4th Cuirassier | 21 Oct 2022 9:34 a.m. PST |
Most of the rules I'm familiar with follow the approach of gun attack factor = X, tank armour factor = Y and if X >= Y, the armour is penetrated. This is broadly true (although not the be-all and end-all of gun vs tank combat obvs), but Y is always static. 100mm is always 100mm. I am wondering if there are any rules out there that rate highly-sloped armour as having in effect infinite thickness, because certain rounds glance off. Years ago a guy in a club I belonged to had a set that did this. Trigonometrically a Tiger II's glacis is 290mm thick (185mm at 40 degrees) to a shot travelling parallel to the ground. His set had it much higher, because sloped. A T-34's humble 45mm at 30% is 90mm on a trig basis, but these rules had it as more. As I recall (and it was a looooong time ago), the principle was that how thick a tank's armour was depended on what was firing at it. Counter-intuitively, armour thickness was not static. A T-34 fired on by a 37mm had a higher armour value than when fired on by a 75mm. So when you resolved AT fire, you didn't just read off the range against the weapon and compare it the armour. You next read off the weapon against the armour to determine what armour value to take, and then you determined the effect. I'd regard this as a bit over-engineered for multi-tank games nowadays, but under-engineering this stuff has its problems too. Has anyone come across anything like this? |
DeRuyter | 21 Oct 2022 10:13 a.m. PST |
I have not seen this level of detail in tabletop games for many years. For PC tank sims these calculations of armor and shot angles are a requirement! I can think of games that fall into the middle of the scale like Easy Eights Battleground and there was a Yacinto (sp) boardgame from the 80s that was very detailed, but I can't recall the name of it. |
farnox | 21 Oct 2022 10:18 a.m. PST |
I've worked with rules that used modifiers for ammunition quality based on nationality but never a variable armor rating. |
stephen m | 21 Oct 2022 10:49 a.m. PST |
DeRuyter The games were Panzer, Armor and 88 which have been released again by GMT as the Panzer series. farnox Ditto 4th I started with Tractics which did all the above except extreme increases due to angle. At extreme ranges the shot is close to falling so angle from the vertical should be reduced. Tractics took the angle of the armour and used it to modify the effective thickness by having a series of columns on a table where the left side is armour thickness, the columns acted as effective angle and the number which corresponded to the intersection had the effective armour thickness. The number of columns you shift is based on the angle. Then shift more if you are not firing directly at the armour face but from an angle. I wanted to add a limit where depending on the shell type at over X columns if the thickness is still Y% of the penetration the shot would bounce. Never pursued it and now there is someone on UTube who is modeling this effect. Hooking up with them may answer many questions wrt this. |
Theron | 21 Oct 2022 11:46 a.m. PST |
I thought all rules did this. That's why a Panther's front armor is usually rated about the same as a Tiger I. Or at least I always figured that the possibility of deflection was factored in there somewhere… |
HMS Exeter | 21 Oct 2022 12:10 p.m. PST |
It's more complicated than that. Sloped armor is indeed more effective than flat vertical. Projectiles striking sloped armor traveling parallel to the ground must penetrate more metal and are more likely to induce deflection. But very few shots hit the armor straight on. There is usually some degree of obliqueness which compounds the variables. To make matters worse, the Russian industrial infrastructure was a confused mess, with various factories dealing with steel of varying qualities. It's not all yablokis to yablokis. |
David Manley | 21 Oct 2022 1:05 p.m. PST |
I thought it was a fairly common thing in WW2 rules |
Timbo W | 21 Oct 2022 1:36 p.m. PST |
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emckinney | 21 Oct 2022 2:12 p.m. PST |
Some WWII AP was designed to "bite into" sloped armor, normalize the projectile relative to it, and then penetrate from this new angle! Of course, this required a blunt or blunt-ish nose, which decreased penetration against simple, vertical armor (compared to a sharp-nosed projectile). If you're going to use slope like that, you need very specific hit locations, you need to take into account which of several (or many) rounds the gun is firing, and you should take into account your exact horizontal angle relative to the target! After all, if you fire from 30 degrees off of dead ahead, you've given vertical armor a 30 degree slope. If the armor is already sloped, you have to use a trig formula to find the effective slope (there are a few online). |
robert piepenbrink | 21 Oct 2022 3:40 p.m. PST |
It would be interesting to produce a graph showing wargaming periods in chronological order vs how many hoops the average participant is prepared to jump through to find out whether he's done any damage. But in this case, while I can see taking slope into account, and in a 1:1 game considering area hit and possibly angle of penetration, I can't see why when changing the gun firing, you'd modify the armor value instead of the "gun attack factor." Can someone spell this out for me? Thanks. |
Dye4minis | 21 Oct 2022 3:58 p.m. PST |
Sound to me like the old set "Angriff" by Z&M enterprises. They also had two other titles based upon the same mechanics. It had the slope of the armor figured in on the charts based upon angle of shot trajectory, but highly simplified for playability. |
4th Cuirassier | 21 Oct 2022 4:48 p.m. PST |
The modifier didn't just represent slope. It reflected the fact that against a big enough round, slope offers little protection. A T-34's armour is 45mm thick sloped at 30 degrees, but fire a 150mm round at it and see where the slope gets you. Fire a 37mm round at it and the slope is quite handy. This is quite well understood ballistics AFAIK. A round does not follow a straight line through armour and indeed if the round overmatches the armour by enough it will crush it slope or no slope. Hence the rules that compared the gun's performance as modified by range with the armour's performance modified by what you were firing at it. |
Wolfhag | 21 Oct 2022 7:01 p.m. PST |
I think Anthology of Armor covers what 4th is talking about. If the armor is 45mm rounds less than 45mm will be more affected by the slope. If greater than 45mm it will be less affected by the slope. It's hard to simulate without a computer. Here is a good armor compound angle calculator: link Before running the armor through the calculator I modify any cast armor as 90% of the thickness. This has a lot of good detail too: PDF link I use 5 different target aspects to determine the hit location using a D20. A likely ricochet location is from the front aspect hitting the sloped roof armor and turret side armor that will stick out at an angle of 70+ degrees. Tiger I & II, Panther, T-34, and many other tanks have this feature. Ricochets will most likely occur on sloped/rounded surfaces with a compound angle of 70+ degrees. When looking at a target aspect you can estimate the area of the target where a ricochet can occur. In my game, the hit location may show 90/3 which is the armor is 90mm thick (compound angle already calculated) and will ricochet on a 1-3 on a D20 (15% chance). Mantlets with a potential Shot Trap work the same way. When the shooter rolls for the hit location the target player rolls a D20 for a potential ricochet. On the Panther mantlet, there is about a 20%-25% chance of the round ricocheting into the turret roof or turret ring. Almost all rounded mantlets have this problem. YouTube link However, a driver/mechanic at the Russian tank museum in Kubinka told me the T-34s do not because ricocheting off the mantlet will hit the glacis, not the hull roof. If penetration = armor there is a chance of spalling damage and no penetration. The round itself must penetrate fully into the compartment and remain intact to cause full internal damage. This means about 120% over-penetration. The heavier the round the more it will cause damage. Uncapped AP rounds penetrate about 10% less against face-hardened armor and APC and APCBC rounds will penetrate about 10% more. Tungsten APCR rounds can shatter apart at ranges under 500m and against highly sloped armor because tungsten is brittle. Brittle and riveted armor spalls more and causes greater internal damage. Also, penetration is somewhat variable about +/-10% round to round. I also have a 5% chance of a critical hit which can be a weak spot with less armor, cupola, suspension, vision port, etc. I pre-calculate everything so the player does not have to perform any math. It's no more complicated than any other system and simpler than Tractics. To complicate things even more different nationalities and branches had different definitions for penetration. This is all from memory so may need some corrections. Wolfhag |
advocate | 21 Oct 2022 7:20 p.m. PST |
And all sorts of vehicles suffered 'mission kills' from weapons that technically couldn't damage them. I'm guessing there were plenty of cases of the reverse happening. You can over think these things. |
Grelber | 21 Oct 2022 10:30 p.m. PST |
This was back in the days when gamers were really interested in the writings of Richard M. Ogorkiewicz (Professor, Royal Military Academy School of Science) on armor design. If you can find a copy of his "Design and Development of Fighting Vehicles," it might provide some information on armor penetration and ammunition characteristics. Grelber |
Martin Rapier | 21 Oct 2022 10:32 p.m. PST |
I understand the concept being described, but I can think of nk of far simpler ways to skin that particular cat through the use of broad anti tank and armour classes. The approach used in 5Cire Brigade Commander springs to mind. |
robert piepenbrink | 22 Oct 2022 3:28 a.m. PST |
Thank you, 4th. That's clear enough. |
donlowry | 22 Oct 2022 8:43 a.m. PST |
In my home-baked rules, the armor for a vehicle (or part of a vehicle) has two factors: It's true thickness and its effective thickness due to the slope (if any). This is because there are possible times when the vehicle is not on level ground, and/or when the enemy round comes in from above or below (such as a gun on a hill, or a long-range shot descending from its peak altitude). |
Murvihill | 23 Oct 2022 5:06 a.m. PST |
I've still got Panzer. It's a fun game if you use it as intended, maybe a couple platoons of tanks on a side max. Unfortunately the urge to field entire battalions turned the whole game into a major grind. |
4th Cuirassier | 24 Oct 2022 1:36 a.m. PST |
I don't recall what set this was because it was a long time ago, only a couple of guys were sold on it, and their copy looked like a fourth-generation photostat. It may not even have been a commercial set. Part of the rationale for the approach stayed with me though, which is that all published AP figures are problematic anyway. Some measure penetration at 90 degrees, others at a more realistic 30 degrees. This reflects that most hits are not square-on, so neither should your armour test be. Within these two approaches, sometimes the AP data is 50% probability of a penetrating hit and sometimes it's not – could be 100% or something in between. When you compare tables of AP data, it isn't always obvious which of the above they have applied. If they agree it's because they're based on each other, and if they disagree it's because you have some of the above factors at work. So while you can knock yourself out Tractics-style working out all these angles to the nth degrees, it's a bit futile if the AP data you're using isn't reliable. Hence the logic that the size of round matters more. It's an inarguable data point and it makes the picky detail superfluous – if you fire a 105mm round at a T60, you do not need to consult an AP table, or know the angle of incidence, or even know the range to know the result. This occurred to me because in spare moments I made an Excel spreadsheet that gives tank fire results according to two different sets. One is Quarrie, which is a classic 70s set where it famously took ages to resolve the result. So I wondered if these or similar rules would work any better if you got a machine to do the heavy lifting. The answer is 'not really', because you still have all the measuring etc to do. If you've got five tanks firing at each other, that's a lot of data to input and lots of opportunities to fat-finger it. Anyway, interesting discussion. Thanks all. |
donlowry | 24 Oct 2022 9:19 a.m. PST |
In my home-baked rules, there is also this: If the penetrating power of the gun (at that range, etc.) exceeds the thickness rating of the armor, there is only a 50% change of penetration, which allow for other random factors, such as compound angles, etc. |