DD000

My initial thought was that the tip was designed specifically to defeat K5, but according to the Swedish document, Kontakt-5 features an angled 17mm front cover plate. The tip looks to be about 20-25mm in length, but since the entire tip is a cone, the actual working length might be about half that. So the entire tip might be defeated by the cover plate alone. Furthermore, if a tiny thing like that stuck to the front of a long rod could defeat K5, then there would be no need for the much larger steel tip of the M829A3.

Its purpose is rather perplexing to me.

7 hours ago, SH_MM said:

My understanding is that the Swedish 120 mm APFSDS used to test the armor apparently already included a special tip to improve performance against heavy ERA. At least the APFSDS projectile has a small notch in the tip and the Swedes found that Kontakt-5 doesn't work that well against modern APFSDS anymore.

 

I've seen the notched tip design before, such as on the charm 3, but the notched tip on the swedish 120mm apfsds seems exceptionally tiny. It seems to me like the tip would be designed to penetrate the ERA/NERA panel without setting it off, although I'm not sure how it does that exactly. If it does set it off though, then it probably doesn't do much of anything. It's easy to see how it could be completely worn away by penetrating the outer plate and front NERA plate, especially if it was a thicker NERA plate of high hardness steel. So while it does technically have a special tip, it's so tiny that I don't think it would perform much differently than a "standard" rod without any special tip in this instance, at least for the test shots on the front wedge and high obliquity shots where it would have needed to penetrated a lot of steel before getting to the NERA filler material.

On 7/17/2018 at 1:54 PM, SH_MM said:

According to British documents on the development of Chobham armor, tandem charges provide superior penetration against it (and other types of special armor). That means the protection levels in Sweden are exaggerated against modern ATGMs.

Which british documents would those be?

Edit:  Also, if the Swedish CE protection estimates are exaggerated against tandem warheads, then could it also be said that their KE protection estimates are exaggerated against long rods with precursor tips like the M829A3 or those with special segmentation?

Well, regardless of what the triple-charge design was supposed to do, apparently it didn't work that well, as the Russians haven't pursued such a design since, to my knowledge. Nor has any other nation even attempted to adopt such a design.

Seems like the tandem charge is here to stay for the forseeable future.

2 hours ago, Bronezhilet said:

It's not better at poking a hole in solid steel, but it should be way better at poking a hole in a NERA package.

Wouldn't that depend on how much spacing there is between the main jet and tertiary jet? If the head of the main jet were touching or nearly touching the tail of the tertiary jet, then I imagine that the bulging of the NERA when initiated by the tertiary jet could still catch the main jet. My impression is that this isn't a true triple charge design in terms of delay between the 3 charges, but that the the main and tertiary charges are used to create a single long jet by precise timing.

Also, something to keep in mind that having a hole in the middle of the main charge does decrease its efficiency. So perhaps a reason that this design hasn't caught on is that it's not the most mass efficient choice when designing a warhead.

21 hours ago, Xlucine said:

Do you really need HE fill at railgun velocities? >2.9 km/s you're matching TNT for energy density in pure KE, and for a typical ~23% TNT mass in a whole artillery shell you only need to impact at 1.4 km/s to match the energy delivered

Yes. Just because it has the same energy doesn't mean it's going to do the same thing.

The point of an HE fill is to create a cloud of fragments to cover a wide area. A metal slug impacting at 3 km/s is just going to create a big hole at the point of impact.

I was going to comment on this yesterday, but I wanted to confirm something first.

You can't really find the total RHAe penetration of two charges by just simply adding the precursor penetration to the main charge penetration. The crater produced by the precursor is small in diameter, so when the jet from the main charge arrives some of its energy is expended widening the crater due to the interactions between the jet particles and the walls of precursor crater.

But even if the target material were sufficient low strength/low density that the precursor could create a crater wide enough that the entire main jet could reach the bottom without interacting the walls, there would still be issues. You'd run into a situation where the inner crater produced by the main jet is wider than the crater produced by the precursor closer to the surface. This crater profile redirects the penetration ejecta towards the path of the proceeding jet, disrupting it. Also, when material is inhibited from leaving the crater, penetration is degraded.

When trying to optimize penetration with multiple charges/penetrators of different sizes, it's much more efficient to go from big to small than small to big. But this is a silly ordering when trying to defeat stuff like ERA.

In the paper "Behavior of Segmented Rods During Penetration" by G. E. Hauver, there were experiments with segmented tungsten rods. They found that the tungsten segments were leaving too much residue at the bottom of the craters, that the subsequent segments had to penetrate, so they tried using gold segments. Gold being much weaker than the tungsten segments they used, and would thus erode more completely and leave less residue. But what they found was that the subsequent gold segments were getting destroyed by the redirected ejecta from the previous segments (due to the "scalloped" profile of the penetration craters).

23 minutes ago, Bronezhilet said:

Eh, a 40mm precursor still has a fair amount of penetration. I'm not at my PC so I can't check my papers, but I think it's around 100-150mm depending on type.

 

It could do that yes, but I think a jet from a 40mm shaped charge will be beat up pretty easily by a NERA layer (with the exception of the jet precursor).

 

I don't think I've seen a K-charge precursor actually. (Or I haven't looked hard enough)

I tried looking through my papers for where I first saw it referenced, but all I could find were references to how a K-charge was used as the main charge in the Hellfire. It's possible that I was misremembering things, but considering that the reduced slug for precursors was one of the original selling points for the K-charge, it would be strange if it wasn't used for that purpose.

A jet from a 40mm shaped charge would get pretty messed up from any typical NERA layer, but the overall influence of it would depend on how many NERA layers there are. If there were multiple NERA layers, then the precursor wouldn't do much. If there was only a single thick NERA layer, then the influence of the precursor would be much greater.

Quick question. Usually there are export models of MBTs with the armor downgraded when sold to other nations, to keep the design of their best armors secret. Was this not the case when the Leclercs were sold to the UAE? Did the Leclercs have indigenous armor?

51 minutes ago, Bronezhilet said:

Unless your precursor is shit, you can (almost) simply do precursor penetration + main charge penetration = total penetration. Actual penetration will be a bit less because the main charge also has to penetrate the slug left by the precursor jet.

If that were the case, then I don't expect the precursor to do much at all, since most precursors are tiny in comparison to the main charge. However, I was thinking that since apparently NERA is a major component in a lot composite armors, then the precursor could pacify an entire NERA plate or two for the main charge, which I imagine would be fairly significant. It all depends on the exact layout and design of the armor. Although given how long tandem warheads have been around, I would be surprised if modern armors didn't take them into account.

Also, there are modern shaped charge designs such as the K-charge that are designed to produce minimal slug, and are used as the precursor in a lot of modern western ATGMs for that reason.

Very late to the party, but in the swedish document where it describes the protection estimates for the Leopard 2 improved, it assumes a single charge for the CE protection value, right? I'm curious as to how tandem charges would affect those estimates, as pretty much all serious atgm threats these days are tandem charges.

I had originally sent this as a PM, but I'm going to post this here as well for general critique and stuff.

Quote

Anyways, the entire point of my inquiry was to get a better sense of the parameters of a molybdenum jet, so that I could hopefully get a better sense of its performance against ERA and NERA compared to traditional copper jets.

Reading a bunch of papers by Manfred Held, it seems that in his experiments the forward portion of the jet is pretty undisturbed after penetrating ERA/NERA. It seems like the forward portion of the jet, due its higher velocity, is able to exceed the reaction speed of the reactive module and clear it before it's disturbed by the moving plates. Maybe I'm interpreting it wrong, but that would imply that there's a velocity threshold, where if the portion of the jet is above a certain velocity (and it's not too far behind the ERA triggering portion of the jet), it'll be little affected by the disturbance effects of the ERA, and has to simply be eroded. Since the high efficiency of ERA is due to its lateral disturbance effects, a jet that can get a higher portion of the jet clear it before it can react would reduce the efficiency of the module.

This is where the knowing the parameters of a molybdenum jet is so important. Particular its velocity distribution. If the increase in velocity of the tip is reflected linearly down the length of the jet, i.e. the entire jet is faster than a copper jet by x amount, then it would be expected that a greater portion of the jet would be able to clear the ERA module. However, if the velocity increase is localized to the tip, then it might even do worse against ERA, as the tip would experience pronounced stretching compared to the other parts of the jet, and would trigger the ERA at an earlier interval respective to the positions of the other parts of the jet, thus enabling it to "catch" a greater portion of the jet.

Of course, everything I just wrote could be nonsense, because in that paper where they demonstrated the effectiveness of a double NERA system, the fastest jet particle to emerge from the armour system was ~6 km/s. The portion of the jet from 6 km/s to 8.25 km/s correlates to a length of about 400mm, which has an ideal hydrodynamic penetration of about 425mm in steel. The LOS thickness of module itself was 99.5mm in steel, and 33mm in unknown material (but I expect it to not be very dense), which is quite far from 425mm of steel. Thus the forward portion of the jet could not have been eroded to that extent just from penetrating the module, which means that the module was somehow able to disturb even the fast forward portions of the jet.

This also makes me wonder if the advantage of the faster jet tip of molybdenum jets could be mediated somewhat by the fact that it would induce NERA modules to have higher plate velocities, if I understand the operating principle of NERA correctly.

 

 

9 hours ago, Militarysta said:

 

This is interesting. Also very useful. What's the source for this exactly?

One thing that jumps out to me is that the values for the mass efficiency against APFSDS is similar to the values you'd expect against small arms bullets, which lends credence to the theory that the nano-ceramics used in the AMAP modules would be about as efficient against long rods as they would against AP bullets. 

What does it say for the 6th material down? The one with a density of 1.0 - 1.1 g/cc. (Also, it triggers me that the rows for the material and values in the second table aren't aligned...)

On 16/02/2017 at 1:23 AM, Toxn said:

Looking at the availble DTIC documents, research and patents; it seems that glass/ceramic armours really were the secret sauce for a long while. You can actually test this by looking at penetration in glass, normalising ME and TE to RHA and then multiplying the two. Even though glass has only 60% of the TE of RHA, it has a whopping 6 times ME. Which means that, overall, it is 3.6 times as efficient as RHA.

This is amazing, given that magic titanium alloy has only 1.8 times the efficiency. Even better; glass is cheap and easilty castable. I can't test harder ceramics directly, but my guess is that they'd be better still. And that's just against long rods - ceramics are even more effective against shaped charges.

Just to clarify something, is the 0.6 TE and 6 ME for glass in comparison to RHA for long rods or shaped charges? Those numbers seem feasible for a shaped charge in a laboratory setting with large spacing behind the module, as SM_HH attested to in his post, but the flow of your post seems to imply that those numbers were for long rods.

Considering AMAP-B, one of the most advanced ceramic armour modules available, is designed specifically for defeating KE threats and advertises a ME of 'only' ~4.2, I have a hard time believing that whatever type of glass they used in those tests decades ago would be close to 50% more effective.

12 hours ago, Militarysta said:

Am I reading this right? This graph seems to state that there's a 120mm KE round introduced in 2003 that penetrates 950mm armour. I assume it's referring to the M829A3, but 950mm is way higher than even the most optimistic penetration estimates for it I've seen. 

There also seems to be a pretty large increase in protection from US 1992 levels to 2002 levels (from 650mm to 850mm). I also assume that this is the upgrade from the M1A2 to the M1A2 SEP, but it's surprising as well. I thought the SEP upgrades were mainly to its electronics, with some upgrades to its armour, but nothing so dramatic. Do you suppose that the CE protection to KE protection ratio has remained constant all this time? If the original M1 had 400mm KE protection and 750mm CE protection, then...

M1A2: 650mm KE, 1219mm CE

M1A2 SEP: 850mm KE, 1594mm CE

Does anyone have a sense of the typical weights of an apfsds round's sabot, fins, nose cap, and tracer compound? I'm trying to get a sense of what percentage of a apfsds round's in-bore and in-flight mass is parasitic weight.

Also, the energy figures are usually differentiated muzzle energy and penetrator energy. Muzzle energy is obviously for the entire projectile assembly, but does penetrator energy typically refer to just dense metal long rod or the entire in-flight projectile (including fins, tracer compound, etc.)?

In general the amount of armor types and materials that can offer more protection against KE ammunition per thickness than steel is extremely low and most of these materials seem to unpractical. DU and tungsten provide better protection per thickness, but their weight efficiency is lower than that of steel. High-hardness steel is more effective per thickness than conventional armor steel (against KE and shaped charges), but it is still heavy (offering only slight weight reductions) and cannot be manufactured that easily (one cannot make thicker high-hardness steel plates; also some alloys cannot be welded). There are some combinations of different steel alloys in a spaced or laminate configuration, which supposedly provide more than 1.5 times - in some cases 1.81 times - the protection of normal RHA. However there is again the issue of weight (and in case of spaced configurations the reduced thickness efficiency).

I posted a photo from an exhibition in the Leopard 2 topic, which showing the amount of different materials (steel, ceramics and nano-ceramics) required to reach STANAG 4569 level 3 protection. Based on this nano-ceramic could provide about 2 times the protection per thickness and 5 times the protection per weight as RHA required for STANAG 4569 level 3. However this might not scale perfectly, as the interaction between ceramcis and small bullets is a lot different than the interaction of ceramcis and longrod APFSDS penetrators.

I suspect that these nanoceramics aren't as efficient against long rods as they are against low caliber AP projectiles. A large portion of the increase in mass efficiency for ceramics vs RHA when penetrated by hard core projectiles at low(er) velocities is that the ceramics are able to shatter the steel/WC core, while they are able to penetrate RHA as a rigid-body. Long rods aren't rigid even when penetrating RHA.

Still, I wonder how these nanoceramics would perform against shaped charge jets.

snip

Thank you very much for the detailed response. It was very informative.

Meanwhile in order to be efficient (in terms of protection per weight) against APFSDS ammunition, steel plates require a certain thickness, in ideal case more than the diameter of the penetrator. This also affects the efficiency of NERA and ERA against APFSDS ammunition: The Soviet Kontakt-5 ERA, as installed on the T-80U turret, is claimed to enhance the protection of the T-80U by 20% to 30% against (older) APFSDS ammunition. Given Russian/Ukranian claims on the protection level of the T-80U, this means that the ERA provides 130 to 180 mm against (older) APFSDS. Given that the Kontakt-5 ERA at the turret consists of 53 mm to 60 mm of steel and 22 to 24 mm explosives (depending on location due to the different slope of upper and lower ERA tiles), this means it can only provide between 2 and 3 times as much protection as steel of the same weight against APFSDS ammo. Not very efficient compared to the ~20 times the protection of steel per weight of early ERA!

That also means that heavy ERA is much less mass efficient against shaped charges than light ERA, doesn't it? I had assumed in the past that the move from light ERA to heavy ERA was met with a proportional increase in efficiency against shaped charges. But if that were the case, then a single Kontakt-5 panel should be able to completely defeat even the larger >150mm ATGMs, and I don't think this is the case.

Also, given that these 'special armours' utilize a large amount of low density materials and air gaps, while not realizing the same dramatic efficiency against KE threats as they do against shaped charges, would it be safe to assume that while they may have equal or greater mass efficiency against long rods as compared to RHA, they are not as volume efficient?

Modern APFSDS ammunition has a more complex construction, using special tips, pre-penetrator, multi-segmented rods, metal jackets or in some cases a composite penetrator, consiting of different (heavy) metal alloys. This allows modern ammunition to be optimized against composite armor, spaced armor and ERA. In extreme cases, this can result in a much higher penetration against special armor than against steel. The Danish Army tested the German DM53 APFSDS against the KEW-A2 (M829A2 with tungsten penetrator), both fired from the L/44 gun of the Leopard 2A5. Despite being shorter and slightly slower - which according to estimations based on the Lanz-Odermatt equation would result in a lower penetration - the DM53 proved to be superior against complex target arrays... supposedly the result of a three-segmented rod construction. According to the German author Rolf Hilmes, who worked as a tank technology expert for the German military procurement agency and who lectured at the German military academy, depending on velocity and range, the DM53 can defeat armor targets that are equivalent to 1,000 mm RHA against conventional penetrators. However he doesn't claim that it can defeat 1,000 mm RHA; in contrast, values from the manufacturer seem suggest a much lower penetration against RHA.

To be fair, if the DM53 is truly multi-segmented, then that is outside the purview of the Lanz-Odermatt equation, as that is an empirically derived formula to predict the perforation of monoblock penetrators. Because the DM53 is multi-segmented, it may very well penetrate more RHA as well as complex armour compared to the KEW-A2, despite being shorter and slower, due to the increased efficiency of rods of lower aspect ratios. But yes, I understand your point that the penetration of a rod against RHA and complex targets may not necessarily correlate.

Wait, why is the DM53 both slower and shorter than the KEW-A2? From the images I've seen of the DM53, it doesn't appear to have a very high diameter as far as long rods go. It should stand to reason to reason that it should be either faster or heavier (longer) than the KEW-A2. Does it have a heavier sabot or something?

First off, hello everyone. First time posting here.

At one point in time, shaped charges were said to make armour irrelevant, as they could penetrate large amounts of steel armour -- more armour than could be practically applied to tanks. But then came complex composite armours, which greatly diminished the penetrative power of shaped charges and spurred the development of APFSDS rounds utilizing long rods of dense metals at high velocities to perforate the armour.

Since then, it has been conventional wisdom that APFSDS munitions were the most efficient anti-weapons, at least for penetrating the thick frontal armour of MBTs. The HEAT rounds of MBTs nowadays being designed more for multi-purpose use than to maximize penetration.

However, since their introduction onto the battlefield, shaped charge rounds have enjoyed a steadily increasing efficiency, defined as the amount of calibers of RHA it can penetrate per charge diameter. Early shaped charges could only penetrate 1 or 2 times its charge diameter, but that number has continually increased over time. Top end ATGMs in service can currently penetrate 7 or 8 times its diameter, while experimental shaped charges have been developed that can penetrate 10 times its diameter (http://www.vif2ne.org/forum/0/arhprint/1028580).

Current APFSDS rounds, on the other hand, cannot achieve the same degree of penetration (into RHA). APFSDS rounds such as the DM63 or M829A3 are often estimated as having around 6 calibers of penetration. However, these estimations are usually achieved using the Odermatt equation, which is a perforation equation, and often against an oblique plate. Shaped charges on the other hand, are often tested for their penetration into a vertical plate of semi-infinite RHA. So not only is high end shaped charge penetration higher than for a given caliber than long rods, but the estimates for long rods are perforation estimates, which serves to inflate their numbers a bit compared to a 'fair' comparison. So it could be said that current APFSDS rounds only penetrate 5 calibers into semi-infinite RHA.

It is commonly known that modern composite armours are much more efficient against shaped charges than they are against long rods... but aren't shaped charges capable of penetrating much more armour in the first place? Shaped charges are expected to be able to penetrate atleast 10 times their own caliber. For long rods to be more efficient, the shaped charge RHA equivalent protection must be over twice that of the KE protection. Is that expected to be the case?

The purpose of my creation of this thread was to hopefully get some thoughts as to whether shaped charges may become comparable to long rods in efficiency in terms of frontal penetration of MBTs (where they have the most advanced armour) in the future. Of course, given the classified nature of much of this information I'm not expecting definitive answer. But the users here seem rather knowledgeable, so I'd like to hear their thoughts none-the-less.