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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

A little low calibre for this thread, but I don't feel like starting a new one for medium calibre guns.

 

http://www.janes.com/article/75087/orbital-atk-progresses-new-medium-calibre-munition-development

 

Looks kinda neat. Would like to know more about the 'command guided' 30mm type for sure.

 

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1 hour ago, Belesarius said:

A little low calibre for this thread, but I don't feel like starting a new one for medium calibre guns.

 

http://www.janes.com/article/75087/orbital-atk-progresses-new-medium-calibre-munition-development

 

Looks kinda neat. Would like to know more about the 'command guided' 30mm type for sure.

 

 

It sounds like they are scaling down the 50mm EAPS guidance system.

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On 11/6/2017 at 2:20 PM, Ramlaen said:

Rarefaction Wave Gun, the bastard child of  traditional large caliber guns and recoilless rifles.


I did a thread on these some time ago.

 

On 11/14/2017 at 10:08 PM, Ramlaen said:

Something I came across while looking for something completely different, a patent on kinetic energy projectiles that lengthen after being fired.

 

SluFeaO.png

 

  Reveal hidden contents

 

 

Extended rods are mentioned in this overview of novel penetrator technologies.

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Wanted the opinion of the forum about guided ammunition for MBTs

 

http://preprod.nexter-group.fr/images/stories/filiales/MUN/char/40055_POLYNEGE_VF.pdf

 

In this case it's a French technology demonstrator (early 2000 I don't have an exact date), but IRC the US have a similar round in development (Plus the M982 Excalibur round that is already in service for artillery).

 

The advantage I see:

 

-Perform the same job than a top attack ATGM while being most likely cheaper (The flight control, electronics and warheads are by all mean the same but it doesn't need a booster)

-Added versatility for MBT (Just send the data from the BMS to the FCS, load the round and fire)

-Slightly faster than an ATGM (600-700 m/s vs 150-300 m/s for an ATGM), so maybe some APS might have a harder time intercepting it (not sure about that though)

 

Cons would be:

 

-The diameter or the warhead is limited by the gun (but the same apply for gun launched ATGM)

-Contrary to an ATGM those rounds have to follow a ballistic arc so in some terrain configuration they might not be able to hit the target.

 

Personnaly I think that the added range and versatility for MBTs is worth it (8km ; fire and forget ; NLOS capability could be a big deal if you have no artillery support available), but perhaps others will see it as a gadget.

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If we are talking active guidance and not INS/GPS my opinion is that

 

-I am really disappointed the XM1111 MRM got cancelled in a rash of short sighted cost cutting.

-Guided rounds fall into the special purpose niche that gun launched ATGMs do.

-Programmable airburst rounds (both the HE and KE variety) seem to have superseded guided rounds due to cost effectiveness.

-NLOS is an attractive potential.

 

 

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On 11/28/2017 at 2:59 AM, Alzoc said:

Wanted the opinion of the forum about guided ammunition for MBTs

 

http://preprod.nexter-group.fr/images/stories/filiales/MUN/char/40055_POLYNEGE_VF.pdf

 

In this case it's a French technology demonstrator (early 2000 I don't have an exact date), but IRC the US have a similar round in development (Plus the M982 Excalibur round that is already in service for artillery).

 

The advantage I see:

 

-Perform the same job than a top attack ATGM while being most likely cheaper (The flight control, electronics and warheads are by all mean the same but it doesn't need a booster)

-Added versatility for MBT (Just send the data from the BMS to the FCS, load the round and fire)

-Slightly faster than an ATGM (600-700 m/s vs 150-300 m/s for an ATGM), so maybe some APS might have a harder time intercepting it (not sure about that though)

 

Cons would be:

 

-The diameter or the warhead is limited by the gun (but the same apply for gun launched ATGM)

-Contrary to an ATGM those rounds have to follow a ballistic arc so in some terrain configuration they might not be able to hit the target.

 

Personnaly I think that the added range and versatility for MBTs is worth it (8km ; fire and forget ; NLOS capability could be a big deal if you have no artillery support available), but perhaps others will see it as a gadget.

 

 

I have been thinking about this a bit.  Here are my thoughts:

For the NATO 120mm, GLATGMs of any sort don't seem to make much sense if they use pure rocket propulsion.  They are very space inefficient because the 120mm cartridge case is strongly bottlenecked:

3uY75QW.png

 

All of the volume inside the ammunition rack occupying the difference between the case diameter and the gun caliber is wasted when using GLATGMs.  This isn't so bad with the 125mm and 105mm guns, because they are not as strongly bottlenecked as the 120mm.  Really, the 120mm NATO smoothbore was designed to do one thing and do it really well, and that is fire the meanest APFSDS rounds on the battlefield so it can kill Soviet frying pan tanks dead.  It's a bit less efficient at everything else, but killing Ivan's endless sea of tanks was understandably prioritized.

 

Wasting volume is an important consideration because volume costs mass.  Every cubic centimeter inside a tank has to be protected by some amount of armor, and armor costs weight.  So wasting any of that space is an inefficiency that adds up surprisingly quickly.

So this gun-launched guided projectile is an improvement over GLATGMs, efficiency-wise because none of the volume of the projectile is wasted by being a rocket motor.  The projectile can, in principle, extend from the maximum overall length of the projectile to nearly the rear inside wall of the case head like M829A3 with all the necessary propellant packed around it.  The only problem is that all the electronics and fin actuators and whatnot in the guided projectile need to be hardened to withstand acceleration inside the gun tube, which is quite a bit higher than the gentler acceleration of a rocket motor.

 

But that still leaves the question of why you would want this in the ammo rack instead of another round of HEAT-MP or APFSDS.  In my opinion, indirect fires are best left to dedicated artillery.  And if the MBTs are out on the prowl without artillery or air support, someone has some explaining to do.

 

The place where I see this sort of round being very useful is on one of those light-medium "expeditionary tanks" that are periodically popular, or even on something like a Centauro.  Those sorts of vehicles are supposed to be light enough that they can be easily deployed internationally to sudden crises in lighter transport aircraft than proper MBTs require.  In that sort of situation, it seems a lot more likely that the expeditionary force won't have proper artillery support, since SPGs have become just as big and almost as heavy as MBTs and will likely be left at home.

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55 minutes ago, Collimatrix said:

snip

 So if I rephrase it:

 

-Better volume efficiency than GLATGM

-Not really useful for an MBT if the combined arms doctrine is carried out properly, plus it decrease the amount of general purpose rounds carried

-Could be useful for AFV acting as a rapid response force or long range recon

 

That raise the question of what will the future expeditionary vehicle look like.

 

Personally I don't think that MBT caliber guns are the way to go (105 - 120 mm) and think that a tandem of 40-30 mm AC plus ATGM is more flexible.

And in the later configuration, ATGM are often strapped externally so you can have a bigger warhead. Granted the volume efficiency problem remain, but it is less prominent since AC round takes less space.

Still it could be a useful concept for existing gun fire support vehicles (MGS, Centauro and all the others)

 

Also truck based SPG can be quite easily used for expeditionary purpose and they pack just as much firepower as tracked SPG.

The French deployment in Mali (Operation Serval) is a testament to that since we were able to quickly airlift 4 Caesar which then chased the enemy in a battlefield roughly the size of metropolitan France.

For more details there is a report from RAND:

 

https://www.rand.org/content/dam/rand/pubs/research_reports/RR700/RR770/RAND_RR770.pdf

 

In my eyes the added bonus having those rounds in MBT is that they are generally closer to the lines which mean a shorter reaction time, if a friendly need support:

 

Direct fire support > Mortar > Artillery > Air support (reaction time wise)

 

So with a multi-purpose warhead those rounds could allow MBT to take the same role than self-propelled mortars with the added bonus of being more resilient to enemy fire (since SPM are often APC based) which would free the later for another front or simply increase the volume of fire.

However saturation and area attack cannot be used with those kind of round (since an MBT can only embark a limited number of said rounds), so they are limited to punctual and high value targets.

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13 minutes ago, Alzoc said:

 So if I rephrase it:

 

-Better volume efficiency than GLATGM

-Not really useful for an MBT if the combined arms doctrine is carried out properly, plus it decrease the amount of general purpose rounds carried

-Could be useful for AFV acting as a rapid response force or long range recon

 

That raise the question of what will the future expeditionary vehicle will look like.

 

Personally I don't think that MBT caliber guns are the way to go (105 - 120 mm) and think that a tandem 40-30 mm AC plus ATGM is more flexible.

And in the later configuration, ATGM are often strapped externally so you can have a bigger warhead. Granted the volume efficiency problem remain, but it is less prominent since AC round takes less space.

So it could be a useful concept for existing gun fire support vehicles (MGS, Centauro and all the others)

 

In my eyes the added bonus having those rounds in MBT is that they are generally closer to the lines which mean a shorter reaction time, if a friendly need support:

 

Direct fire support > Mortar > Artillery > Air support (reaction time wise)

 

So with a multi-purpose warhead those rounds could allow MBT to take the same role than self-propelled mortars with the added bonus of being more resilient to enemy fire (since SPM are often APC based) which would free the later for another front or simply increase the volume of fire.

However saturation and area attack cannot be used with those kind of round (since an MBT can only embark a limited number of said rounds), so they are limited to punctual and high value targets.

 

 

That is an accurate paraphrase, yes.

There is some merit to the AC+ATGM configuration for a light tank.  I am not quite sure what you mean by a "tandem AC," though.  AC+ATGM certainly allows a lot more flexibility in vehicle design, and in particular it allows the turret to be a lot smaller since it doesn't need to handle the enormous gun breech.  IMO, ATGMs from such a vehicle should be fired vertically and then thrust vector towards the target.  Swingfire ATGM had this capability (or close to it) decades ago, and electronics have only gotten better and cheaper since then.  Also, I think there's a case to be made for having this sort of vertically-launched ATGM be a general-issue weapon, not just a specialized item for light tanks.  That would mean that an ATGM crew could get away with exposing only the spotter and guidance module (if SACLOS or beam-riding) while the ATGM tube is hidden behind cover.

 

MBT caliber guns are attractive for anything that's expected to fight MBTs.  It's a lot harder to counter APFSDS than it is to counter ATGMs.  Also, gun ammunition is usually smaller for the same ballistic capability than missiles until very extreme velocities.  Using a gun barrel simply as a tube to fling a rocket out of seems silly, however, unless it's a rocket-assisted, gun-fired projectile, which has some interesting potential efficiency advantages for kinetic energy penetrators.  Gun ammunition will tend to be lighter or smaller for a given number of shots than rockets as a general rule though, and I think that can't be overlooked for expeditionary units, which may be in a precarious logistical situation.  Gun ammunition will tend to be cheaper as well, but I don't think that's an enormous consideration for many expeditionary force scenarios.  Presumably expeditionary forces are being rushed to the scene of an international political disaster in small numbers because getting a force to the scene quickly is the overriding consideration.  If their ammo is expensive, it's not a big deal.

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2 hours ago, Collimatrix said:

I am not quite sure what you mean by a "tandem AC," though.

I just meant a tandem of an AC in combination with an ATGM, not a twin AC or something like that.

May have phrased that one poorly.

2 hours ago, Collimatrix said:

MBT caliber guns are attractive for anything that's expected to fight MBTs.  It's a lot harder to counter APFSDS than it is to counter ATGMs.  Also, gun ammunition is usually smaller for the same ballistic capability than missiles until very extreme velocities.  Using a gun barrel simply as a tube to fling a rocket out of seems silly, however, unless it's a rocket-assisted, gun-fired projectile, which has some interesting potential efficiency advantages for kinetic energy penetrators.  Gun ammunition will tend to be lighter or smaller for a given number of shots than rockets as a general rule though, and I think that can't be overlooked for expeditionary units, which may be in a precarious logistical situation.  Gun ammunition will tend to be cheaper as well, but I don't think that's an enormous consideration for many expeditionary force scenarios.  Presumably expeditionary forces are being rushed to the scene of an international political disaster in small numbers because getting a force to the scene quickly is the overriding consideration.  If their ammo is expensive, it's not a big deal.

In general if you want to use a full pressure gun, you better use a tracked vehicle since it will save weight on the suspension, and the vehicle will also be smaller.

But at the same time a tracked vehicle will often exceed 20 metric ton anyway.

Tracks are more efficient weight-wise but they  automatically put the vehicle above a  minimal weight.

 

The M8 is an exception since it was designed to be just light enough to be squeezed inside a C-130, and I guess that some serious compromises were made for that.

 

Light tanks can potentially be airlifted by tactical aircrafts but have, generally, a greater logistical trail than wheeled vehicles (higher fuel consumption and no parts commonality with APC and IFVs deployed alongside them) which is also a problem for an expeditionary force. Also their effective range will be smaller.

 

A Centauro II will barely fit in an A400M and for the US army to airlift such a vehicle would require the use of a C-17 (which is not as flexible as a C-130 in term of possible landing zone).

The MGS will fit in a C-130 thanks to it's unmanned turret but it's nowhere near the capability of a Centauro II (and most likely of a B1 Centauro as well, especially in the AT department) but it's quite an old design anyway.

If it were to be remade nowadays, I think it would end up heavier and larger.


In the end I think that there is two school:

 

-The European one which use heavy (25-30 metric ton) IFV-based vehicles in combination with the A400M (which is a sort of heavy tactical aircraft). The vehicles may use either a gun (which is not the best idea for wheeled vehicles) or an AC+ATGM combo

-The US that use lighter and less protected wheeled vehicles (Stryker family) and if a bigger vehicle is needed will just use a C-17 and land it on a better airstrip.

 

In the end it mostly comes down to the US having access to a heavy lift strategical aircraft and having vastly superior logistics than European country, while the European will have access to a better tactical aircraft.

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5 hours ago, Alzoc said:

I just meant a tandem of an AC in combination with an ATGM, not a twin AC or something like that.

May have phrased that one poorly.

In general if you want to use a full pressure gun, you better use a tracked vehicle since it will save weight on the suspension, and the vehicle will also be smaller.

But at the same time a tracked vehicle will often exceed 20 metric ton anyway.

Tracks are more efficient weight-wise but they  automatically put the vehicle above a  minimal weight.

 

The M8 is an exception since it was designed to be just light enough to be squeezed inside a C-130, and I guess that some serious compromises were made for that.

 

Light tanks can potentially be airlifted by tactical aircrafts but have, generally, a greater logistical trail than wheeled vehicles (higher fuel consumption and no parts commonality with APC and IFVs deployed alongside them) which is also a problem for an expeditionary force. Also their effective range will be smaller.

 

A Centauro II will barely fit in an A400M and for the US army to airlift such a vehicle would require the use of a C-17 (which is not as flexible as a C-130 in term of possible landing zone).

The MGS will fit in a C-130 thanks to it's unmanned turret but it's nowhere near the capability of a Centauro II (and most likely of a B1 Centauro as well, especially in the AT department) but it's quite an old design anyway.

If it were to be remade nowadays, I think it would end up heavier and larger.


In the end I think that there is two school:

 

-The European one which use heavy (25-30 metric ton) IFV-based vehicles in combination with the A400M (which is a sort of heavy tactical aircraft). The vehicles may use either a gun (which is not the best idea for wheeled vehicles) or an AC+ATGM combo

-The US that use lighter and less protected wheeled vehicles (Stryker family) and if a bigger vehicle is needed will just use a C-17 and land it on a better airstrip.

 

In the end it mostly comes down to the US having access to a heavy lift strategical aircraft and having vastly superior logistics than European country, while the European will have access to a better tactical aircraft.

This is what Colli means by "rocket-assisted, gun fired projectile" by the way: 

:P 

 

 

 

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I have been searching for informations regarding current Chinese APFSDS ammo for a discussion in another forum... seems interesting.

 

21l3nrq.jpg

 

The older APFSDS design had a windshield and a copy of the M829A2's "stepped tip" to maximize penetrator length. According to the original poster, the left APFSDS shown in this image has a WHA penetrator, the other one has a DU one and is therefore shorter (due to keeping a desired velocity I assume).

 

NORINCO%2527s+APFSDS+Rounds.jpg



195155jjz86x9gb4migqmw.jpg.thumb.jpg

07503063885F7E1690E894DC5EB961E4DE49705F

 

The Type II M APFSDS has a penetration of 220 mm at 66.4° at 2,000 metres or roughly 550 mm along the line-of-sight. It has a muzzle velocity of 1,700 m/s and is overall a bit lighter than the DTW-125. The PTZ98 II round for the 120 mm smoothbore gun has similar armor penetration, but a lower muzzle velocity of only 1,660 m/s... so it either has better flight characteristics or a longer penetrator (overall length of projectile is 655 mm, so penetrator length most likely is less than 600 mm). The 105 mm DTW2 APFSDS penetrates 150 mm at 71° at 2,000 m, which is roughly 460 mm along the line of sight.

125 mm BTJ1 HEAT penetrates 180 mm steel at 68° or roughly 480 mm unsloped steel, so performance seems somewhat poor.

 

 

old_125mm_ammo.jpg

125 mm Type IIM or 125 mm DTW-125 APFSDS in front, at the left side is an old 105 mm APFSDS not being sold anymore

 

8r8ID6u.jpg

Old 105 mm APFSDS has a penetration of 460 mm (220 mm at 61.4°) and a muzzle velocity of 1,530 m/s.

 

JI6J4MR.jpgfmglH2L.jpg

The 105 mm BTA2 APFSDS seems to be nearly identical to the DTW2, but has a much higher penetration 220 mm at 66.42° at 2,000 m. That's about 550 mm along the line of sight! Muzzle velocity is slightly better than on the DTW2 and old APFSDS (1,540 m/s instead of 1,530 m/s). The projectile is much longer (703 mm vs 636 mm), but the weight has slightly decreased from 6 kg to 5.9 kg for the projectile. Do the Chinese utilize composite sabots?

 

cP0SxN7.jpg

125 mm DTW-125 APFSDS on the top, unknown two other rounds.  Note that the 120 mm APFSDS seems to be a lot more beefy (longer road) than the previous PTZ89 II. The 105 mm APFSDS also has a "DTW" name, so it is probably the DTW2 above.

 

 

1jkolj.jpg

727nb0I.jpg

These two photos confirm that the upper APFSDS is indeed the DTW-125

 

 

KN6dAII.jpg

JUvhsf0.jpg
 

The APFSDS round is called DTW-125 and supposedly capable of penetrating 220 mm steel at 68.5° slope and 2,000 m distance, which is roughly equal to 600 mm along the line of sight. The muzzle velocity is 1,740 m/s and the overall weight of the complete round (both parts) is 21.36 kilograms. Dispersion at 1,000 m is 0.25 x 0.25 m on average. Some claim that the DTW-125 and DTW10-125 APFSDS rounds can only be fired from the Type 99(A) tanks.

 

DHUeO0xUAAArMgE.jpg

 

D7YS4BN.jpg

For the VT-4 the Chinese manufacturer NORINCO is offering the BTA4 APFSDS. I wonder if this is equivalent to the Type II M or the DTW-125...

The size comparison between BTA4 and BTJ1 HEAT suggests that the BTA4 APFSDS is identical in length to the Type II M. I personally would asusme that Type II M and DTW-125 were identical (seem to be similar sized), if it wasn't for the differences in armor penetration and velocity. So that points to a stronger powder charge or a composite sabot.

 

Vvll4uu.jpg

 

J4iPwyF.jpg

FlLtHrF.jpg

tCxWZsb.jpg

The latest round is the DTW10-125, which has a slightly longer penetrator than the previous DTW-125. Supposedly it has no ballistic cap, but the penetrator extends into the tip. I remember reading similar patents from the 1980s or 1990s suggesting this layout, doesn't seem to be cutting edge. No performance data, but claimed to be 650-700 mm.

 

 

 

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The website of the Iranian military industrial complex has an interesting selection of some odd ammo...

 

xW1AMHO.jpg

105 mm APFSDS with 460 mm penetration against  a steel target. No range data, no velocity. But look at the shape of the sabot... that's just odd.

 

hO5toIW.jpg

106 mm recoilless rifle ammo

 

QUMUwkz.jpg

My personal favorite: a 122 mm HEAT shell for howitzers. Seems to be a copy of the 125 mm HEAT shell adopted for the smaller calibre. 220 mm at 60° penetration.

 

whXsahJ.jpgTWOIxIh.jpg

Old Soviet 125 mm ammo. Note that the penetration for the 105 mm APFSDS would exceed that of the BM-42 Mango based on their way of writing just a number without range data...

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Chinese APFSDS diagram: I can read Chinese, and that sounds about right.

 

The top line translates to "This shell's (read DU penetrator) layout is basically identical to the tungsten alloy shell (illustration 64), except for *text is cut off*.

 

The right one is indeed the DU penetrator. The tungsten penetrator's description is obscured by the watermark.

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      [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 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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