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LittleWhiteMouse

Examples of Battleship Dispersion at Close Ranges

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Vertical dispersion has remained a black box -- one of the few mechanics not fully understood in World of Warships.  It is poorly understood and discussions are so often plagued with anecdotes rather than evidence.  I thought to take some steps and measures to correct this and decided to compile some examples of dispersion at closer ranges.  This was initially inspired to put to rest in my own head the "myth" of close-range Soviet battleship dispersion. I wanted to see how good it was but this required us having a battleship with comparable ballistics to get a good example of this.  Similarly, I wanted to examine battlecruiser dispersion at close ranges and see how it compared.  With the ships released in 2020, we now have those ships to provide an accurate comparison.  Sovetsky Soyuz provides Soviet battleship dispersion with her premium sister-ship, AL Sovetskaya Rossiya providing American battleship dispersion.  On the battlecruiser side of things we have Siegfried (which uses cruiser rather than battlecruiser dispersion) paired off with Bismarck and her American battleship dispersion.

The following dispersion maps were made firing 180 AP shells at a stationary Fuso bot.  Shots are coming in from right to left (Fuso is effectively bow-tanking).  Target was locked on and firing ships were using the Aiming System Modification 1 upgrade.

J2DT6Gf.jpg
Sovetskaya Rossiya at 15km.

EoqVSt1.jpg
Sovetsky Soyuz at 15km

As you can see, the two Soviet battleships have comparable dispersion areas.  The sigma value between the two ships differs, but this does not influence the overall dispersion area.  Once things get in close, something weird happens and all comparisons go right out the window.


4z4PGMr.jpg
Sovetskaya Rossiya at 5km.

F3Jv5Vp.jpg
Sovetsky Soyuz at 5km

The smaller horizontal dispersion area of Sovetsky Soyuz also translates to a smaller vertical dispersion area.  What's strange is that the vertical dispersion length for Sovetskaya Rossiya increases while Sovetsky Soyuz's does not.  This could be owing to a small sample size (only 180 shells fired) but I remain doubtful.  We can conclude that ships using Soviet battleship dispersion do have a much tighter shell grouping at close ranges, however and are much less likely to overshoot / undershoot their aim point.  This correlation between smaller horizontal dispersion values and tighter close-range dispersion carries over with cruiser dispersion.

LCMqoTh.jpg
Pommern at 15km

sNlobie.jpg
Siegfried at 15km

I'm fudging a little with this one, though not by much.  Pommern has the same guns as Bismarck.  The only Bismarck at 15km dispersion area I had on file predated her switch over from French-Italian battleship dispersion to her new American dispersion.  So I pulled out Pommern as my comparison simply because she's the most recent.  Each one of these dispersion maps takes about 2 hours to put together, so I hope you understand this lapse.  Anyway, there's no comparing the two ships.  Cruiser dispersion is hella good at 15km, making a mockery of everything seen so far.

SYt4YQf.jpg
Bismarck at 5km

VOPqKac.jpg
Siegfried at 5km

At 5km, Bismarck's vertical dispersion doesn't seem to have changed very much, increasing by only a small margin.  Siegfried suffers the same. 

Conclusions

So what can we draw from this?

  • Mapping these SUCKS.  Seriously, as rewarding as these are to look at when they're done, they're a multi-step process I abhor.  It takes forever, so much can go wrong and you never know if it's worthwhile until they're finally done. 
  • It's nigh impossible to determine shell fall while looking down the gunsights.  Seriously, the skewed perspective makes it very difficult to tell where anything is landing.  Thus what you "feel" might be wonky dispersion could in fact be very tight.  Similarly good dispersion might actually be far worse than you imagined. Watch your replays.
  • Tighter Horizontal dispersion values at close range correlates to tighter vertical dispersion.  This honestly surprised me. I held the (mistaken) belief that shell velocities and flatter trajectories would influence vertical dispersion more at very close ranges but that does not appear to be the case.

Honestly though, more testing and examples are needed.  Roma would be an excellent candidate to verify if the above statements are true.  Similarly I want to test Slava and Thunderer for actual battlecruiser examples.

 

 

Edited by LittleWhiteMouse
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Nice write up. I've never understood how the game codes battleship accuracy. Just put it down to luck/rng. My New Mexico missed every single shell yesterday at a stationary, Sideon Baltimore at 8km... Could only laugh at the drunken gunnery skills.

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Once again LWM,

Great stuff.  Your analytics are excellent and thanks!

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3 minutes ago, LunchCutter said:

Nice write up. I've never understood how the game codes battleship accuracy. Just put it down to luck/rng. My New Mexico missed every single shell yesterday at a stationary, Sideon Baltimore at 8km... Could only laugh at the drunken gunnery skills.

Or Italian battleship shell quality control.

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Ah, glad you're getting a chance to test this.

I've been trying to work out why very low tier battleships feel so inaccurate despite their horizontal dispersion formula, sigma and number of guns are sometimes not being not far removed from top tier (Dreadnought and Conqueror both with 1.8 sigma).
They're not running Aiming Systems Mod 1 but their targets also don't have Concealment module or even often camo.

Ships at low tier *are* significantly smaller which might account for it, but it still seems more than this.
From the How it Works video on dispersion it claims that *every turret* creates it's own dispersion ellipse when a salvo is fired, but I'm unsure how close you'd have to be for these to get properly wonky compared to where you think you're aiming at. 

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In a quick examination of this photos (and thanks so much for preparing) the mathematical relationships between horizontal and vertical dispersion can be discerned. Horizontal dispersion is reported a linear function in mathematical terminology of the form:

y = mx + b

Where:

y = dispersion

x = range

m = factor applied to x 

b = fixed minimum dispersion at distance zero (arguably the distance between the front and back turrets when firing a broadside salvo)

The effect of this equation that some ships have a very tight horizontal dispersion at close range (Kremlin, for example) whereas others (Slava) had a signficantly greater dispersion at very close ranges. The "m" factor though controls the dispersion at distance with Slava essentially maintaining its rather broad dispersion at close range to the far distance resulting in very much tighter dispersion that ships (again like that Kremlin) that has a comparatively large "m" factor.

(the sigma defines the distribution of the shells falling along this project center line)

The vertical dispersion shown above though does not seem to have any "m" factor at all and is essentially "zero" (0) as the distribution does not materially increase with distance nor decrease at close ranges. Basically rather than a y = mx + b relationship this equation changes to y = b (as zero times distance obviously equals 0). It sure would be nice if WG reported the "b" value used for various ships as that would allow us to better understand overall shell accuracy.

(I seem to have run out of "Thanks" or "Thumbs up" notifications, but please consider yourself thanked!!!)

Edited by DJC_499
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1 hour ago, DJC_499 said:

The effect of this equation that some ships have a very tight horizontal dispersion at close range (Kremlin, for example) whereas others (Slava) had a signficantly greater dispersion at very close ranges. The "m" factor though controls the dispersion at distance with Slava essentially maintaining its rather broad dispersion at close range to the far distance resulting in very much tighter dispersion that ships (again like that Kremlin) that has a comparatively large "m" factor.

(the sigma defines the distribution of the shells falling along this project center line)

The vertical dispersion shown above though does not seem to have any "m" factor at all and is essentially "zero" (0) as the distribution does not materially increase with distance nor decrease at close ranges. Basically rather than a y = mx + b relationship this equation changes to y = b (as zero times distance obviously equals 0). It sure would be nice if WG reported the "b" value used for various ships as that would allow us to better understand overall shell accuracy.

Yep.
Interesting point about vertical dispersion not changing much (at all?) with range, it's been something I've always assumed it would do.

The horizontal dispersion fomulas are on the wiki. And follows exactly that.
Russian battleship dispersion is [(Range in km) x 11.9m + 33m] vs US Battleship [(Range in km) x 10m + 60m ] vs Slava [ (Range in km) x 5m + 105m]

There are currently 11 horizontal dispersion formulas I'm aware of.

Spoiler


Destroyers and IJN CAs        (Range in km) x 7.5m + 15m                128m@15km                
All destroyers of all tiers and nations σ2.0.
All IJN cruisers except Mogami mounted with the 155mm guns
Premium US Cruisers: Albany σ2.0?, Atlanta σ1.7, Flint σ1.7? 
Premium Russian cruiser tIII Aurora σ2.0?, tX Smolensk σ2.0, 
Premium French cruiser: tX Colbert σ2.0

IJN cruisers got buffed to destroyer dispersion back in patch 0.7.11 - Zao might have had it earlier

Cruisers                          (Range in km) x 6.9m + 33m                137m@15km
All cruisers Tier I to Tier VIII cruisers unless otherwise mentioned.        σ2.0
All cruisers Tier IX and Tier X cruisers unless otherwise mentioned.      σ2.05
IJN Cruiser: tVIII Mogami mounted with the 155mm guns (σ2.0?)
UK Premium Cruiser: tVIII Cheshire        σ2.05
US Premium Cruiser: tIII St. Louis σ1.8, tIII Charleston σ1.8, tVIII AL Montpelier σ2.15
German Premium Cruiser: tIX Siegfried σ2.05 (with 380mm guns, yes really)

Azuma and Yoshino Dispersion         (Range in km) x 9.5m + 15m                158m@15km
IJN Premium Cruisers: tIX Azuma σ2.05,  tX Yoshino σ2.05 

Graf Spee/Battlecruiser Dispersion     (Range in km) x 8.4m + 48m        174m@15km
German Premium Cruisers: tVI Admiral Graf Spee σ1.9, tIX Agir σ2.05
US Premium Cruiser tIX Alaska σ2.05
Russian Premium Cruiser: tX Stalingrad  σ2.65
US Premium Battleships: tVII Florida σ1.7, tIX Georgia σ1.8
UK Premium Battleship: tX Thunderer σ1.9
French Premium Battleship: tVIII Champaign σ2.0

"Slava Dispersion"        (Range in km) x 5m + 105m                        180m@15km
Russian Premium Battleship: tX Slava σ1.9
I've seen Slava's dispersion described as getting better at long range but I assume this is just hyperbole. It does only gain 5m per km however.

"Mikasa Dispersion"                (Range in km) x 7.7m + 69m                185m@15km
Premium IJN Battleship: tII Mikasa σ1.8
A shock to anyone who has ever actually tried to shoot anything with Mikasa...

"Japanese Battleship Dispersion"        (Range in km) x 7.2m + 84m        192m@15km
Techtree IJN  Battleships: tIII Kawachi σ1.8,  tIV Myogi σ2.0, tV Kongo σ1.8, tVI Fuso σ1.5, tVII Nagato σ2.0, tVIII Amagi σ1.8, tIX Izumo σ2.0, tX Yamato  σ2.1
Premium IJN  Battleships: tIV Ishizuchi        σ2.0, tVI Mutsu σ1.8, tVII Ashitaka σ1.8, tVIII Kii        σ1.7, tVIII Ignis Purgatio/Ragnarok σ1.9, tIX Musashi σ1.8, tX Shikishima  σ2.1
Pan Asian Premium Battleship: tIX Bajie  σ2.1

"Warspite Dispersion"                                 (Range in km) x 10.3m +51m                206m@15km
UK Battleship: tVI Queen Elizabeth σ2.0
UK Premium Battleships: tVI Warspite σ2.0, tVII Hood 1.9s, tVIII Vanguard σ2.0
US Premium Battleship: tX Ohio σ2.0

"American Battleship Dispersion"                            (Range in km) x 10m + 60m        210m@15km
US Battleships: tIII South Carolina σ1.9, tIV Wyoming σ1.5, tV New York σ1.8, tVI New Mexico σ1.5, tVII Colorado σ2.0, tVIII North Carolina σ2.0, tVIII Kansas σ1.5, tIX Iowa σ1.9, tIX Minnesota 1.8, tX Montana σ1.9, tX Vermont σ1.95
US Premium Battleships: tIV Arkansas Beta σ1.5, tV Texas σ1.8, tV Oklahoma σ1.8, tVI Arizona σ1.8, tVI W. Virginia 1941 σ1.8, tVII California σ1.9, tVIII Alabama σ1.9, tVIII Massachusetts σ1.7, tIX Missouri σ1.9
US Premium Cruiser: tX Puerto Rico  σ2.2
UK Battleships: tIII Bellerophon σ1.8, tIV Orion σ1.6, tV Iron Duke σ1.8, tVII King George V σ1.8, tVIII Monarch σ1.8, tIX Lion σ1.8, tX Conqueror σ1.8
UK Premium Battleships: tIII Dreadnought σ1.8, tVII Duke of York σ1.8, tVII Nelson σ1.9
German Battleships: tIII Nassau σ1.8, tIV Kaiser σ1.8, tV König σ1.8, tVI Bayern σ1.8, tVII Gneisenau σ1.8, VIII Bismarck σ1.8, tIX Friedrich der Große σ1.8,  tX Großer Kurfürst σ1.8
German Premium Battleships: König Albert σ1.8, tVI Prinz Eitel Friedrich  σ2.0, tVII Scharnhorst  σ2.0, tVIII Tirpitz σ1.8, tVIII Odin σ2.0, tIX Pommern σ1.5
Russian Premium Battleships: tIV Nikolai I σ2.0, tV Oktyabrskaya σ1.8, sVII Poltava σ1.7, tIX AL Sov. Rossiya σ1.8
Russian Premium Cruiser: tIX Kronstadt σ2.05

"Russian Battleship Dispersion"                                               (Range in km) x 11.9m + 33m        212m@15km
Russian Battleships: tIII Knyaz Suvorov σ1.5, tIV Gangut σ1.4, tV Pyotr Velikiy σ1.7, tVI Izmail σ1.6, tVII Sinop σ1.5, tVIII Vladivostok σ1.6, tIX Sovetsky Soyuz σ1.7, tX Kremlin σ1.8
Russian Premium Battleships: tVIII Lenin σ1.7

"The Dispersion formerly known as German Battleship"            (Range in km) x 9.8m + 66m           213m@15km
French Battleships: tIII Turenne σ1.8, tIV Courbet σ1.8, tV Bretagne σ1.8, tVI Normandie σ1.6, tVII Lyon σ1.5, tVIII Richelieu σ1.8, tIX Alsace σ1.6, tX Republique σ2.0
French Premium Battleships: VI Dunkerque σ1.7, VIII Gascogne σ1.9, VIX Jean Bart σ1.9, tX Bourgogne σ1.8
Italian Premium Battleships: tV Giulio Cesare σ1.9, tVIII Roma/AL Littorio σ1.8
Pan European Premium Battleship: tV Viribus Unitis σ1.8

 

Edited by SoothingWhaleSongEU
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55 minutes ago, LittleWhiteMouse said:

This correlation between smaller horizontal dispersion values and tighter close-range dispersion carries over with battlecruiser dispersion.

LCMqoTh.jpg
Pommern at 15km

sNlobie.jpg

Isn’t Siegfried unique among the supercruisers in game in that she utilizes the standard cruiser dispersion curve rather than the supercruiser/battlecruiser dispersion formula, just as Puerto Rico utilizes the USN/UK/KM battleship curve?

Edited by Nevermore135
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3 minutes ago, Nevermore135 said:

Isn’t Siegfried unique among the supercruisers in game in that she utilizes the cruiser dispersion curve, just as Puerto Rico utilizes the USN/UK/KM battleship curve?

Correct!  Lemme remove the "battle" thingie.

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These results are so weird that it is hard to imagine the Fuso is bow tanking. I would say it was broadside. There wasn't a lot of difference in horinzontal dispersion for the russians BB, only vertical dispersion

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9 minutes ago, WarStore said:

These results are so weird that it is hard to imagine the Fuso is bow tanking. I would say it was broadside.

Angle of target has no bearing no shell dispersion.

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1 minute ago, Lert said:

Angle of target has no bearing no shell dispersion.

It is seems as the shells as coming from top to bottom, not right to left. That is what I mean

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The low vertical dispersion of Soviet BBs helped them delete anything that gave them their broadside. However, when enemy ship bow-on or begin to angle, their shell will shatter to enemy belt. USN BBs and their super heavy AP shells have best vertical penetration in game and their floating arc give them ability to plugin-fire even when enemy ship bow-on I used to citadel bow-on Bismarck by Mass and citadel bow-on Musashi by Georgia at 7 km by plugin-fire through their deck under their first main gun turret. 

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15 minutes ago, WarStore said:

These results are so weird that it is hard to imagine the Fuso is bow tanking. I would say it was broadside. There wasn't a lot of difference in horinzontal dispersion for the russians BB, only vertical dispersion

Yeah I think on first glance most of us assume that LWM's dispersion tests are fired at a broadside rather than nose-on Fuso because it looks so weird compared to what we see in game (as LWM says).

We know shots over and under shoot but it's not so clear how much by, compared to it being very obvious with wonky horizontal salvos.

Edited by SoothingWhaleSongEU

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5 hours ago, SoothingWhaleSongEU said:

Ah, glad you're getting a chance to test this.

I've been trying to work out why very low tier battleships feel so inaccurate despite their horizontal dispersion formula, sigma and number of guns are sometimes not being not far removed from top tier (Dreadnought and Conqueror both with 1.8 sigma).
They're not running Aiming Systems Mod 1 but their targets also don't have Concealment module or even often camo.

Ships at low tier *are* significantly smaller which might account for it, but it still seems more than this.
From the How it Works video on dispersion it claims that *every turret* creates it's own dispersion ellipse when a salvo is fired, but I'm unsure how close you'd have to be for these to get properly wonky compared to where you think you're aiming at. 

I might be able to help you there, having calculated the maximum turret angles of a sample set of ships.  Hood I used for large distance between turrets, Colorado for average, and Nelson for short.  Here are those angles:
image.png.4a0fa44d1e449f71190c70b2717daf09.png

And here's what that actually looks like with ellipses (though not scaled to each ship's dispersion)
image.png.e78af05e78f51dc473a47d3fe2e1ec40.png

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1 hour ago, thegamefilmguruman said:

I might be able to help you there, having calculated the maximum turret angles of a sample set of ships.  Hood I used for large distance between turrets, Colorado for average, and Nelson for short.  Here are those angles:
image.png.4a0fa44d1e449f71190c70b2717daf09.png

And here's what that actually looks like with ellipses (though not scaled to each ship's dispersion)
image.png.e78af05e78f51dc473a47d3fe2e1ec40.png

This is very useful...I thought the difference between the ellipses of the turrets would be more significant. Long ships (or those that have a LOT of guns) seems to be affected more by this). But at nominal engagement distances it seems to be a non-issue.

6 hours ago, SoothingWhaleSongEU said:

Yep.
Interesting point about vertical dispersion not changing much (at all?) with range, it's been something I've always assumed it would do.

The horizontal dispersion fomulas are on the wiki. And follows exactly that.
Russian battleship dispersion is [(Range in km) x 11.9m + 33m] vs US Battleship [(Range in km) x 10m + 60m ] vs Slava [ (Range in km) x 5m + 105m]

There are currently 11 horizontal dispersion formulas I'm aware of.

  Reveal hidden contents


Destroyers and IJN CAs        (Range in km) x 7.5m + 15m                128m@15km                
All destroyers of all tiers and nations σ2.0.
All IJN cruisers except Mogami mounted with the 155mm guns
Premium US Cruisers: Albany σ2.0?, Atlanta σ1.7, Flint σ1.7? 
Premium Russian cruiser tIII Aurora σ2.0?, tX Smolensk σ2.0, 
Premium French cruiser: tX Colbert σ2.0

IJN cruisers got buffed to destroyer dispersion back in patch 0.7.11 - Zao might have had it earlier

Cruisers                          (Range in km) x 6.9m + 33m                137m@15km
All cruisers Tier I to Tier VIII cruisers unless otherwise mentioned.        σ2.0
All cruisers Tier IX and Tier X cruisers unless otherwise mentioned.      σ2.05
IJN Cruiser: tVIII Mogami mounted with the 155mm guns (σ2.0?)
UK Premium Cruiser: tVIII Cheshire        σ2.05
US Premium Cruiser: tIII St. Louis σ1.8, tIII Charleston σ1.8, tVIII AL Montpelier σ2.15
German Premium Cruiser: tIX Siegfried σ2.05 (with 380mm guns, yes really)

Azuma and Yoshino Dispersion         (Range in km) x 9.5m + 15m                158m@15km
IJN Premium Cruisers: tIX Azuma σ2.05,  tX Yoshino σ2.05 

Graf Spee/Battlecruiser Dispersion     (Range in km) x 8.4m + 48m        174m@15km
German Premium Cruisers: tVI Admiral Graf Spee σ1.9, tIX Agir σ2.05
US Premium Cruiser tIX Alaska σ2.05
Russian Premium Cruiser: tX Stalingrad  σ2.65
US Premium Battleships: tVII Florida σ1.7, tIX Georgia σ1.8
UK Premium Battleship: tX Thunderer σ1.9
French Premium Battleship: tVIII Champaign σ2.0

"Slava Dispersion"        (Range in km) x 5m + 105m                        180m@15km
Russian Premium Battleship: tX Slava σ1.9
I've seen Slava's dispersion described as getting better at long range but I assume this is just hyperbole. It does only gain 5m per km however.

"Mikasa Dispersion"                (Range in km) x 7.7m + 69m                185m@15km
Premium IJN Battleship: tII Mikasa σ1.8
A shock to anyone who has ever actually tried to shoot anything with Mikasa...

"Japanese Battleship Dispersion"        (Range in km) x 7.2m + 84m        192m@15km
Techtree IJN  Battleships: tIII Kawachi σ1.8,  tIV Myogi σ2.0, tV Kongo σ1.8, tVI Fuso σ1.5, tVII Nagato σ2.0, tVIII Amagi σ1.8, tIX Izumo σ2.0, tX Yamato  σ2.1
Premium IJN  Battleships: tIV Ishizuchi        σ2.0, tVI Mutsu σ1.8, tVII Ashitaka σ1.8, tVIII Kii        σ1.7, tVIII Ignis Purgatio/Ragnarok σ1.9, tIX Musashi σ1.8, tX Shikishima  σ2.1
Pan Asian Premium Battleship: tIX Bajie  σ2.1

"Warspite Dispersion"                                 (Range in km) x 10.3m +51m                206m@15km
UK Battleship: tVI Queen Elizabeth σ2.0
UK Premium Battleships: tVI Warspite σ2.0, tVII Hood 1.9s, tVIII Vanguard σ2.0
US Premium Battleship: tX Ohio σ2.0

"American Battleship Dispersion"                            (Range in km) x 10m + 60m        210m@15km
US Battleships: tIII South Carolina σ1.9, tIV Wyoming σ1.5, tV New York σ1.8, tVI New Mexico σ1.5, tVII Colorado σ2.0, tVIII North Carolina σ2.0, tVIII Kansas σ1.5, tIX Iowa σ1.9, tIX Minnesota 1.8, tX Montana σ1.9, tX Vermont σ1.95
US Premium Battleships: tIV Arkansas Beta σ1.5, tV Texas σ1.8, tV Oklahoma σ1.8, tVI Arizona σ1.8, tVI W. Virginia 1941 σ1.8, tVII California σ1.9, tVIII Alabama σ1.9, tVIII Massachusetts σ1.7, tIX Missouri σ1.9
US Premium Cruiser: tX Puerto Rico  σ2.2
UK Battleships: tIII Bellerophon σ1.8, tIV Orion σ1.6, tV Iron Duke σ1.8, tVII King George V σ1.8, tVIII Monarch σ1.8, tIX Lion σ1.8, tX Conqueror σ1.8
UK Premium Battleships: tIII Dreadnought σ1.8, tVII Duke of York σ1.8, tVII Nelson σ1.9
German Battleships: tIII Nassau σ1.8, tIV Kaiser σ1.8, tV König σ1.8, tVI Bayern σ1.8, tVII Gneisenau σ1.8, VIII Bismarck σ1.8, tIX Friedrich der Große σ1.8,  tX Großer Kurfürst σ1.8
German Premium Battleships: König Albert σ1.8, tVI Prinz Eitel Friedrich  σ2.0, tVII Scharnhorst  σ2.0, tVIII Tirpitz σ1.8, tVIII Odin σ2.0, tIX Pommern σ1.5
Russian Premium Battleships: tIV Nikolai I σ2.0, tV Oktyabrskaya σ1.8, sVII Poltava σ1.7, tIX AL Sov. Rossiya σ1.8
Russian Premium Cruiser: tIX Kronstadt σ2.05

"Russian Battleship Dispersion"                                               (Range in km) x 11.9m + 33m        212m@15km
Russian Battleships: tIII Knyaz Suvorov σ1.5, tIV Gangut σ1.4, tV Pyotr Velikiy σ1.7, tVI Izmail σ1.6, tVII Sinop σ1.5, tVIII Vladivostok σ1.6, tIX Sovetsky Soyuz σ1.7, tX Kremlin σ1.8
Russian Premium Battleships: tVIII Lenin σ1.7

"The Dispersion formerly known as German Battleship"            (Range in km) x 9.8m + 66m           213m@15km
French Battleships: tIII Turenne σ1.8, tIV Courbet σ1.8, tV Bretagne σ1.8, tVI Normandie σ1.6, tVII Lyon σ1.5, tVIII Richelieu σ1.8, tIX Alsace σ1.6, tX Republique σ2.0
French Premium Battleships: VI Dunkerque σ1.7, VIII Gascogne σ1.9, VIX Jean Bart σ1.9, tX Bourgogne σ1.8
Italian Premium Battleships: tV Giulio Cesare σ1.9, tVIII Roma/AL Littorio σ1.8
Pan European Premium Battleship: tV Viribus Unitis σ1.8

 

You forgot the special Soviet cruiser dispersion formulae that Tallinn and Mikoyan got. And that Riga and Petropavlovsk uses JP battlecruiser dispersion. Otherwise, everything is as you said.

For Tallinn and Mikoyan:

(Range in km) x 9.3m + 51m

166m@15km

For JP supercruisers, Riga and Petropavlovsk:

(Range in km) x 9.5m + 15m

158m@15km

 

Edited by hanesco
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I want alpha gunnery back so bad.. Where vertical dispersion was actually a thing and horizontal dispersion was actually significantly tighter. It was so much better. 

 

 

I want this back.

 

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32 minutes ago, hanesco said:

This is very useful...I thought the difference between the ellipses of the turrets would be more significant. Long ships (or those that have a LOT of guns) seems to be affected more by this). But at nominal engagement distances it seems to be a non-issue.

 

The ellipses would be longer, but the angles are correct on them.  I think the length of the ellipses in my illustration might be throwing perception off as they would be much longer in game.  Maybe I should redo that graphic some time.  I should also point out that the angles calculated are the maximum ones possible calculated with the target perpendicular and centered between the turrets.  Angling your ship 45 degrees to a target will reduce the difference in angles by half, meaning your overall dispersion will be tighter (though the exact dispersion on the front and rear turrets will differ by a few meters in width).

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8 hours ago, LittleWhiteMouse said:

using the Aiming System Modification 1 upgrade.

This chaps my butt a bit.  USN BBs can't take ASM1, supposedly because their dispersion is already good.  Yet there are ships now with that already-good dispersion that can.  Can you spell "power-creep"?

Shenanigans!

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15km is not close range. That's on the higher mid-range area. Close is 4km to 12km, medium is 13km to 20km, long is 20km+ . Under 4km ships have some kind of special accuracy thing and of course, soviet ships also have the best of it. 

Soviet researchable line BBs have their 'special' accuracy modifiers kick in at 12km and under. Any comparison testing between the rossiya and soyuz should be done at 10km in my opinion.

Slava has a completely different accuracy value set. It is 'normal' to other ships at under 15km (aka, in bias-speak that means 'bad' because compared to other soviet ships, it sucks) and over 15km its vertical and horizontal accuracy narrows down significantly. Comparing Slava to Thunderer would not yield a valid comparison as Thunderer does not have a wide-to-narrow accuracy chart... Thunderer accuracy is much better at close range than it is at long range but its not godly like Slava at long range. 

 

Here's a funny tidbit: Yamato HE has nearly the same weight and initial velocity that Kremlin's AP shells have. Yamato and Kremlin have nearly identical horizontal dispersion values at 11km's (IJN having 1m narrower actually). So, that means Yamato, if it uses HE should be landing shells on target with the same crazy high accuracy as Kremlin right? ... aaaah but we know that's not true. Even when you test this vs a static Smolensk or Minotaur that can be citadel'd by Yamato HE you will see the hits to citadel are sporadic and unreliable..whereas a Kremlin will consistently land multiple citadels per salvo. Consider too that HE has a WIDE area of effect to hit citadel compared to AP shells.. its that messed up.

The difference is in the vertical. Whereas Yamato's nearly identical velocity/weight HE rounds to Kremlin AP spreads itself over a wide vertical area, the Kremlin AP lands almost on the dot at the vertical position the aimpoint was aimed at when fired.

Since sigma bunches shells towards the center that means Yamato's much higher sigma (2.1 vs 1.7) should be kicking in too.. and it does but Yamatos vertical is so big and it gets bigger the shorter the range, that not even that makes a difference. Kremlin's vertical (aka tech tree soviet BB line's) most likely starts at 'normal' USN-like values at 20km and narrows down progressively.. when hitting 12km its vertical gets narrowed at a much higher rate.

The ellipses of IJN vs Soviet seems to look like this (image is with sigma applied)..and this is at those 11km's IJN HE vs Soviet AP. Since the HE round should have almost the same ballistic trajectory or damn close to it yet the shells fall short and long a LOT while Kremlin's all land on the hull and most on the aimed for citadel area that to me shows the soviet vertical has to be half as narrow or even narrower than that so that nearly identical ballistic shells have this big a difference.

 

dispersion.jpg

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58 minutes ago, ramp4ge said:

I want alpha gunnery back so bad.. Where vertical dispersion was actually a thing and horizontal dispersion was actually significantly tighter. It was so much better. 

 

 

I want this back.

 

interesting the guns narrow down like in WOT after 4 seconds of being kept static on target. Wonder if they kept that in game without giving the visual XD

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Perhaps there are other game mechanics at work other than simple ballistics equations?

 

E.g. how is that, shooting  a broadside BB at point blank range from another BB, its still possible to have half the salvo miss over and under? At this range the horizontal and vertical dispersion "cone" should be significantly smaller than the hitbox of the target. Its almost as if the dispersion is scaling to an arbitrary outcome, and not directly correlating with range.

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1 hour ago, Skyfaller said:

interesting the guns narrow down like in WOT after 4 seconds of being kept static on target. Wonder if they kept that in game without giving the visual XD

 

Wouldn't that be something?

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