Shaped Charge Hollow Charge Hohlladung

Panzerfaust
WW II German Infantry Anti-Tank Weapons
Page 1: The Shaped Charge

Theory of the Shaped-Charge Warhead
shaped chargeBefore we start with the different AT weapons I feel a word on the general mechanism of a hollow- or shaped charge warhead is necessary for the understanding of the weapons themselves.
The theory of the shaped charge has probably been known since 1883, though the first-ever military use of this concept in a conflict was the attack on the belgian Fort "Eben Emael" by german troops on May 10th 1940.

shaped charge explosionWhen a shaped charge (see pic. A) detonates the energy is concentrated to the center of the hollow space in front of and along the axis of the charge (see simplified in pic.B). This phenomen, called the Monro - effect, is still not completely understood in every detail. A forceful jetstream of the explosion gases results that hits the steel target with a speed of typically 8000 meters per second (26,000 fps) and penetrating pressure in excess of 10 million kg/cm2 (3.4 mio. pounds per square inch; other sources: 1.2 million kg/cm2 = 0.44 mio. pounds per square inch) (see pic.C). The effect can be increased by putting a metal "liner" to the surface of the hollow. When the explosion occurs, the liner metal is formed into a spike of molten metal (although there is some discussion on whether it is liquid or solid; most times it is referred to a "plasma" jet, plasma not in the technical subatomic sense but in the sense of an in-between state of the metal between liquiduous and solid). To be most effective, the shaped charge has to be detonated at the right distance from the target. If it detonates too close to the armor, the plasma-jet hasn't formed out before hitting the surface and the effect is lessened somwewhat. If detonated too far from the armor surface, the plasma jet has unfocused and partly spent itself already (this effect is used in applying spaced armor, described below).

Because the effect is independent from the kinetic energy of the warhead, it doesn't matter with which "carrier" the shaped charge is being brought onto the target; both target range and weapon velocity are not a factor, the charge can be literally laid onto the target and still have the same devastating effect. shaped charge vs. steel plateThe only variabels which effect the performance are the kind of explosive used, the shape of the hollow cone and the distance to the target surface at the moment of detonation.

Another problem was that if stabilized during the flight by spin, that spin would unfocus the detonation jet stream and hence increase its diameter but lessen its force. Therefore shaped-charge projectiles should not be stabilized during flight by means of spin as is the case with almost any gun bullet or cannon round, but rather had to rely on small fins for some degree of stabilization.The low speed and lack of powerful stabilization make for an inherently rather inaccurate weapon that will deteriorate in accuracy exponentially with range.
Still, because it didn't require a complicated apparatus to achieve a high-energy muzzle velocity in order to work, the shaped charge was the ideal basis for a cheap, lightweight close-range infantry AT weapon.

Composition of the German Shaped Charges

The germans used code numbers to denominate the different explosives developed and produced. The explosive material the germans used for the shaped charges in the different AT weapons discussed on this site carried the code explosive #96. This explosive #96 was a 50 : 50 mixture of the explosives #14 and #104.
#14 was the explosives code for the standard Füllpulver 02, better known as Trinitritoluene and abbreviated TNT. TNT inherently lacks 70% of the oxygene it would need for a complete oxidationit's during it's combustion/explosion; this is the reason why explosions from munitions containing solely TNT make black dust clouds - soot. Because of this it is favorable to combine it with other explosives such as Hexogene that have an excess of inherent oxygene.
#104 was the explosives code for Hexogene, a Cyclotrimethylenetrinitramine that is better known as RDX or Cyclonite. Hexogene is a very effective explosive made up of Hexamethylenetetramine and Nitric Acid with additions of Methanale, better known as Formaline, and Ammonium Nitrate. Both TNT and Hexogene are highly toxic.
In some shaped charges (but not the Panzerfaust weapons themselves) the mixture composition was changed to 60% TNT and 40% Hexogene, this combination had the explosives - code-number #95.

To make for the critically important right detonation distance from the target surface, often a hat or other extender was fixed to the front of the shaped charge itself (see pic.A above).

Defeating Shaped Charge Munitions

Although the shaped charge is still in use today as a warhead for AT weapons such as infantry RPGs and ATGMs as well as for multi-purpose tank ammunition (HEAT - High Explosive Anti-Tank; despite it's name those rounds are only against lightly armored APC's and as explosive charge ammunition; modern tank guns rely on high-velocity SABOT kinetic energy penetrators for fighting enemy tanks), even back in WW II armored vehicles weren't completely helpless against this new technology and the resulting threat posed by infantry carrying them. The problem could be approached by two ways: through a) new tactics and b) new technology and hardware in the farthest sense.

New Tactics
Even in the Finnish-Russian winter war it became apparent that isolated tanks could be killed by daring infantry. Although the tanks had become more sophisticated by then, the advent of potent AT weapons such as the Panzerfaustnow completely prohibited the isolated use of tanks without accompanying infantry. Combined arms tactics were vital more than ever.

New Hardware
The destructive force of an exploding hollow charge is concenztrated to a relatively small area immediately to the front of the warhead. If this pointed blowtorch - like explosion is slightly off course due to a unfavorable impact angle, as sometimes happened on sloped and rounded surfaces (a problem sometimes encountered in the employment of Faustpatrone warheads against russian T-34 tanks), the detonation is used up more or less harmlessly to the side of the armor.
The shaped charge will melt anything that comes in front of it. But only for a short distance. The idea now is to simply prematurely detonate the warhead at a safe distance from the actual armor. Any kind of spacing will do, even air. The charge explodes harmelessly into the air between the predetonating hardware and the actual armor. So even the air between a thin metal shield for predetonating the warhead and the actual armor serves as an actual increase in effective armor thickness.

Because this shield for predetonating the shaped charge is not meant to be solid additional armor but merely meant as a trigger for the premature explosion, any device that will serve this purpose will do, even mesh wire, as we will see.

(Today, although spaced armor is still used by armored vehicles, it is more common to employ reactive armor against shaped charges: explosive reactive armor - little boxes of explosives attached onto the actual armor - on the tank will explode against the impacting shaped charge and therewith counter-force the warheads explosion. This method seems to enjoy particular popularity among the russian and israeli forces. Another approach is the use of heat-absorbing materials as part of the composite armor that is made up of sandwich layers of different materials including ceramics. Althoug conceived of as early as WW II by the germans, layered composite armor saw it's first widespread use when the british introduced their Chobham armor many decades after WW II; today such armor is widely used by most modern heavy battle tanks in the west.) German infantry advances together with StuG III

Germany

For the germans the coordination and cooperation between the different arms aInfantry riding on Pz V Panthernd weapons already were an integral part of their early-war Blitzkrieg tactics. Later in the war a special kind of infantry was developed that was especially trained in the cooperation with tanks. This new special branch of infantry later even got their own suggestive name and were henceforth known as "Panzergrenadiere" ("Tank Infantrists"), a term still in use today to describe mechanized infantry.

SdKfz 250/1The soldiers either rode on top of the tanks or kept pace with the highly mobile armor units by using armored halftracks, the smaller "leichter Schützenpanzerwagen" SdKfz 250 ("light armored personnel carrier"; see picture) and the bigger "mittlerer Schützenpanzerwagen" SdKfz 251 ("medium APC") whenever available.

But the germans, who did a lot of development in the area of shaped-charge infantry antitank weapons, knew very well of the potential threat these weapons posed to armor and were conceiving methods to equip their armor against that.

Zimmerit Coating Jagpz IV with Zimmerit coating

To defend against the attachment of magnetic hollow charges (allied counterparts of the Hafthohlladungen) the germans developed the "Zimmerit" coating for their tanks (more info on Zimmerit).  Zimmerit consisted of about 40% Barium Sulphate, 15% of ocre/sand pigment (=color), 10% Zinc Sulphide and 10% glue mixed with sawdust; the remaining 25% were Mowilith, a polyvinyl-acetate. The putty was applied onto the surface of a tank's armor in a first layer that was about 5mm thick and a second layer 24h later which was 3mm thick. The second coat was shaped inot large grooves giving the Zimmerit it's distinctive look (see pic. at right: Jagpanzer IV with Zimmerit application). The whole applied putty then was hardened using blowtorches.

Zimmerit on Panther glacisThe Zimmerit had no armor value whatsoever and therefore didn't really affect the mechanism of the shaped charges themselves, it was simply meant as a thick layer of nonmagnetic paste so that the magnets of attached hollow charges wouldn't hold. The rough surface produced by the grooves was also supposed to hamper the attachment of non-magnetic glue-based sticky mines. Zimmerit was first introduced in 1943 on PzKpfw III tanks. Later all german battle tanks received this treatment.
The picture at left shows the glacis of a PzKpfw V Panther (the bow machine gun is missing).
Because the feared use of magnetically attached shaped charges by the allies did not take place to a sufficient scale to justify the tedious procedure of attaching zimmerit - esp. the expected use of such weapons by the russian army never realized to a considerable degree -, the whole idea was abandoned again in late fall 1944 (for the Pz V Panther coating was dropped in September 1944) and Zimmerit was from then on rarely added to new vehicles (to read more about Zimmerit click here and here).


Spaced Armorlate StuG III in full dress of tracks and Schürzen

It was also realized that anything that would prematurely detonate the shaped charge would greatly enhance armor protection against these weapons. Anything, even the among tank crews popular adding of spare track parts or wheels to the armor of tanks or additional crew stowage bins and equipment affixed to the armor surface achieved this. The german tankers weren't much different from tankers in the rest of the world in this respect. Spare track parts can be seen most often attached especially to the front of tanks. (picture at right: This late model StuG III can be seen with several strips of spare track parts added to the front and with a full complement of lateral Schürzen).

PzKpfwg III Ausf M with Schürzen on hull and turretThe germans were the first to realize and standardize this effect. They fitted many tanks with the so-called Schürzen ("skirts").
Note: There is some controversy over whether the skirts were developed as spaced armor, or whether they were added to improve overall armor rating against the russian AT rifles encountered in the east (the 14.5mm PTRD and PTRS). IMO it seems that although they were probably initially developed to aid defeat kinetic energy penetrators by increasing overall armor thickness, the potential of these spaced armor plates against hollow charge ammunitions was realized quickly and the concept of skirts was retained primarily for this side effect (as evidenced by the -albeit rather rare- use of mesh wire skirts, and application of skirts on armor surfaces that were practically immune from AT rifle fire, such as Panther side armor)
These Schürzen were thin steel plates or rather sheet metal added to the main armor body of the hull and/or the turret at considerable distance. Thickness was 5mm, except for turret skirts which had 8mm thickness.
The picture at right shows a Pz III with a full set of Schürzen at it's sides and around the turret.

The effect of this spaced armor was again the premature detonating of shape-charge weapons that would explode into the air behind the Schürzen.

Pz IV with Schürzen section missing
The flimsiness of the Schürzen is documented in the many reports of Schürzen coming off in rough terrain or woods as shown in many pictures. It was usual that one or more sections of the shields were missing on tanks in the field.
The picture at left shows a late model Pz IV with turret and side Schürzen, notice the rightmost Schürzen - section is missing.

StuG III with bent Schürzen This picture shows a war-weary late StuG III with completely battered Schürzen bent at odd angles.
 

The Zimmerit coating addressed above was sometimes also applied to the Schürzen.
 
 
 
 
 
 

 
Soviet Union
The Soviet Union's Red Army is widely known for it's extensive use of tank-riding infantry. Originally, the close coordination with the infantry was the only way for the russians to protect their tanks to a degree from the new german weapons. Russian tanks too often had spare track parts attached to the front and/or forward hull sides.
 
 

But the russians also developed their own solutions to this problem in the forms of shields similar to the german's Schürzen. Some of these were solid thin metal plates while others were simply mesh-wire frames.

Just like the german mesh wire - application this sufficed for the purpose of posing an obstacle for prematurely detonating a shaped charge warhead. Both kinds of shields were mass-produced factory items. The rumor that the russians also installed improvised spaced armor with common bedsprings is wrong and might stem from a misinterpretation of the pictures showing the mesh-wire type of shields.
The picture at left shows a russian T-34/85 with the mesh-wire type shields in front of the Reichstag in Berlin, date April 1945. The same vehicle is shown below in a drawing.

 
 

This rare picture at right shows the solid-type shields attached to an IS tank destroyer. This picture nicely illustrates the considerable spacing between the shield and the main armor.

The russians introduced their shields rather late in the war; also contrary to the germans who applied the Schürzen onto if not all then most of their tanks, the russian's shields don't seem to have been used as widely.

(these pictures have been contributed by courtesy of the Russian Military Zone, an excellent authoritative site on russian WW II tanks and AFVs)
 
 

Western Allies US infantry advances alongside M4 Sherman

The western allies, especially the americans and the british, encountered Panzerfaust weapons en masse ever since setting foot to european continent soil in their invasion in Normandy; the deadly potential of these weapons became apparent immediately behindUS Infantry riding on M10 Tank Destroyer the beaches in the fighting in the famous bocage terrain of Normandy.
 
The americans too countered this threat at first by developing new tactics that emphasized the close coordination between tanks and infantry. Later, the fast moving tank units that advanced into german-held territory were accompanied by infantry that kept up with the speed of the armored spearheads in their armored halftrack APC's. Also, american troops too could be seen riding on the tanks. M3 halftrack APC

Although the americans didn't develop spaced armor for their tanks in a standardized or mass-produced way, their crews excelled at improvising and overcoming this by adding all sorts of additional armor themselves.

Also, in the way that german tanks are associated with Schürzen and russian tanks are associated with infantry riding on them, M 5 Stuartthe american tankers are known for their gratuitous loading of all kinds of accessories onto their vehicles.
Sandbagging and especially the attachment of spare tracks seem to have enjoyed particular popularity.

M4 Sherman with spare tracks attached to front
The light tank Stuart M 5 shown in the picture at right has a considerable amount of sandbags loaded to it's front and also features spare track attached to the turret sides.
 
 

The M4 Shermans at left and below both have two rows of spare track added to their front.

This improvised "spaced armor" in the form of additional track parts, stowage bins etc. however cuts both ways.
On one hand, any track or spare wheel steel that an enemy round or a shaped charge has to plow through increases the effective armor thickness.
On the other side, such accessories served as projectile catchers for rounds that would otherwise maybe have ricocheted off the slope of the armor. This problem does not apply to shaped charges to the same degree that it affects KE (kinetic energy) projectiles (i.e., regular tank AP projectiles).
 

It is hard to decide whether this drawback offsets the advantages of providing some additional layer of armor. In terms of shaped charges the additional tank tracks, wood crates etc. certainly were valuable (however these often would still not suffice to stop the hollow charge munitions). It seems however that at least the american tank crews felt they were better off attaching these things than leaving their tank clean; it was their lives who were at stake, so they should know best and who are we to second-guess them.

Another almost standardized method was the construction of a wooden frame that encompassed the front and sides of the vehicle and held in place a thick layer of sandbags, as shown in the illustration at left of an M4E3A8 "Easy Eight" Sherman.

Although far from being an official item, these constructions are the closest of being an eqiuivalent to the german and russian shields in terms of effect and of being common practice.

Besides providing for a wide space from the actual main armor, the filling of the sandbags (sand) made for a relatively good material against hollow charge explosions.
 

These wooden frames were unique constructions; on this other late war picture of an M4A3E8 shown at right the gratuitous amount of sandbags is laterally held in place by wooden panels nailed together.
 


 
 

This rather blurry picture of an M4 Sherman (a late WW II picture, notice the wide tracks) shows that even bundles of tree logs were used! If you carefully look at the side of the tank, you can also see the additional armor patches that were welded over critical parts of the tank's armor.

 

Another factory way of increasing the frontal armor was the increase of the armor itself. Many shermans were converted into the so-called "Jumbo" variant that featured a very thick front armor. On other shermans used for assault purposes, a thick layer of concrete was cast onto the front hull.
 


 

This last picture shows an M10 Tank destroyer in use with the british forces, where it was called Achilles. It illustrates that the practice of adding spare tracks, spare wheels and other things to the armor to increase protection wasn't limited to the german, russian or american forces; rather, this is a habit that is found among tankers everywhere in the world.

A last interesting fact is that towards the end of the war the british thought about using the german Zimmerit coating for their tanks, too. After the german collapse a team was sent to germany to investigate the manufacturinmg of Zimmerit for the possible use onm british tanks in the Pacific against the still fighting japanese. The war ended before any of this realized. (You can read more about the british investigation here).
 


 
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© 1998, 1999, 2000, 2001, 2002 created by M.Hofbauer August 29th 1998; document ver. 1.4a mod 121102
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