Hood v Vittorio Veneto

[Maciej]

Still, the "British" tests were not using the original array materials and, most important, they were not respecting the right gap distance between the 2 plates (that is the very key design feature to ensure the "precession" motion to the shell and its, at least partial, decapping)

Last time about “ability”/”unability”, “flawed”/”unflawed” test, just for clarification.
I may be wrong, but I have feeling that whole thing about “flawed” British tests refers to series in 1948. And only those.

In 1948 more than structure was made, with total thickness of 300 lbs ( conbination of 60 lbs + 240 lbs, and 80+220), and compared to single 320 lbs plate.
As we can see – it corresponds to ~8” single plate.
Clearly something different compared to Littorio armour. So those tests could be considered “flawed”

But those were not only “spaced array” tests in Royal Navy!
They tested spaced arrays in different configuration since 1903.
Actually “littorio configuration” was tested against 15” shell in … 1919.*
So had some knowledge about that.

Yes I know, older different materials
And shells too.

[Maciej]

OK, some drawing. I hope it is clear enough.

Incoming shells with descend corresponds to 12 and 22 km.
In Littorio - incoming shell of KGV
in KGV, incoming shell of Littorio.

Armour thickness as over machienery in both classes. Over magasines in KGV will be problematic - belt armour followed hull shape, so in different place, different angle.

Actual descend on drawing. In Littorio 10 and 23 degrees
I know actual descend of KGV at that range with “new gun” was a bit lower, but I added something to gain “used gun” descend. Of course in real live exact descend will be a bit different, depends on actual gun usage.
In KGV, descend are 7 and 17 degree, for the same reason. Iittorio’s guns were more “flat”

In case of longer range, British shell had to travel a bit over 6 meters to strike under the belt armour. ( sea flat, no “speed wave”, 10.5 m draft, no roll )
In case of KGV, Italy shell had to travel ~13 meters to hit under the belt.

If we add 6 degree roll – see in drawing.

Yes in “ordinary battle” and try to penetrate citadel in 1:1 fight Littorio should be more capable ( if shells are with the same quality and armour the same quality )
But in case of “critical (un)lucky hits”?
I know – counting only on such a hits is a bit dangerous.
But dismissing such possibilities was dangerous too.

In case of fight against Hood - it was explained. What could You expect with ship ~20 years older? Only hope for Hood: hit first, and hit hard (say destroy fire control, block some turrets - even if hit is not perforation, and so one), before enemy puts some shells in Hood's hull. Any such a shell will have devastating potential. And if hits are more or less equall in numbers on both sides. Poor, old Hood.

Littorio_KGV_shells.png (87.03 KiB) Viewed 638 times

[Alberto Virtuani]

Maciej wrote: "Yes in “ordinary battle” and try to penetrate citadel in 1:1 fight Littorio should be more capable"

Hi Maciej,
Correct. Once we all accept that at average to short battle distance, in a broadside confrontation, Littorio's have a huge advantage over KGV's (basically from 12 to 22 km Littorio's are immune at any inclination against the British 14" , even accepting the British tests results, while KGV's are never at 0° inclination, are not immune at 20 km with 20° inclination or at 18 km with 30°), we can move to your question regarding "lucky" hits:

"But in case of “critical (un)lucky hits”?"

Here I do agree the shallow belt is exposing Littorio's to more risks than KGV's.
Thanks for the very clear pictures above, I'm afraid I will never be able to produce such self-explanatory graphs......

The risk of such hits, as your graph shows clearly, is evident at long ranges (the 22km of your example, at 12 km it's negligible due to the long distance that the shell has to travel UW.....
I have always said that at relatively long ranges, KGV's have an advantage due to their horizontal protection and also due to the shallow belt. Therefore, in our scenario, if the British admiral is carefully avoiding to close range, keeping at least over 20 km and controlling his ship's inclination, he would have an advantage over Littorio's squadron.

On the other side, if he is determined to close range (as well as the Italian one according to our scenario), as per British doctrine, he would face an Italian ship with a significant inclination, thus the distance that has to be traveled UW by the British shell would be much larger than 6.2 meters in the worst case, already starting from 22 km and enhancing while the distance is closed. Once the distance is short to average, even if the 2 battlefleets turn on almost parallel courses, the flat trajectories will avoid the risk of any under-belt penetration.


Regarding your proposed scenario of 6 degrees roll, I agree again that this would even more expose Littorio's to a huge risk, but from 22 km, I don't expect many hits with a sea like the one you propose , thus this situation is a very, very "lucky" one, even if it cannot be discarded at all, of course......


In conclusion, IMHO the real risk for Littorio's is not coming from UW hits, I would be more concerned by a long range (as well a bit "lucky") hit impacting the outboard horizontal armor without passing through the 70 mm upper belt, due to the Littorio's inclination, and having "only" the 36 OD+10HT upper deck and the main 90 (machinery) to 100 (magazines) OD + 12 mm HT of the main armor deck to penetrate........


Bye, Alberto

[alecsandros]

@Alberto

After 2nd Sirte, Littorio went back to port, passing a severe storm. The degree or roll as written in Bagnasco's latest book was 3 to 5 degrees, IIRC.

In that battle, because of heavy seas and poor visibility, total number of hits for British + Italian guns combined was around 5 or 6 out of 3000 rounds fired.

[Alberto Virtuani]

@Alecsandros:
Hi Alec, indeed..... look more North Atlantic winter seas.....

Ciao, Alberto

[alecsandros]

@Alberto
Probably,
And I guess hits would be hard to obtain, if at all, in worse weather then 2nd Sirte.

[Maciej]

Personally, I expect British wil try to close range to it's prefered ~12 km or closer.
Untill 1943 details of Littorio's protection was unknown. There were rumors of "decaping" structure and so one, but, as usual, should be taken not blindly.
So deep penetrating hits into citadel, not likely.
But in British doctrine artillery was not to sink enemy battleship, but to make her unable to fight. And than she was to be sunk by torpedos.

In such a short range, fast action, question will be who will score more hits. At that distance, even not penetrating hit to turret, could disable it.
The same to fire controls, and so one.
Who put more shells to enemy, will win. In case of disablement machinery by penetrating hits - Littorio will have better chance to do it to enemy than vice versa.
(hardly surprising, Littorio was a bit larger)
In case of blow up enemy? Or just flood it's magazines?

[Alberto Virtuani]

Hi Maciej,
I agree with you that who hits more, usually wins. At 12 to 15 km distance however the non-immunity of KGV's would pose a great threat to their survival as fighting ships.

Magazines blowing up is probably impossible on both type of ships (KGV being too low in the hull, Littorio belt being practically immune against 14" shell).

I would then add to the key variables, the reliability of the 14" turrets, that even in 1943 were prone to problems.....

At long ranges only, Italian shells spread problem (if not solved by measures taken) would have been another.

Bye, Alberto

[alecsandros]

@Alberto
Still digging,
But I'm sure the 14" gun also had severe dispersion beyond 20km.

Best,

[Maciej]

At North Cape DoY had output ~63%
Win long time engagement with sea far from "flat calm". And still was able to fire 450 shells.

One gun was out of action virtually all time.
Most were minor problems miss one or two salvos ba single guns.
More serious were 2 or 3 guns missed teen, numbers of salvos constantly.
I did not check it exactly, but "on eye calculation" suggest that at last 7 guns were on action all the time.
Possibly for 1 or 2 salvos 6. After firing 30+ broadsided.
All 10 for only short time, as 1 gun missed 71 salvos out of 82 ( not fired for over 2 hours )

What was Littorio prolonged fire result?
I'm curious, as some loss of output was common in battleships. Something like 80% was quite correct result. 63% is far from perfect, but it was long time engagement. For first hour it was higher. How to compare to Littorio real performance, and expected reliability?

In case of bad weather - I remember comment of result of water incoming into turrets mechanisms on Littorio, when she was back from one action. Ingres of water inside turrets mechs, was common, and unavoidable, I think, problem what heppen next.
In "Littorio battleships", I rmember some comments, that situation was so bad, that if turret will be started, some short curcuits and putting turret out of action was expected.
KGV had no such problem, thanks to hydraulic power ( yes I know had different problems )
In good weather ingres of water was nor existing, but what about reliability of turrets? On both.

[Maciej]

@Alberto
Still digging,
But I'm sure the 14" gun also had severe dispersion beyond 20km.

Best,

Newer haerd about that.
Where can I found such information?

[Alberto Virtuani]

Maciej wrote: "What was Littorio prolonged fire result?"

In 1943, during gunnery trials, Littorio, Vittorrio Veneto and Roma fired a total 554 15" shells and lost only 17 shots, with a 3.1% loss, mostly given by the brand new Roma (source: Bagnasco)

Of course, it would be wrong to compare trials (or coastal shelling...) with a real fight, however I never heard about reliability problem of the 15" turret/gun mechanisms.
Perhaps these good performances were also helped by a lower maximum RoF of the Italian gun.

Bye, Alberto

[Maciej]

Virtually 100% output in 30+ broadsided seems very impressive.
Question – what was practical ROF that time.
Not theoretical, but in those firings. More time to do so – less mistakes.
But still very impressive result

And BTW, it is hardly sure, that KGV will be on parallel course to Littorio with no any inclination.
That time, belt amour is quite harder to penetrate ( works both ways, but due to geometry, vertical armour gives faster more extra protection compared to inclied )
At any resonable range, if commander will not make grave mistake, or some lucky hit apply, both should have citadel more or less save against each other.

[alecsandros]

@Alberto
Still digging,
But I'm sure the 14" gun also had severe dispersion beyond 20km.

Best,

Newer haerd about that.
Where can I found such information?

I'm trying to find it again myself.
It's in one of the discussions on this board... somewhere

So far I've found info on 15" and 16" British gun patterns, BUT NOT on the 14 ", which I thought I was going to find immediately

[Alberto Virtuani]

Maciej wrote "Question – what was practical ROF that time."

Hi Maciej,
unfortunately actual RoF during trials is not reported. Sea was from calm to rough but visibility was very good. The range was quite long, based on the high elevation of the main guns of Littorio firing in an available photo (almost 20°).

In 1940, the gunnery trials gave a RoF of about 1 round per gun per minute in a shorter duration trial, so I don't expect more than that.

In any case, even after Second Sirte, the hypercritical Adm Iachino (who had to justify his own errors....) mentioned several problems (optical rangefinders, ammunition quality, water incoming in turrets (due to very bad weather conditions), but he never pointed to any problem linked to the reliability of the main guns/turrets, and no major outage is reported during firing actions in WWII.

I think this aspect never represented a problem for the Italian 15".


Bye, Alberto