McKaughan, Museum Ordnance July 1995
Mr. Churchill’s Tank, The British Infantry Tank Mk. IV, Schiffer, 1999
ZIMMERIT; Production and Application Methods, Donald Spalding, AFV NEWS, January – April 1983 issue
Imperial War Museum IMG B9098
Bundesarchiv
‘Rubber Zimmerit?’, Bob Eburne, Military Modelling, Vol.29, No.11, October 1999
“Zimmerit” Anti-Magnetic Plaster for AFVs, British Intelligence Objectives Sub-Committee report, Major J.W. Thompson and Mr. C.E. Hollis, July 1945
‘Protection of Jap Tanks Against Sticky Grenades’, Tactical and Technical Trends, No. 25, May 20, 1943.
Zimmerit, Mike Gibb
MUN3435, Imperial War Museum, London
Stuart; A History of the US Light Tank, R.P. Hunnicutt, Presidio Press
Century Tracks No.1, Les sherman Francais de la liberation 1943-1945, Claude Gillono,
Waffen Revue Issue 27
Waffenamt Prüfwesen (WaPrüf) dated 19th November 1944
On Zimmerit, Archive Awareness, 7th August 2013
CAMD RF 38-11369-419, Field Report of substance scraped off German tanks
CAMD RF 38-11355-2219, Laboratory analysis of material submitted for testing Zimmerit, Retrieved from https://stugiii.com/zimmerit.html
Battle Experiences Against the Japanese,HQ European Theater of Operations, US Army 1st May 1945
US Military Intelligence Bulletin, 3rd May 1945, Panzerhandmine 3
Stuart Macrae’s “Toy Box”
‘Supplies to the USSR despatched between 1st October 1941 and 31st March 1946’, Russia (British Empire War Assistance) HC Deb 16 April 1946 vol 421 cc2513-9
ТРОфЕИНАЯ БРОНЕТАНКОВАЯ ТЕХНИКА ВЕРМАХТА (Captured Vehicles of the Wehrmacht) 2007
Memorandum on British Armour No.2, Camouflage, dated 21st February 1945
The US M3 Medium Series in Australia, Paul Handel, 2001
Australian Military Modelling Society, M3 Medium Tank by Al Bowie
The Sherman Tank.com Gallery
Panzer IV: The Panzerkampfwagen IV Medium Tank, 1939-1945 by Kevin Hjermstad
26th Panzer Division in Italy 19433-1945, Daniele Guglielmi
Germany’s Tiger Tanks, D.W. to Tiger I, Thomas Jenzt