Hood v Vittorio Veneto

[Maciej]

Once again about British tests
Those tests in 1948 was later, than test of reconstructed Littorio’s plate.
As it was discovered “slight advantage” of that protection, next series of trials were done to determine optimal configuration ( except distance between plates – that was constant ).
Yes in those later tests different plates were used, not the same as in Littorio.
Performance of Littorio’s configuration was known that time.

And back to other tests.
British invented “All or Nothing” armour scheme, basically the same as used in Nevada. It was introduced in Inflexible build in XIX century. Identical principle, and reasoning as in Nevada. Realization was a bit flawed, as citadel was too short, but idea was identical, and repeated ( with various modifications ) on later classes.
Than British invented “Bismarck style” of protection. First was small battleship Renown ( XIX century ), and later Majestic class ( started before Renown was even launched ) and later ships. There were identical concerns about its capability, as later on Bismarck, including current on various forums. That time AP round was solid shot. Uncapped.
Than Russian invented cap was added to shell – obvious idea was to build such a structure to remove that cap, before it strikes “man armour”.
It was tested in 1903. It was not used on any other ship, so could not be considered “to proove own superiority”, as it was idea to put such decapping structure on RN ships ( if had real advantage ).
Structure failed.
Than were new shells, new armours, so in 1908 new tests were done. Structure failed.
Than against very better shells – green boys. So again test, how it will work with such a structure
Structure failed.

Than next series of tests in 30-thies.

With all that knowledge, does anybody believe, that British had no idea how to perform correct tests?

[Maciej]

And I forget. In 1948 tests when attacked by 14" shell angle of impact 45 degree was used. So don't say that "on hull inclination" was ignored. It was 30 degree descend of shell +15 degree of inclination (or other combination).
Structure gives no better protection than solid plate.
Against British shells.
Other shells were not tested

[Maciej]

I do agree, but I haven't yet seen a final comparison table that can be universally accepted......

Me too.
And I think it will never be done.
To make thing the same, there is need to use various corrections, and recalculate tables.
Sooner or later ( I think very soon ) someone will state, that whole tables are flawed, as were not historical, but “artificially calculated”, so for sure wrong.
So with lack of other data, we have to work on what we have.
But it is good to remember context, to avoid too serious conclusions, very well justified, but based on wrong initial data.

[alecsandros]

So lets say it was equivalent of 360 mm plate.
Not bad, but not so superior.

The British tests that you quote are flawed, as they did not use the materials used by the Italian or German navies, did not properly space the plate, and did not decline the plates at the historical angles used in foreign battleships.

Rheinmetal Borsig trials showed that a fully decapped shell will shatter in contact with a KC plate of minimum 0.6 diameters in thickness (so 400mm shell will shatter against 240mm KC plate). The problem was to ensure "full" decaping, and that required considerable space between initial plate and main plate.

The RN built a model of the RM armour array and tested it and the RM array has a very small space between the the two plates.

... The Italian armor array is built with specific materials, that the RN did not use. Plate thickness was 70+10mm , then 250mm air (spacing the plates), and then 280mm main belt. Hardness, depth of cimentite, etc, used in Italian plates is different from British contemporary plates.

The results obtained by the Italians in 1929-1930 were replicated and confirmed by the Germans in 1936-1937, in almost all aspects.

[alecsandros]

Correct me if I’m mistaken, but in those tests German shell were used, not British.
So if we are interested how Littorio is protected against say Bismarck’s shells – than this test is important.

Yes, Littorio is well protected against Bismarck AND Littorio shells, according to Italian tests, which were replicated, several years later, by German engineers.

[dunmunro]

Correct me if I’m mistaken, but in those tests German shell were used, not British.
So if we are interested how Littorio is protected against say Bismarck’s shells – than this test is important.

Yes, Littorio is well protected against Bismarck AND Littorio shells, according to Italian tests, which were replicated, several years later, by German engineers.

Can you point us to a source?

[alecsandros]

Correct me if I’m mistaken, but in those tests German shell were used, not British.
So if we are interested how Littorio is protected against say Bismarck’s shells – than this test is important.

Yes, Littorio is well protected against Bismarck AND Littorio shells, according to Italian tests, which were replicated, several years later, by German engineers.

Can you point us to a source?

The one available on the internet that I know of is
"Theory of German Armor piercing projectiles", ADM 213/951, dated 1946.

Link:
http://www.bismarck-class.dk/miscellane ... chive.html

The relevant info for our discussion comes from pg 78, 79, 82 , 83, 98.

[dunmunro]

The one available on the internet that I know of is
"Theory of German Armor piercing projectiles", ADM 213/951, dated 1946.

Link:
http://www.bismarck-class.dk/miscellane ... chive.html

The relevant info for our discussion comes from pg 82 and 83.

Thanks. A very interesting document.

However the RM used cemented armour on both plates (above document states homogeneous and cemented) and the RM used an "egg crate" structure to attach the two plates together where the above document used cement only.

The RN tests used an egg crate structure based on the actual RM design.

[alecsandros]

The one available on the internet that I know of is
"Theory of German Armor piercing projectiles", ADM 213/951, dated 1946.

Link:
http://www.bismarck-class.dk/miscellane ... chive.html

The relevant info for our discussion comes from pg 82 and 83.

Thanks. A very interesting document.

However the RM used cemented armour on both plates (above document states homogeneous and cemented) and the RM used an "egg crate" structure to attach the two plates together where the above document used cement only.

The RN tests used an egg crate structure based on the actual RM design.

There are multiple variants in the document including 2 homogenous plates, and 2 KC plates, IIRC.

RN tests did not respect minimal distance between plates, did not use Italian plates or historical declination of plates.

[alecsandros]

The German trials fitted almost exactly on the Italian trials results, including minimal distance between plates and minimal thickness of successive plates. Note the 70mm and 280mm thicknesses of plates, with 250mm distance between them, used in the Rheinmetal Borsig drawings - fig.44 , pg 83.

[dunmunro]

The one available on the internet that I know of is
"Theory of German Armor piercing projectiles", ADM 213/951, dated 1946.

Link:
http://www.bismarck-class.dk/miscellane ... chive.html

The relevant info for our discussion comes from pg 82 and 83.

Thanks. A very interesting document.

However the RM used cemented armour on both plates (above document states homogeneous and cemented) and the RM used an "egg crate" structure to attach the two plates together where the above document used cement only.

The RN tests used an egg crate structure based on the actual RM design.

There are multiple variants in the document including 2 KC plates, IIRC.

RN tests did not respect minimal distance between plates, did not use Italian plates or historical declination of plates.

The RN test did use RM distances, construction techniques cemented armour on both plates and the tests were conducted at 30 deg obliquity. The above document only mentions homogeneous and cemented armour with either a 600mm airspace or a 250mm cement filling.

[Maciej]

I think, there is some misunderstanding here.
I’m not trying to say that Littorio had weak armour.
I’m trying to say that overall performance of that spaced array was not as great as 460 or 500 mm of Krupp Cemented single plate ( or what ever value )
Against British shells it was “slight better” than single plate of the same thickness.
Actually than a bit thicker, as British considered construction supporting those plates as weight of ~20 lbs plate so to ~10-11 mm.
It was confirmed by live full scale test.
So that structure is say the same in protection as say 370 mm plate ( that “sligth” difference )
And inclined 15 degree
Still very fine protection. Belt a bit shallow – but if shell hit that belt, had a lot of steel to penetrate.
But it is not as great at half a meter of steel. In shorter battle ranges, it was possible to penetrate it.
If that structure will be real equivalent to ~500 mm or more, it will be unpenetrable in any realistic distance.

[alecsandros]

The RN test did use RM distances,

Source.

construction techniques cemented armour on both plates

What materials did they use for the armor plates ?

and the tests were conducted at 30 deg obliquity.

Meaningless - what was the declination of the plates ?

The above document only mentions homogeneous and cemented armour with either a 600mm airspace or a 250mm cement filling.

The above document mentions several types of armor arrays, but you have to do more then skim through it looking at the pictures.

[alecsandros]

Against British shells it was “slight better” than single plate of the same thickness.
Actually than a bit thicker, as British considered construction supporting those plates as weight of ~20 lbs plate so to ~10-11 mm.
It was confirmed by live full scale test.

The British tests were flawed.

That is the problem. It is irrelevant if they presented equivalent thickness of 200 or 500mm.

A fully decapped shell will shatter against a KC plate of about 0.6D thickness (see ADM213/951). The problem was to ensure full decapping.

[Maciej]

The RN test did use RM distances,

Source.

ADM 281/31

construction techniques cemented armour on both plates

What materials did they use for the armor plates ?

Class C armorur.
Class C in British therms mean face hardened. For obvious reasons it was British produced plates. I have seen some time ago exact parameters of those plates, but what difference makes it anhyway?
Biger difference is in shell construction.

and the tests were conducted at 30 deg obliquity.

Meaningless - what was the declination of the plates ?

Repeat 30 degree to plate.
It means 30 degree to plate.
Doesn’t mater if plate declined 15 degree and descend of shell 15 degree ( correspond to distance over 20 km ), or if plate is declined 30 degree, and point blank range.
Simple 3d geometry.

The British tests were flawed.

No German tests were flawed. They uses wrong shells!
Yes I know for years that everything British is flawed, and they simply can’t do enything right.
They tested various spaced arrays since 1903.
And through those 40+ years had simply no idea how to do that.
And rest of the world learned in year or so.

Or other possibility is available.

British engineers were equally adequate to imlement various tests ( in 40+ years period, so more than one generation ), but there was some reason why various sides had different conclusions.
Possibilities –
1. very different armour plates with very different capabilities
2. very different shells construction, so decapping works different due to various reasons
3. both above.