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    • By SH_MM
      [title image]
       
      Hollow charges and armor protection - their alternating progression
       
      The term "hollow charges", which is commonly used in German, is not very accurate for the explosives so called. The somewhat more general American term "shaped charge" is a better description of the measures necessary to achieve the desired effects with these charges. Apart from the explosives used by glider pilots at Fort Emeal, it is of great importance for the vast majority of the extensive and versatile range of applications of shaped charges developed since the Second World War that their suitably shaped surface is covered with a layer of inert materials, preferably metals.  The individual elements of the liner are accelerated to velocities of several km/sec and, through special selection of the initial shape and dimensions, it is possible to transform these liner bodies into projectile-like structures which are best suited to combat the respective target.
      This possibility of adapting the effector to the structure of the target to be engaged is very important for the use of hollow charges, but the application potential of these charges, given their early and impulsive nature, is far from exhausted by what has been developed in this field so far. This is particularly true when it comes to combating targets whose design is already tailored to protect against the known hollow charges.
      This will be explained in more detail below; in addition, examples will be used to illustrate the many different ways in which explosives can be used to obtain targeted effects and counteractions.
       
      The effect of explosive devices attached to armour panels - the "spalling effect"
       
      In most cases of using detonating explosives, the energy released by the detonation is transferred to inert materials. In the case of armour plates on which explosives are detonated, the direct effect is relatively small. Although the detonation pressure exceeds the strength of the armour material many times over, the material goes into a state of fluidity and is slightly pressed in at the surface - something similar happens when damp clay is pressed. The depressions that occur are small because the time during which the detonation pressure is sustained and the material is in a flowing state is very short. This only lasts until the relaxation of the highly compressed explosive decomposition products towards the free surface of the detonator has taken place. If, for example, an explosive layer of 2 cm thickness is placed on an armour plate, the impact time on a surface element of the plate during detonation is about 2/800000 sec, i.e. 2.5 µsec. During this time only a slight displacement of the plate material can occur. The example of an explosive layer applied to the surface of an armour plate and detonated there is also suitable for explaining a phenomenon that is very important and is referred to several times in the context of the present comments:
       
      [Figure 1]
       
      Under certain conditions, material parts detach from the rear side of the armour plate and are propelled at quite high speed into the space behind the plate. This so-called " spalling effect " occurs whenever a limited area in a body, where the material is under very high pressure, reaches a free surface of the body (see figure 1). There, the material parts compressed under high pressure relax and advance perpendicular to the surface. The relaxation is thus associated with acceleration. While the relaxation spreads into the interior of the pressure area, all material parts that have been compressed by it are accelerated. If the relaxation wave reaches the rear end of the pressure area, i.e. the zone in which the material particles are not compressed and therefore remain at rest, the parts that have been set in motion by the relaxation break off at this point and continue their motion only outside, provided that the tensile stress that occurs exceeds the tensile strength of the material.
      In the case of the spalling effect, one observes a separation of disc-shaped plate parts on the back of an armour plate exactly opposite the surface covered by the explosive on the upper side (see also Figure 15). This surface must not be less than a certain size, because the accelerated, spalling parts must not only overcome the tensile strength of the detachment from the inner plate parts, which remain at rest, but also the shear stresses at the edge of the spalling plate. In general, this is only then the case when the diameter of the overlying explosive layer exceeds the thickness of the armour plate, otherwise a " bulge" appears on the underside of the plate.
      The effect of the " squash head " projectiles is based on this spalling effect. The explosive in the bullet cap is released when the projectiles impact on of the armour plate is spread and then detonated. 1)
       
      The effect of unshaped, uncontained explosive charges in the free atmosphere

      If an uninsulated explosive device is detonated in the open atmosphere without any special design or arrangement, its effect is relatively small at a distance from the source of detonation. Although the pressure behind the detonation front, which in modern explosives can reach speeds of is advancing at about 8 km/sec, is quite high. It is in the order of several hundred thousand atmospheres, but it rapidly decays as it spreads in all directions, distributing energy and momentum over areas that grow quadratically with distance.
      By contrast, special arrangements, which should be mentioned here because they are to a certain extent related to hollow charges, can be used to achieve a sufficient pressure effect even with unshaped, unchecked explosive charges at greater distances, for example against flying targets.  If, for example explosive charges are arranged at the corners of a regular polygon and detonated simultaneously, a very effective superimposition of the pressure occurs on the axis of symmetry of the arrangement at distances of up to several diameters of the polygon - in the so-called Mach area. Towards the end of the Second World War, the possibility of using such charge arrangements from the ground against enemy aircraft flying in pulks had been considered. In model tests with 6 charges of 50 kg trinitrotoluene (TNT) each, regularly distributed on a circle of 100 m diameter, a pressure of about ~15 bar was measured 350 m above the ground in the vicinity of the axis of symmetry.
       
      Protective effect of multilayer armour

      In order to be protected against the spalling effect of squashing head projectiles and similarly acting warheads, it is advisable to provide armour which consists of at least two layers with a gap between them. For this reason alone, the development of anti-tank ammunition was therefore based on paying special attention to multilayered armour. The requirement for penetration of structured armour with air gaps is also indispensable in other respects. The same conditions apply, for example, when an armour is hit by a plate covering the running gear or by a "skirt" attached to the running gear. In the case of more or less abrupt impact, the point at which the ignition of a shaped charge warhead takes place can then be up to several metres away from the point at which its main effect should begin. In addition to standard single-layer targets, the testing of hollow-charge ammunition therefore includes targets consisting of several plates spaced at certain distances from each other (see Figure 2).
       
      [Figure 2]
       
      In principle, the mode of action of hollow charges meets the above-mentioned requirements very well, much better than is the case with conventional impact projectiles. When a kinetic projectile hits a armour surface, a high pressure is created in both the armour material and the projectile. Starting at the tip, a pressure condition is built up in the bullet, which leads to the phenomenon described earlier in the treatment of the spalling effect on the free surface of the bullet. Tensile stresses occur which begin to tear the bullet body before it has penetrated the target surface. They can cause the bullet to disintegrate into individual parts after penetrating the first plate, which are then stopped by a second plate of a multilayer target (see Figure 3 a and b).
       
      [Figure 3]
       
      If, on the other hand, hollow charges with a lined cavity are detonated on the target surface, the so-called hollow charge jet is generated, which is sometimes called a "spike" because it is initially coherent and usually occurs in a solid state. With the hollow charges commonly used today, the jet disintegrates as it advances into a series of small - often spindle-shaped - very fast projectiles, whose frontal velocities can reach about 10 km/sec; the last ones still achieve about 2 km/sec. When the first particle hits the surface of the shell, a pressure in the order of 1 million atmospheres is created there; the shell material begins to flow and an approximately tulip-shaped crater is formed, similar to the penetration of a body of high velocity into water. The volume occupied by the crater is released by displacing the armour material towards the free surface. When the second jet particle hits the bottom of the crater, repeat the process, as well as the impact of the following particles. Each particle continues the displacement of the target material where the previous one stopped until schliefilich creates a channel of penetration through the whole plate.
      The flow of the material particles associated with the displacement of the target material ends at the free surface. Partly at the upper side, partly at the lower side of the armour plate and partly also at the already created penetration channel, which is subsequently narrowed again slightly.
       
      The following jet particles not consumed during penetration continue their path after passing through the penetration channel and act on obstacles that are on their path. If they hit another armoured plate, they can continue the penetration process there undisturbed.
      In contrast to the behaviour of the compact kinetic projectile, the individual elements act on the armour one after the other, independently of each other, and it does not seem so important at first whether the armour is massive or in separate parts, because a disturbance at the tip of the projectile does not affect the following parts.
      Nevertheless, the so-called "bulkhead armour", in which a number of thinner armour plates are arranged with air gaps between them, also provides increased protection against hollow charges: The penetration channel created by the impact of the particles of the hollow-charge projectile is relatively narrow and is of the same order of magnitude as the plate thickness when using thinner plates of the bulkhead armour. When the hollow-charge particles strike these thin plates, the hole in the plate is created essentially by the fact that the material elements of the plate which are caught by the high dynamic pressure are forced away from the plate under the influence of the tensile stress acting perpendicularly to the free surface, both on the upper and the lower side of the plate. The penetration channel therefore runs almost perpendicular to the plate surface, regardless of whether the hollow charge particles generating the pressure impact obliquely or vertically. The tensile stresses induced at the plate surface as a result of the dynamic pressure are in any case perpendicular to the plate and also have an effect in this direction (see Figure 4).
       
      [Figure 4]
       
      If now diagonally incident subsequent particles reach the previously created penetration channel running approximately perpendicular to the surface, they find a much reduced cross-section for their passage compared to the vertical incidence (see Figure 5). There is thus an increased probability that they will come into contact with the wall as a result of path variations, as a result of which their contribution to the penetration performance is lost. The affected particle disintegrates explosively, since - as described above - the high pressure occurring during wall contact induces tensile stresses on the free surface of the particle, causing it to burst. In Figure 6, a TRW image converter camera is used to illustrate how a steel ball of 2 mm diameter is sprayed after it has penetrated a very thin plastic film at very high speed. Figure 7 shows the piece of a hollow charge jet in which a similar burst was triggered on a particle by touching the wall. As can be seen from the figure, the small debris of the disintegrated particle spreads sideways to the direction of the beam, apparently away from the wall that was touched. It is important that the propagation of these fragments into the free space behind the plate is possible. At massive targets this free space is not available, the particle splinters would be held together and their impulse could contribute to the penetration even if the particle had touched the wall before. That's why it's important, armoured plates and air gaps of certain thickness should follow each other.
       
      [Figure 5, figure 6 and figure 7]

      This leads to bulkhead arrangements which, when hitting the wall at an angle, cancel out the effects of a high portion of the hollow charge jet due to the increased probability of the jet particles touching the wall and their subsequent disintegration into the gap. The weight of the armour required for this, in relation to the unit area, is considerably less than in the case of solid armour. It is essential that this provides increased base protection against both balancing projectiles and shaped-charge ammunition, and it is noteworthy that this effect occurs in both cases by inducing the decay phenomenon on impact at high velocity. However, in the case of a balancing projectile, the entire mass of the energy carrier is captured by the destructive tension waves on first impact, whereas in the case of a hollow-charge jet only the mass portion corresponding to the respective impacting jet particles is captured.
       
      Measures to avoid disturbance of the shaped charge jet

      However, it is not clear why rear particles of the hollow charge jet must necessarily come into contact with wall elements of the penetration channel created by the previous ones. Should it not be much more possible to ensure that the particles
      aligned very cleanly and without "staggering" movement exactly on the cavity axis? However, this means that the slightest deviations from central symmetry must be avoided in the structure of the hollow charge. The whole rigor of this requirement is that it relates not only to the dimensions of the charge, but also includes the homogeneity of the materials used and that - as has already been shown - even differences in the size and orientation of the crystals in the explosive and in the copper of the liner have an influence. This requirement is even more stringent if one takes into account that the properties of the crystals mentioned above change over time, i.e. as they age, and that changes are also triggered during processing. A very sensitive influence can also be expected from the way the detonation is initiated.
      With the aforementioned and similar requirements with regard to precision, the production of hollow charges has set goals whose pursuit in the past has already brought about significant progress with regard to the generation of an undisturbed hollow charge jet during detonation, and in the future, through the tireless efforts of research and technology, even further perfection can be expected. In addition to this somewhat utopian-looking reference, however, it must be emphasized that the hollow charge principle is very flexible and includes a wealth of other possibilities for counteracting disturbances which oppose the effective targeted use of the explosive energy released during detonation. For example, it is not necessary for the hollow charge jet to dissolve into a number of particles as it progresses. Some of the irregularities in the behaviour of the particles will only develop during the tear-off process and can be avoided if the hollow charge jet is constructed in such a way that it does not tear.
      The reason for the dissolution of the hollow charge jet into a number of particles of different velocities is that the individual jet elements already have a different velocity when they are formed. In the case of the hollow charges currently in use, there is a velocity gradient in the beam from about 8-10 km at the tip to about 2 km at the end.The consequence is that the jet is constantly stretched as it progresses and eventually dissolves into more or less parts according to the strength properties of the material .2)
       
       
      The programmed shaped charge jet

      By special selection of the parameters of a hollow charge (type and density of the explosive, dimensions and shape of the cavity, wall thickness and material of the cavity lining, shape as well as wall thickness and material of the casing, position and extension of the ignition elements) it can be achieved that differences in the velocity of the individual elements of the jet are prevented at all.
      The relationship between the distribution of mass and velocity in the jet and the charge parameters was already known shortly after the discovery of the
      the lining of the cavity achievable effect by Thomanek quite detailed results. 3)
      This connection is achieved by following each individual sub-process during the detonation of the charge and the deformation of the liner by calculation. When the detonation front reaches the individual zones of the liner body, the material there enters a state of flow under the influence of the detonation pressure and is accelerated inwards. The speed at which the lining elements are accelerated depends on how long the pressure remains at the zone under consideration or, which comes to the same effect as how far the outer surface of the detonator is from this point. Thus, the influence of the width of the explosive coating on the velocity of a panel is obtained.
      For example, consider a cylindrical charge with a cone as a cavity and a diameter of 8 cm. The time required for the dilution wave to reach the top of the cone from the outer surface is then 4 cm/approx. 800000 cm/sec, i.e. approx. 5 microseconds; in the central zones of the cone with an explosive coating of 2 cm, this time is only half as long and the impulse transmitted to the lining elements by the detonation pressure in this time is therefore half as large.
      Of course, the speed also depends on the wall thickness of the lining body at this point and the density of the lining material.  The initial velocity of the lining elements can be specifically influenced by a suitable choice of the wall thickness and it can change at will between the tip and base of the lining cone. One speaks of "progressive" or "degressive" liners, depending on whether the wall thickness increases or decreases towards the base. The influence of the liner's wall thickness/explosive coverage ratio then has a further effect on the jet elements that are emitted when the liner zone converges on the cavity axis. In addition, the mass and velocity of the jet elements formed depend on the angle at which the convergence takes place, i.e. the opening angle of the cavity. Peak angles result in high velocities for small masses, and the opposite is true for obtuse angles.
      The previous remarks should serve to explain, at least by way of indication, how it is possible to determine the dependence of the distribution of mass and velocity in the jet on the charge parameters. With the knowledge of these interrelationships, it now seems possible to create projectile-like structures from the cladding bodies, in which the initial length and the distribution of mass and velocity over this length are predetermined, i.e. the hollow charge jet can be programmed.
       
      Up to now, almost all attempts have been made to obtain a jet with the greatest possible penetration capacity. This led to the familiar design forms: cylindrical on the outside, cavity for example 60° cone with copper liner, initiation of the detonation now often by detonation wave deflection at the rear edge of the detonator, whereby better use of the explosive volume and higher beam tip velocities are achieved (compare also Figure 16). The resulting beam is then a constantly stretched structure with a velocity of up to 10 km/sec at the tip and about 2 km/sec at the end, which is followed more slowly by the rest of the cladding mass, the so-called "slug". 4)
      As already mentioned several times, the differences in the velocity of the individual beam elements cause the initially coherent structure to be broken up into a sequence of particles. Nevertheless, very good results have been achieved with the described type of charges, especially against massive targets.
      Penetration depths of up to 6 charge diameters have been achieved. In contrast, when using targets with air gaps, the distance travelled in the massive parts of the target is greatly reduced. In the future, requirements for the performance of hollow-charge ammunition should be geared to these reduced amounts; this would mean that modern hollow charges should be developed to penetrate structured targets rather than exaggerated penetration performance in massive targets. An attempt should be made to program the hollow-charge jet, i.e. to adapt it to the structure of the target.
      In the following we will try to explain by means of examples that there are many possibilities to modify the beam of the currently used hollow charge.

      A completely different motion sequence of the particles of the beam from this type of charge can be obtained by replacing the centrally symmetrical ignition by a (one-sided) eccentric one.The individual beam particles then no longer move one behind the other on the cavity axis, their paths point in a fan-like manner in different directions (compare Figures 8a and b) 5) The following example is intended to show how even a slight change in the cavity shape can noticeably influence the beam and its effect.  Figure 9a shows a cladding body whose shape can be roughly described as a cone which ends at the base in a spherical zone. Figure 9b shows the penetration channel of an externally cylindrical charge produced using this liner.
       
      [Figure 8 and figure 9]
       
      The explanation for the peculiar shape results from the velocity distribution in the hollow jet. The front part of the jet comes from the cone-shaped part of the cavity and corresponds to the jet from a cone, which stretches as it advances. For the subsequent jet elements, which originate from the spherical zones at the base, it is decisive that the tangent at the cavity becomes steeper and steeper towards the base. The consequence is that the successive jet elements become faster and faster towards the rear, thus approaching each other and leading to a thickening of the jet in this rear area. On impact, the effect is increased in the form of a widening of the penetration channel.
      While with the hollow charge described above, a concentration of energy occurs in the rear jet section, it is also possible to achieve this in the front jet section. For this purpose, the cavity must be spherical at the apex and end in a cone at the base (see Figures 10a and b). The penetration channel is wide at the top and has the shape of a hemisphere followed by a narrow conical part. 6)
      If the cavity, which is essentially delimited by a cone, is spherical at both the apex and the base, the penetration channel will consist of a wide part at the armour surface, followed by a narrow conical part and a further widening at the end. Following these examples, it should be considered possible that the effectiveness of the individual sections of the hollow charge jet can be determined in quite a different way, especially if it is taken into account that other parameters of the hollow charges can also contribute to this by their specific choice.
       
      [Figure 10]
       
      As explained in the previous section, other velocity distributions are possible in addition to the velocity gradient in the jet of the commonly used hollow charges that leads to rupture. It is also possible to achieve that all beam elements have the same velocity, provided that the relevant charge parameters are adjusted to it in each zone of the cavity. If, for example, the wall thickness of the cladding is selected in such a way that it is in the same ratio to the corresponding width of the explosive coating for all zones, the cladding elements of all zones receive the same initial velocity on detonation and thus also all the beam elements that are separated from them when flowing together on the cavity axis.
      As a result, the jet is represented here by an "overlong projectile" with a rather high velocity. A sketch of the principle of such a charge is shown in Figure 11. The nozzle-shaped body attached to the base has the purpose of preventing the decomposition by-products from coming into direct contact with the free atmosphere when the base zone is accelerated, thus avoiding a premature drop in pressure. In a similar way, other causes of disturbance are to be avoided, whereby a number of experiments are always necessary before a principle path can be realized.
       
      [Figure 11]

      Instead of a single rod-like projectile, a sequence of several such rods can be obtained in which the individual elements have the same velocity, with the velocity of the rods differing from each other.
      In addition, from the special solution of the identical velocity of all beam elements, transitions to the common hollow charge with the large velocity gradient in the beam can also be developed. In particular, the case can also be realized in which the difference in the velocity of the following beam elements is so small that the beam is only broken when all obstacles of the target have been overcome. How such a continuous beam reacts to protective measures that disturb a particle-dissolved jet is still to be investigated. In any case, the disturbances caused by the rupture process are avoided here (compare Figure 12).
       
      [Figure 12]

      Also, the range of possible variations in the structure of the shaped charge jet is so wide that an adaptation to very different target compositions seems possible. Not insignificant is the fact that the energy of the effect carriers from a hollow charge can be distributed in a targeted manner to mass and velocity, i.e. the jet can obtain a greater mass at the expense of the velocity of its elements and vice versa.
      As investigations have shown, the protective effect of certain materials depends on the speed of the projectiles. 7) However, such measures need not refer to the entire jet, but can be limited to parts of it, for example to the front or rear parts of the target.
      A special group of shaped charges has not been mentioned so far, namely those with a flat, especially blunt conical cavity. ln contrast to the pointed conical cavity, the attainable velocities are lower here. The speed of the structure previously referred to as the jet is no longer very different from that of the so-called following slug. It can be achieved by methods which will not be discussed in detail here, that the jet and slug components - i.e. the entire mass of the liner - merge into an at least temporarily coherent structure. lf the difference in the speeds of the front and rear parts is sufficiently small, it is absorbed by internal expansion work, and a projectile with a uniform speed of about 2000 m/sec is created. Figure 13 shows a series of such projectiles from charges with a flat cavity, using X-ray flash images.
       
      Figure 14 shows a section through a captured specimen of cohesive projectiles. Such projectiles are particularly characterized by stable flight at long distances and have already found 'a versatile application today, especially as a replacement for natural fragments (see also cover picture and Figure 15).
       
      [Figure 13, figure 14 and figure15]
       
      In connection with the efforts to combat future targets, which may be unknown at present, it should be mentioned that it is possible and possibly very useful to arrange projectile-forming hollow charges in a special way one behind the other. If this is done taking into account all the side effects of the detonation, and if such an arrangement is ignited appropriately, one obtains a sequence of projectiles flying one behind the other at fairly high speed, the mass of which is considerably greater than that of particles of the hollow charge jet.
      It is also possible to combine a projectile-forming charge with a jet-forming charge with an acute-angled cavity. Figure 16 shows such a charge, also known as "tandem charge".
      It was designed to create a strong follow-on effect inside the tank. On detonation, the jet from the rear charge penetrates through an opening in the apex of the front flat-cone charge. Only after this has been done is this charge also detonated; the flat liner body is formed into a projectile which follows the jet from the rear charge through the channel created by it and comes into effect there depending on the intended purpose.
       
      [Figure 16]
       
      These examples are intended to show that there are almost no limits to the imagination when it comes to exploiting the potential inherent in the principle of forming effective projectiles by transferring explosive energy to inert materials. There are many ways to develop explosive charges that can be effective against complex targets and do not necessarily require a gun to reach the target, but can be used in warheads of missiles. Of course, there will always be possibilities to achieve sufficient protection by suitably constructed armour. What should be particularly emphasized here, however, is the view that there is hardly likely to be a miracle cure for all types of shaped charges and that, apart from a temporary predominance on one side or the other, there will probably continue to be mutual efforts to perfect shaped charges on the one hand and protective armour on the other.
       
    • By Ronny
      I see many knowledgeable members here so i decided to make an account to ask some question
      According to many historical accounts, the armor of WW II battleship is very thick: can be between 410-650 mm of steel
      Thick enough that they can even resist penetration  from 12-16 inch canon 


       
      Compared to these massive round, it is probably obvious that missiles such as Harpoon, Exocet will do little or nothing against the armor belt: No penetration and probably nothing more than a small dent.
      Anti tank missiles such as AGM-65, AGM-114 or Brimstone can penetrate the armor but all their warhead will do is penetrating a tiny hole into the massive battleship, it likely will hit nothing significant given that a battleship have massive volume of space). Furthermore, i heard space armor is extremely effective against HEAT warhead as well).
       
      But what if the two are combined? HEAT + explosive warhead: aka BROACH.
      With a frontal shape charged and secondary follow through bomb
      This is the working principles of the system:


       
      BROACH was designed to help small cruise missile penetrate bunkers. So i have some question:
      1- Because concrete and soil are very brittle, unlike steel, I think the precursor charge likely much drill bigger hole in them than it can drill on steel armor belt of a battleship, so even if we use missile with BROACH warhead to hit a battleship, it won't drill a hole big enough to allow the secondary warhead to pass through. Is that a correct assessment?
      2-  Looking at the cutaway of the missiles. How come the detonation of the frontal shaped charge doesn't damage/destroy the secondary warhead or at very least propel it to the opposite direction? 
       
      3-  Can supersonic missiles such as Agm-88 (Mach2) , Asmp-A (Mach3) , Rampage , Asm-3 (Mach 3) , Hawc (Mach 5) penetrate the armor belt of a battleship? or they simply don't have enough velocity and density?
       
       
       
    • By Jeeps_Guns_Tanks
      (M4A3E8, ultimate production Sherman)
      This is a work in progress, please feel free to comment, or help me with info and links.
       
       
      Click here to see the new The Sherman Tank Website!
       
      All content is still discussed and previewed in this thread. If you have feedback or want to help with the content, this thread is the best place to do it. 
       
       
       
      The Epic M4 Sherman Tank Information Post.
      SHERMAN: M4: M4A1: M4A2: M4A3: M4A4: M4A6: M50: M51
       
         The Sherman tank over the last several decades has had its reputation severely soiled by several documentaries, TV shows, and books, all hailing it as a death trap, engineering disaster, or just a bad tank. The Sherman tank may be the most important, and arguably the best tank of the war.  The only other contender for the best tank award would be the Soviet T-34. These two tanks are very comparable and would fight each other in later wars, staying very comparable through their service lives.
       
         This post will cover why the Sherman was a better tank than anything Germany, Italy or Japan produced during the war, on both a tactical and strategic level. I will not be reproducing the work of others, and will link to the places that already cover some information. I will cover all the major changes made to the each Sherman model.
       
         I will try and cover the many post war variants as well, but that could take months, there are a lot of variants of this venerable tank, including ones that involve putting the engine from one hull type into another hull type and or tanks modified by other countries with no feedback from the American designers. I’ll try and get civilian use in here as well. Some variants have heavily modified turrets, or replaced it with a new one.
       
      Basic Sherman History: The Big Stuff
       
         To really know why the Sherman was designed the way it was, you have to know about the M3 Lee. The M3 was the predecessor of the M4. It was based on M2 medium, the US Army’s only foray into modern medium tank design, and was the fastest way a tank could be designed with a 75 mm M3 canon fitted. The US lacked the jigs to make a turret ring big enough to house a gun that large in a turret; the Lee went into production while the turret ring problem was being solved, by mounting the gun in a sponson mount. It had become clear to the US Army that the 75mm canon would be needed based on feedback from the British, and observations of how the war was developing in Europe.  
      One of the reasons for the reliability of the M4 design was the use of parts that started their design evolution in the M2 medium and were improved through the M3 production run. Over the life of M3 Lee and M4 Sherman the designs were continually improved as well, so a final production, M3, or M4A1, bared little resemblance to an initial production M3 or M4A1, yet many parts would still interchange. This is one of the reasons the Israelis had so much success updating the Sherman to the M50 and M51, these tanks used early small hatch hulls, that never had HVSS suspension installed, but the hulls took the updated suspension with few problems.
         
         When the Lee went into production, though it was far from an ideal design, it still outclassed the German and Italian armor it would face, and its dual purpose 75mm gun would allow it to engage AT guns with much more success than most British tanks it replaced. It was reliable, and well-liked by its users. When the British got enough Shermans, the Lees and Grants were sent to the Far East and saw use until the end of the war fighting the Japanese. The Lee excelled at infantry support, since it had a 37mm canon that could fire canister rounds, along with the 75mm gun and a lot of machine guns. Many of these Lee tanks ended up in Australia after the war.
       
       
      Lee variants:  The Combat RV
       

      (early M3 Lee)
       
      M3 Lee:
       
         This was the first version of the tank and used a riveted hull with the R975 radial engine powering it, the suspension and tracks were very similar to the M2 medium.  Early production tanks had an M2 75mm instead of the improved M3 gun. These tanks had a counter weight mounted on the shorter barrel. All Lees had a turret with 37mm M5 gun. The early production version had two hull mounted, fixed .30 caliber machine guns, another mounted coaxially with the 37mm gun, and another in a small turret, mounted on top of the 37mm turret for the commander.
       
         They built nearly 5000 of these tanks. The M3 was improved on the production line with things like removal off hull machine guns, and hull side doors. The mini turret mounted M1919A4 was not a popular feature, and was hard to use, but it remained on all Lees, and were only deleted from the Grant version produced exclusively for the British.
       
         If this version had a major flaw, it would be the riveted armor plates could shed rivets on the inside of the tank and these rivets bounced around like a bullet. This was bad for the crew, but, rarely resulted in a knocked out tank. A field fix for this was welding the rivets in place on the interior of the tank.  Most of the M3 Lees produced went to the British. 
       

      (cast hull M3A1)
       
      M3A1 Lee:
         This version of the Lee had a cast hull, and R975 radial power. It was really the same as the base Lee in most respects including improvements. 300 built. These cast hull tanks have a very odd and distinctive look. They look almost like a M3 Lee was melted. This hull casting was huge and more complicated than the M4A1 casting. Most of these tanks were used in the United States for training.
       
      M3A2 Lee:
         This Lee had a welded hull and the R975 powering it. 12 built. This version was more of a ‘proof of concept’ on welding a hull than anything.
       
      M3A3 Lee:
         Another welded hull but this one powered by the GM 6046 Twin Diesel. 322 built, like the base Lee, with the same improvements. This is the first vehicle the 6046 was used in, and most of the bugs were worked out on this model.
       
      M3A4 Lee:
         This version had a riveted hull and was powered by the A-57 multibank motor. This motor was so large the hull had to be stretched for it to fit; it also required a bulge in the top and bottom of the hull to fit the cooling fan. They also had to beef up the suspension, and the suspension units designed for this would become standard units on the Sherman. This would be the only version of the Lee with the improved bolt on offset return roller VVSS, otherwise this tank was very much like the base M3. 109 built. This motor’s bugs were worked out on this tank and would go on to power a large chunk of Sherman production. 
       

      (Monty's M3A5)
       
      M3A5 Grant:
         Another welded hull, powered by the GM 6046 Twin diesel with a new bigger turret to house British radios. 591 built. This new turret deleted the small machine gun turret on the roof of the 37mm turret. This version was used only by the British. The famous General Montgomery’s personal M3A5 is on display in England, at the Imperial War Museum in London. 
       
      . . .
       
         The majority of Lee and all Grants saw service with the British, and many Lees went to the Soviet Union. They were generally well liked by both nations and more reliable than most of its British and German contemporaries.  These tanks were better than the enemy tanks they faced until the Germans up gunned the Panzer IV series. When they were replaced with M4s of various types the M3 were shipped to the Far East for use in Burma and New Guinea. The Japanese had no tank that could take on a Lee, let alone a Sherman. Using soldiers as suicide bombers, and mines still worked though, there was also a pesky 47mm AT gun, but it was rare.
       
         They saw limited use in the US Army’s hands some seeing combat in North Africa, because US combat units lost their Shermans to replace British losses, and a few were used in the PTO. The Sherman owes it success to the lessons learned producing the Lee and from its use in combat.  The 75mm gun and automotive systems, even the more complicated ones, would be perfected in the Lee and re-used in M4, and the Sherman only had one motor not tested in the Lee first.  Many of the Lee variants were produced at the same time and the numbering system was more to distinguish between hull and engine types, not to model progression like in aircraft, and other tanks.  This practice was carried over to the M4 series as were all the engines used in the Lee.
       
         Many people familiar with the way the United States designated aircraft during the war figure it was carried over to tanks and think an M3A1 was an improved M3, and an M3A2 was an improved A1. This is not the case, as many of these versions were produced at the same time, and they all received the same sets of improvements, though some factories took longer to implement things than others.
       
         The M4 went into production as soon as the jigs for the turret ring were produced and ready to be used. Production actually started on the cast hull M4A1 first, with the welded M4 following right behind it. Like the Lee, there were many version of the Sherman in production at the same time. There are many photos of Lee’s coming off the production line, with Shermans in the line right behind the last Lee, so there was no real gap in production between the two tanks at most of the factories.
       
       
      The Sherman variants: The Design Matures
       
       
         First off, Americans referred to the Sherman as the M4, or M4 Medium, or Medium, the Sherman name was not commonly used until post WWII. The British came up with the name for the M4 and referred to it with their own designation system that will be covered in more detail later. They also named the Lee, and Stuart, and at some point the US Army just stuck with the naming scheme. The full story behind this is still a minor mystery, with US war time documents confirming the ‘general’ names were at least used on paper by the US Army during the war.
       
         Now let’s cover the factory production versions of the Sherman. Also keep in mind, it is very hard to define just how a Sherman may be configured without really knowing where and when it was produced. In some rare cases, large hull, 75mm armed Shermans got produced with normal ammo racks, when the norm for large hatch hull tanks was wet ammo racks. 
       
       
      . . .
       

      (this is a very early production M4 with DV ports that are not welded closed and have not had armor added over them)
       
      M4 Sherman:
          These tanks used the same R975 motor as the M3, and M3A1. The vast majority of the bugs in this automotive system were worked out before the M4 even started production. This really helped give the Sherman its reputation for reliability and ease of repair. The M4 had a welded hull with a cast turret mounting the M3, 75mm gun. Early variants had three hull machine guns, and two turret mounted machine guns. The hull guns were all M1919A4 .30 caliber machine guns, two fixed, and one mounted in a ball mount for the co-drivers use. The fixed guns were deleted from production very rapidly. The turret armament remained unchanged for the whole production run: Using the M3 75mm gun with the M1919A4 coaxial machine gun and M2 .50 caliber mounted on the roof. The turret would be the same turret used on all early Shermans and would be interchangeable on all production Shermans. This version was not produced with the later improved T23 turret but did get some large hatch hulls in special variants.
         
          There were two variants of the M4 to be built with the large hatch hull. The first, the M4(105) was a large hatch hull mated to the 105mm howitzer, on the M52 mount, in the standard 75mm turret. These hulls did not have wet ammo racks or gyro stabilizers, and the 105mm turrets had an extra armored ventilator, the only turrets to have them. The M4 (105) gun tanks had a special mantlet, with four large screws in the face, unique to 105 tanks. Production started in February of 44, and continued well into 45, with late production M4(105) tanks getting HVSS suspension. These tanks were used as replacements for the M7 Priest in tank units, and spent most of their time being used as indirect fire support, like the M7 they replaced.
         
          One other variant of the M4 to get the large hatch hull(100 or so small hatch casting were made as well), this was the M4 ‘hybrid’, this hull was welded, but used a large casting very similar to the front of the M4A1 on the front of the hull. It was found that most of the welding hours building the welded hull tanks were spent on the glacis plate. They figured by using one large casting, incorporating the hatches and bow gun would save on welding time and labor costs.
       

      (This is an M4 hybrid, large hatch tank. but with no wet ammo racks)
       
         These M4 hybrids were used by the British to make Ic Fireflies. They liked the 75mm turret these tanks came with since they already had a loaders hatch, this saved them time on the conversion since they didn’t have to cut one.
       
       
         These large hatch M4s did not get the improved T23 turret, but did have wet ammo racks and all the large hatch hull improvements. Most of these tanks were shipped to Europe or the Pacific, making survivors rare.   
       
       
         The M4 along with the M4A1 were the preferred US Army version of the Sherman until the introduction of the M4A3. This tanks was made in five factories from July of 42 to March of 45, 7584 produced.
       
       

      (this image is a small hatch M4A1 with DV ports welded closed and add on armor over them, not the very early turret with small mantlet. The suspension on this tank was probably updated from the early built in roller type during a depot rebuilt. Image from the awesome sherman minutia site)
       
      M4A1 Sherman:
         This was virtually the same tank as the M4, with the same motor and automotive systems and armament. The key difference was the cast upper hull. This huge upper hull casting was one piece. This was a very hard thing to do with casting technology at the time, and something the Germans could not have reproduced, they lacked the advanced technology, and facilities needed to do so. Everything from hatches to wheels, and turrets, and guns were interchangeable with the M4 and other Sherman models. This version saw production longer than any other hull type. It also saw all the upgrades like the improved large hatch hull with wet ammo racks, the T23 turret with 76mm gun, and HVSS suspension system. It was 30 of these M4A1 76 HVSS tanks that were the last Shermans ever produced. The M4A1 was also the first to see combat use with the improved M1 gun and T23 turret during operation Cobra. Three factories produced 9527 M4A1s with all turret types from Feb 42 to July of 45.
       
         The US Marines used one Battalion of these tanks on the Cape Gloucester campaign, small hatch M4A1 75 tanks. This was the only use of this tank by the Marines. 
       

      (M4A2 75 mid production with improved drivers hoods, from this angle you can not tell the difference between an M4 M4A2, M4A3, image courtesy of the sherman Miniutia site)
       
      M4A2 Sherman:
         This version of the Sherman used a welded hull nearly identical to the M4, but with a pair of vented armored grates on the rear hull deck. The M4A2 tanks used the GM 6046 twin diesel. This version was produced with all the improvements the other types got, like the large hatch hull with wet ammo racks, the T23 turret with improved M1 gun, and HVSS suspension. This version would see very limited combat in US hands, most being shipped to Russia with a few early hulls going to the Brits and USMC. This was the preferred version for Soviet lend lease deliveries, since the USSR was using all diesel tanks. It was produced in six factories with 10,968 of all turret types produced from April of 42 to July 45.
         
         A little trivia about this version, the Sherman used in the movie Fury, was actually a late production M4A2 76 HVSS tank. The only way you can tell a late A2 from a late A3 is by the size of the armored grills on the back deck. They did a great job of hiding this area in the movie.
         
         The Marines operated a lot of small hatch and a fairly large number of large hatch M4A2 tanks, until the supply of 75mm armed version dried up in late 1944. Then they switched over to large hatch M4A3 75w tanks, but there were some A2 holdouts amongst the six battalions. 
       

      (this is an M4A3 large hatch 75mm tank, it has wet ammo racks and a hatch for the loader.)
       
      M4A3 Sherman:
       
         This would be the base for what would be the final Sherman in US Army use, seeing action all the way out to the Korean War in US Army hands. This tank had a welded hull just like the M4, A2, and A4, but used a new motor. The Ford GAA V8, this motor took some time for its bugs to be worked out, so unlike say, the Nazi Germans, the US Army didn’t use it until it was ready for serious production. When it was, it became the preferred US Army version of the tank in both the 75mm and 76mm armed tanks. It would see all the improvements, and be the first hull type to take the HVSS suspension system into combat for the US Army. The M4A3E8 or M4A3 tank with T23 turret and HVSS suspension bolted on would be the final and ultimate US Army Sherman. It would be produced in three factories with all turret types, 12,596 built in total between June 42 and June of 45.
       
         After WWII when the Army wanted to standardize on one Sherman type, any M4A3 large hatch hull they could find would have a T23 turret and HVSS suspension installed on it. The Army was so thorough in these conversions no M4A3 large hatch 75mm gun tanks are known to have survived with the original turrets installed.  Any M4A1 HVSS 76 and M4A2 HVSS 76 tanks in Army inventory would have been robbed of their suspensions and turrets so they could be installed on M4A3 large hatch hulls.
       
      (an M4A3E2 Jumbo with correct M3 75mm gun)
      The M4A3E2 Jumbo, Fishers fat and special baby!
       
         FTA was the sole producer of one very special variant of the Sherman, the M4A3E2 Jumbo. This version of the Sherman was the assault Sherman, though not expressly designed for it, was manufactured to be able to lead a column up a road and take a few hits from German AT guns or tanks so they could be spotted without having to sacrifice the tank. It had a lot of extra armor, and could take a lot of hits before being knocked out, but was still not impervious to German AT gun fire. Only 254 of these tanks were produced, and all but four were shipped to Europe for use by the US Army. They were all armed with the M3 75mm gun. There was a surplus of M1A1 76mm guns in Europe due to an aborted program re arm 75mm Sherman tanks with the guns. Many of the Jumbo’s ended up with these guns, but none were ever factory installed.
       
         The tank was no different in automotive components from the M4A3 tanks, with the sole difference being the slightly lower final drive gear ratio, going from a 2.84:1 ratio in the base Shermans, to 3.36:1 on the Jumbos. This reduced the top speed slightly but helped the tank get all the extra armor moving. The Jumbos were well liked by their crews and in great demand; no more were built though, the only batch being produced from May to July of 1944.   Had the invasion of Japan been needed, a special Jumbo with larger turret that included a flame thrower was considered, but we all know how that story ended.
       
         This version of the Sherman was issued to the Marines when the M4A2 75mm tanks went out of production. The version they would have been issued, would all have been large hatch M4A3 75w tanks,  and they may have gotten some with HVSS.    

      (this is an M4A4, the best way to tell is the extra space between the road wheels)
       
      M4A4 Sherman:
       
         This tank is the oddball of Sherman tanks. It had a welded hull and used the A-57 multibank motor. A tank motor made from combining five car motors on one crank case. As complicated as this sounds, it was produced in large numbers and was reliable enough to see combat use, though not in American hands in most cases. In US use they tried to limit it to stateside training duty. The Brits found it more reliable than their native power plants, and liked it just fine. This version never got the improved large hatch hull or T23 turret with M1 gun. Most were shipped to the Brits via lend lease and many were turned into Vc Fireflies, making it the most common Firefly type. The Free French also got at least 270 of these tanks in 1944. The Chinese also received these tanks through lend lease but not many. The US Marines operating these tanks in the states as training tanks, 22 of them for two months before they were replaced by M4A2s. This tank had a longer hull, like its Lee cousin to accommodate the big A-57 motor. It was the first Sherman version to go out of production. It was produced in one factory (CDA) from July of 42, to November of 43 with 7499 built.
       
         The A4 has the honor of being the heaviest and largest standard Sherman. The larger hull to accommodate the A57 motor, and the motor itself added weight. The British used these tanks extensively in combat. These tanks show up in British test reports as well, often pitted against tanks like the Cromwell in reliability or other tests, and usually coming out ahead. Anyone who has ever changed the spark plugs on their car should really be able to appreciate how hard a motor made by tying five six cylinder automobile engines together, on one crank would be. 
       
      . . .
       
         All Sherman variants share a lot of details and most spare parts interchange. Only the motors really call for different parts. All early Sherman tanks had 51mm of armor at 56 degrees on the front hull, and 76mm on the front of the turret. The 56 degree hulls are called small hatch hulls because the driver and co-driver had small hatches that forced them to twist sideways to get in and out. They also started out with direct vision ports along with periscopes for crew vision. Even the cast tanks matched these specs and the hatches from a cast tank could be used on a welded tank.  These early hulls had some of the ammo racks in the sponsons above the tracks. Not a great place for ammo, but not an uncommon one for it either. As they improved the hull, they added plates over the direct vision ports and eventually removed them from the castings. Large plates were eventually welded over the ammo racks on the sides, and this extra armor was eventually just added into the casting on the cast hulls. It’s safe to say no small hatch tanks were factory produced with a 76mm gun or improved T23 turret.
       
         The major hull change came when they upgraded the drivers and co drives hatches making them bigger. They also thickened the front armor to 64mm but reduced the slope to 47 degrees to fit the new driver’s hatches.  The M4 (hybrid and 105 only), M4A1, A2, and A3 were produced with these improved large hatch hulls. Many of these improved large hull tanks had the original 75mm gun and turret. Even the M4A3 with HVSS suspension was produced with the 75mm gun and turret. Most of the large hatch production was with the new and improved T23 turret.  These larger hatch hulls would still accept the majority of the spares the older hulls used and the lower hull remained largely unchanged and would accept all the suspension types. Any large hatch M4A3 hull was likely converted to an M4A3 76 HVSS post WWII.
       
         Through the whole production run minor details were changed. The suspension saw many different version before the final HVSS type was produced. The track types also changed and there were many variants made from rubber and steel, or steel. There were even at least six different types of road wheel! There are so many minor detail changes, the scope is to big to cover in this post, needless to say, the only other tank I know of with so many minor changes over the production run was the Tiger, and in the Tigers case it’s just sad, with so few produced, it means almost no two tigers were the same. This was not the case for the Shermans and the changes did not slow production down at all and in many cases were just different because a particular part, like an antenna mount, or driver’s hood, could have been sourced from a different sub-contractor, and the parts may look different, but would function exactly the same. Tiger parts are not good at interchanging without modification, and a crew a craftsmen to custom fit them. The changes made to the Sherman were either to incorporate better parts, or to use a locally made substitute part for one in short supply, so making their own version allowed them to continue production without a slowdown.
       
         To really get a handle on these differences there are two really great sources.
       
         This is the easy, way: Sherman Minutia site  a great site that really covers the minor detail changes on the Sherman tank very well.  You can spend hours reading it and looking over the pictures. It explains little of the combat history of the Sherman but covers the minor changes on the vehicles themselves very well. You can spend hours on this site learning about minor Sherman details. It is also a primary source for this post.
       
         Another great way is to get a copy of: Son of a Sherman volume one, The Sherman design and Development by Patrick Stansell and Kurt Laughlin. This book is a must have for the Sherman plastic modeler or true enthusiast. It is filled with the tiny detail changes that took place on the Sherman production lines from start to finish. They cover everything from lifting eyes to ventilators, casting numbers, to most minor change to the turrets. Get it now before it goes out of print and the price skyrockets. I liked it so much I bought two!
       
         The turret saw continual change as well, but remained basically the same. The 75mm gun never changed but its mount and sighting system did. The turret lost the pistol port, and then gained it back. It gained a rotor shield over time and an extra hatch. All these detail changes are covered on the site above and in the Son of a Sherman book. The important thing to note was the tank saw continual improvement to an already reliable, and easy to produce design. The Sherman was easy to produce for an industrial nation like the USA, but beyond Nazi Germany’s technical capabilities for several reasons, like large casting and the gun stabilization system, or even multiple reliable motors to power the tens of thousands of tanks made.
      In the basics section I’m only going to cover one more thing. The Sherman tank was not as blind as the tanks it faced. The M4 series, from the first production tank, to the final Sherman that rolled off any of the production lines, were covered in periscopes or view ports for the crew. The gunner had a wide angle periscope that had incorporated the site for the main gun, and they very quickly added a telescopic site to go with it. The commander had a large rotating periscope in his rotating copula. The loader had a rotating periscope and the driver and co-driver had two, one in their hatch, and another mounted in the hull right in front of them once the DV ports were deleted (non-rotating). Later version added a direct vision cupola and a periscope for the loader in his new hatch. All these periscopes could be lowered and the port closed, and if damage easily and quickly replaced from inside the tank. All this gave the Sherman an advantage in spotting things outside the tank; they were still blind, just not as blind as most of the tanks they would face. Finding an AT gun in a bush could be very challenging for any tank, and infantry if not scared off by the presence of a tank in the first place can sneak up on one pretty easy.
       
         This was a big advantage when it saw combat and throughout the tanks career it was always one of the best if not the best tank of the war. It was reliable, the crew had a good chance of spotting enemies before other tank crews, the gun was stabilized, fast firing, and accurate. It was as good or better than most of the tanks it faced, even the larger German tanks. These tanks were largely failures, with only long debunked Nazi propaganda propping up their war record. The Sherman has the opposite problem.
       
      Sherman Builders: Just How Many Tank Factories Did the US Have Anyway?   
      They Had 10 and 1 in Canada.
       
         Most of the information in this section will be a summation of the section in Son of a Sherman. Other stuff I had to dig around on the internet for. Anyone who has more info on the tank makers, please feel free to contact me.  Parts from all these tank makers would interchange. Many used the same subcontractors. I don’t think anyone has tried or if it’s even possible to track down all the sub-contractors who contributed parts to the Sherman at this point. Some of the manufactures were more successful than others, some only producing a fraction of the total Sherman production, others producing large percentages. By the end of production, all the US and her allies needs for Shermans were being handled by just three of these factories.
       
      American Locomotive (ALCO)
         ALCO also produced M3 and M3A1 Lees, and made Shermans up to 1943. They were a fairly successful pre-war locomotive manufacturer founded in 1901 in Schenectady, New York. They also owned Montreal Locomotive works. ALCO made several version of the Sherman, and stayed in the tank game until the late 50s, helping with M47 and M48 production. The company went under in 1969.
       
      Baldwin Locomotive Works (BLM)
         Baldwin was another early producer, building three versions of the Lee, The M3A2, M3A3, and M3A5. They mostly built small hatch M4s, with just a handful of M4A2(12). They were out of the Sherman game by 1944 and out of business by 72. They were founded in Philly in 1825, and produced 70,000 steam locomotives before it died.
       

      (M4A4 and M3s being built side by side at CDA, photo courtesy of the Sherman Minutia site )
       
      Chrysler Defense Arsenal (CDA)
           Chrysler Defense Arsenal is kind of special. It was a purpose built tank factory, funded by the US Government, and managed and built by Chrysler.  Construction on the factory started in September of 1940. Completed M3 Lee tanks were rolling of the line by April of 1941. This was before the factory was even finished being built. It was built to stand up to aerial bombing. They produced M4A4, and M4 tanks as well and M4 105s, M4A3(105)s, and M4A3 76 tank and nearly 18,000 of them. Chrysler was the sole producer of M4A3E8 76 w Shermans, or the tank commonly known and the Easy 8. They produced 2617 units, but post war many A3 76 tanks were converted over to HVSS suspension. A very big chunk of the overall Sherman production came from this factory and it went on to produce M26 Pershing tanks.
         
          Chrysler built this factory in a suburb of Detroit, Warren Township Michigan. Chrysler used it’s many other facilities in the Detroit area as sub manufacturers, and many of their sub-contractors got involved too. CDA not only produced the tanks, it had the capacity to pump out huge numbers of spare parts.  CDA lived into 90s before Chrysler defense systems got sold off to General Dynamics. It took part in making the M26, M46, M47, M48, M60 and M1 tanks.
       
      Federal Machine & Welder (FMW)
         I couldn’t find much out about FMW, Son of a Sherman says they were founded in Warren Ohio in 1917. They produced less than a thousand M4A2 small hatch tanks.  They were slow to produce them, making about 50 a month. They were not contracted to make any more Shermans after their first 540 total, 1942 contract.  They did build some M7, and M32 tank retrievers. They were out of business by the mid-fifties.
       
      Fisher Tank Arsenal (FTA)
          Fisher Tanks Arsenal (FTA) has a lot of common with Chrysler Defense Arsenal, except this time Uncle Sam went to Fisher Body, a division of General Motors. Fisher decided to build the tank plant in Grand Blanc, south of Flint Michigan. The factory broke ground in November of 1941 and the first M4A2 Sherman rolled off the line in January of 1942, before the factory was fully built.
       
         The M4A2 was something of this factory specialty, in particular early on, with them producing a large number of the small hatch M4A2 sent off to Russia, and a few of the rarer large hatch 75mm gun tanks, around 986 small hatch tanks, and about 286 large hatch tanks.
         
         They also produced nearly 1600 large hatch, 76mm gun tanks, or the M4A2 (76)w. These tanks went exclusively to Russia as part of Lend Lease. These tanks were ordered over four different contracts and the final ones off the production line were all HVSS tanks. The HVSS suspension may have seen combat with the Russians before the US Army used it. Oddly, this factory also produced M4A3 76w tanks, but never with the HVSS suspension. Fisher produced a significant number M4A3 and Large hatch 75mm tanks at their factory, but nowhere near their M4A2 production.
       
      Ford Motor Company (FMC)
         Ford was a surprisingly small player in the Sherman tale. They are very important in that they developed the Ford GAA V8 covered earlier, and a lot of spare parts. But they only produced 1690 small hatch Shermans between June of 42 and Oct 43. They built a few M10s as well. All these tanks and tank destroyers were produced at their Highland Park facility.  After 1943, they stopped building tanks, and wouldn’t get back into until the 50s, and even then it was just for a large production run over a short time, of M48s.
       
      Lima Locomotive Works (LLW)
         Lima was one of the first producers of the cast hull M4A1. It did not produce any Lee tanks. Its production capacity had been taken by locomotives to the point just before Sherman production started. They produced the first production M4A1, that was shipped to England, named ‘Michael’, and it’s still on display at the Bovington Museum. They produced Shermans from February of 42, to September of 1943, producing M4A1s exclusively, and they built 1655 tanks.  The war was a boon for Lima, they’d been in business since 1870, and the contracts from the military for locomotives really helped them out. Post war, they failed to successfully convert to diesel electric locomotives and merged with another firm.
       
      Montreal Locomotive Works (MCW)
          MLW was owned by American Locomotive. They produced some wacky Canadian tank based off the Lee chassis, called the Ram, and Ram II, these floppy creations were only armed with a 2 pounder in the Rams case, and a 6 pounder, in the Ram IIs case, and they produced almost 2000 of the wacky things, what’s that all aboot? They eventually got around to producing a proper Sherman tank, the M4A1 “Grizzly”, producing only about 188 tanks. A very few had an all metal track system that required a different sprocket. Other than that, there was no difference between a grizzly and an M4A1 manufactured by any other Sherman builder. Don’t believe the Canadian propaganda about it having thicker armor!
       
      Pacific Car & Foundry (PCF)
         PCF was founded in 1905 in Bellevue Washington. The only west coast tank maker, PCF produced 926 M4A1s from May of 1942, to November of 1943. As soon as production stopped they started production on the M26 tractor, the truck portion of the M26 tank transporter. They never got back into tank production, but still exist today as PACCAR Inc., one of the largest truck makers in the world. 
       
      Pressed Steel Car (PST)
         PSC was one of the big boys of Sherman production, and they also produced the final M4s made, a group of 30 M4A1 76 HVSS tanks. PSC was founded in Pittsburg in 1899, but their tank factory was in Joliet, Illinois. They were the second manufacturer to make the tank and across all the versions they made, they produced 8147 Sherman tanks.  
       
        They started tank production with the M3 Lee in June of 41, and stopped production on that in August of 1942. They then produced the M4A1 from March of 42, to December of 43, and the standard M4 from October of 42 to August of 43.
         
         They were one of the final three tank makers to stay in the tank making business after 1943, along with CDA and FTA. PSC would produce large hatch M4A1 76 tanks, including HVSS models late in the run, totaling more than 3400 M4A1 tanks. They produced 21, M4A2 76 HVSS tanks, towards the end of 45.
         
         They were out of business by 56, with no tank production after those final 30 M4A1 76 HVSS tanks. 
       
      Pullman Standard (PSCC)
           Pullman Standard was a pretty famous luxury train passenger car maker, and another company that made rolling stock combined into one company. Pullman Palace Car Co was founded in 1867, or there about. I’m sure some train geek will be dying to fill me in on the company’s history but I’m not really going to look deeply into it. It does make for one of the more interesting stories about a Sherman tank producer. Their main tank factory was in Butler, Pennsylvania. And they helped produce some Grant tanks before they started Sherman production.
         They produced the M4A2 from April of 42 to September of 43, and produced 2737 tanks. They also produced 689 standard M4 Sherman tanks from May of 43, to September of 43.  Soon after these contracts were finished the US Government broke the company up due to some anti-trust complaint.  
       

       
         The thing to remember about all the Sherman makers is each one had a small imprint on the tanks they produced. So, yes, an M4A1 small hatch tank was the same no matter who made it and all parts would interchange with no modification needed, but the tanks from different makers still had small, cosmetic differences. They may have been something like nonstandard hinges on the rear engine doors to the use of built up antenna mounts instead of cast. Or wide drivers hoods or narrow, to where the lift rings on the hull were and how they were made or even Chrysler's unique drive sprocket they put on all their post A4 tanks.  None of this meant the parts couldn't be salvaged and used on another Sherman from another factory without much trouble. Some factories may have produced tanks faster than others, but they all produced them within the contracts specification or they were not accepted.
    • By Militarysta
      About tank guns and amunition, hope it will be interesting topic :-)
       
      In penetration data I will base on russian sources -they are ussaly most credible (the best). I will ussaly give value for monolith steel plate slopped on 60@ - it's the best scenario for APFSDS penetrator. In sucht scenario (slopped on 60@ plate) penetration value can be bigger at even 17-20% then on 0.degree plate - this is caused by "asymmetry loads back surface" of the plate):

       
       
      First:
      M829
      M829A1
      M829A2
      M829A3
      M829A4
       
      M829:
      DOI: 1985
      penetration at 2km, on plate slopped by 60@: 540-560mm RHA:
       
       

       
       
      M829A1
      DOI - 1989 (in some sources - 1988) 
      penetration: at 2km, on plate slopped by 60@: circa 700mm RHA
      this round was to weak to overcome T-80U and T-80UD and T-72B m.1989 whit Kontakt-5 ERA, what was "suprisly" discover on tests in circa 1994. The same story was whit DM43 prototypes..
       

       
      M829A2
      DOI - 1992
      penetration: at 2km, on plate slopped by 60@: circa 740mm RHA
      Fist US round whit composite sabot.
       
      (lack good photos)
      insted of this:
       
      KE-W so M829A1 but whit WHA penetrator, and KEW-E3 so M829A2 whit WHA long rod.

       
       
      M829A3
      DOI - 2003
      penetration: at 2km, on plate slopped by 60@: propably circa 800mm RHA, but is not sure value,
      round devleoped to everpas heavy ERA but whit unkown result
       

       
       
      M829A4
      DOI -2016 :-)
       
      penetration - no idea 
      It's very interesting round
       

       
      data link is  for APFSDS round?!
      I have a hypothesis...
      Ok so it have data link to be programmed, it is said to be capable to defeat 3rd generation heavy ERA (Relikt, Knife, etc.) and active protection systems (hard kill). It seems that focus is primary on defeating heavy ERA. But then again, why do you need to program just a long rod fired by a big gun?

      There are few options:

      - Gudining the round,
      - Precursor,
      - "Intelligent" control over propelant charge ignition (dependant on propelant temperature, environment temperature, gun service life, range to target etc.)

      And truth to be told hypothesis that there is some sort of precursor in the rod is the only hypothesis that makes sense. Control over propelant charge ignition is not needed and probably not possible at all with current technology, besides the M829A4 (and all newer US ammo types for 120mm smoothbore) use insensitive propelant charges. And it is nowhere mentioned in any document avaiable for public. Guiding the rod to target? Perhaps possible from technical point of view, but why? Again it was nowhere said that FCS for M1A2SEPv3 have ability to guide any type of rounds. And manouvering of the rod during flight means loss of a lot of energy, even if this manouvering would be done to "cheat" the APS for example.

      So perhaps the option is to somehow use a precursor that is "fired ahead" of the main rod.


       
       
      So how the rod designs looks like here? The rod is made from two segments, the "precursor" and the main rod behind it. How they are connected? it might be some sort of polymer, glue that can be weakened by heat and the release precursor, and during flight rods heat up pretty nicely.

      The precursor can also be relased based on a simple difference of speed between it and the main rod, and main rod can be slowed down by some sort of additional fins (aerodynamic breaks) released at specific point programmed by FCS. In such case precuros would initiate ERA and the main rod would have a clear way to main armor of the target.

      How to cheat APS tough? Counting that precursor will be qualified by APS as threat and APS will be initiated, creating a time gap in APS reaction so it won't be able to counter the main rod? Possible yes, but then there is question, if APS will just not ignore the precursor, and this might happen, now of course there is a question how dangerous is precursor itself? For a MBT or vehicle with similiar levels of protection, for it's front it won't be dangerous in most cases, sides? If they do not have any addon armor, very possible. For lightweight platforms, yeah precursor also will be dangerous.

      Of course these are only hypothesis, and we will see if other nations will also design APFSDS rounds with data link. Then we might get closer to the truth. Right now, treat it as food for thoughts.
       
      of course this data link coud be placed only for security resons, as one person on TankNet had wrote:
       
      :-)
       
      ps. prefragmentet APFSDS during flying exist now, as smal-scale models and test object:

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