Hood v Vittorio Veneto

[Alberto Virtuani]

Maciej wrote: "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."

Hi Maciej,
here I still don't follow you.....
At a certain point in time, after closing range, as you propose as scenario, the 2 battlefleets will be forced to fight on almost parallel courses with very limited target inclinations (except if they turn to avoid shells, thus loosing their own fire precision....).

At any distance, between 10 and 22 km, Littorio's are immune at any inclination against the British 14", accepting the British tests results (giving their belts equivalent to around 400 mm KC, vertical).
KGV's are never immune at 0° inclination, are not immune at 20 km with 20° inclination nor at 17/18 km with 30° inclination, even assuming the cautionary "fighting instructions" penetration tables for the Italian 15".
At 40° (or more) inclination (difficult to maintain in a broadside duel.....), the KGV belt may behave better against the Italian 15", but the traverse bulkheads would not (e.g. the aft one (9.8") would be vulnerable under 17 km....... the fore bulkhead (11.76") is vulnerable under 13-14 km) at 45° inclination.....)

I still see a huge advantage for the Littorio's group at average to very short ranges....


As I said already, have I been the British admiral, I would carefully avoid to close range, staying at more than 20 km in my IZ and counting on better horizontal protection, better guns spread (if any) and better RN gunners training.....


Bye, Alberto

[dunmunro]

The RM did not test Littorio's armour against RM 38.1cm guns:

However, a series of tests carried out by Colonel of Naval
Weapons Bianco di San Secondo at the 'Cottrau' range inViareggio that
ended on 3 April 1935 produced results that lent validity
to General Pugliese's choice: an armoured structure consisting of a 70mm O.D.
plate placed at a distance of only 25cm in front of a 280mm KC.
plate had fully withstood heavy calibre (320mm) projectiles fired
under conditions to simulate, with various horizontal angles of
impact, those of 381mm projectiles fired from the optimum combat
distance of 16,000 metres.

Based on these results, and favourably supported by Admiral
Fernando Farina, chief of the Office for Preparation of New Ships
(Marinalles), the final decision was to fabricate the armoured belt of
the new battleships using composite elements. These consisted of
70mm O.D. plates + 280mm K.C. plates, firmly attached to each
other at a distance of 25cm (with the gap filled with inert water-
repellent material, or cement foam called 'cellulite'), to be applied to
the exterior of the hull in the same manner as single thickness
armour was attached
(Bagnasco, p.29)

The RM tests themselves are suspect.

[dunmunro]

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

There were problems at 2nd Sirte that led to a loss of output and a slowing of the RoF.

[Alberto Virtuani]

Dunmunro wrote: "There were problems at 2nd Sirte that led to a loss of output and a slowing of the RoF."
Hi Duncan,
which is your source please ? I'm only aware of water coming into the fore turret due to the very bad sea conditions. If this is the cause for the loss of output, it has nothing to do with the output under normal conditions (as in our scenario).

Bye, Alberto

[alecsandros]

The RM tests themselves are suspect.

... The Italian tests were manifold, and the 320mm one is the only one with documentation to be found and published.

They had the same general knowledge in 1929-1930, as Rheinmetal Borsig did 6 to 7 years later... (R.M.B. confirmed their findings)

[dunmunro]

Dunmunro wrote: "There were problems at 2nd Sirte that led to a loss of output and a slowing of the RoF."
Hi Duncan,
which is your source please ? I'm only aware of water coming into the fore turret due to the very bad sea conditions. If this is the cause for the loss of output, it has nothing to do with the output under normal conditions (as in our scenario).

Bye, Alberto

Bagnasco states that water entered the FC station causing several salvos to be missed and for the RoF to fall.


According to Bagnasco VV only fired 19 rounds at Battle of Cape Spartivento (Nov 26-28 1940). All 19 rounds, in 7 salvos, were fired from her after turret in a space of about 10 minutes. Theoretically, she should have fired 21 rounds, so her output in that engagement was 19/21 or about 90%.

At Matapan VV fired 91 rounds but 11 rounds failed to fire (7 in Turret 1 and 2 each in the others). So 91/102 = 89%. (Bagnasco p.198)

During gunnery trials in July 1941 VV ordered 63 rounds to fire but 5 rounds failed to fire so her output was 58/63 or 92%. (Bagnasco p.204).

These are the only trials were the rounds requested could be compared with rounds fired. The results are in line with most battleship actions, of short duration, in WW2 but they don't suggest any superiority for RM 38.1cm guns.

[dunmunro]

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

Best,

That is just not true. The RN fired these guns at long range on many occasions and dispersion was never a problem.

[dunmunro]

Hi all,
I

Kevin32422 wrote: "To me the Vittorio Veneto has a few things better than the Hood "

Please, please, even discounting the more powerful guns, the far better protection (vertical, horizontal and underwater), the secondary armament, the AA armament, the fact she was 20 years newer and the structural construction (look how Roma's hull reacted to the explosion of the main magazines, having been already severed...) she was at least immune to the German shell that doomed the British battlecruiser....


Bye, Alberto

Roma broke in two as she sank, just as Hood did.

[dunmunro]

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

360mm @ 15d doesn't equal 400mm @ 0d. Obliquity doesn't work that way. At 12km, with 0 target inclination, total obliquity againt VV would be about 24deg and 14in SV would equal about 1850fps and this combination is not immune to an RN 14in.

The RN had witnessed Hood being defeated by a KM 38cm shell and the RN knew that the RM was using a HV 38.1cm gun. It seems unlikely that the RN would fight a close range battle in 1942 against an opponent whose guns were likely to be as good as Bismarck's. After the experience of Denmark Straits, the RN revised it's tactics for dealing with Tirpitz and they recommended fighting her at 18km or greater, to take advantage of UW hits.

[Maciej]

here I still don't follow you.....

So let me explain.
Bosth ships had similar max speed, so any dictation of distance will be problematic at best. But lets say, both want to fight at 12 km ( as in picture ).
In 1:1 or even 3:3 fights, when both sites are in expected battlerange, I expect situation closer to B ( from picture ) than A.
With this - parallel courses, even the same speed - still there is ~30 degree inclination.

inclination.png

(19.12 KiB) Not downloaded yet

[Maciej]

Roma broke in two as sank, just as Hood did.

Yes. But Hood instantly. Roma after ~half an hour.
Could be stated - who cares, both sunk, but loss of live was different. And theoretically, Roma should survive more internal damage after penetrating hits

[Maciej]

360mm @ 15d doesn't equal 400mm @ 0d. Obliquity doesn't work that way

Yes, but if I understand original post correctly, Littorio's armour was more resistive, so possibly 360 mm of British equals to 400 mm of Italian?
If I miss something, correct me.

[paul.mercer]

Gentlemen,
Surely all the theories about shells v armour and angle of hit is still a hypothetical question, it may be important when it comes to actually sinking a not so heavily armoured ship like Hood, but in a battle with roughly equal conditions,crew training etc. between two or more equally armed and armoured battleships it would surely depend on who hits most. How would you rate a ship with 10 x 14" (all working properly!) against 8x15" (or 9 in the case of the Italian ships). Would the rate of fire from the 14" overwhelm the vital upper areas of the more powerfully armed 15" ships? In one of the pictures of the Bismarck wreck it shows a hit right on the turret Barbette which may have been a 14" from KGV or a 16" from Rodney, either way I would have thought that it would have been enough to disable the turret which surely shows that a shell does not have to actually penetrate a ships armour to cause considerable damage, add hits on the control centres or range finders and even the most heavily armoured ship is effectively out of the battle - of course hits from the 15" opponent could also do the same! So,more smaller calibre guns against fewer larger calibre guns, what to choose?

[Alberto Virtuani]

Dunmunro wrote: "Roma broke in two as sank, just as Hood did."

Hi Duncan,
not at all. Roma did not break in two as a consequence of the magazine explosion but only when, after capsizing, the decks were solicited by traction forces they were not built to resist to, due to water already present in the hull following the 2 bombs.

Roma was afloat for 23 minutes after the bomb stroke. Hood broke immediately and sank in 2 minutes. That's the reason why the poor brave sailors of Hood died all except 3, while Roma allowed around 600 people out of 1900 to escape.

you wrote: "360mm @ 15d doesn't equal 400mm @ 0d."

370 mm is the equivalent of the "slight" increase of efficiency of the Italian array (please see Maciej post at the end of pag.24 of this thread).
Hood's belt was inclined only 12° and it's considered to be 320 mm vertical equivalent instead of 305 effective (5% better).....It should work as well for Littorio's, I guess, if we are not back to the same "story" that British do things better than Italians because they are British......

As I said, the Italian belt is thus immune to 14" shell at any distance over 10 km (at 9 km the 14" is able to penetrate only 396 mm armor at 0° target obliquity).

you wrote: ".....RN revised it's tactics for dealing with Tirpitz and they recommended fighting her at 18km or greater, to take advantage of UW hits."

Here, I totally agree with you, as I said several times. Not many chances for KGV's against Littorio's at short range.
I would just say 18 km is a bit optimistic (immunity only from 30° obliquity against the Italian gun), I would have chosen 20 km at least.

Paul Mercer wrote: "Would the rate of fire from the 14" overwhelm the vital upper areas of the more powerfully armed 15" ships? "

Hi Paul,
yes, you are right but only if the 14" quadruple turret problems are solved. In no real battle the British 14" ships turret achieved an output better than 75% in a short engagement, sometimes much less...... Perhaps it was better to have less guns but more reliable .

Bye, Alberto

[Alberto Virtuani]

Maciej wrote: "In 1:1 or even 3:3 fights, when both sites are in expected battlerange, I expect situation closer to B ( from picture ) than A. With this - parallel courses, even the same speed - still there is ~30 degree inclination."

HI Maciej,
it could be B or A or something in between, however even in B situation, KGV's are not immune under 18 km against the Italian 15".


Bye, Alberto