More spread for naval 12" and 14" artillery?

[LemoN]

Well, I've toyed around with these a bit and noticed that the "spread" is so low it actually makes them far less effective than they could be.

One salvo (something like 8 to 10 rounds?) will always impact in an area roughly 2x2 action spots big. After that salvo is fired the next salvo will impact somewhere else and also hit only a small area. Here's the thing, the current naval arty has something like 70 rounds, just barely enough to saturate a large area with fire with the current "spread" of the rounds. I'd like to see the naval artillery fire less rounds but saturate a larger area.

[Paper Tiger]

Amen to that! I was fooling around with a 14" Battleship this afternoon in a mission I'm constructing and the shells landed very tightly. I got two salvoes: the first saw all the shells land within a very small space, 2-3 action spots, and the second came in elsewhere in the target area but again, very tightly grouped into 2x2 action spots. The same as you reported. This from a battleship about 14 miles from the target area. Is this realistic?

[YankeeDog]

Naval rifles were designed to be very accurate, since their primary mission was to hit other ships on the move at considerable distances. With this said, just because they are capable of firing very tight sheafs, doesn't necessarily mean that they would do so against a ground target. The FDC on board the BBs would certainly have capability to give each turret slightly different elevation/bearing settings to spread the shells out more.

I'm actually also not sure that BBs and Cruisers would usually fire full broadsides when firing indirect against ground targets; much of the footage I've seen of the U.S. Navy firing against ground targets (admittedly, mostly from the PTO) shows the big ships firing one turret, or even occasionally one gun, at a time. I do wonder if, for CM purposes, BB fire coming in as pairs of shells (representing one turret firing at a time) wouldn't be more realistic.

If my Grandfather was still alive, I would ask him -- he was a gunnery officer aboard the Heavy Cruiser U.S.S. Baltimore and saw action in the PTO. But he passed away a few years ago and I never got around to asking him this particular question.

[LemoN]

Naval rifles were designed to be very accurate, since their primary mission was to hit other ships on the move at considerable distances. With this said, just because they are capable of firing very tight sheafs, doesn't necessarily mean that they would do so against a ground target. The FDC on board the BBs would certainly have capability to give each turret slightly different elevation/bearing settings to spread the shells out more.

While they were designed to be very accurate, they were nowhere near as accurate as the game currently depicts at a range of 10-15 miles, especially not the WW1 guns we currently have in the game (12" and 14").

For instance:

As modernized in the 1980s, each turret carried a DR-810 radar that measured the muzzle velocity of each gun, which made it easier to predict the velocity of succeeding shots. Together with the Mark 160 FCS and better propellant consistency, these improvements made these weapons into the most accurate battleship-caliber guns ever made. For example, during test shoots off Crete in 1987, fifteen shells were fired from 34,000 yards (31,900 m), five from the right gun of each turret. The pattern size was 220 yards (200 m), 0.64% of the total range. 14 out of the 15 landed within 250 yards (230 m) of the center of the pattern and 8 were within 150 yards (140 m). Shell-to-shell dispersion was 123 yards (112 m), 0.36% of total range.

So, let's take the most accurate battleship guns ever made, use the 0.64% spread pattern, use a range of 15km and we still have a spread pattern of 100m. Now, with WW2 era stuff you'll probably be looking at at last 200m spread at that range, probably more for the older 12" and 14" guns.

[YankeeDog]

While they were designed to be very accurate, they were nowhere near as accurate as the game currently depicts at a range of 10-15 miles, especially not the WW1 guns we currently have in the game (12" and 14").

For instance:

So, let's take the most accurate battleship guns ever made, use the 0.64% spread pattern, use a range of 15km and we still have a spread pattern of 100m. Now, with WW2 era stuff you'll probably be looking at at last 200m spread at that range, probably more for the older 12" and 14" guns.

Overall, I absolutely agree with you; the shell dispersion of naval gun salvos in the game is far too tight. For starters, when firing indirect at distant shore targets I really don't think BBs would fire with the individual turrets converging; they would fire with the guns in parallel. So even if the guns were 100% precise and the shell impacts were an exact copy of the layout of the gun barrels on the ship, you'd expect the impact pattern to be dispersed in a line the length of the distance between the fore turret and the aft turret -- a distance of something like 100m on a ship like the USS Texas that supported the Normandy landings. The dispersion of BB salvos in the game appears to be significantly less than this. And of course, no gun actually has anywhere near this level of precision.

But in regards to the test you cite, it is important to recognize that the guns themselves didn't change at all from WWII to the 1980s, and actually changed only a little from WWI to WWII. The test you cite is looking at 15 shells fired from 3 barrels, so it's measuring the ability of the modern FDC system to compensate for barrel heating, rifling wear, etc., and get succeeding shells fired from the same barrels to fall as closely as possible to where the first shells fell. This is one of the areas where modern integrated digital/radar FDC systems that have gotten much more precise than the old analog systems.

But this is a little different than the shell dispersion of a single, full broadside. Here, you'd probably see less of a performance difference between 1944 and 1987. Now, on average, the 1987 fire control systems would probably be able to get the mean point of impact of this broadside much closer to the intended aim point, but the actual dispersion of the shells within a single broadside fired from cold guns would not be all that different from what could be accomplished in 1944.

[YankeeDog]

As a side note, other than the direct fire done during the first hours of the landings at Omaha (which in any event was not called in from spotters onshore), in my own perusal of the accounts of the history of the USS Texas (which are quite extensive and detailed), I've never found anything to suggest that her main battery was ever used for the kind of local support that would be represented in a CMBN scenario. She was actually only on station off the Normandy beaches from 6-8 June, and then again from from 11-18 June, though from what I've read she actually fired her 14" guns over the Normandy beaches for the last time on 16 June because after this date the front lines were beyond the range of her guns.

Later, she supported the assault on Cherbourg, but her entire action in that operation was limited to firing on shore batteries, and so is not relevant to CMBN.

To be sure, between 6-8 June she completely emptied her magazines of 14" shells, and nearly did did this again from 11-16 June, so that's a lot of 14" shells fired over the Normandy beaches. But from what I've read, after 6 June, all of her main battery fire missions were at deeper targets -- enemy held towns, suspected locations of German artillery batteries, etc., and usually directed by spotting plane.

I'm not as familiar with the action history of the USS Arkansas, but from what I have read, it's pretty similar. Overall, the inclusion of 12" and 14" naval support in CMBN is arguably not really justified at all from a strict realism standpoint. So BFC may not be interested in putting too much effort into refining the details of large caliber naval gunfire for the game. They're a bit of cotton candy added to the game for fun, not really an asset that needs to be careful, realistic representation to correctly model combat on the CM scale.

Always fun to play with the big guns, tho.

[Michael Emrys]

So much for the BBs (and BTW, that sounds about right to me). But what about the 6" and 8" cruisers? How much were they used in the US sector of the front as on-call direct support of ground forces? I am aware that naval spotters went in with the ground forces in order to provide that, some of them becoming early casualties in fact. But how much was really done? And the same question applies to DDs as well, although their shorter range would confine their support to pretty close to the shoreline.

Michael

[YankeeDog]

So much for the BBs (and BTW, that sounds about right to me). But what about the 6" and 8" cruisers? How much were they used in the US sector of the front as on-call direct support of ground forces? I am aware that naval spotters went in with the ground forces in order to provide that, some of them becoming early casualties in fact. But how much was really done? And the same question applies to DDs as well, although their shorter range would confine their support to pretty close to the shoreline.

Michael

I don't have a definitive answer, unfortunately. I've encountered numerous references to main battery fire from cruisers off Normandy being directed by "shore parties" -- much more so than with big guns of the Texas or Arkansas, but this still doesn't answer the question of how often this shore-directed fire was in direct, close support of ground combat, and how often it was fire sent deeply behind enemy lines, that was simply spotted from a convenient elevation on shore when visibility was good (or fired at distant enemy-held elevations that could be seen from far away).

It is worth noting that the main batteries of some of the cruisers off of Normandy actually had better range than the 14" guns of the Texas -- the Texas' main battery range was limited to 22,000 yds. because her turrets could only elevate 15 degrees (the theoretical range of the guns themselves was something like 35,000 yds., IIRC). Towards the end of her time off of Normandy, they actually deliberately flooded the torpedo blister on one side of the hull to induce a slight list and give her guns an additional 2 degrees of elevation. Not sure how much range this added... certainly not a huge amount.

But the 8" guns on the newer cruisers off Normandy, such as USS Quincy, which was a Baltimore Class Heavy cruiser, had a max range of a little over 30,000 yds. They also had newer and better fire control systems. So these cruisers were able to fire deeper inland, and do so more quickly and accurately, than the Texas.

Given all this, but lacking definitive information one way or the other, my SWAG is that the 8" cruiser main batteries were much more likely to have been used in close support of ground forces, though this was probably still fairly rare if it did happen -- an 8-in shell is a lot of boom to be dropping close to friendlies, and generally smaller calibers would have been tasked with close support.

As for the DDs, I have definitely read account of their guns being used in close support in the first few days of the invasion. Probably they weren't used much for shore support once a substantial number of 105mm and 155mm batteries were established ashore, though, as they really wouldn't offer any advantage. And there was a lot of need for the DDs to be doing convoy screening to protect against U-boats, E-boasts, etc. But it is worth noting that the range of the 5"/L38s on most of the U.S. destroyers actually was pretty darn good, partially because the dual purpose (surface/AA) turrets on most of the DDs could elevate to a full 45 degrees (and beyond) -- they had a max. range of over 15km.

[YankeeDog]

Whups, How could I forget about the USS Nevada, rescued from the mud of Pearl Harbor!

She was off of Utah for the first couple of weeks of the Normandy campaign, returned to fight off of Cherborg at the end of June, and also had 14" guns. While her original gun/turret design was very similar to that of the Texas, hers had been updated to allow more elevation and give her a much better range - 34,000 yds.

I did find one brief mention of her firing "within 600 yards of Allied front lines" during the Cherbourg fighting here:

http://www.globalsecurity.org/wmd/agency/ssbn-733.htm

But that's the best I've found so far, on the internet or in print, that supports the USN BB guns being used in close support of ground combat during the Normandy campaign.

[Michael Emrys]

Thanks for the info, YD. I will keep it in mind while playing.

Michael

[Calibration]

If you are interested in the details of the typical accuracy of US naval rifles up to WW2 see here.

http://www.navweaps.com/index_inro/INRO_BB-Gunnery_p1.htm

Scroll down to the table in note 26 and you will see that expected salvo pattern sizes were in the region of ~1.4 to 3.4% as percentage of range in 1944.