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New here, but I've followed this thread (and Mech Warfare) for a good while.   I attend the United States Military Academy and it is branch week here. Armor brought an M1A2 SEPv2 which, whil

Was posted on otvaga - diploma work on ramjet APFSDS design (in russian). PDF    

48 minutes ago, David Moyes said:

I don't know what they mean by Southern Asia? South Korea isn't actually in the south.

 

But... but, but it's name contains "south", so it must be in south or?  :D

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6 hours ago, David Moyes said:

I don't know what they mean by Southern Asia? South Korea isn't actually in the south.

 

One should keep in mind that these terms aren't set in stone and not always the same in the same language. For example the term "Middle East" in the German language consists of Pakistan, India, Bangladesh, Bhutan, etc.

 

Still counting either South Korea or Japan to "South Asia" seems very wrong...

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https://apps.dtic.mil/dtic/tr/fulltext/u2/1045347.pdf 
 

“76mm gun M1A1 and M1A2: an analysis of US anti-tank capabilities during WW2” 

 

It’s a “historical piece”, but an interesting read nonetheless.
@Jeeps_Guns_Tanks, there’s some schematics for the M93 HVAP, M62 APC, and M42 HE at the very end, if you don’t already have them. 

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1 hour ago, Lord_James said:

https://apps.dtic.mil/dtic/tr/fulltext/u2/1045347.pdf 
 

“76mm gun M1A1 and M1A2: an analysis of US anti-tank capabilities during WW2” 

 

It’s a “historical piece”, but an interesting read nonetheless.
@Jeeps_Guns_Tanks, there’s some schematics for the M93 HVAP, M62 APC, and M42 HE at the very end, if you don’t already have them. 

 

Awesome. I do not have that report, or the schematics for those shells, at least at that quality. 

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More info on DM73, KE2020Neo, Rh130mm and MGCS.

- Super confirmed that DM73 is the same good old DM53/63 projectile and sabot but with more powerful propellant. Existing DM63 rounds can be upgraded to DM73. 8 Percent performance improvement over DM63.

- KE2020Neo will get a new "DM" designation in 2-3 years, mass production expected for 2025. Entirely new design both for projectile and sabot. Design is not yet finalized.

- There is not enough info currently to simulate T-14 armor for trials and experiments with the new ammo.

- Rh130 has 50 percent more chamber volume than 120mm, and also 15 percent higher pressure tolerance, producing an undisclosed higher muzzle velocity.

- The intended tank engagement range with 130mm APFSDS is 4-4.5km. Engineers doubt that APFSDS can be effective at that range vs moving targets, perhaps guided munitions might be more efficient.


https://www.edrmagazine.eu/more-on-rheinmetall-tank-guns-and-ammunition-evolution

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On 3/5/2021 at 4:09 PM, alanch90 said:

- 99 percent implied that the autoloader is based/inspired on the Japanese Type 10´s but still is an original design (that´s what i call a discreet F-U to the French and their experience with the Leclerc).

Even if France is experienced doesn't mean they are necessarily good at it. Just comparing the speed of the Type 90 and Leclerc you can already begin to see the flaws in the Leclerc system. Mainly how long it takes between the round being pushed into the breech and how long it takes the breech block to shut afterwards.

Spoiler

 

 

 Japan's solution was to attach the rammer arm on a pivot point so that the breach can close sooner during the retraction stroke.

Spoiler

EfTnryjUEAgqJ-F?format=jpg&name=large

 

Then you get to the Type 10 where it's pulling out entire reloads in the time it takes for just the mechanism stage of the Type 90 (which was already incredibly fast).

Spoiler

 

 

I had high hopes for the K2's autoloader, but it just seems to be a Leclerc autoloader with faster motors.

Spoiler

 

 

This leads me to believe that there is limitations from the fundamental design and any significant improvements in speed would require a complete redesign anyways, so they might as well just copy the good one.

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On 3/9/2021 at 4:02 PM, Jackvony said:

New Nexter Munitions APFSDS called 120 SHARD. Maybe related to that round we saw with a datalink a few years ago?

  Reveal hidden contents

1497021725_06-french-apfsds-ofl-120-f1b-ng.jpg

 

 

That was never intended to be a datalink, it's just a flexible primer.

 

On 3/24/2021 at 9:54 AM, Atokara said:

Even if France is experienced doesn't mean they are necessarily good at it. Just comparing the speed of the Type 90 and Leclerc you can already begin to see the flaws in the Leclerc system. Mainly how long it takes between the round being pushed into the breech and how long it takes the breech block to shut afterwards.

 

Leclerc's autoloader loading time was increased (reducing the rate of fire to 9-10 rounds per minute instead of 12) as the ammunition were too violently rammed into the chamber,  sometimes resulting in a rebound of the ammunition.

 

How reliable are the Type 90 and 10 autoloader ?

 

I wouldn't rely my reasoning on short videos. Does any official data exist regarding the performance of these devices ?

 

Quote

I had high hopes for the K2's autoloader, but it just seems to be a Leclerc autoloader with faster motors.

 

In any case, the South Korean delegation paid much attention to the Leclerc's autoloader during their visit at Eurosatory many years ago.

 

b40dDZ6.jpg

 

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2 hours ago, Sovngard said:

 

I wouldn't rely my reasoning on short videos. Does any official data exist regarding the performance of these devices ?

It's Japan we are talking about here. You'll be hard pressed to find accurate numbers on how much ammo their tanks carry, let alone a full write up on the autoloader performance. That being said there is no evidence that there was any reliability issues where you might expect to see them brought up such as interviews with design leads:

https://dl.ndl.go.jp/view/download/digidepo_1283286_po_TRDI50_04.pdf?contentNo=4&alternativeNo=

Type 10 design outlines specifying improvements needed over the Type 90:

https://drive.google.com/drive/u/0/folders/0B8KVYt57g6q_QTVHN1EyMThwRnM

 

The only autoloader related "issue" I've seen in regard to the Type 90 was that the 1st prototype was unable to mount one as the cooling system for it's CITV took up too much space at the back of the turret.

Spoiler

Image

 

Either way it seems reliable enough that such a speed was adopted into service.

Spoiler

 

As you pointed out, the Leclerc's fire rate was reduced when it ran into issues. Therefore I see no reason why Japan wouldn't reduce the speed if they were running into issues as well. it's not like Japan was brand new to autoloading designs in the 90s either when they've been prototyping systems since the 50's

Spoiler

ayxsHjG.jpg

 

Either way it seems like it's a reliable enough design where Rheinmetall would toss up a big middle finger to the French design in favor of a Japanese design for a gun that will be mounted on a joint French/German vehicle.

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On 3/24/2021 at 9:54 AM, Atokara said:

Even if France is experienced doesn't mean they are necessarily good at it. Just comparing the speed of the Type 90 and Leclerc you can already begin to see the flaws in the Leclerc system. Mainly how long it takes between the round being pushed into the breech and how long it takes the breech block to shut afterwards.

Those videos have the fishy look of being sped up...

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7 hours ago, SH_MM said:

Those videos have the fishy look of being sped up...

Source videos if you want to do your own timing. All the above vids above were timed from first frame of muzzle flash to first frame of the FCS unlocking the main gun using a 30fps timer. All vids are directly from the military or military sponsored vids.

 

 

 

 

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So I've seen this image used a whole lot across the internet as an estimate for the proportions of DM53 and I thought I would do my own measurements on it to see how things line up.

Spoiler

9wknumx.png

 

Disclaimer: I am merely providing my own interpretation of the measurements using the same methodology as whoever originally posted the image. Pixel measuring is an inherently inaccurate measurement tool and very subjective especially on blurry images such as this as people will have different opinions on which pixels can be considered part of the rod and which cannot. I accounted for pixel bleed as best I could by ignoring the softer and less consistent outlines where it was applicable. I do not consider my measurements any more correct and encourage other people to do their own measurements to compare to as well. In the image M829A3 and DM53 are not scaled exactly the same, there is a few px difference, so the ratios for both OP and my measurements will vary between the rounds.

 

Both DM53 and M829A3 don't have any officially published lengths, so people have gone to pixel measuring as a way to get estimates.

 

I started with M829A3 first by taking the pixel ratio for OPs estimate of 930mm. At 696px long this gave a ratio of 1.3362. The sabot diameter is always 119.9mm which makes it an excellent scaling tool which is what I used for my measurements(here I rounded it up to an even 120mm for simplicity sake). At 90px wide the ratio I got was 1.333 repeating. At a 0.003 difference OP did a good job measuring 829A3 imo as my ratio gave me a total length of the projectile of 928mm, only a 2mm or less than 2 pixel difference in our measurements. For all intents and purposes I consider M829A3's measurements accurate as can be estimated using this method.

 

Now onto DM53. Using OPs estimate of 760mm that gives us a ratio of 1.381818. Going off of the sabot which is 88px wide, I get a ratio of 1.3636 repeating. Now the difference here is a bit bigger (10mm or just over 7 pixels difference which I consider far outside the margin of error of 1-2pixels from M829A3) and when applying my ratio to the 550px long rod I get to total length of exactly 750mm. I actually found that OPs measurements for the diameter of DM53 lined up pretty well with mine just being a 1mm difference, but that is understandable due to the smaller pixel count of the diameter.

 

My last issue is with how OP measured the depth that the actual penetrating rod goes into the fin section. The pic of M829A3 is a proper cross section and we can see exactly where the rod ends so there is no estimates there, however the DM53 pic isn't a cross section and OP has given his own estimate of where he thinks it might end. To find a more accurate (but not exact) estimate in the ball park of where it might end I utilized the ratio of fin length to depth that the rod goes into that section. Here I also brought in a diagram of Type 10 APFSDS and I will explain why later.

 

M829A3 has 125mm long fins based on my measurements, 28mm or 22% of that length is overlapped by the penetrating rod.

DM53 has 110mm long fins based on my measurement and OPs estimate puts his estimate of where the rod might end at a depth of 54mm or just shy of 50%

 

Here I brought in a diagram of Type 10 APFSDS, because despite how secretive the Japanese are about their military equipment, we know quite a bit on this round. I used it as a control value to compare my estimates of M829A3 and DM53.

Spoiler

VBGrkTF.png

At 748mm long for the projectile and 350 pixels across I got a ratio of 2.13714. With the sabot at 56 pixels in diameter applying my ratio gives 119.6mm which is well within the margin of error (which is expected as we already know the measurements).

 

Now that we know the Type 10 diagram is accurate we can go back to the fins. Type 10 has 117mm long fins and a 32mm rod depth into the fin section which gives a 27% overlap (M829A3: 22%, OP's estimate DM53: 50%). And that is where my issue lies. I went ahead and gave DM53 the same overlap as Type 10 at 27% as M829A3 has a very different and longer fin design that pushes farther past the projectile body. 27% of 110mm gives 30mm and when measuring to the penetrator tip that OP estimated we get a 625mm penetrator length and an overall projectile length of 750mm for DM53.

 

Let me know if I screwed up anywhere.

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On 4/20/2021 at 7:13 AM, Atokara said:

So I've seen this image used a whole lot across the internet as an estimate for the proportions of DM53 and I thought I would do my own measurements on it to see how things line up.

  Hide contents

9wknumx.png

 

Disclaimer: I am merely providing my own interpretation of the measurements using the same methodology as whoever originally posted the image. Pixel measuring is an inherently inaccurate measurement tool and very subjective especially on blurry images such as this as people will have different opinions on which pixels can be considered part of the rod and which cannot. I accounted for pixel bleed as best I could by ignoring the softer and less consistent outlines where it was applicable. I do not consider my measurements any more correct and encourage other people to do their own measurements to compare to as well. In the image M829A3 and DM53 are not scaled exactly the same, there is a few px difference, so the ratios for both OP and my measurements will vary between the rounds.

 

Both DM53 and M829A3 don't have any officially published lengths, so people have gone to pixel measuring as a way to get estimates.

 

I started with M829A3 first by taking the pixel ratio for OPs estimate of 930mm. At 696px long this gave a ratio of 1.3362. The sabot diameter is always 119.9mm which makes it an excellent scaling tool which is what I used for my measurements(here I rounded it up to an even 120mm for simplicity sake). At 90px wide the ratio I got was 1.333 repeating. At a 0.003 difference OP did a good job measuring 829A3 imo as my ratio gave me a total length of the projectile of 928mm, only a 2mm or less than 2 pixel difference in our measurements. For all intents and purposes I consider M829A3's measurements accurate as can be estimated using this method.

 

Now onto DM53. Using OPs estimate of 760mm that gives us a ratio of 1.381818. Going off of the sabot which is 88px wide, I get a ratio of 1.3636 repeating. Now the difference here is a bit bigger (10mm or just over 7 pixels difference which I consider far outside the margin of error of 1-2pixels from M829A3) and when applying my ratio to the 550px long rod I get to total length of exactly 750mm. I actually found that OPs measurements for the diameter of DM53 lined up pretty well with mine just being a 1mm difference, but that is understandable due to the smaller pixel count of the diameter.

 

My last issue is with how OP measured the depth that the actual penetrating rod goes into the fin section. The pic of M829A3 is a proper cross section and we can see exactly where the rod ends so there is no estimates there, however the DM53 pic isn't a cross section and OP has given his own estimate of where he thinks it might end. To find a more accurate (but not exact) estimate in the ball park of where it might end I utilized the ratio of fin length to depth that the rod goes into that section. Here I also brought in a diagram of Type 10 APFSDS and I will explain why later.

 

M829A3 has 125mm long fins based on my measurements, 28mm or 22% of that length is overlapped by the penetrating rod.

DM53 has 110mm long fins based on my measurement and OPs estimate puts his estimate of where the rod might end at a depth of 54mm or just shy of 50%

 

Here I brought in a diagram of Type 10 APFSDS, because despite how secretive the Japanese are about their military equipment, we know quite a bit on this round. I used it as a control value to compare my estimates of M829A3 and DM53.

  Hide contents

VBGrkTF.png

At 748mm long for the projectile and 350 pixels across I got a ratio of 2.13714. With the sabot at 56 pixels in diameter applying my ratio gives 119.6mm which is well within the margin of error (which is expected as we already know the measurements).

 

Now that we know the Type 10 diagram is accurate we can go back to the fins. Type 10 has 117mm long fins and a 32mm rod depth into the fin section which gives a 27% overlap (M829A3: 22%, OP's estimate DM53: 50%). And that is where my issue lies. I went ahead and gave DM53 the same overlap as Type 10 at 27% as M829A3 has a very different and longer fin design that pushes farther past the projectile body. 27% of 110mm gives 30mm and when measuring to the penetrator tip that OP estimated we get a 625mm penetrator length and an overall projectile length of 750mm for DM53.

 

Let me know if I screwed up anywhere.

 

Don't hold me on this but as far as I know, there was a picture of a brochure of DM53 posted sometime in the past on the net where it said the penetrator body was 685mm though I don't remember if it also said anything about the diameter;

 

Regardless of this, i think comparing DM53 to Type 10 AFPSDS is a bit of a moot point and it would do us better to compare DM53 to M829A1/2 which both have 680x22mm and 690x22mm penetrators respectively in a projectile body roughly ~760mm long (though it's 779mm long in total).

 

There's also the case of yet another, I believe Rheinmetall brochure from 2014 or so stating that the projectile body of DM53 is 745mm long (i'm assuming that they excluded the fins that extend beyond the body of the main body of the projectile.

 

I've done my own share of estimates on DM53 and 63 in my free time and this is what I had got:

DM53:

unknown.png?width=150&height=675

 

DM63:

unknown.png?width=122&height=640

 

Did an estimate for DM53 once again just a moment ago;

unknown.png?width=222&height=676

 

 

In regards to the DM63 estimate, since i already had numbers for diamater and the stuff, i just did a comparison of how long fins on the 53 and 63 are, substracted the difference and that's how i got to ~770mm total length and 745mm "effective projectile length" (or perhaps it could be called in-flight length?).

 

 

edit: just found this, i don't know where this comes from but the penetrator length matches what was said in the Brochure, diameter is a bit too high though it also matches if you count in the ribs which in my estimates were roughly 25.8mm

 

IMG_4483.JPG.a248c8f17f29ef012c1baba30e9d5441.jpg

 

And overall i think this graphic is legit; 

DM13 estimate:

unknown.png?width=258&height=594

 

DM23:

unknown.png?width=1220&height=569

 

DM33:

30896ce2407eefc7a8fc48af074b05fafbad2be7

 

They all roughly fit with penetrator length, diameter is a bit iffy cause I dunno what kind of criteria they used for diameter there.

 

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3 hours ago, Sheffield said:

Regardless of this, i think comparing DM53 to Type 10 AFPSDS is a bit of a moot point and it would do us better to compare DM53 to M829A1/2 which both have 680x22mm and 690x22mm penetrators respectively in a projectile body roughly ~760mm long (though it's 779mm long in total).

My primary reason for this is the fact that its got a proper diagram with listed lengths which is pretty hard to come by past DM33. It acted as essentially a control group to make sure I was doing proper measurements. However after cross checking with your measurements I can't find any fault in your measurements either despite them being different from mine and I have a few guesses as to why.

 

3 hours ago, Sheffield said:

There's also the case of yet another, I believe Rheinmetall brochure from 2014 or so stating that the projectile body of DM53 is 745mm long (i'm assuming that they excluded the fins that extend beyond the body of the main body of the projectile.

Here is the first one. When measuring I was measuring from tip to ends of the fins. I found a diagram of 105mm Type 93 to compare against the Type 10 as there was no indication for either method and saw that the fin tips weren't included in the measurement for the Type 93 meaning that you were right with the exclusion of fins. Now this is a big problem for my control. By all accounts my numbers appeared to line up despite this error, but I went back to check anyways and found that I mis-measured the sabot diameter at 56px instead of the actual 57px and this would've tipped me off immediately to the fact that my scale was wrong. Going and measuring the cartridge diameter also shows the scale was off in a much bigger way. As it turns out that somewhere in the process of the Type 10 diagram being passed around the internet, it got stretched in the vertical axis, and when correcting for this, the exclusion of the fins got me an actually accurate scale.

 

Basically I went into it thinking my control group was accurate, but it ended up just throwing off my other measurements. That combined with the fact that the images are so blurry means that a few pixels can make a big difference. Just switching the sabot size on DM53 from 88px to 87px changes the overall length back up to 759mm alongside OPs original estimate. With the DM53 picture being so blurry compared to the M829A3 it's not surprising that one was accurate and 1 got messed up just from image clarity. Either way I found my mistake and also what just can't be helped with such an imprecise and subjective measurement system and this is exactly why I wanted other people doing their own measurements.

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Helo.

Is there accurate data on the projectile weight of 3BM59/60?

 

And why are the bore tip speed values so inconsistent from source to another? I have a feeling that NIMI is somewhat lowballing it's rounds. Either because its export or Because they dont want to Publicly declare .

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      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 Molota_477
      M1 CATTB
      pic from TankNet.
      I feel uncertain whether its cannon's caliber was 140mm or not, I found a figure at the document AD-A228 389 showed behind, which label the gun as LW 120.But in many ways I've found its data in websites all considered to be 140mm.

      AFAIK,the first xm291(140)demonstrator was based on xm1 tank, and the successor was the''Thumper'' which was fitted with a new turret look like the CATTB but still m1a1 hull(Maybe it was CATTB's predecessor? )

      I will really appreciate if anyone have valuable information to share
    • By Domichan
      Hello all,
      I apologize for the fact that my first post is a question. I am a Dutch collector of medium and large calibre AP ammunition and I recently bought an 105mm APFSDS-T projectile, that is marked with the designation DM53. The 120mm DM53 is well known, but I cannot find any information on the 105mm DM53. I do know the IMI M426/DM63 round exists, for I have seen pictures of that, which would indicate that a DM53 would exist as well, in accordance with the way German ammo designations go. Questions to Rheinmetall, the Bundeswehr and various collector groups have remained unanswered. 
      Among the experts here, is there anyone who has information on this type of APFSDS-T Round?
      Thank you in advance,
      Domichan
       

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