The Viribus Unitis Battleship: 1:25 Model; Main Gun Turrets

Lezt

Junior Member
Oh radar, how magical you are.

Lets go to gunnery basics

if you want to hit a target,

1) you need to know that it exists - detection/search
2) you need to know how far away it is from you - ranging and bearing
3) you need to know where the target is trying to move to so you can predict its path and check the flight path.
4) you need to know which way you are going so you can compensate your firing solution for your own movement.

Radar is a double edge sword, active radars helps detect enemy ships while they also get picked up with radar warning devices.

So lets look at Tirptiz, she is equipped with a FuMO81 Berlin, FuMO63 Hohentwiel K, FuMO 213, FuMO 26 and FuMB 6
FuMO63 Hohentwiel K is a surface search set for 20-60 km
FuMO81 Berlin is a centimeter search set for 20-30 km
FuMO 213 is a AA gunnery set with a 40-60km range, 35 m accuracy, and a bearing accuracy of 1.15 degrees.
FuMO 26 is a surface gun laying set wutg a 20-25 km range, 70m accuracy and a bearing accuracy of 0.25 deg
FuMB 6 is a passive warning set.

The Iowa had a Mark8 and SL/SO/SK
Mark 8 main battery fire director 37 km, 0.11 deg bearing accuracy and range accuracy to 5m
SL surface search to 39 km
SO air and surface search to 65 km air, 29 km surface
SK air search to 300 km.

US radar is simply better.

Knowing where the enemy is, does not mean that you can predict where the enemy will go. It also doesn't mean that your guns can hit it.

Iowa during test shoots off Crete in 1987 fired from 34k yards (32km), for a dispersion of ~200m (0.64% of range) and time to target was around 50-60 seconds. it is to a point where accuracy doesn't really matter, it is a statistics hit ratio game at that point.

Bismark gun data at the proving grounds was about 0.5-0.8% of the range.

Thus my perspective is, US radar is very good, German optics is very good. Both had very good electromechanical calculators.

The radar warning device will pick up the other's radar and warn of impeding danger.

Iowa should get target lock quicker and start firing faster. but in an ideal case where both is fully functional, both should see each other coming when they are within firing range.

Away from plunging fire range, broadside range, the German radars have sufficient resolution for accurate gun lay.
 
...

There are other limiting factors such as ammunition hoists

...
... I'll sure read your posts here, Lezt, hope you'll address the hoists, too ... also _continuous_ supply of shells on American battleships, which made all of them (shells) accessible _at once_, but at battle conditions created delays in their transport towards the shell hoists (have no book with me now so I hope you understand what I'm saying :)
 
Great discussion guys!
it's paid holiday here today so I checked on Lezt now :)
....

lets look broadsides...

Bismark have 6x 15cm guns, 8x 10.5cm guns per broadside

8x 10.5cm gun
ROF: 15-18 RPM
Weight of shell: 15.1 kg HE, 15.8 kg AP
Range: 17.7 km
(Campbell at pages 247 and 248: SKC/33
EDIT 900 m/s at the barrel; 5547/105=53 calibers)

6x 15cm gun
ROF: 10-12 RPM
Weight of shell: 45.3 kg HE, 45.3 kg AP
Range: 23 km
(Campbell at p. 241: SKC/28
EDIT 875 m/s at the barrel; 7815/149 is something like 52 and a half calibers)

Iowa have 10 5" gun per broadside
10x 5" gun
ROF: 15-22 RPM
Weight of shell: ~25 kg
Range: 16 km
(Campbell at p. 139: 5" Mk 12, with the comment I retype:
"Although neither shell weight nor muzzle velocity was particularly great, rate of fire, reliability, accuracy life and rates of training and elevation in the power-worked mountings were all satisfactorily high."
EDIT 792 m/s at the barrel; 4.83/0.127=38 calibers only)

So in a minute of secondary broadside,
Bismark can throw 4.5 tonne - 5.4 tonne of HE shells ti 17.7 km, and 2.7 tonne - 3.26 tonne to 23 km
here you wanted to divide by two, right?
18*8*15.8 is about 2275

and 2.7 tonne - 3.26 tonne to 23 km
OK: 12*6*45.3 max

Iowa can throw 3.7 tonne - 5.5 tonne of HE shell to 16 km
OK 22*10*25 max

Thus if there are no lucky shots, Iowa would likely have its superstructure (and more importantly, radar, range finders etc) shredded by secondary battery fire before its secondary battery can respond.

...
... I see your point, but what I originally meant was the damage caused by the main-caliber guns because of "all or nothing" concept, but never mind :) (you sure know about _innocuous_ hits scored by the Prince of Wales when with the Hood, which caused the Bismarck took in _some_ water contaminating the fuel)
 
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in response to
... the Bismark would have to fight off aircraft, cruisers, destroyers and battleships by itself.
... the Iowa (BB-61) had been on "an anti-Tirpitz deployment" at one point (now I quickly checked wiki and it was in August-October of 1943, stationed in Newfoundland) ... could be interesting to see how big was her group there
now I tried to find out using google, and one of the problems could be instead of 'Argentia', as in
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often 'Argentina' was offered :) so just several loose points:
  • Commander Task Force 24 operated there at that time, under Admiral Oldendorf (must be the one from the Surigao Strait one year later :)
  • huge number of Destroyers, and several Escort Aircraft Carriers, were _always_ in the area (Greenland convoys)
  • some Cruisers were expected to be there, too
so, had the Tirpitz taken it down through the Denmark Strait, she likely would've been engaged by aircraft and harassed by smaller units first, to meet the Iowa later (and her fate ...)
 

Lezt

Junior Member
... I'll sure read your posts here, Lezt, hope you'll address the hoists, too ... also _continuous_ supply of shells on American battleships, which made all of them (shells) accessible _at once_, but at battle conditions created delays in their transport towards the shell hoists (have no book with me now so I hope you understand what I'm saying :)

I don't think I know enough about the hoists to definitively agree which is better.

For one, the 5" guns had a very good hoisting system and the gun is in a turret. the powder charge and the shell is hoisted separately and is in the same position relative to the gun breech no matter which bearing the gun is pointing at.
5in38mount_diagram.jpg
015750a.jpg



The German 10.5 cm is a pedestal mounted gun with a gun shield and ammunition is hoisted to several distribution points on deck and then human chained to each gun. ammunition is once piece.
WNGER_41-65_skc33_Graf_Spee_No2_pic.jpg

WNGER_41-65_skc33_ammunition_pic.jpg

So the gun crew will have to work open to the elements and the human supply chain is open to strafing and splinters.

Is this an issue thou? a lot of destroyers have open pedestal guns and the gun crews work them just fine in rough seas. on the capital ships, the 10.5 cm are pretty high up.

This of course is not an issue with the 15cm guns, which are in full turrets and have integral hoisting devices. so they are as protected from strafing, splinters and weather as the american 5" counterparts if not better (thicker armor).

This goes back to the design philosophy of two tier guns or three tier guns; The 150cm is a much more potent weapon against surface targets with 50% better range. the 10.5cm is just as potent as the 5" anti air. you also does not need sustained firing rates vs air attacks as aircraft is so fast and if the weather is so bad that the men cannot fight on deck, it is unlikely that an aircraft can press an attack too. Two tier gun designs also saves weight and complexity (less ballistics computation etc)

In conclusion, I don't know. I am not convinced one design is better than the other. The German 3 tier gun setup is much better than the Japanese 3 tier gun setup. The american 2 tier gun setup is much better than the british 2 tier gun setup. but if the amerain 2 tier gun setup is better than the german 3 tier? I really don't know.
 

Lezt

Junior Member
All good points fine gents :)

Initialy in 1939/40 German get better optics the best so normaly detect ennemy in first and get the first shot always important but after UK and US get better systems with radars and even if in 1943 Tirpitz get radar i think, normaly UK, US have an advantage for detection, accuracy.
In 12/43 During the the Battle of North Cape King Gorgege V detect in first and fire also.


Remains curious, for history... why Kurita retreat ?

It is a good what if for a wargame :cool:
Forbin,

The battle off Samar was well discussed here:
https://www.sinodefenceforum.com/the-battle-off-samar-oct-25-1944.t7801/page-3

Its good reading on Kurita's actions
 

Lezt

Junior Member
Jura,

I don't think I know enough about the main hoists to really say much.

USS Texas bombarded Cherbourg in 1944 by firing 255 rounds of 14" over 34 minute. Or 7.5 RPM with 10 guns for 0.75 RPM per gun. That gun was designed for a 1.25-1.75 RPM

Probably the gun crews were not firing flat out.

USS Massachusetts fired 786 16" shells at Jean bart at Casablanca, from 8 am to I think noon. without much of a hitch, although it is at a much lower firing range

The sinking of Yamashiro by West Virginia, Tennessee. California, Mississippi, Pennsylvania and Maryland... The US ships didn't report any shell interruptions although the shooting only lasted 15 minutes.

If we play the statistics game,

Bismark with 8 guns at 2.3-3 RPM/gun for 18.4-24 rounds per minute
Iowa with 9 guns at 2 RPM/gun for 18 rounds per minute

if we throw the other BBs of that age in there:
KGV with 10 guns at 2RPM/gun for 20 RPM
Yamato with 9 guns at 1.5-2RPM/gun for 13.5-18 RPM
Richelieu with 8 guns at 1.2-2.2RPM/gun for 9.6-17.6 RPM (real hoist issue here)
Littorio with 9 gims at 1.3 RPM/Gun for 11.7 RPM

Given that battleship sizes are comparable, it would suggest that Bismark still had the highest potential for spewing out the most shell for hitting a funnel or damaging the superstructure followed by KGV.

It would also suggest that the Scharnhorst may not be that bad.. with 9 guns at 3.5 rounds per minute, it throws out 31.5 RPM to damage the superstructure even if it does not penetrate.
 
hey, seeing you online:
... The US ships didn't report any shell interruptions although the shooting only lasted 15 minutes.

...
"With the men lying down and resting as much as possible they were exhausted due to the extreme heat and lack of air and would not have been able to continue the ammunition supply without reliefs many more minutes."
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