Heavy Secondary Guns

[Delta Force]

I was just wondering about how heavy a secondary gun can get before it conflicts with the operation of targetting the main gun. I know that during the dreadnought era heavy secondaries were abandoned for that reason, but such confusion will tend to happen when the shells are half the weight of the main battery. With main guns having much more power, would a return of 8 inch guns be feasible for warding off heavy cruisers and battlecruisers?

[miketr]

6" range is the upper limit I would say.

Michael

[Sachmle]

If what you're shooting at is too big for a 6" AP round to deal with, you should be shooting it with your main battery anyway. Not many ships were designed to fight 2 or more large targets at once. Theoretically, you could engage a BB with you main battery and an accompanying heavy cruiser with an 8" secondary, but  a 6" AP round should still get a heavy cruisers attention. If the cruiser is too armored for that 6" round to do damage, switch to HE and burn up the upper works, throwing off their shooting. If you have a large enough ship to mount 8+ main battery (12" or larger) AND enough 8" guns (at least 6 per side IMHO) to have effective fire control for those 8", than a heavy cruiser shouldn't bother you anyway as long as it's outside of torpedo range.

[P3D]

I was just wondering about how heavy a secondary gun can get before it conflicts with the operation of targetting the main gun. I know that during the dreadnought era heavy secondaries were abandoned for that reason, but such confusion will tend to happen when the shells are half the weight of the main battery. With main guns having much more power, would a return of 8 inch guns be feasible for warding off heavy cruisers and battlecruisers?

If you are putting 8" guns on the ship in any significant numbers, and armoring the turrets to any acceptable degree, you are already adding so much weight that an extra main gun turret would just make more sense.

[Kaiser Kirk]

While I am featuring 18cm secondaries, that is something of a deliberate error. 
It pencils out well, and so makes sense for a young navy, and may be superior in the opening minutes.
However they won't be as fast to train, and the heavy shells will wear out the gun crews in longer fights.

Again, on paper they look marginally superior- and may be in limited circumstances- after all,  the ability to engage & spot shell splashes at the limits of 18k FC is appealing.

OTL, 7" secondaries in the USN, 17cm in the German Fleet, 19cm in the Austrian were all tried and generally found a bit heavy.

So overall, for an experienced navy, I would think the 6" or less choice makes sense.

[Jefgte]

Actualy, for our Nverse, 6" for secondary is a classis heavier choice.
Some countries use smaller guns - 140mm-127mm-120mm.

These secondaries are made essentially to repulse DDs & Cruisers.

----------------
You could choose to have a big BB with 4T4x14"  & 2 fire control towers to engage 2 medium BBs or to "overgun" a classic 4T2x16" BB
We are in Nverse & we could imagine much different artillery installation.


Jef  ;)

[Kaiser Kirk]

Well..in my view... secondary guns come from two development fields in a way.

The first is a true secondary, devolved from the intermediate batteries of the predreadnaughts.  The High Seas fleet still expected their secondaries to be used in battleship actions, and had the "heavy" 6.75". In a way, those were to be "dual purpose" -  anti BB/AC and anti-DD.  For my Bavarians, I expect the 18cm to be used in large ship fights firing volleys of HE/SAP between main battery volleys.

The second is more common and as an evolution of anti-boat guns.  The Hotchkiss 47mm revolver cannon was ostensibly anti-boat gun...it was just too light. Then as torpedo boats got larger/faster and torpedoes had greater ranges,  you saw heavier and heavier. Dreadnaught had 12pdrs (3"), Revenge had 6".

I think the 140-127-120mm tendency is because we're looking back. However, if P3D is correct on the 'rule of thumb' for spotting shell splashes, then a 120mm gun is "only" useful out to 12km- and torpedoes have been able to be launched from beyond that since the 1913 tech, while Fire control went to 18km with the 1912 tech. 

Which I find vaguely humorous as it's a point in favor of my intended 18cm secondaries which I didn't even consider at the time.

[Sachmle]

Yes and no and the 120mm Kirk. Yes, they're hard to spot past 12-14kyds due to small splash. However, when fighting off a torpedo attack one doesn't take time to spot shell splashes and fire salvos, one fires full RoF and hopes the mass of shells hits something. This is why the 120mm, heavy enough to slow a DD in one hit, stop in 2-3, sink in 4-5, but firing much faster than a 150/140mm gun is a nice anti-DD weapon on smaller capital ships.

I intend mine to be the main weapon on my DDs, and a secondary on my BC. The BBs will still get the 130mm as it's not much slower RoF and has a 30kg shell over the 24kg of the 120mm for more stopping power. Once DDs get big enough (2,000-2,500t) I'll drop the 120mm altogether and put 130mm on the DDs too.

[Kaiser Kirk]

With DDs going from 750 to 1000 to 1500 tons... I think the ability of the 120mm to even slow will be diminished.

As for range- yes, once you have an idea of if you have the general range I would expect full fire. The first volleys I would expect ladders to help the FC crew call an actual range, then full volleys. Ladders won't be helping much if you can't pick out the individual splashes, and a head-on aspect for a DD will be hard to make a good purely optical solution either stereo or split.

[Sachmle]

With DDs going from 750 to 1000 to 1500 tons... I think the ability of the 120mm to even slow will be diminished.

And this will bare true in combat, and the 130 will replace the 120 in service. Until proven ineffective though, the theory of rapid fire medium weight shells will play out. I actually have no BCs on the block as of yet, so depending on news from China and Switzerland, combined with a review of the fighting off Afrika, we may well see the DKB drop the 120 from capital ships completely and just use the 130, leaving the 120 just to be mounted on DDs where weight is more of a concern.

[Kaiser Kirk]

It will be interesting to see it gamed out.
My little exercise at the end of the Bavarian battleship thread seemed to show the 18cm and 15cm breaking even for stopping a Destroyer charge, I don't think I considered 12cm in that effort <looks>...nope did not. 

The thing I found there was because the 18cm shell could engage at a longer range (bad shell form factors limited the guns, coincidentally to about 1km/cm) the slower 18cm fired longer and closer in benifited from better (flatter) trajectories, so  total # of hits was 18.8 for both the 18cm and 15cm. 

[miketr]

Just so people are aware what I am doing with FC when I sim battles is fire control of X generation doesn't effect range to shot it gives bonus to hit.  You might be able to fire out to 22,000 yards but without Director Fire Control you have horrible chances of hitting.  While 2nd Gen Fire control makes it possible to hit out that far with some chance of success.

Michael

[P3D]

Yes and no and the 120mm Kirk. Yes, they're hard to spot past 12-14kyds due to small splash. However, when fighting off a torpedo attack one doesn't take time to spot shell splashes and fire salvos, one fires full RoF and hopes the mass of shells hits something. This is why the 120mm, heavy enough to slow a DD in one hit, stop in 2-3, sink in 4-5, but firing much faster than a 150/140mm gun is a nice anti-DD weapon on smaller capital ships.

I intend mine to be the main weapon on my DDs, and a secondary on my BC. The BBs will still get the 130mm as it's not much slower RoF and has a 30kg shell over the 24kg of the 120mm for more stopping power. Once DDs get big enough (2,000-2,500t) I'll drop the 120mm altogether and put 130mm on the DDs too.

You would be wasting ammo if shooting at a target outside spotting range. The German doctrine for quick-firing (at least for battleships) was to spot until the range is found (target is straddled by the shots) then switch to rapid firing.
So you'd need to establish range first on the destroyers, and without spotting you could have errors of 500-1000 yards. And you would exhaust your ammunition with and RPM of 5-10 pretty fast.

IMHO differences between 12 and 13cm guns are marginal at most, and could be partially offset by designing a heavier HE shell for the 12cm.

[Delta Force]

Well, the reason why I am looking at the 8 inch gun is because it has superior armor penetration compared to the 5 inch and deck penetration fairly close to the 14 inch gun. The bursting charge is also much more powerful on an 8 inch shell. The only problem is that the train rate tends to be a lot slower than the 5 inch guns, around 3.5 to 6 degrees per second. I'm not sure how fast of a train rate is needed to take on a cruiser or destroyer though, but the 8 inch would have a range edge on the 5 inch guns, so perhaps it could take out the ships before they could close close enough for that to be a problem.

[snip]

Really, if you are going to be taking on ships at the range were an 8" gun would be more effective then a 5" gun, then you should just be using you main guns. Like P3D pointed out earlier, in armoring the 8" guns in the numbered needed for the roles you want them for, an additional main gun turret could most likely be fitted. More main guns is generally better as they are more useful and having a uniform battery helps with effective fire control. In the pre-Dreadnaught era, your approach would be a valid one, but with the tech level we have now, and with what other nations have put on the water, this concept is hopelessly obsolete.