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Post by christian on Sept 3, 2019 4:58:05 GMT -6
version: 1.08
the armor penetration of larger guns seem to be severely lacking despite the huge rof and weight penalty
im unsure if large guns are intended to have lower than actual pen or if this is a bug with large guns underperforming
after having played around with facehard (an armor penetration programme made specifically for naval shells by nathan okun)
(il provide a folder of all i input into the programme if it is desired)
there are 2 real life examples of 20/21 inch guns we have the german 53cm gun (21 inch) and the japanese 20.1 inch gun
using the values from the 53cm gun which are the following 4400 pound total shell weight 3760 pound shell body mass 2700 feet per second velocity
hitting a 49 inch plate made out of US Class A armor steel with a 2 inch concrete backer at point blank velocity (2700) results in a complete EFF penetration (i can post a folder with a picture of the intire facehard thing)
japanese 20 inch gun has the following 4200 pound total shell weight 3612 pound shell body mass 2550 feet per second velocity
hitting a 45 inch steel plate with the same properties as the above plate for the 53cm gun
result is a complete EFF penetration (enough of the shell has made it intact through to explode)
it is to be noted both guns still do atleast 43 inches of pen at 5000 yards
the 20 inch gun in game with 100% ap technology will only achieve around 33 inches of penetration with 0 armor technology
while a real life 20 inch gun firing at what is 1945-1950s armor technology will achieve 40 inches of pen ATLEAST
unsure if its a bug that penetration is this low or if its intended
it is to be mentioned both guns firing at a range of 18k yards range both guns will penetrate 20 inches of 20 degree inclined armor with an angle of fall of around 12 for the japanese gun and 11 for the german gun (32 degrees impact for ijn gun 31 for german gun)
both easily go thorugh a 20 inch plate the japanese does 21 inches at most german one up to 23 inches
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Post by rimbecano on Sept 3, 2019 6:06:10 GMT -6
The issue is, neither of those guns were ever built. The muzzle velocities you list are for what the Germans and Japanese thought they might be able to build in that caliber, possibly with some degree of undue optimism (both governments were given to grandiose plans for miracle superweapons that would crush the allies once and for all, which seldom actually came close to the hype that was drummed up for them).
Plenty of ships were built by multiple navies in the 16" and lower caliber range, and many guns were built, tested, and used in combat, so plausible performance for weapons up to 16" is well documented. Few 18" guns were built, most by one navy. No guns over 18" were built. Therefore the devs have to pretty much guess at the performance of such weapons, and they can't trust the numbers given by the Germans or Japanese because both were given to "we're going to rule the world by making all our weapons bigger" triumphalism. So they have to be conservative.
I do think that the way things are in RTW2 somewhat underestimates the performance that 17"+ guns would have managed after 20 years if the Washington treaty had never been signed, but I understand the devs desire to prefer more conservative numbers.
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Post by mobeer on Sept 3, 2019 14:13:22 GMT -6
It is very hard to tell what an in-game -1, 0 or +1 gun represents and what affect the in-game year has.
For example in my 1947 game a 18" +0 manages 15" at 15000 yards. This compares badly with the figures below for the British Mark 1. Would this mean that gun is a +1 equivalent, despite being built in the 1920s? If so, then what would the Japanese 40cm gun be, given it has superior penetration? +2?
Plus what rating should a US 16"/50 Mark 7 get, to ensure it has better penetration than the US 18"/48? In my 1947 game the real 16"/50 would have twice the side penetration of a game 16"+0 at 30000 yards - it would need a 16"+53 to match side penetration of the real gun at this range.
I think we just have to accept at some point that the game is a game and that the relative figures are far more important than the absolute ones.
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Simplified from Navweaps for armour piercing: Britain: 18"/40 (45.7 cm) Mark I, 1506 kg, 2270 fps penetrates 18.0" side at 15000 yards 18"/45 (45.7 cm) Mark II 1920, 1506 kg, 2500 fps 18"/45 (45.7 cm) Mark II 1921, 1323 kg, 2600 fps
USA: 18"/48 (45.7 cm) Mark 1, 1315 kg, 2700 fps, never fired, estimated 13" side or 3.5" deck at 28800 yards 18"/47 (45.7 cm) Mark A, 1746 kg, 2400 fps, estimated 6.25" deck at 25000 yards, more than 16" side at shorter range
Japan: 40 cm/45 (15.7") Type 94 (18" gun), 1460 kg, 2559 fps, 34" side at 0 yards, 19.4" side\4.3" deck at 21872, 14"\7.4" at 32808
and for comparison: USA: 16"/50 (40.6 cm) Mark 7, 1225kg, 2425 fps, 15" side or 6.65" deck at 30000 yards
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Post by tbr on Sept 3, 2019 15:04:33 GMT -6
The stats you get on navweaps and other sites are relativ to a "standard" armor quality, mostly at the time of their in-service testing. Often it was a "standard" which was inferior to the state of the art armorplate then used in new BB`s. This is still being done in tank armor, whatever real armor a tank has is re-calculated as rolled homogenous armor (RHA) equivalent and AP round performance is expressed in RHA as well. So the "18.0" penetration in 1918 is definitively of an armor quality tht is state-of-1918 or significatnly earlier. By 1947 the armor quality in your game is likely quite a lot higher. Also, there migh be an issue with how the RNG (or your choices) affected your AP tech progress. Remember that the table you get in the design screen i based on your armor and AP values at that point in the game. That written, 15" at 15kyd "feels" a tad low.
Edit: RTW1 armor worked a lot like RHA equivalency with armor getting progressively lighter over timefor the same effective thickness, RTW2 uses an armor quality value however, so the effectiveness o armor per armor inch in newly designed ships rises over time.
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Post by mobeer on Sept 3, 2019 17:07:08 GMT -6
I can see there is a an "ArmorMod=xx" setting in the ship class file that gives a 2 digit number, presumably for armour quality. However if I compare a new ship and an old ship with different ArmorMod values, the "Armour penetration table" dialog seems to ignore this setting and just use thickness. An old ship rebuilt and a brand new ship with higher ArmorMode rating seem to always get the same immunity zone range.
It would seem that if newer ships have better quality armour then the old ship refit should have a narrower immunity range?
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Post by aeson on Sept 3, 2019 19:05:20 GMT -6
I can see there is a an "ArmorMod=xx" setting in the ship class file that gives a 2 digit number, presumably for armour quality. However if I compare a new ship and an old ship with different ArmorMod values, the "Armour penetration table" dialog seems to ignore this setting and just use thickness. An old ship rebuilt and a brand new ship with higher ArmorMode rating seem to always get the same immunity zone range. It would seem that if newer ships have better quality armour then the old ship refit should have a narrower immunity range? If the immunity zone calculator in the ship design menu looks at the design's armor quality then, sure, you'd expect an old ship to show a narrower zone of immunity than a new ship with the same armor thickness against the same caliber and quality of gun, but as far as I'm aware the immunity zone calculator available in the design menu doesn't account for the effects of an inclined belt or the chosen armor scheme (sloped deck, flat deck, or protected cruiser) so I don't see any particular reason to expect it to account for the actual armor quality of the ship in question rather than using current-best armor quality.
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Post by archelaos on Sept 4, 2019 2:39:39 GMT -6
The issue is, neither of those guns were ever built. The muzzle velocities you list are for what the Germans and Japanese thought they might be able to build in that caliber, possibly with some degree of undue optimism (both governments were given to grandiose plans for miracle superweapons that would crush the allies once and for all, which seldom actually came close to the hype that was drummed up for them). Plenty of ships were built by multiple navies in the 16" and lower caliber range, and many guns were built, tested, and used in combat, so plausible performance for weapons up to 16" is well documented. Few 18" guns were built, most by one navy. No guns over 18" were built. Therefore the devs have to pretty much guess at the performance of such weapons, and they can't trust the numbers given by the Germans or Japanese because both were given to "we're going to rule the world by making all our weapons bigger" triumphalism. So they have to be conservative. I do think that the way things are in RTW2 somewhat underestimates the performance that 17"+ guns would have managed after 20 years if the Washington treaty had never been signed, but I understand the devs desire to prefer more conservative numbers.
How much optimism come in those data for 50-51 inchers can be easily pointed out as Japanese one was supposed to achieve 25% pen increase to 18 incher while difference between real Japanese 16 and 18 inchers is about 10-12%
RTW may be overly optimistic in armour strength, but if so, armour of battleships from 1930s is completely useless, as it was between 12-14 inches, which means that heaviest, on KGV, it just barely protects against 14inch guns at engagement ranges.
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Post by christian on Sept 4, 2019 8:05:34 GMT -6
The issue is, neither of those guns were ever built. The muzzle velocities you list are for what the Germans and Japanese thought they might be able to build in that caliber, possibly with some degree of undue optimism (both governments were given to grandiose plans for miracle superweapons that would crush the allies once and for all, which seldom actually came close to the hype that was drummed up for them). Plenty of ships were built by multiple navies in the 16" and lower caliber range, and many guns were built, tested, and used in combat, so plausible performance for weapons up to 16" is well documented. Few 18" guns were built, most by one navy. No guns over 18" were built. Therefore the devs have to pretty much guess at the performance of such weapons, and they can't trust the numbers given by the Germans or Japanese because both were given to "we're going to rule the world by making all our weapons bigger" triumphalism. So they have to be conservative. I do think that the way things are in RTW2 somewhat underestimates the performance that 17"+ guns would have managed after 20 years if the Washington treaty had never been signed, but I understand the devs desire to prefer more conservative numbers. "The issue is, neither of those guns were ever built."
by pearl harbour the 1st of 2 barrels and 1 mount for the japanese 510mm gun was getting its breech mounted onto the barrel both guns were built and shells for both exist the 530mm gun did even fire several times and we have test data on it along with the fact a mount for it exists "No guns over 18" were built."
not the case the germans made a 21 inch gun as mentioned above the japanese had a 480mm gun which had a barrel made the japanese also had a 510mm gun which had a barrel made in addition to that plenty guns non ship mounted were made such as the french 450mm rail gun and the japanese 550mm bomb test cannon from ww2 "Therefore the devs have to pretty much guess at the performance of such weapons, and they can't trust the numbers given by the Germans or Japanese because both were given to "we're going to rule the world by making all our weapons bigger" triumphalism. So they have to be conservative. "
neither am i using japanese or german numbers im using an armor piercing calculator made by a very respected AMERICAN author who has spent over 20 years studying armor penetration and armor not only is this calculator the best armor piercing calculator for naval shells in existance (supperior to things like demarre and so on) it is extremely good at simulating a multitude of things the main problem i find is that 20 inch guns have similar performance to 16/18 inch guns and the diffrence in pen between 16 and 18 inch guns is very small this seems right if we compare the 18 inch japanese gun to the american 16 inch gun which paints a wrong picture the american 16 inch gun is a very good 16 inch gun the japanese 18 inch gun is a very AVERAGE 18 inch gun better comparison would be japanese 16 inch gun to japanese 18 inch gun NOTEwhile guns of ww2 were ALOT more powerful than their respective armor what we have in game is a combination of problems armor is currently too heavy in rtw 2 by quite a bit this makes armor less valuable for smaller ships (its about 25% heavier than it should be but on the other hand guns pen alot less than they should whats important to remember about guns is that the shell mass does not scale linearly with shell size a shell that is 15 inches weights about HALF of an 20 inch shell if not less than half thus going from 18 to 20 inches is a weight increase (for the japanese 18 inch gun) of around 500kg (1/4th in weight increase) while traveling at the same speed when exiting the barrel in addition to that the 20 inch shells weight is more thus has more energy thus keeps energy better at range thus better range penetration this means that a 20 inch gun should have around 1/4th more energy in it but the shell is also bigger so its not 1/4th pen increase as more shell surface area hits either way the pen increase is MASSIVE considering a god damn 1/4th energy increase
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Post by archelaos on Sept 4, 2019 12:12:58 GMT -6
the main problem i find is that 20 inch guns have similar performance to 16/18 inch guns and the diffrence in pen between 16 and 18 inch guns is very small this seems right if we compare the 18 inch japanese gun to the american 16 inch gun which paints a wrong picture the american 16 inch gun is a very good 16 inch gun the japanese 18 inch gun is a very AVERAGE 18 inch gun better comparison would be japanese 16 inch gun to japanese 18 inch gun Using the table from navweaps (the same you link in another thread) difference between JAPANESE 16.1 and 18.1 guns is less that 10% at point blank range (28,8 in vs 31,7) against f.e. British cemented, despite the fact that shell weights around 30% more (2249lb vs 3219lb).
Interestingly, difference between 16.1 and 18.1 is much smaller then between 14 and 16.1 (as well Japanese - 23,6 vs 28,8 vs British cemented, or 18%).
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Post by rimbecano on Sept 4, 2019 14:05:16 GMT -6
"The issue is, neither of those guns were ever built."
by pearl harbour the 1st of 2 barrels and 1 mount for the japanese 510mm gun was getting its breech mounted onto the barrel both guns were built and shells for both exist the 530mm gun did even fire several times and we have test data on it along with the fact a mount for it exists OK, if the 530mm was fired that does mean there would be actual muzzle velocity data for it. It's only a single data point, but at least it's a data point. Since the 510mm does not seen to ever have been fired, its performance in purely speculative. A bomb test cannon is likely to be a mortar, with a high trajectory and low muzzle velocity. It doesn't tell you what the muzzle velocity for a gun of that caliber would be. It can be as good an armor piercing calculator as you wish, it still can only take an impact velocity and a shell and give you a penetration, it can't give you the muzzle velocity for a gun that was never fired. For the 510 mm gun, I maintain that, in the absence of an actual test firing, we have no data on its performance other than what the Japanese thought they could get. For the 530, yes, we can take the muzzle velocity that the Germans actually got, so we have a good idea how well it would have penetrated. Penetration scales linearly with shell size, more or less. Shell mass scales with the cube of caliber, the mass of armor of a given thickness that the shell has to push through on impact scales with the square of caliber, so the total thickness needed to stop the shell scales directly with caliber.
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Post by christian on Sept 5, 2019 14:44:35 GMT -6
"The issue is, neither of those guns were ever built."
by pearl harbour the 1st of 2 barrels and 1 mount for the japanese 510mm gun was getting its breech mounted onto the barrel both guns were built and shells for both exist the 530mm gun did even fire several times and we have test data on it along with the fact a mount for it exists OK, if the 530mm was fired that does mean there would be actual muzzle velocity data for it. It's only a single data point, but at least it's a data point. Since the 510mm does not seen to ever have been fired, its performance in purely speculative. A bomb test cannon is likely to be a mortar, with a high trajectory and low muzzle velocity. It doesn't tell you what the muzzle velocity for a gun of that caliber would be. It can be as good an armor piercing calculator as you wish, it still can only take an impact velocity and a shell and give you a penetration, it can't give you the muzzle velocity for a gun that was never fired. For the 510 mm gun, I maintain that, in the absence of an actual test firing, we have no data on its performance other than what the Japanese thought they could get. For the 530, yes, we can take the muzzle velocity that the Germans actually got, so we have a good idea how well it would have penetrated. Penetration scales linearly with shell size, more or less. Shell mass scales with the cube of caliber, the mass of armor of a given thickness that the shell has to push through on impact scales with the square of caliber, so the total thickness needed to stop the shell scales directly with caliber. "It can be as good an armor piercing calculator as you wish, it still can only take an impact velocity and a shell and give you a penetration, it can't give you the muzzle velocity for a gun that was never fired. "i dont need to get its precise muzzle velocity do i though ? i took the same velocity of the yamatos gun which is quite low (780m/s) while the nagato 41cm gun has 790m/s either way i dont need the precise muzzle velocity as i just need a general picture of how well the gun performs (and no there is no way the 20 inch gun was getting less than 750m/s velocity as travel time gets too long and its not a superheavy shell which means it would be horribly inneficient) sure if it was an american gun 740m/s would be more accurate but the shell weight would also be 1/5th higher if not more "For the 510 mm gun, I maintain that, in the absence of an actual test firing, we have no data on its performance other than what the Japanese thought they could get."
guns in game are based on real life guns but are not exact copies of one gun i dont need the precise muzzle velocity because we know that every single gun made (except for american 16 inch guns) had above 730m/s muzzle velocity and below around 850m/s muzzle velocity thus taking a low estimate of 780 is a good quess as that is also around what most guns achieved (2550 feet per second) if you want me to list every gun below 730m/s velocity that was used in 1940 on capital ships i can us guns 16"/45 gun, Mk 8 1-5 (1939 16"/45 gun, Mk 8 6-8 (1945-47) british guns 16/45 gun, Mk 2B (731m/s but i will include it) a grand total of 3 capital ship guns across the intirety of 7 major naval powers (granted ussr is a bit of a stretch calling a major naval power) "Penetration scales linearly with shell size, more or less. Shell mass scales with the cube of caliber, the mass of armor of a given thickness that the shell has to push through on impact scales with the square of caliber, so the total thickness needed to stop the shell scales directly with caliber."but it dosent in game the 20 inch gun has almost the same pen as the 16 inch gun it makes no sense that the 16 inch gun has just 11% less pen than a 20 inch gun that makes NO SENSE (29.3 inches of pen at 5k yards against 33 inches of pen at 5k yards) or the fact the 18 inch gun has just 5.45 % worse performance than a 20 inch gun despite the fact that in real life assuming the same velocity for the japanese 20 and 18 inch gun the 20 inch gun pens almost 8 inches more (37.2inches vs 45 inches) which is a whopping 16.9% more penetration it also makes no sense that the 20 inch is barely as good at maximum range as a 16 inch gun or that they have ALMOST the same deck penetration the 20 inch shell should by all account fall faster and penetrate ALOT more deck armor than a 16 inch shell "A bomb test cannon is likely to be a mortar, with a high trajectory and low muzzle velocity. It doesn't tell you what the muzzle velocity for a gun of that caliber would be."
in this case no it was a rebored 41cm gun which was made to fire bombs (with cut down tails so it could fit) at an armor plate with an obliquity of 20 degrees this was done to simulate the muzzle velocity of a falling bomb hitting a flat plate guns muzzle velocity was around 300 m/s either way for naval guns yes its irrelevant and its also too big for a proper comparison NOTE pen figures from ingame used are without any armor research at allAttachments:
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Post by mycophobia on Sept 5, 2019 15:07:06 GMT -6
Regarding the reason why "max" penetration might be too low, I suspect is due to the fact that there is no way for armor value to actually exceed designer limit, and 40" armor simply wouldn't matter in context of the game. (We know angling matter, but not sure if that just adds to flat armor thickness or some other process of calculation).
I agree that gun penetration post 16" seems a little under represented, but the reasoning might simply be that it defeats all effective armor anyway (this might be in part tied to the problem that armor weights too much). In any case I agree the higher end of Gun penetration/armor thickness could use some work.
Also, it might be that different caliber gun benefit differently from AP research, might be interesting to test the difference with or no AP tech. (Though I suspect shell quality should be more important for high caliber guns, not less)
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Post by rimbecano on Sept 5, 2019 17:32:33 GMT -6
(and no there is no way the 20 inch gun was getting less than 750m/s velocity as travel time gets too long and its not a superheavy shell which means it would be horribly inneficient) Not true. Just because less than 750 m/s would have been unacceptable/useless doesn't mean that it might not have been the best the gun could do. If we didn't have the German 21-inch as a data point, for all we know, it could have been the case that a 20-inch gun with acceptable performance was not possible with the technology of the day. It might still be the case that the Germans had the technology to do it and the Japanese didn't. And while the German 21" shows that a gun of that caliber with a particular muzzle velocity *could* be built, it's just one datapoint, so we don't know if it corresponds, in game terms, to a 21" -1, 0, or +1, or even a +4. Every single gun *made*, or every single gun *accepted for service* by the relevant navy? We need record of actual test firings, because without that, we don't know that the gun might not have underperformed and been rejected for service. We don't know that the gun might not have burst when fired, etc. For that matter, do we have inspection records from after the German 21-inch test firings to establish what kind of barrel wear resulted? It's possible, if unlikely, that the guns sustained sufficient wear in the test that they would not have been accepted for service (if they weren't already guaranteed not to go into service by the fact that the Germans didn't have a ship to mount them). Penetration scales linearly with shell size *at a given muzzle velocity*. It could be the case that guns over 18" were exceedingly difficult to build and the German 21" was something like a +4 or +5, and the performance of a +0 would be even worse than in game. I do not believe this to be the case. I believe that guns with acceptable performance up to at least 22" were probably possible, and that IRL gun performance likely would have been better than it is in game if such weapons had been built and used widely. But with just one datapoint above 18", we can't rule out the more pessimistic possibility entirely, so I don't have much problem with the devs being conservative on the matter, other than the disappointment at not being able to smash through 22 in" of armor at decent range.
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Post by aeson on Sept 5, 2019 20:47:07 GMT -6
Having taken a brief look at the program overview pages for the calculators on the NavWeaps site, it seems like these calculators that christian is basing his numbers off of take striking velocity - not muzzle velocity - as an input. I would therefore be interested to know if and how christian is calculating the striking velocities he's using to generate his numbers, because using the muzzle velocity as the striking velocity is wildly inaccurate except at very short range.
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Post by rimbecano on Sept 6, 2019 1:12:28 GMT -6
Having taken a brief look at the program overview pages for the calculators on the NavWeaps site, it seems like these calculators that christian is basing his numbers off of take striking velocity - not muzzle velocity - as an input. I would therefore be interested to know if and how christian is calculating the striking velocities he's using to generate his numbers, because using the muzzle velocity as the striking velocity is wildly inaccurate except at very short range. The download page for the programs gives the Basic runtime and a program called Oblicalc as prerequisite downloads, so I assume he's taking a muzzle velocity and running oblicalc to get the striking velocity. The download page doesn't say explicitly that oblicalc outputs a striking velocity, but to calculate angle of fall you'll need to know what air resistance is doing to the shells velocity, so I'd think striking velocity would be an output.
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