ShakyJake

Well yes, that's an assumption. The shell is hitting the forward side hull, which makes it a little easier to forget about that.

What Yankeedog says correct. When a shell is capable of significantly more penetration than what the armored plate represents, it won't lose a proportional amount of energy getting through it, but rather much less. There should also be some deformation of the nose in the shell as Yankeedog says, but I'll ignore it now out of convenience. Nathan Okun's published equations for single-plate equivalency of two spaced plates is expressed as: Total Resistance = [(Resistance Plate1)^1.4 + (Resistance Plate2)^1.4]^(1/1.4) With a little manipulation of the above equation, you can substitute a gun's penetration for the total resistance, and the plate you're examining for one, and the remaining plate will effectively become the remaining penetration potential of the shell. Rearranging the equation it could be expressed as: Remaining Penetration = [(Gun Penetration)^1.4 - (Resistance Plate)^1.4]^(1/1.4) In the OP's scenario, you have both a Stuart and Sherman being penetrated at about a 500m range. I can't see the Stuart's profile, but the Sherman is being struck at around a 30° angle, so we'll assume the same for the Stuart. The shell passes through both 29mm armor plates on the Stuart, and penetrates the 38mm side hull armor on the Sherman. At 500m, the 75mm L/70 can penetrate up to 168mm at 0°. So doing it step by step, we find that: Stuart first side armor plate: 29mm@30° ~ 35mm, shell penetrates with 154mm of penetration remaining. Stuart second side armor plate: 29mm@30° ~ 35mm, shell penetrates with 140mm of penetration remaining. Sherman first side armor plate: 38mm@30° ~ 48mm, shell penetrates with 116mm of penetration remaining. So from a pure penetration point of view, the OP's scenario is highly probable. Following the calculations through, it could even exit the second Sherman to go through a third Sherman completely before being stopped on the side armor of a fourth. It would even appear that some minor deflection of the shell may have happened in this case, as the two explosion sprites don't quite line up with the Panther's position in the back. So everything above is probably working as intended in the physics model. The only thing missing is the HE burster setting off the shell after the first penetration. The shell shouldn't have continued through so many penetrations without detonating, and if casualties are being determined with the HE burster calculated on each penetration as surmised in the half-track thread, that could be a problem.

Well, if this scenario was to happen in real-life with that requirement, I imagine the HE burster would have gone off after all... eventually. If the HE burster's fuse is anything like the standard model, it has to be armed though the centripetal force of the shell's rotation pulling a side stop out of the way of the percussion pin and the starter block, after which the only thing keeping the two apart is a spring. Since there's no magical way to say "detonate on 30mm or more of armor!" to the fuse, it would have to operate on impulse, so that once the shell lost a proper fraction of its current velocity the starter block would continue traveling forward (against the resistance of the spring) into the pin, setting it off. Even though each small penetration is less than the designed-for resistance, so many of them all in probably less than a tenth of a second would have probably been a sufficient impulse to strike the pin. Take that with a grain of salt, if you like. It's not documented fact or researched opinion, but rather a chance for me to throw a little Engineering towards something fun for a change. I'd even be willing to bet that a shell designed under that specification would probably go off by firing it through a thick enough bank of leaves. Well, a very thick bank of leaves. It is a fairly interesting piece of engineering, though, as this would allow shells to be fired into a target behind concealment or light cover without risk of the shell detonating prematurely, assuming it all worked correctly. Thanks for the share.

Sorry, but I don't know that I'm following your meaning, here. All German AP rounds 20mm and up had an explosive filler. The only shells to lack this bursting charge was the tungsten-cored PzGr.40 ammunition, for obvious reasons. If this Panther was using the standard PzGr.39 ammunition (which had a bursting charge), you'd expect it to detonate the shell immediately following the first penetration. I suppose it's possible that thin-skinned vehicles might have armor too thin to set off this bursting charge, as it's the sudden deceleration of the shell as velocity is lost through the penetration which triggers the fuse. This is complete speculation on my part, though if the engine models the physics to this level that's pretty cool indeed.

Shouldn't the HE bursting charge preclude something like this? Or is there some chance modeled in the game that the fuse will be defective, and this was an extraordinary piece of luck (well, for him at least)?

It doesn't really say "deployed" anywhere, so far as I've found. It'll just say "not deployed" in the profile picture if it's not actually deployed. If you give your MG squad a movement order and hit "/" to give them a deploy order afterwards, they'll start to do it when they stop. You can also check that they've got the order by looking in the proper order tab (can't remember which it is), and making sure that the deploy order is greyed out (currently being ordered to do it).

That's good to know, and certainly something I didn't know before. Thank you. This might be getting a bit off-point and just a correction, but the additional protection I'm speaking of on the Tiger mantlet does not come from the overlap of mantlet and front turret armor. It was a complex shape, and some sections of the mantlet itself were simply thicker than the 100mm figure (sometimes much thicker). There were also 100mm sections, as well as the areas in front of the trunions which seem to have been 90mm. The point I was trying to make is that sometimes these books tend to pull a single value for armor thickness based on an average, since some structures might be too complex to list individually. I'm not saying that's the case with the Panther (and Bastables seems to have a very good explanation here anyway), but offering this up as a suggestion.

According to some sources, sure. But then, GvA gives 100mm as the thickness of the the Tiger's mantlet, too, and there've been core measurements made since showing it to be around 120mm or more in many spots. Separate case, I know, but it's a possibility that could explain this.

Well, after creating my own little test scenario and having at it, I agree that "weapon mount" is a hit to the mantlet. Hits to the "front turret" are considerably more rare, but there is some area showing from the front under and to the sides of the mantlet that can be hit and penetrated. When I used a 20x zoom "over the shoulder" of the 76mm Sherman, it was actually pretty easy to see precisely when these spots were getting hit. I'll also say that I was running into the same problem. Despite loading a scenario with a number of target tanks and 76mm Shermans, any hits on the weapon mantlet (at 200m to recreate your own woes) failed to penetrate. Against a 100mm cast turret (equivalent to about 95mm of RHA), this works out to be equal to the calculated penetration of the M62 round at 30° and 250m. Barring any lateral angle, approximately half of the mantlet's aspect would give this 30° angle or less, so I really expected to see at least some partial penetrations there. Then again, I've seen a few sources that also say this mantlet was more than 100mm, some even going as high as 120mm. This would change the scenario a bit, as in the above case penetration was rather close to begin with. In any case, your idea of the penetration being made "easily" goes right out the window, and if the mantlet is indeed as much as 120mm thick, I guess it fits the ballistics for it to resist even a 76mm APCBC at such short range.

I believe "weapon mount" here refers to the entire weapon system, including the barrel, but not necessarily the mantlet. So in your case my guess would be that shots are hitting the barrel and bursting, knocking the gun out, but failing to continue and penetrate the turret. And based on the discussion talking about exactly your suggestion that the TacAI allow fine-aiming to target weaker areas, I think you'll find them rather unswayed on that point. They seem to have their minds quite made up about firing center mass.

Nope, that AT gun in the HBO clip is again the 3.7cm PaK 36. It has a very distinctive shape compared to the PaK 38. When this episode first aired, I had actually wondered to myself just how many of those 37mm guns were still around and being used in June of 1944.

Hmmm, it might be worthwhile to maybe generate a few charts showing the relative penetration of various guns, shown together, for that purpose. I've just done a fresh reformat and don't have Matlab installed at the moment, but I could probably do that later when I have some time. Or, having the data out of Rexford's book (and particularly the equations), it might be possible to create some kind of embedded function in javascript or something on a webpage. I don't have any experience at all with that, but if someone had some pointers for where to look I'd be appreciative.

Just how common were smoke grenades in real life, during this time? I seem to recall reading that there were very few issued, and those were generally colored smoke for marking purposes?

Didn't the M-18 have the better 5x magnification optics, as well? That could account for part of the higher kill ratio, if it was simply a more precise gun platform.

One must grokk with deliberation, but never with inordinate haste.

Hmmm, do units fire on contacts without further information? If not, I'll miss that feature I think. I always thought it was a cool little feature to the game that there were times where your tanks could come upon something (generic tank model), put a hasty round through it, and then back away to safety without ever really knowing what it was in the first place. It added a certain amount of chaos and confusion to the engagement, in my mind.

I haven't seemed to notice it in the AAR's posted so far, but does spotting ever occur at less then full detail? I always liked how tanks in CMBO and CMBB would show up as blocky general models until it could be more closely identified. So far in the AAR, it seems that whenever you actually "see" something, you know exactly what it is. Or are we seeing the descriptions only after you've had time to figure out what they were, Bil?

Redken and Rocky Balboa, thanks for posting that document. I remember those butterfly diagrams, though what I'd seen was in English and likely translated from that, or another similar to that one. Realistically, though, it's one thing for an engineer like me to sit back and do number crunching on angles and effective resistances, and quite another for a man freshly drawn into the army in the early 40's and likely with considerably less education trying to decide how best to fight his tank. That training manual at least shows that there was an effort to get this knowledge to the crewmembers, from there it's anyone's guess. In this case, the sweet spots shown on the diagram work particularly well because the Tiger had such strong side armor relative to most other tanks. It might not have been considered a particularly good idea to try it with the thin-skinned PzKpfw IV's and Panthers. Less numbers, more AAR!

Indeed. A capped round has a better chance to "grab" at the armor on an angled hit and turn pivot the shot to penetrate inward. The slope multiplier calculations reflect this with their "effective resistance", which is what the angled plate would be equivalent to if it were a single vertical plate. Slope multipliers for normal AP rounds without the armor cap are much higher than for APC/APCBC rounds.

This is probably true of most every tank out there. While the slope multiplier for a 30° hit on the front armor would likely be no more than 1.3x the base armor thickness, even at relatively low T/D ratios for very thin side armor that slope multiplier against 75mm-ish hits is going to be about 2.5-3.5 times the base armor thickness. It would be somewhat risky, though, as much more than this angle is quickly asking for disaster. Doing a little more math (I'm a math nerd, sorry I can't help it!) for the profile of a Tiger at a 30° angle, the frontal armor would actually measure about 3.2m across in the sites of a gunner looking directly at him, while the side armor would measure 3m across as well. That's an even chance of a shot from that aspect hitting either front or side, which would probably be rather unnerving, and an extremely likely chance between much of the front and all of the side that a low shot will hit the drive system.

Thanks of the AAR update, Bil! Sadly, I don't think you can find this book anymore. At one time when I'd asked, Rexford had said that if there was enough demand that another run might be made, but I don't believe that's an option anymore. Sure. Calculating the 0° penetration of the 75mm L/40 ABCPC against FH armor at 300m gives us a figure of 98mm. We'll look at the PzKpfw IVH's upper and lower hull only (the 50mm turret front will be easily penetrated here barring any extreme angle). I'll use a lateral angle of 0° (head on), 20°, and 30°, and show the compound angles for the hit and effective resistance for those 80mm plates. Lateral Angle 0° Upper hull @10° = 82mm Lower hull @15° = 84mm Lateral Angle 20° Upper hull @22° = 91mm Lower hull @25° = 96mm Lateral Angle 30° Upper hull @31° = 104mm Lower hull @33° = 108mm So at this range the average penetration of the Sherman's gun can handle about a 25° lateral angle from the PzKpfw IV before penetrating the upper hull is no longer better than average, and a 20° angle before penetration of the lower hull becomes less than ideal. At 30° lateral angle, only the exceptions at the upper range of the variable penetration should be getting through. I saw a document posted with this on another forum, so it's definitely out there. IIRC, it was a doctrine to be used solely against fixed defensive positions, though, so perhaps not to be used when it was likely flanking fire was to be received? They definitely understood slope effects enough to have made this a smart choice.

@ Bill and Battlefront.com No problem at all. Doing this kind of calculation was truly a joy for me when I bought the book years ago, since it gave me a chance to apply my engineering math background towards something I actually enjoyed doing for a change. There is one minor point I'd like to ask, though, if that's alright? I'm assuming a flaw multiplier of 0.90 being used for hits on the glacis, from your post giving the plate thicknesses and what the game treats the thicknesses as. The charts in Rexford's book gives a more unforgiving multiplier to this specific T/D ratio and for medium flaws, and he even includes a passage with this specific gun and armor matchup illuminating the severity of the flaw. To quote page 29, Same exact ammunition against the same exact glacis as we have in this thread, so a good reference. Using the calculated 0° resistance of that plate to be 123mm from his equations, his figure of 104mm effective resistance seems to indicate about a 0.85 flaw multiplier, and this is exactly what the table for medium flaws on the previous page shows for this T/D ratio and hit angle. It might be only a 5% difference, but that could mean all the world in some scenarios. It would mean more decisive penetrations in some cases, and in my earlier example with the 61° compound angle it would bring the plate's resistance down to a bare millimeter higher than the 75mm L/48's penetration at this range. The glacis would still be far tougher than the expectation which some people have of spitwads and hurled beer bottles punching through it, but might this be a bit more accurate? Thanks, and please forgive any presumption here.

I think you might be misunderstanding the way he's using the term "marginal" here, Txema. Having a marginal advantage in penetration here means that there is slightly over a 50% chance of penetration, since the penetration value for the projectile is an average of the upper and lower range it can fall between. So, under an ideal circumstance of being directly head on to the target and at that range, it will probably penetrate, just as he has said. However, once any kind of imperfect conditions start creeping into the equation, things start to become more iffy. Using the calculations out of my copy of "WWII Ballistics: Armor and Gunnerery", the 0° resistance of the Sherman's 51mm glacis @56° comes out to 123mm, or 110mm with a 0.90 flaw multiplier (is this what's being used?). So the 75mm L/48 APCBC with 127mm penetration at 300m and 0° will most likely penetrate in this shot. However, if the tank were to have a 20° lateral angle to the firing tank, the compound angle would become 58°. Only two degrees can't make much of a difference, right? Not so. With the flaw multiplier, the 0° resistance for the 51mm glacis @58° becomes 120mm. That's a 10mm increase in resistance from just 2°. Give the tank a lateral angle of 30° and the compound angle becomes 61°. At this angle, the plate will have an effective resistance of 136mm, and now the 75mm L/48 has become unlikely to penetrate, all from just a 5° difference in shot angle. It's hard to judge from the screenshots how much this plays in this specific AAR, even the tank being just a few degrees nose up to PzKpfw IV and with some small lateral angle can give this much additional protection. Btw, I am very saddened to hear about Lorrin Rexford Bird. I had been very excited to find him on this board after buying his book (and the principle reason I registered!), and had wondered why the E-mails we were exchanging dried up several years ago. He was definitely an expert in this, and all the calculations I made above were done straight out of his book.

Out of curiosity, I took that technical diagram and actually measured the vertical profile for that thinner glacis, and it came out to be a bit bigger than I expected. It measures just under three-quarters as what the 30mm+50mm upper hull does, and two-thirds as much as the lower hull. If a shot were randomly to strike somewhere withing those three areas, my math estimates a 25% chance of that thinner plate being the point of impact. At about a 72° angle from the normal I'd imagine the slope multiplier would more than compensate for that thin 20mm plate, but I wonder how much good that would have done with overmatching involved from hits by larger caliber guns. So after spending about half an hour digging through boxes in my closet looking for that copy of "World War II Ballistics: Armor and Gunnery" (whose cover has made an interesting change in color from bright orange to green in the decade since I bought it), I can make some calculations from the tables and equations. It seems that plate would have an effective resistance of 96mm to hits that are perfectly horizontal to it from 75mm APC/APCBC rounds. That's better than I'd expected. Anything bigger than 75mm would probably have a bigger impact to overmatching. Then again, any ordnance bigger than 75mm would also probably punch through the front of that with little trouble, anyway.

That's good to know, I think I'll try the same. It's a shame, though, because the concept of the game does sound really cool. If it were to come out sometime in the future, I'd probably still get it.