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Friday, April 28th 2006, 9:53pm

Here for a better way to use facehard. It'll allow you to change mv and shell wieght, estimate the trajectory and then the penetration.

I can tell you now that the 345mm or 360mm won't penetrate 120mm-150mm of deck armour at that range. Needs to be 30.000yds+


Friday, April 28th 2006, 10:51pm

Would the following be an accurate statement?

Well since its been more or less concluded that you can't hit effectively at 30,000+ yards, the deck penetration becomes a non-factor.


Friday, April 28th 2006, 10:56pm

Considering the thickness of deck armour on modern battleships, yes.

Kaiser Kirk

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Saturday, April 29th 2006, 12:19am

RA: I presume you're correct on the 12cm-15cm range, I tend to think in English measurement units, so 15cm doesn't translate mentally into 6" automatically. Suggesting penetrating 6"<30k does seem off doesn't it.
I know the next threshold would be about 10cm, or 4" which might be more attainable. I think 3.5"-4" would be the mid 20s range band? At work right now…on break of course…anyhow, something to play with after work.


Originally posted by Ithekro
Would the following be an accurate statement?

Well since its been more or less concluded that you can't hit effectively at 30,000+ yards, the deck penetration becomes a non-factor.

Hmm, so we should only worry about vertical penetration and not the horizontal characteristics?

Overall we're putting the cart before the horse. I wanted to find out if upgunning to 36cm was feasible, and if it was I was going to bother looking at the cost/benefits of doing that, but I still don't have the answer to if it's feasible.

Kaiser Kirk

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Saturday, April 29th 2006, 3:42am


I know where I got those figures. I was playing with a 36cm gun a bit, trying slow heavy shells in BigGun.

Caliber = 36.0 cm (14.2 inch)
Shell weight = 766 kg (1688 lbs)
Muzzle velocity = 693 m/s (2272 fps)

20.0 deg 21600 meters 43.3 sec 436 m/s 26.8 deg
25.0 deg 24600 meters 52.7 sec 428 m/s 33.6 deg

18.0 deg 20200 meters ... 10 cm
21.2 deg 22400 meters ... 12 cm
24.4 deg 24300 meters ... 14 cm
24.7 deg 24400 meters 25 cm
27.7 deg 26000 meters ... 16 cm

I know Okun's work is better than BigGun, but I wonder about being to accurate, but this was the toy that put reinforced the idea in my head. Shells are very heavy though and MV slow.

IF 36cm is an option, I was going to do a range of "test" guns, from /40 to about /54 in 345 and 360 and see what I got. This was simply one of the first varients I started with.


Saturday, April 29th 2006, 12:26pm

That would be a rather similar gun to the WW French 15"/40 - heavy, slow shell with a rather curved trajectory. The slow shell will make longer range hits harder to come by, as longer flight times certainly don't help the odds of the target being there when the shells arrive.

One of the problems for deck penetration in WW is that many ships have ahistorically high amounts of deck armor, armored decks of 5.5"-6+" are not at all uncommon and it's only 1930.


Saturday, April 29th 2006, 1:01pm

To answer the main point if 360mm is viable, no I don't think that it is. It unecessarily adds another calibre to the Netherland's navy. The 345/54 is a far, far better belt penetrator than the 360/40 guns outlined above. It is worse for decks, but not by a great deal.

Kaiser Kirk

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Saturday, April 29th 2006, 5:32pm

===deck armor ===
As for the opposing armors...I believe the vessels operate in a slightly different threat regieme. Would the Dutch actually know SATSUMA's deck armors? I suspect that is why most countries simply designed with thier own known performance parameters in mind.

The old Dutch BCs have 80mm deck armor, the 30,000t DeRutyers have 125mm, the new 38,000t Utrechts have 150mm. The Dutch traditionally over armor, they would assume the opposing ships would have equal or less armor.

Class Est Comp Replacement Deck
Fuso ~1918 1938 50mm- Public
Nagato ~1920 1940 65mm- Public
Tai'pei 1928 1948 100mm- Not public. Presume close to DeRutyer, 120mm
Babur ~1912 1932 won't be a factor
Akbar ~1927 1947 100mm- Not public. Presume close to DeRutyer, 120mm
Shah Jahan ~1932 1952 30k Not public. Presume close to DeRutyer, 120mm, perhaps closer to contempary Utrecht 140mm ?

As such a mild difference in deck penetration could indeed be viewed as useful.

A rebuild ZP would have to stay in service until ~1953!!! That new 10 year extension is really the burr in the reconstruction. A brand new build would only have to stay in until 1954 or so. However the Taipei, Akbar, and Shah classes will all be in service for most of that time. Furthe the treaty may well expire, or that 10 year clause rolled back. It is reasonable to expect that a rebuilt 36cm ZP would be effective for at least 10, if not 15+ years against a substantial portion of the enemy battleline.

As for the 36/40- as I said it was a toy. Actualy I think I built it as the first step in an effort to figure out what deck armor a 26k ship may need. However it planted the seeds that acceptable deck performance was possible in that range. It's not the final version. I'd like a little faster and a little heavier. But the 766kg shells already wouldn't fit under Rock's rule of thumb.

I just felt that before going out and trying multiple iterations of the gun(s) with differing calibers and shell wieghts and designing a follow on to Isjelsijk to carry them, I should find out if I can upgun the ZPs to carry such things and just how heavy I can make the shells. a basic question still not answered. At this point, I'm inclined to use S&G as the model and simply declare I can mount up to twin 381mm as that's the only OTL comparison available.

I do realise a slow shell would have increased Accuracy problems, a quick comparison of the /40 and /50 showed a 30knt vessel would have moved about 400' at the 21500m range due to speed differences. The question is if the reduced accuracy is worth the chance to actually do critical damage.

One idea that intrigued me was to do something like the USN did- provide tables for two different powder charges. As I recall, for the Iowa's 16"/50 page they had a reduced charge meant for longer ranges to penetrate decks. I was thinking I had that from NavWeaps, but it doesn't appear so- though they do note


Like the Mark 5, the Mark 8 APC projectiles were designed for use against Japanese ships ("Plan Orange") at long range in the Pacific Ocean by firing them at a lower muzzle velocity and at a higher gun elevation, which allowed a steeper angle of fall to further enhance deck armor penetration.
but that's not quite the citation I was thinking of, but probably speaks to the same issue.

=====Mixed Calibers=====
As for the mixture of shells, how is 345mm, 360mm and 381mm any worse than the current 280, 310, 345 and 381, or the WW1 RN's 305mm, 343 and 381? Or the USN's 12", 14" and 16"- esp when the 16" for the Iowa would not fit the hoists for the 16" for the Colorado, nor the Alaska's 12" fit the Arkansas.

Further, when replacing the Ijelsijks I will likely mount 360mm not 345mm anyhow. Frankly, shrinking the number of shell types from 4 to 3 is not a concern. The Dutch certainly have the cargo handling skills that figuring out where which shell goes will not be a problem.

===Okun =========
Off Topic:. Nathan Okun's formulas are more correct, but I believe they are also more correct than those the Navies of the era knew. I probably shouldn't rely on them as they constitute hindsight. Perhaps if when/if we sim combat they should come in as the 'real' vs expected. RAM used BigGun for earlier Dutch weapons, so I figure continuing it is reasonable.

Oh, and thanks for the site link, I've used the facehard tables for a bit, but never tried using the formulas proper, the site looks to make that a great deal easier.

Kaiser Kirk

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Saturday, April 29th 2006, 6:07pm

Combat regimes.

Early I noted that the expected combat scenarios are either relatively longer ranges – 20-26k or night/island fighting in the 15k- range.

The 345mm/54 681kg shell has the following expected performance

11000 meters ... 4 cm
11300 meters 50 cm
14200 meters 45 cm
15000 meters ... 6 cm
17700 meters 40 cm
19000 meters ... 8 cm
21600 meters 35 cm
23400 meters ... 10 cm
26400 meters 30 cm
27000 meters ... 12 cm
29400 meters ... 14 cm
31500 meters ... 16 cm

Which means there is no hope to penetrate expected OPFOR decks in normal combat ranges. Belt penetration, while good, is just acceptable at 20k and rapidly declines. Basically the gun is borderline ineffectual at the expected outer range band and quite good below that.

the “Toy” 36/40 766kg
11500 meters 40 cm
12600 meters ... 6 cm
15200 meters 35 cm
16100 meters ... 8 cm
19500 meters 30 cm
20200 meters ... 10 cm
22400 meters ... 12 cm
24300 meters ... 14 cm
24400 meters 25 cm
26000 meters ... 16 cm
27400 meters ... 18 cm

Deck penetration is exactly what I think I need for the long range and the belt penetration is just acceptable at the short range and would get better. There is a 5-6000m IZ where HC/SAP would be a preferable round.

BUT I do share the accuracy concerns with such a slow shell. Now, if I can add weight to the shell, I can likely boost MV and keep roughly the same penetration characteristics. So again, the limits of what I can upgrade To are important in determining the modeling parameters to see upgrading is worth it.

Further all of this is with ‘average’ 1.0 shells. RAM established that naval artillery and shells were the main
Dutch specialty.

Edit: Found the post where RAM indicated 1.1 shells would enter testing 1931.
I also browsed NavWeaps to check the KGV's MV- 14"/45 :2,400. North Carolina with Mk8 shells meant for long range anti-deck : 2,300, and the Francesco Caracciolo is listed as slowest on the 381mm/40 at 2,297fps. I know the KG's were though accurate shooters, I haven't read complaints about the NC's, and Mass. did nail Jean Bart (ok, stationary)- but no idea how the Italian weapons fared on that monitor.
Anyhow the lowest practical limit would seem to be ~2,300-2,400fps- somewhat faster than 'toy' up there.

Kaiser Kirk

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Sunday, April 30th 2006, 7:27am

So, instead of using the ‘toy’ here’s a 360mm/52 which has two standard charges, one for 793mps, and one for 699mps.

Critical in all this is shell weight and what is “reasonable” for the Wesworld Dutch to have.
BigGun gives a default of:
WW1 “default” : 646kg
WW2 “default” : 698kg
Well the time frame is 1930…
1930 ‘default’….((698+646)/2) = 672 kg ?
Ave. Dutch oversizing 18.6% : 672 *1.186 = 828kg
which admittedly isn’t far off from the ‘superheavy’ but seems a logical extension of their past efforts.

Caliber = 36.0 cm (14.2 inch)
Shell weight = 828 kg (1825 lbs)
Muzzle velocity = 793 m/s (2603 fps)
Relative ballistic performance: 1.00
Muzzle energy = 260.6 megajoules = 96044.8 foot-tons
Relative muzzle energy: 1.05
Barrel length: 52 calibers
7.2 deg 12900 meters 50 cm
7.6 deg 13500 meters ... 6 cm
9.6 deg 16200 meters 45 cm
10.3 deg 17100 meters ... 8 cm
12.8 deg 19900 meters 40 cm
13.6 deg 20800 meters ... 10 cm
17.1 deg 24300 meters 35 cm
17.8 deg 25000 meters ... 12 cm
20.4 deg 27200 meters ... 14 cm

then with the sub-charge
Muzzle velocity = 699 m/s (2293 fps)
Relative ballistic performance: 1.00
Muzzle energy = 202.3 megajoules = 74551.3 foot-tons
Relative muzzle energy: 0.82

8.7 deg 12200 meters ... 6 cm
10.7 deg 14300 meters 40 cm
11.9 deg 15500 meters ... 8 cm
15.0 deg 18400 meters 35 cm
15.8 deg 19100 meters ... 10 cm
19.9 deg 22300 meters ... 12 cm
20.9 deg 23000 meters 30 cm
22.7 deg 24200 meters ... 14 cm
25.8 deg 26000 meters ... 16 cm

The difference is that the latter can penetrate expected enemy decks at the ranges one can actually fight in. From 26,000 down to 21,000 or so, they can use the subcharged version, once the range gets under 21,000 or so, they can switch to normal charges.


Sunday, April 30th 2006, 8:20pm

Looks good to me. A veritile weapon that can be effective within combat ranges.

As for it fitting on the ZP or the length of time the ships will need to stay in service, that would be for someone else to figure out. I was going to upgun the Chilean Dreadnoughts to 14 inch rather than the Nordmark 340mm, but more or less the difference in ability verses cost was not high enough.