Interesting Battleship gun facts

[Guest]

Battleship guns are just devices for throwing projectiles. The natural measure of such a device would be how fast and how heavy a projectile it can throw, how accurately it can throw them, and how many times it can thrown them before it is too worn to throw them effectively.

How fast and how heavy a projectile a gun can throw can be, slightly simplistically, rolled into the single measure of how much muzzle kinetic energy the gun can impart on a projectile.

Here are some results from my claculation of major WWII battleship gun's kenetic energy with APC shell, units in Joules, descending order

British experimental 18"/45 intended for N-3 battleship: 4.92e8
Japanese 18"/45 guns for Yamato: 4.4e8
US 16"/50 MKVII for Iowa and Montana: 3.28e8
Italian 15"/50 for Littorio: 3.23e8
French 15"/45 for Richeliu: 3.04e8
British 16"/45 for Nelson: 2.88e8
German 15"/47 for Bismark: 2.69e8
British 15"/42 for Hood: 2.68e8
British 14"/45 for KGV: 1.93e8

Several interesting observations:

1. It appears the British 18"/45 caliber gun originally intended for the N-3 class battleship is, by the measure of the kenetic energy it imparts to its intended APC shell, the most powerful naval ever seriously intended for installation afloat, nearly 10% more powerful than Yamato's 18" gun of 15 years later. Both 18" guns enjoy a very large margin of superiority, >30%, over any other gun in kenetic energy imparted.

2. Italian 15"/50 cal gun is very nearly as power as America's much praised 16"/50 MKVII used on the Iowas, and a full 20% more powerful than Bismark's 15"/47. French 15"/45 caliber gun is also quite powerful. Both were significantly more powerful than Nelson's 16"/45 guns.

3. German 15"/47 gun used in Bismark is only very slightly stronger than Hood's 15"/42, despite being 20 years later.

4. British 14"/45 used on KGV is quite weak, about 25% weaker than Hood's 15"/42.

Next I calculate how weight efficient the gun is in imparting the kenetic energy to the shell by dividing the muzzle kenetic energy by the gun weight, including breech mechanism. Joules / KG of gun weight, in descending order:

French 15"/45 for Richeliu: 3234
British experimental 18"/45 intended for N-3 battleship: 3043
Italian 15"/50 for Littorio: 2863
US 16"/50 MKVII for Iowa and Montana: 2700
Japanese 18"/45 guns for Yamato: 2697
British 15"/42 for Hood: 2641
British 16"/45 for Nelson: 2628
German 15"/47 for Bismark: 2423
British 14"/45 for KGV: 2406

Some more interesting results:

1. The French gun for Richelieu was by far the most efficient gun in terms of weight of the gun versus the muzzle kenetic energy it imparts on its APC projectiles.

2. British 18"/45 intended for N-3 again scored very highly

3. Italian 15"/50 rounds out top 3.

4. The much praised US MKVII 16"/50 is almost indistinguishable from the Japanese 18"/45 in weight efficiency, despite the popular image in the states that praises the Iowa guns and pan the Japanese gun. Perhaps projectile design distinguishes the effects, but the efficiency of the guns themselves are almost equal, with Japanese 18"/45 gun fully justifying its increased bulk and weight over the US 16"/50.

5. The Japanese 18"/45, the US 16"/50, the old British 15"/42, and Nelson's 16"/45 are cluster about each other in efficiency, very nearly comparable to each other, differing by less than 3% from the most to the least, where as the top 3 guns were quite spread out, with the French gun almost 15% more efficient than any in this cluster.

6. KGV's 14"/45 and Bismark's 15"/47 both scored badly, but only a little worse than the big cluster described in 5.

These measures purely measure how hard each gun can throw shell, and how much the guns weigh compare to how hard they throw their shells. It does not measure accuracy or longevity.

[Guest]

I guess the conclusion is the british 18"/45 gun killed by Washington was indeed an hidden gem that never had the opportunity to show its excellence. Even discounting its caliber advantage, pound for pound it still would have been a good gun 20 years after it was designed.

French and Italian naval guns are very seriously underestimated, they are in fact amongst the best in the world in performance, while Bismark's guns, glory of Krupp not withstanding, were sub-standard and quite seriously overrated.

Iowa's 16"/50 caliber guns are also somewhat overrated in the US, its performance, in relation to its weight and size, is entirely average when compared to other contemporary guns. Yamato's 18" guns scored about as well on a ton-by-ton basis.

British guns, with exception of the 18"/45, generally scored poorly in performance and weight efficiency.

[Foeth]

This is all fascinating, but without taking the shell design into account rather meaningless. I could throw 10E9J worth of pecan pie without damaging anything other than the pie. Having a good weight ratio isn't worth much if you can't penetrate armour. The Italian gun was both inaccurate as well as prone to wear. The size of the charge and the weight of the shell may have been a design choice. Also, the twin turret design on Bismarck could fire in 2/3's of the time of most other tripples.

[Tiornu]

I could throw 10E9J worth of pecan pie without damaging anything other than the pie.

Believe me, I've tried.
Using various possibilities for the British 18in/45 shell and velocity, I get a consistent advantage in ME for Yamato's 46cm gun of roughly 2-4%. I used 2565fps for Yamato and these figures for the British gun:
2837 lbs at 2700fps
2916 lbs at 2650fps
3320 lbs at 2500fps
However, my math skills are are, well...did I say "skills"?

[Laurence Batchelor]

I guess the conclusion is the british 18"/45 gun killed by Washington was indeed an hidden gem that never had the opportunity to show its excellence. Even discounting its caliber advantage, pound for pound it still would have been a good gun 20 years after it was designed.

French and Italian naval guns are very seriously underestimated, they are in fact amongst the best in the world in performance, while Bismark's guns, glory of Krupp not withstanding, were sub-standard and quite seriously overrated.

Iowa's 16"/50 caliber guns are also somewhat overrated in the US, its performance, in relation to its weight and size, is entirely average when compared to other contemporary guns. Yamato's 18" guns scored about as well on a ton-by-ton basis.

British guns, with exception of the 18"/45, generally scored poorly in performance and weight efficiency.

I believe Britain had major problems with these guns however.
Constructional/design problems, problems inside the barrel through getting worn out too quickly and also poor accuracy.
All of this led them to believe that any future gun larger than 16", they believed had to be constructed differently and all of the above overcome.
They were amazed to find 25 years later of course the Japanese had.

[Vlad]

slight nitpick point, but the Bismarck guns are actually 52 calibers long, not 47. they are 38cm/52 (or approximately 14.96"/52)

[Werner]

Chuck: just a curiosity: what is your formula? It would seem to me (and General Bull) that chamber volume and caliber in length are the governing factors here.

If I had a 16-inch/50 with full charge, reduced charge and the 16/45 bag charge, I get three distinct muzzle velocities as measured by doppler radar, which translates to distinctly different muzzle energies.

That big bright flash from the gun is the garland of inefficiency for the designer. It is wasted propellant.

The USN 8-inch with identical propellant flies at different speeds, angles nd ranges depending on whether the tip is 4 or 6 caliber-radius.

You can't make more than the most basic calculations based in these calculations.

Mr. ar has a table in one of his books which is more interesting. It shows the striking energy and angle for these guns, which reorders them substantially.

[Guest]

I could throw 10E9J worth of pecan pie without damaging anything other than the pie.

Believe me, I've tried.
Using various possibilities for the British 18in/45 shell and velocity, I get a consistent advantage in ME for Yamato's 46cm gun of roughly 2-4%. I used 2565fps for Yamato and these figures for the British gun:
2837 lbs at 2700fps
2916 lbs at 2650fps
3320 lbs at 2500fps
However, my math skills are are, well...did I say "skills"?

I used 1506 KG (3320 lbs) for British APC 18" shell, firing at 762m/s (2500 fps).

I used 1460 KG (3219 lbs) for Japanese APC 18" shell, firing at 780 m/s (2559 fps).

Applying KE = 0.5*Mass*Velocity*Velocity, I get 4.37e8 Joules for the Japanese gun, and 4.44 e8 Joules for the British gun.

-Chuck

[Guest]

slight nitpick point, but the Bismarck guns are actually 52 calibers long, not 47. they are 38cm/52 (or approximately 14.96"/52)

That's because the Germans count the start of the barrel length from a different point than the British.

[Guest]

Believe me, I've tried.
Using various possibilities for the British 18in/45 shell and velocity, I get a consistent advantage in ME for Yamato's 46cm gun of roughly 2-4%. I used 2565fps for Yamato and these figures for the British gun:
2837 lbs at 2700fps
2916 lbs at 2650fps
3320 lbs at 2500fps
However, my math skills are are, well...did I say "skills"?

I used 1506 KG (3320 lbs) for British APC 18" shell, firing at 762m/s (2500 fps).

I used 1460 KG (3219 lbs) for Japanese APC 18" shell, firing at 780 m/s (2559 fps).

Applying KE = 0.5*Mass*Velocity*Velocity, I get 4.37e8 Joules for the Japanese gun, and 4.44 e8 Joules for the British gun.

-Chuck

I might have accidentally mixed up a heavier shell weight with the muzzle velocity of the lighter shell in the first calculation, but the style still remains, with consistent velocity and shell weight, the British 18"/45 was more powerful than the Japanese 18"/45.

- Chuck

[Guest]

This is all fascinating, but without taking the shell design into account rather meaningless. I could throw 10E9J worth of pecan pie without damaging anything other than the pie. Having a good weight ratio isn't worth much if you can't penetrate armour. The Italian gun was both inaccurate as well as prone to wear. The size of the charge and the weight of the shell may have been a design choice. Also, the twin turret design on Bismarck could fire in 2/3's of the time of most other tripples.

Well, it still pays to discover who designed the best gun independent of the shell.

Reliable numerical data on gun accuracy is hard to come by, and it is not clear to me what standard is being applied for barrel life and whether the same standard is applied to all nations. But yes, the Italian gun is reputed to suffer from excessive dispersion and short barrel life.

[ingura]

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[Guest]

German 406 mm SK C/34 intended for the H-class weighted 159,000 KG including the breech, which is very heavy for a 16" gun and much closer in weight to Yamato's 168,000 KG 460mm gun than to USN's 127,000 KG 16"/50 MKVII.

It fired a 1030 KG shells which is quite light for a 16" gun. But its muzzle veolocity of 810m/s is also quite high.

The muzzle KE is 3.37e8 Joules, which makes it slightly more powerful than US 16"/50 MKVII, and the most powerful naval gun less than 18". But it's weight to KE ratio is 2125, which is very poor.

In conclusion, it is a quite a powerful gun both overall and for its caliber, but not quite as powerful on a caliber by caliber basis as the Italian 15"/50. However, the German gun was also exceptionally heavy, much heavier than other 16" guns and almost as heavy as 18" guns. But it was not nearly as powerful as any 18" gun. So on the basis of its great weight, it was in fact the least weight efficient gun we've seen.

[Tiornu]

One interesting thing about the German 16in gun is that the shell is actually heavy by German standards. A 16in shell proportionally equal to Bismarck's 15-inchers would weigh about 2140 lbs.

[ingura]

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[Guest]

Did I miss something? The diagram above tells us the data for the coastal use of the 16" gun speaking about 940 m/s muzzle velocity and 600 kg shell weight...

I'm confused...

For that gun I am using values provided http://www.NavWeaps.com. The values of 1030 kg and 810 m/s are much more believable for a ship mounted naval gun of WWII because it falls much closer to the typical values encountered. 600KG would be an extraordinarily light weight for a 16" ship board APC shell. USN's 16"APC shell weigh over twice as much. 960 m/s would also be a unprecedented muzzle velocity for a major caliber gun firing a full sized APC shell.

Using your data the new kinetic energy of that gun would only be 2.76e8 Joules, which is a substantial reduction from the value derived from its original naval shell weight and muzzle velocity. This suggests that propellant charge has been reduced to achieve the performance you describe, with the added muzzle velocity only made possible through drastic cuts in shell weight.

I suspect in coastal applications the gun was retuned to fire a much lighter projectile using a slightly smaller propellant charge, to achieve the twin aims of longer range and longer barrel life. Afterall, the chance the gun will be called upon to fight another fully armored battleship would seem to have been reduced by its installation at a coastal defense position.

[Tiornu]

In its coast-defense role, the gun could use the 1030kg shells intended for service afloat, or they could use a 600kg HE shell. Campbell says the MV for it was 1050m/s giving a maximum range of 56,000m. (I'm guessing this implies a gun elevation near 45deg.) The velocity indicated in your graph may refer to a worn barrel, or the gun may have been calibrated for different propellant charges.

[Rodders]

I have been led to believe that the British 15" naval gun was the best gun produced for the RN. It was a simple design and became the most reliable gun in the RN armoury and equal to any other 15" in any navy.
What let this gun down were the crappy shells produced for them. Better shells would have devastated the German fleet at Jutland as they would have got into the ships vital areas before detonating instead of breaking up and only partially detonating.
The 16" and 14" gave considerable trouble on their introduction with the Nelson and King George V classes and there were gun makers engineers aboard Prince of Wales during her engagement with Hood against the Bismark trying to rectify inherant gun problems. That engagement was the first time her guns were fired in anger as they say, and after an initial shot most of the guns were unable to be loaded again straight away as intended.
The 16" and the 14" were a direct result of the Yanks sticking their noses in and telling everyone what to do at the Washington Treaty Talks.
Mind you, no change there to this day, eh?

[Werner]

The 16" and the 14" were a direct result of the Yanks sticking their noses in and telling everyone what to do at the Washington Treaty Talks.
Mind you, no change there to this day, eh?

The 14-inch was a compromise position because the British demanded a maximum 12-inch caliber, and the Americans insisted on 16-inches. The 14-inch was acceptable to the USN because they had a fine 14-inch/50, and the negotiators believed the British would not go through the development effort for a new gun, and adopt the existing 13.5-inch gun instead.

Britain, seeing the need for numbers rather than individual ship qualities, went to Washington hoping for battleship limits of 25,000 tons and 12-inch guns.

[Guest]

I have been led to believe that the British 15" naval gun was the best gun produced for the RN. It was a simple design and became the most reliable gun in the RN armoury and equal to any other 15" in any navy.

Equal is a dangerous word especially when the specific characteristics are so different. Equal in what specific way? By judiciously tweeking the weight one gives to each characteristic of a gun while keeping in mind the result one would like to see, one could make any weapon seem equal to or superior to any other weapon in the final tally.

In terms of power, The British 15" gun is considerably inferior to every other 15" naval gun that ever saw service, except for the WWI German 15" gun on the Baden class.