As every report about the performance of the 381/50 OTO/ANSALDO cannon for the Littorios keep getting bounced for “not enough info” I decided to open a post to collect every possible data regarding this gun so that a complete report can be made about it.
The main issues from the report managers seems to be:
The difference between the charges needed to fire what the italians called “prima carica” (first charge) and “seconda carica” (second charge) durnig their testing trials that made them differ so much in term of fire rate.
Possible info about the rammer installed in the turret and how much it could have affected the reload rate of the gun.
As a first image here’s a simplified diagram of the tower showing that the charges were loaded in two parallel racks directly into the tower, meaning that the only delay during the reload should be accounted to the rammer’s speed.
Please remember to stay on topic as derailing this post will only slow down the collection of data about this gun.
PS:
Yes, I know that, by logic, even if the “seconda carica” test that reached up to 30s average reload time was made with only 3 charges instead of 6 the rammer inside the tower wouldn’t have screamed “wait a minute!” and waited up to 45s to load the remaining 3 charges, but we need data, as logic is not accepted in a report.
If I understood correctly the point we must demonstrate is that the only time increase between a “seconda carica” and a “prima carica” is the time taken by the elevator to descend 1 level and by the rammer to ram into the breech the remaining 3 charges bags. Is that correct?
These original footage is from the 1941 film “La nave bianca”, shot on a Littorio Class BB.
IMO these footage are useful because at 3:21 we can see that the loading sequence in the lower elevator occurs simultaneously, even if there were 6 charges (I could not understand the exact number in the video but it seems to me that the number is still more than 3), this would be confirmed because from the images we see that the sailors slide on two slides placed one above the other both groups of charges. And since the transfer to the lower elevator occurs simultaneously and the same thing happens for the transfer from the lower elevator to the upper one, we can conclude that the only increase in time occurs in the loading phase of all the charges in the breech.
I can also suggest to search for the upper elevators dimensions and speed, distance between the breech and the elevator and the speed of the rammer. With those data we can estimate the time.
I found that apperently minimum fire rate was 28 seconds, that would be for 3 wrappers for sure. ( AGGIUSTANDO IL TIRO Nuovi elementi sulle artiglierie e le battaglie navali italiane, 1917-1943 )
Thanks to @TheWarmFridge I also got a hold on a copy of “the Littorio Class: Italy’s last and largest battlleships” and, after reading it, there’re some things certain:
Italians only used 2nd charge (seconda carica) during training to limit the damage sustained by the barrels due to extremely aggressive wear that the N.A.C and F.C.4 (the two propellant mixes at that time) caused.
Each propellant bag weighted around 44Kg
2nd charge had two possible configuration: a 4 charge one and a 3 charge one based on the shell loaded (still no mention about what those shells were)
The average time that a trained crew (after all the fixes that the italians made to the initial project of the 381mm gun) managed to achieve is 30s for both the Ansaldo and the OTO version.
Knowing the minimum time is quite the big deal as we now know that, for a 2nd charge shot, the reload time averaged between 28s and possibly 32s.
We still need to find out about the correct use of the 2nd charge and how they handled them during trials, but we now have another piece of the puzzle.
The 381/50 guns, as previously mentioned, were separate-loading guns, that is, with separate projectiles and propellant charges, the charge being composed of several elements. There were two types of shell: armour-piercing, known in the Regia Marina as ‘ball’, in chrome-nickel steel (weighing 885kg, with 10.16kg explosive charge, delayed-action base fuse, steel cap and ‘Silumin’ light alloy ballistic cap, and a total length of about 170cm), and SAP shells with similar physical characteristics (weight 824kg, 29.51kg explosive charge, delayed-action base fuse, ballistic cap). During the war, the use of ball projectiles did not cause any significant problems, but the SAP shells displayed a tendency to detonate later than they were set to, for example after having completely passed through the hull of a light vessel. The propellant charges used N.A.C. type powder (produced by Dinamite Nobel) or F.C. 4 (produced by Bomprini-Parodi-Delfino) and were packed in bags of cotton or silk waste sewn in 44kg ‘wrappers’; each was provided with a small charge of more sensitive explosive to ensure ignition. The so-called Charge 1, for combat use, consisted of two series of three ‘wrappers’ each; for Charge 2, normally used for practice or for coastal bombardment in areas where range had to be wide to the tube liners, the number of elements varied from two to four depending on the type of shell used. For training purposes only a Charge 3 was used. A 774kg high-explosive shell was also reportedly tested for the 381/50, but it does not seem that this was ever used aboard the Littorio class ships.
Pager 345 (Appendix 3):
Results of gunnery exercises conducted during the period 1938–1941 (from G Colliva, ‘Il tiro navale italiano’ in STORIA militare, n. 199 [April 2010])
Gun Type
Charge
Training Year
A (km)
B (%)
C (s)
D (m)
E (m)
O.T.O. 381/50 guns
First
1939–40
21.0
7.0
63.0
290.0
267.0
Second
1939–40
17.0
10.7
37.5
185.0
344.0
Second
1940–41
20.0
7.3
29.7
422.0
500.0
Ansaldo 381/50 guns
First
1939–40
22.5
3.7
59.0
416.0
364.0
Second
1939–40
17.4
9.5
47.0
360.0
315.0
Second
1940–41
18.8
6.2
30.6
309.0
360.0
152/55 guns
First
1938
16.5
–
–
228.0
342.0
First
1939
15.8
2.1
40.5
278.0
405.0
First
1940
17.6
5.6
31.0
33.0
462.0
A = range in kilometres; B = percentage of hits on target; C = average rate of fire in seconds; D = longitudinal dispersion in metres (average of the deviation in range × 2); E = range span in metres (range of shortest round – longest round)
On page 73 it states “The rate of fire, with a trained crew and at average elevations (that is to say, around 15°), was in the order of 1.3 rounds per minute, or one round every 45 seconds for each gun.” 🙃
As I understand the whole thing, the full combat charge (“First Charge”) takes ~45seconds, while the training charge (“Second Charge”), with a lower number of bags, is the one that takes ~30 seconds.
So the conclusion is that the in-game rate of 1.3 rounds per minute is actually perfectly fine.
That’s the operational time of the gun during combat.
A balanced mix of speed and weariness to keep constant volleys on a target while preserving the guns and their internal components from failures.
Other navies had those values too, but also conducted several training test where they pushed the guns to the limit, some of them even in a fixed firing position (aka at the reload angle) to shorten the time and possibly train the crew only on that particular task.
A good example that we need multiple sources for everything is the reload rate of the 152mm during those tests. The average was about 31s (we know they can go down to 12s) as shelling wasn’t the main focus on those trials for the 152mm as they were used as heavy AA support in a simulated combat scenario with air attacs.
The elevators were able to carry only 3 propellant bags per tray and they had 2 parallel trays able to be loaded simultaneusly.
If one of the 2nd charges needed 4 bags to fire the projectile it means the rammer inside the tower needed to make the complete load cycle to prepare the gun.
If the average time is 30s and the minimum is 28s with the projectile that only needed 3 bags it means that a full load, only focusing on reload, was around 32-35s, in line with other trials conducted by other navies.
We need two pieces:
Time taken by the elevator to descend 1 level.
Time taken by the rammer to ram 1 cycle.
With these data however we would still need to use logical reasoning to convince them. What will you base your argument on to convince them?
This one would be the end game as no other complains could be made. (as it was an automated system guiding that part of the process)
The only thing we know, as now, is that the rammer was slightly faster while loading the shell than when loading the charges.
It was programmed like this as the shell easily entered the chamber due to its shape while the charges, being cylindrical pouches, were a bit trickier to handle. (not “end of the world” trickier if someone want to ask, as they were already alligned and ready, but they were still cylindrical pouches so it was safer not to ram them full force into che chamber).
Raw data, as they seem to not accept any logic that’s not backed up by that. (at least in this situation)
Data that can prove the actual performance of the gun, zoning out all the safety measures that the italians took to preserve the guns, is the best way to clear any doubt.
If they will complain about this too then we’ll know that we can’t do anything else to persuade them, as there’s no better data avaiable. (unless someone can bring back the dead and interview one of the offiacials managing the guns on the Littorios? )
Found out the problem about the Littorio’s RoF and compiled a report explaining everything that caused confusion about it.
For the solution without the tecnical gibberish about shells and charges here’s the paragraph about it:
Spoiler
Now on the main topic: how the italians reloaded their heavy guns.
They used a method called “Caricamento ordinario”.
In this method the shell was loaded first and then the bursting charges were loaded into the powder chamber.
To be fully operatonal the powder chamber must be fully loaded so that the carges were closely in contact with the “Cannello” (the igniter) to avoid missfires or, in the worst case scenario, the return of the shell in the powder chamber and its detonation inside it.
For a first charge shot there were no problems as all six charges were loaded, securing the powder chamber, but what happened for the 2nd and 3rd charge shots?
In this case the missing gaps in the powder chamber were filled with a special pouch called “Stoppaccio”. This charge was inert and easily flammable, with exactly the same dimensions of a normal charge.
Its role was to push the true charges against the igniter and secure the projetile, completing the load.
This can be seen in this image (this is a visual representation from the author):
This means that, even during 2nd and 3rd charge shots, the loading mechanism must complete its entire cycle to secure both the chamber and the projectile in place to avoid major damage on the gun.
This validates the average times achieved by italian sailors during the 1941 trials where they reached a 30s average reload due to their better training and solved issues with these massive guns.
If you want to comment the report please only add additional information that support it, do not clutter it as it only slows down the validation process.
So basically what this means is that the gun was always loaded with the maximum amount of bags, regardless if they were actually full powder bags in the case of 1st charge, or a mix of full bags and inert bags in the lesser order charges?
So the reputation of the Littorios having slow firing guns by design was a myth all along huh?
I think it’s a mith probably stemmed by the use of primarly british sources by the hystorians, mostly because the italian language is pretty hard and translating hand written diaries and reports was nearly impossible for them without someone willing to help.
This meant that most of those reports were observations during combat or official printed statements meant to train how to properly and safely handle these massive guns to minimize risk of injuries or damage to the guns.
Now that the italian hystorians are also helping translating all those documents stored in the military vaults we’re getting better information about the italian navy in general.
( an example is one of the sources that I used, dated 2019, which is extremely new for normal standards).
