HerrTom

I think the important thing to now its that the ratings tend to be along the lines of, STANAG 4569 Level IV, protection from 14.5mm at 500m or 155 artillery shell at 30 meters. 500 meters is a fair distance, but also puts some thought into the power of these fragments. Unfortunately, I still haven't been able to find out what STANAG defines as "protection," particularly against what is as variable as an artillery shell.

So we can solve the THOR equations to figure out what kind of velocity a fragment needs to penetrate a certain thickness of armor: As you can see, the heavier fragments (as expected) perform better at penetrating armor - requiring less velocity to do so. As the armor gets thicker, the fragments begin to require prohibitively fast speeds to penetrate. Typically on an artillery shell it seems the initial velocity is in the realm of 1.5 km/s. Using the data generated for the angular dispersion plus some more to accommodate the shape of the shell, we can arrive at the fragmentation pattern for a shell travelling in the negative x direction. The dip in the negative x direction comes from the nose of the shell obstructing some fragmentation, and the larger dip in the positive x direction is the same for the base - a more significant effect for the more significant blockage provided by the base of the shell. This can all be combined together by some clever interpolation (good god it took a while to figure out how to massage the data to make that possible!). If we select a fragmentation density - say 1 fragment per square meter, we can generate a contour plot showing us the thickness of armor required to generally have no perforations. Note the axes are not the same scale - this is to provide a better visualization of the regions. At this density, a single artillery shell is likely to perforate a BTR 12 times at ranges up to 7 meters. If we set the criteria to only 1.2 perforations per artillery shell (on average), we can see that our BTR isn't safe even up to 20 meters away! This can all be consolidated into a few lines showing the maximum distance that you're likely to penetrate a 1x1 meter target with 0.2, 0.4 ... 1.8 fragments per artillery shell. The flat region at the top might be because I capped the maximum fragment size I analyzed.

Thanks CptMiller. I thought of a couple more plots that might be more directly useful at showing the danger from artillery shells. I'll try to put them together tonight. I want to show the thickness of a 1 square meter plate that has a 50% chance of being perforated as you move around an artillery shell. Not sure where you got 10x faster from. A .50 calibre bullet has around 2700 FPS muzzle velocity, or 833 m/s. These fragments are travelling up to 50% faster, though I didn't show any that have similar mass to a 42 gram bullet. These are also steel compared to lead, and offer slightly better penetration power. I might put together some charts for bullets as a better grounding source, however limited that can be. Thanks for the idea!

THOR So as not to clot this up with duplicate plots, I only grabbed the interesting ones from the THOR runs: Here's the penetration velocity from a 5 g fragment according to THOR. Not much at all, eh? THOR, as previously mentioned, was the standard, as best as I can tell, for modeling armor protection. Unfortunately, as I previous mentioned, it seems to have problems with fragment-like objects. This is further reinforced by the surprising results that the Soviet Artillery Effects study showed, which as far as I can tell, old armor/artillery models used THOR. I suspect the truth lies between R&I and THOR here. THOR predicts the armor is pretty resistant to 5 gram fragments at ranges beyond 5 meters, while R&I predicts danger out to 20 to 30 meters. If we step up to 10 gram fragments, shown above, we can see the density start to fall off. It does so sharply. If you refer to the probability curve I posted earlier, you can see that the probability of has a strong negative curvature to it, so the larger we go, we'll see much fewer fragments. These 10 gram fragments are impressively dangerous, however. THOR predicts these 10 gram fragments maintaining a velocity of 146 m/s after punching through 10mm of armor, at a density of 1.03 fragments per square meter. Even under the conservative THOR model, our BTR gets perforated with 11 fragments of greater than 10 grams. That's going to cause some damage - whether it's injuring crew members or passengers, or damaging equipment. Unfortunately, this same barrage in CMBS presents absolutely zero identifiable damage to the BTR. It's worth noting that all this data is probabilistic, but CM clearly doesn't reflect this data. I'd say, from what I've shown here, at least light armored vehicles are more resistant in-game to artillery fire than they should. Combine this with the reports that we've seen from the SAE as well as front-line combat in Ukraine, and I'd say there's a fairly strong case here. I know these plots only show a single case of 12 shells, but it takes a while to write and generate them! I've recorded observations from a number of tests, both in real games and purposeful tests, in addition to the one presented here, but I don't have good enough data to present more plots on those cases. I leave tonight with this question: What else do we need to know here? What more can I do to help us understand this? Thanks everyone for helping in this thread, and I hope to see more discussion.

Recht & Ipson So, the BTR-70 has 10mm armor at its thickest. Seems artillery shell fragments can easily penetrate this! Here's the maximum velocity of a 1 gram fragment as it travels from the blasts. It can be seen that the fragments barely lose their velocity This can be used to calculate the velocity if a fragment impacts something. Say... a 10mm thick plate of armor on a BTR. So you can see the velocity of the fragment after penetrating a 10mm plate at any point in our artillery distribution. We can combine this with the density of the fragments greater than a certain mass. And, for the sake of thoroughness (if you can call it that haha), the same plots for a 5 gram fragment: At the BTR's position, we have the following data points: Density of fragments > 1 gram: 2.42 frags/m^2 Density of fragments > 5 grams: 1.49 frags/m^2 Penetration velocity of fragments > 1 gram: 98 m/s Penetration velocity of fragments > 5 grams: 270 m/s I showed earlier (the common knowledge) that heavier fragments are more deadly - and this is confirmed here (probably because I used the same model). If we take the dimensions of a BTR-70 (7.5 m X 2.8 m X 2.3 m) and call the average cross section presented to the artillery shells here as the average between the front and side cross sections, we get about 12 square meters. So this barrage hit our BTR with 29 fragments greater than 1 gram, which probably don't have enough energy to cause significant damage inside the vehicle. It also hit with 17 fragments greater than 5 grams, which certainly have enough energy to cause some significant damage to whatever they hit. According to Recht and Ipson's model. Next post, I'll run it using THOR.

I fired a 36m area fire mission from a single gun on basic training so I can get shells on target faster. That also affect the precision and the number of spotting rounds. A CEP of 20 meters seems pretty tight though, I agree. Some shells landed further than 40m away that I didn't grab for this plot.

Correct, Muzzleflash. The 12 shells introduced an average of 3.55 fragments per square meter where the BTR was sitting. The 12 shells caused absolutely no damage to either vehicle until the BTR ate a 152 aft of the turret, so I've got a fair amount of data on non-damaging strikes. Edit: Haha, haiduk, muzzle flash, it all looks the same to me before my second cup of coffee!

Maybe on the range you can hit 5/5 shots... But 100/100 is a bit steep! That part is probably fantasy, or at the very most partially truthful.

Minor correction. In my rushing to finish the post before going to bed I forgot that I had a log scale! I thought the number of fragments seemed low... It's 10^0.55 per square meter at the BTR and 10^0.75 at the BMP. 3.55 and 5.62 respectively. Leading to 64 fragments hitting the BTR and 90 hitting the BMP. Now we're coming with gas! Makes a lot more intuitive sense haha.

Grabbed some data from shells landing around the BTR on another test. 12 shells landed before the final one hit the roof of the BTR. And the fragment density calculated from each impact: The center black O is the BTR's position, and the right-hand O is the BMP-2's position. Wasn't testing it, but some shells landed remarkably close, so I logged it anyway!. the BTR sees approximately 0.55 fragments per square meter, while the BMP sees 0.75 fragments per square meter. This means the BTR was hit by approximately 10 shell fragments from the barrage, while the BMP-2 was hit by approximately 12. (It's worth noting here that the fragments that hit the BMP are probably much more lethal owing to the closer impacts it saw!) We can pull the distribution of fragments I made earlier and generate a probability of any fragment being any specific size: What I need to do next is compound the probability of the fragment size with the distance from impact of the shell and fragmentation density to generate a probability of a perforation of a certain sized target - then I can apply it here and see if what we're seeing is accurate per the maths! But it's late... so that's something to do tomorrow!

Never fear! I haven't forgotten about this. I ran a few tests with artillery, and it seems direct hits are different than I remember them in v3 a long time ago - I think you may struggle to replicate TFO's paintball Abrams result. Direct hits seem to be fairly universally fatal to tanks, with a few key exceptions. This Abrams was hit in the engine compartment, which while only a partial penetration managed to kill the entire crew. You can see on the right side of the turret it previously survived a hit - but that location is probably the thickest armor on the tank, so understandable. It received a second hit shortly afterwards which landed directly on the turret top, this one penetrated and would likely kill the crew, too. Those craters practically under the tank would likely cause more damage than they do, but I can't really quantify that yet. Same with a Bradley. A hit to the turret top killed it dead. Near hits are also capable of killing armored vehicles, too. This hit to the front of a BTR-70 killed the drive and knocked the vehicle out. The thing currently in my mind from the previous data I collected is that light armored vehicles like BTRs, BMPs, and Bradleys may be more vulnerable to nearby shell impacts than is modeled. I'm gonna try to make some plots on some of the data I've collected.

Shame, sometimes I wish they'd save their ATGMs in favor of actual tanks, and leave the BTRs or Strykers to RPGs. Thanks for the replies everyone!

In the absence of a command signal from the laser, it's possible that the missile maintains its attitude and altitude. So not guided, but autopiloted, in a sense. May make a fair amount of sense too, since you don't want your missile to veer wildly if battlefield obscurants block the laser. Modern electronics are certainly small enough to do that, especially for a short flight time of only a few seconds.

What counts as armor? Would that prevent them from launching ATGMs on cars, trucks, or maybe even BTRs?

I'd be terrified of an army driving Pintos. Think of the cajones! How confident can one be? Like Napoleon capturing that bridge over the Donau by pretending the war was over.

I don't dismiss it out of hand but there already was a big thread on it, and felt further discussion would derail this thread in a similar manner. I do, however, regret mentioning it! I fail to see how the 80s fit into the world picture now, let alone AA83. A lot went into the scare there, from poor communication between the KGB and Statsi to the "Evil Empire" speech. So they were afraid that they'd use an exercise as a cover for an attack, which was part of many Pact war plans... How is that relevant? (Though I, too, remember the Cod Wars!) Prepared for the worst always has to have a grain of salt. Should we be prepared for the Goa'uld returning to earth? You have to be prepared as economically feasible and reasonable, and maintaining a 1980s military is damn expensive. I know that money will come from NASA's budget and am vehemently opposed to that! I never suggested NATO couldn't win either. I said fighting a war with NATO that Russia can't win is a low priority. The only way this becomes feasible is if Russia doesn't see unity in NATO, hence the comments on political strength. I hope I'm not sounding condescending or arrogant or anything like that, I assure you I don't mean it that way. But is it really necessary to jump down everyone's throats like this? You might be getting hostile replies because of a perceived aggression on your part...

More on the Stryker? I'm going to ignore that since there already was a (hilarious) 9 page thread on that. Forbes does have an interesting point on the integrity of NATO, but if we look at past actions, even those that might indicate high casualties, NATO has stood by itself. More realistically one might look at a fragmentary or piecemeal reaction as the independent states deliberate what to do. "Much like the 190s miiary buildup deterred the Soviet leaders from doing anything stupid" As far as I know, after Stalin died the USSR's policy was largely preserving its own hegemony, not world domination. They may have been posed offensively, but that was because of their lessons in the GPW, such that Soviet leaders believed the only way to defend the USSR from the west was through decisive offensive action. It wasn't imperial goals, they were scared stiff! Edit: I meant to say also that this all seems rather alarmist. Russia seems to have enough problems internally and in the Donbass already. An ultimately unwinnable conflict with NATO seems it should be low on the priority list. The important thing is not maintaining military strength, but political strength. Make sure any actor knows that NATO will react, and react in force, and you've done more than a tank brigade can ever do.

0823 A Russian artillery spotter is seen rolling through Pryvitnoe. Unfortunately, no one is in position to take a swing at it. 1st platoon, 2nd company takes cover in the forest while the last remaining T-64 from 4th platoon systematically engages the Russian IFVs in the woodline north of the canal. Boom! An earsplitting shockwave makes the dismounts' ears ring. The shot travels quickly downrange. Which connects with a BRM-3. The T-64 reloads and fires a second shot. But a Bastion races back! The Bastion strikes true a split second before the round annihilates the BMP in revenge. Meanwhile, another BMP finishes off a mortally crippled artillery spotting vehicle. BMPs in Pryvitnoe continue to race north. Hopefully the HQ section blocking their advance can ambush them... 2nd platoon, 2nd company takes cover in the bushes. They can't move without getting the attention of the Russian BMP-3s... and neither can their own IFVs. 2nd platoon's BMP-2s are going to inch forwards through the bushes, hoping to get a glimpse of some Russian units from the good concealment. Another barrage of artillery continues lands on the ford, though it may be too late to interdict any remaining Russian forces. A surviving RPG team from 1st Company manages to fire off a pair of shots at the previously spotted T-72 in Pryvitnoe. The shot lands in the turret ring, and while it didn't blow the tank to smithereens, I think it's knocked out. The situation: My last tank is destroyed, which was one of the only things keeping the Russians from advancing north in the field to the east of Pryvitnoe. Things look grim, but I'm happy that I at least took out another T-72! Might be close to throwing in the towel. I have no delusions of lasting until 3rd company arrives, 17 minutes from now!

Beautiful! Thank you!

30mm fire from BMPs and 155mm artillery fire. The autocannons are really where they shine, I think.

I agree with you on the rest, but I'm a bit confused on this bit. A BMP battalion has as many ATGMs as BMPs, plus the AT platoon. If it's made of BMP-2s, the Konkurs can even be dismounted. BTR formations used to have a Metis in every platoon, but I'm not sure if that's still the case, plus the weapons platoon carrying a few heavier ATGMs. It seems like a lot of anti tank capacity to me. Though it's similar to the firepower in a Stryker unit, with slightly longer range.

You'll get it tonight. Had to make sure my vehicles looked good as you turned them to expensive scrap!

So you're kinda talking about a lighter version of the M728 CEV? https://en.m.wikipedia.org/wiki/M728_Combat_Engineer_Vehicle

I think you may have missed the satire there! It's a cautionary tale about feature creep, and by Jove it's too real! Too real... Really though, doesn't the Stryker offer essentially the same role as the BTRs do in Russian formations? The low of the high-low mix, offering good mobility and moderate fragment protection at a low, affordable price! Plus some fire support when you need it. At least the US doesn't have some seven-odd types of APCs and IFVs in service. Now THAT is a logistical nightmare.

Maybe that was a different game then haha. I support the scoot arc. You could also do it as a waypoint like hull down, where the waypoint is where it goes after firing, arc or not.