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Penetration vs Range - 8/23/2019 3:37:19 PM   
engineer

 

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I have a gunnery combat algorithm question. The penetration values for naval guns reflect values that align with engagement ranges of 15k to 20k yards for the most part.

In watching a variety of test night engagements, I have seen the US 5" guns penetrating Japanese light cruiser belt armor sometimes. These are typically at close ranges of 6000 yards and less.

Does the algorithm for penetration vs. armor consider range and apply penetration bonuses at short range?

Checking ballistics data on the guns, a battleships will always penetrate other battleships and at close enough ranges even an Allied heavy cruiser could penetrate the belt armor on a "Kongo". Hornfischer also makes this point in his discussion of the Naval Battle of Guadalcanal in Neptune's Inferno. Likewise, the data on the US 5" shows it would have enough penetration to get through Japanese CL belt armor at close range.



< Message edited by engineer -- 8/23/2019 3:40:44 PM >
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RE: Penetration vs Range - 8/23/2019 8:11:16 PM   
Dili

 

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The penetration values appear to be at "zero" range, a 16" does not penetrate 828mm at 15k. I suppose there is an algorithm in game that takes in account the range, but i never seen any explanation.

(in reply to engineer)
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RE: Penetration vs Range - 8/23/2019 10:04:51 PM   
engineer

 

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OK, thanks, that's the trick. The penetration values are not uniformly rated for zero range. For example, the US 8" guns have 200 mm and the 5" Mk 12 have a 50 mm penetration. The 16" Mk 7 has that high 0 range penetration.

Using Navsource as a reference, US 8" Mk 14 used on the treaty cruisers has a 254 mm penetration at 9000 yards, so a zero range penetration ought to be at least 300 mm or so, plenty to hit a Kongo class at point blank. 200 mm is a good value at 12,000 yards. The 5" Mk 12 has 127 mm penetration at 4000 yards. 50 mm is good value for 11000 yards. The 16" Mk 6 gun on the NC and SD classes, the 0 range penetration is given as 755 mm.

I've been running repeated night battles modeled on the Guadalcanal engagements and getting curiously indecisive outcomes on the gunnery. This would suggest, the guns are underpowered.

There's a whole 'nuther dimension looking at the armor placement on the ships, especially on the battlewagons where the naval architects started sloping the belts in order to give thicker effective armor, but that is for a different thread.



< Message edited by engineer -- 8/23/2019 10:06:18 PM >

(in reply to Dili)
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RE: Penetration vs Range - 8/23/2019 10:47:52 PM   
Dili

 

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Many naval combats were indecisive.

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RE: Penetration vs Range - 8/24/2019 2:53:06 PM   
engineer

 

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It's not what I don't know, but what I know for sure that messes me up.

The US 8" in AE has the same 275 penetration as the Japanese 8" after double checking the scenario editor. The mismatch there is, accordingly, much less than I thought. Navsource gives the Japanese 8" a penetration of 190 mm at 10940 yards while the US 8" Mk 9/14 shows a penetration of 254 mm at 9000 yards and 200 mm at 12400. I did recall the US 5" mark 12 correctly. The US 8" Mk 12 (Wichita, Baltimore and some of the late war upgraded Treaty Cruisers that were upgunned), had similar ballistics with the Mk 19 shell. However, the Baltimores were issued the Mk 21 shell that had a 335 lb weight. This translated into greater penetration at all ranges. It could go through 254 mm of armor at 10,800 yards.

So if we take the Japanese 8" gun as a base, the US Mk 9/14 should get penetration value about 15% greater and the Mk 12 a bonus of about 30% greater, but only on Baltimores.

In the bigger scheme of things, that is just fine tuning.

The US 5" guns are under-rated by more than 50% across the board. I got one test battle last night that night that seems to show Japanese CL's are more vulnerable to shell-fire, but the sample size needs to increase.

Also, I need to dig in and do the corresponding research on the IJN destroyers to give them the benefit of the same design assumptions.


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RE: Penetration vs Range - 8/24/2019 5:11:51 PM   
inqistor


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The only explanation of Naval Gunnery Algorithm, I recall, was mention by JWE, that at certain ranges hit is against deck armor, because of ballistic trajectory. Otherwise we can only guess.

I would be very careful in comparing penetration values for different countries, unless tests were made by the same facility. Different countries used different methods during testing, and this weird 10940 yards for Japan clearly indicates, that those are Japanese values for 10km. I read something, about US Naval tests long ago, and I'm sure they used completely different method, that ground forces. But for comparison:
- US ground forces used low grade RHA as targets, and penetration was described as "at least half of fragments on inside part of target"
- Germany used combat grade RHA (even hardened sometimes), and penetration was defined as "at least half of projectiles go through entirely"

So, US values would be quite optimistic in comparison to German ones. And remember, that "penetration" means that at least 50% projectiles will penetrate, not 100%.

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RE: Penetration vs Range - 8/25/2019 1:03:20 AM   
engineer

 

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The oddball figures aren't too hard to back out. The Japanese figures are footnoted to a history of the Takao and represents a 10,000 m range. I agree with your conclusion 100% The US values are nice round penetration values in inches so I would suspect the testing either resulted in a curve or they used sample targets and noted the range that met the penetration criteria. Navsource does provide the reference back to the US values and double checking that would be worthwhile if I can run it down. The definitional points about armor type and definition of penetration success are perfectly valid.

From Worth's In the Shadow of the Battlecruiser, he notes that Japanese cruisers all used homogeneous armor and that their 8" shells had no trouble penetrating the homogeneous armor used on the US 8" treaty cruisers built prior to the Brooklyn class. However, the USN then switched to far greater use of face hardened armor that was significantly more robust against the Japanese 8" shells, which had been optimized by design for dealing with homogeneous armor. He buttresses his argument with multiple examples of close range hits on US light cruisers that were defeated by the hardened armor.

Worth also notes that the armor values on the old Omaha class were not from a single plate of homogeneous armor, but laminations of thinner plates which are inherently weaker at resisting shellfire. The raises the question of whether we should be digging into the variable too, penalizing ships with laminated armor with lower effective armor ratings and giving bonuses to those vessels where it can be confirmed they had face hardened armor.

I haven't been tracking the statistics, but I've been seeing some deck armor hits even in short-range night actions. I have not seen any result in penetration. However, the angle of shot fall at these ranges is so low, I'm surprised at the overall number. That being said, I'm favorably impressed by the additional flavors of hits in AE vs. WitP classic with fire control, upper works, etc.

One thing that I have not seen yet is a battleship AP shell that hits and passes through an unarmored vessel without detonating. Those are well documented in the historical literature. That may be going several lines of code too far for the sake of verisimilitude so it would simply be a sweet outcome and does not rise to a complaint on my part at all.

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RE: Penetration vs Range - 8/25/2019 8:05:18 PM   
Alfred

 

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quote:

ORIGINAL: engineer

I have a gunnery combat algorithm question. The penetration values for naval guns reflect values that align with engagement ranges of 15k to 20k yards for the most part.

In watching a variety of test night engagements, I have seen the US 5" guns penetrating Japanese light cruiser belt armor sometimes. These are typically at close ranges of 6000 yards and less.

Does the algorithm for penetration vs. armor consider range and apply penetration bonuses at short range?

Checking ballistics data on the guns, a battleships will always penetrate other battleships and at close enough ranges even an Allied heavy cruiser could penetrate the belt armor on a "Kongo". Hornfischer also makes this point in his discussion of the Naval Battle of Guadalcanal in Neptune's Inferno. Likewise, the data on the US 5" shows it would have enough penetration to get through Japanese CL belt armor at close range.




Range is factored into the algorithm.

Alfred

(in reply to engineer)
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RE: Penetration vs Range - 8/25/2019 8:06:58 PM   
Alfred

 

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quote:

ORIGINAL: Dili

The penetration values appear to be at "zero" range, a 16" does not penetrate 828mm at 15k. I suppose there is an algorithm in game that takes in account the range, but i never seen any explanation.


Not how the algorithm is set up.

Alfred

(in reply to Dili)
Post #: 9
RE: Penetration vs Range - 8/25/2019 8:10:09 PM   
Alfred

 

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quote:

ORIGINAL: engineer


...I've been running repeated night battles modeled on the Guadalcanal engagements and getting curiously indecisive outcomes on the gunnery. This would suggest, the guns are underpowered.


A very erroneous conclusion.


There's a whole 'nuther dimension looking at the armor placement on the ships, especially on the battlewagons where the naval architects started sloping the belts in order to give thicker effective armor, but that is for a different thread.


There is no slope in AE.






Alfred

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Post #: 10
RE: Penetration vs Range - 8/25/2019 8:22:23 PM   
Alfred

 

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quote:

ORIGINAL: engineer

It's not what I don't know, but what I know for sure that messes me up.

The US 8" in AE has the same 275 penetration as the Japanese 8" after double checking the scenario editor. The mismatch there is, accordingly, much less than I thought. Navsource gives the Japanese 8" a penetration of 190 mm at 10940 yards while the US 8" Mk 9/14 shows a penetration of 254 mm at 9000 yards and 200 mm at 12400. I did recall the US 5" mark 12 correctly. The US 8" Mk 12 (Wichita, Baltimore and some of the late war upgraded Treaty Cruisers that were upgunned), had similar ballistics with the Mk 19 shell. However, the Baltimores were issued the Mk 21 shell that had a 335 lb weight. This translated into greater penetration at all ranges. It could go through 254 mm of armor at 10,800 yards.

So if we take the Japanese 8" gun as a base, the US Mk 9/14 should get penetration value about 15% greater and the Mk 12 a bonus of about 30% greater, but only on Baltimores.

In the bigger scheme of things, that is just fine tuning.

The US 5" guns are under-rated by more than 50% across the board. I got one test battle last night that night that seems to show Japanese CL's are more vulnerable to shell-fire, but the sample size needs to increase.

Also, I need to dig in and do the corresponding research on the IJN destroyers to give them the benefit of the same design assumptions.




The AE modifications were implemented by a team leader who

1. Had trained at Fort Sill

2. Was an artillery officer in Vietnam

3. Is a qualified naval architect and retains his professional registration

4. Has a book deal to produce a scholarly treatise on C18th French warship construction

5. Runs his ballistic software packages just for the fun of it.

6. Oh, and is very articulate in pointing out the technical deficiencies found in websites which provide only partial data.


All of the above providing the right kind of experience and intellectual knowledge required to transfer real world datum points to the code limitations of the AE engine. All of which has been previously publicly discussed at length by the relevant dev.

Alfred

(in reply to engineer)
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RE: Penetration vs Range - 8/25/2019 9:15:13 PM   
Dili

 

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quote:

ORIGINAL: Alfred


quote:

ORIGINAL: Dili

The penetration values appear to be at "zero" range, a 16" does not penetrate 828mm at 15k. I suppose there is an algorithm in game that takes in account the range, but i never seen any explanation.


Not how the algorithm is set up.

Alfred


I am not seeing what is different than what you have said. If you say range is factored into algorithm is not similar when i say that range is taken in account by algorithm?

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Post #: 12
RE: Penetration vs Range - 8/25/2019 11:38:33 PM   
engineer

 

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OK, so we have an appeal to authority on the development team vs appeals to a variety of alternate authorities with their own credentials, including the historical record from the war. That's what makes the editor invaluable to a patient enough user.

There is quite a nice paper on the whole topic I ran across today in digging into the background of the USN Empirical Penetration Formula here. The bottom line is that we have a complicated interaction of the shell weight, diameter, velocity, angle of impact to the armor (which can include the armor placement) and armor type. The USN formula mixes different types of armor which throws in an error factor without getting into the details (which seem to be in other papers I haven't run down yet).

So it seems that a systematic approach is possible with a zero range penetration value against homogeneous armor, then doing the adjustments on the armor protection in the ship classes with penalties for the old laminated armor like the Omaha's, bonuses for face hardened armor, giving bonuses for the sloped armor that would the decrease the angle of obloquy compared to a vertical slab of armor. I need some more research on cemented armor for UK warships. Simplifying assumptions would include using turret face armor and broadside orientation for belt armor.

AE's surface combat module is a huge improvement on WitP classic. I do sometimes wonder if a better approach is to play the perceived code instead of squeezing the historical tactical considerations into the surface combat module.



(in reply to Dili)
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