Hood v Vittorio Veneto

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Re: Hood v Vittorio Veneto

Post by alecsandros » Tue May 03, 2016 2:10 pm

And also, the experience of Hessen: the German 380mm gun was rated at 335mm perforation out to 25km. Hessen had a 225mm thick world-war 1 armor. Tirpitz struck it repeatedly, from 25km, with no perforations.
... Real life obliquity and perforation are far less then expected in 90* attacks...

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Re: Hood v Vittorio Veneto

Post by tommy303 » Tue May 03, 2016 6:21 pm

To the best of my knowledge, the firing trials against Hessen were conducted with nose fuzed shells instead of the much more expensive and difficult to produce base fuzed HE and AP. Consequently, there would be little penetration of armour

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Re: Hood v Vittorio Veneto

Post by alecsandros » Tue May 03, 2016 7:11 pm

... That is what Tobicke wrote,
But the description of the damage he gave , with the 28 and 38 centimeters projectiles perforating the upper deck (40mm Whotan) but NOT the main armored deck, and description of pushing back of main armor belt inboard by the impact shock, are consistent with heavy APC rounds strikes. HE shells would explode against the upper deck , and also explode against the armor plate, instead of pushing back the plate, unless some weak support behind the plate.

It would be , also, rather curious to present the resistance of German armor arrangement (array), and it's merits, when under fire by HE shells (and no word on APC shells).

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Re: Hood v Vittorio Veneto

Post by paul.mercer » Fri May 06, 2016 8:12 pm

Gentlemen,
Would a direct hit on a turret with a 14/15/16" shell affect the crew inside even if it did not penetrate - I thinking of something like being given a blow with a hammer on the top of a bucket that is on your head - not quite a large calibre shell of course but enough to make your head ring!

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Re: Hood v Vittorio Veneto

Post by alecsandros » Sun May 08, 2016 5:50 pm

paul.mercer wrote:Gentlemen,
Would a direct hit on a turret with a 14/15/16" shell affect the crew inside even if it did not penetrate - I thinking of something like being given a blow with a hammer on the top of a bucket that is on your head - not quite a large calibre shell of course but enough to make your head ring!
... All 14" hits (and 15" and 16") on turrets , in WW2, that I know of, produced at least partial incapacitation of the turret/gun/guns.

The well documented hit on USS SOuth DAkota's forward gun turret at Guadalcanal was caused by a indirect hit of a possible APC shell fired by Kirishima. The turret was no longer able to traverse, lost power and was no longer usable in battle.

A spectacular situation was the final battle of Bismarck, when HMS Rodney obtained 1 or 2 simultaneous hits on Bismarck's forward turrets, knocking them out immediately (one of them fired one more salvo about 35 minutes later, indicating it wasn't destroyed. It then remained silenced)

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Re: Hood v Vittorio Veneto

Post by dunmunro » Mon May 09, 2016 9:43 pm

Penetration table for RM 381/50 from Bagnasco, p339.

range(meters)/obliquity (table appears to calculate angle of fall and target inclination)
____90d/80d/70d/60d/50d/deck (90d = 0 target inclination)
26k 325/318/299/266/223/124
24k 348/340/320/285/238/~105
20k 412/392/367/326/280/74
19k 416/406/380/338/260/67

One can see that at target inclinations over 30d that QE's 330mm belt would provide adequate magazine and machinery protection.

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Re: Hood v Vittorio Veneto

Post by Alberto Virtuani » Tue May 10, 2016 8:05 am

@Dunmunro:
Hi Duncan,
even according to the above data, QE's are anyway not immune at 20 km, 30° target angle and just "slightly" immune at 24km, where our scenario foresees a smaller target angle for the approach, as QE's could not risk to have their fore turrets wooded (see pictures above).....

However, as I have already pointed out in a previous post, the penetration data that you have posted here are the cautionary ones from the RM "fighting instructions" (Direttive e norme per l'impiego della squadra navale), giving to the CO's a distance at which penetration has to be considered sure in any real battle situation.

From the very same page of E.Bagnasco book, here below the results at "balipedio" (gunnery camp) where the 381/50 Italian gun had been actually tested:

range(meters) 90d/deck (90d = 0 target inclination, KC armor)
0k 814/-
18k 510/73
28k 380/130

Therefore much more favorable penetration data that (once interpolated) would mean no immunity at all for QE's even at 26 km distance and 30° target angle....

If we want to compare apples with apples, we should assume at least something intermediate.

Bye, Alberto
Last edited by Alberto Virtuani on Tue May 10, 2016 9:58 am, edited 8 times in total.
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Re: Hood v Vittorio Veneto

Post by alecsandros » Tue May 10, 2016 8:14 am

@Alberto
What do the values mean ? Are they perpendicular impacts against the face of the plate, or do they asume the angle of fall per given range ?

My impression is that they are 90* impacts...

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Re: Hood v Vittorio Veneto

Post by Alberto Virtuani » Tue May 10, 2016 8:20 am

@Alecsandros:
Hi Alec,
it's not specified but I would assume AoF (still less than 19.5° at 25 km....) is taken into account as it says "spessori di corazza verticale perforata in funzione della distanza.... (= thickness of vertical armor perforated as function of distance.....)
I would anyway assume an intermediate value as a realistic one, thus giving no immunity to QE's from around 25 km even with a 30°target angle.

They are reported also by http://www.navweaps.com/Weapons/WNIT_15-50_m1934.htm where they are the same as the actual tests mentioned by Bagnasco but they are defined as according to "USN empirical armor penetration formula".....

Bye, Alberto
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Re: Hood v Vittorio Veneto

Post by Dave Saxton » Tue May 10, 2016 3:15 pm

dunmunro wrote:Penetration table for RM 381/50 from Bagnasco, p339.

range(meters)/obliquity (table appears to calculate angle of fall and target inclination)
____90d/80d/70d/60d/50d/deck (90d = 0 target inclination)
26k 325/318/299/266/223/124
24k 348/340/320/285/238/~105
20k 412/392/367/326/280/74
19k 416/406/380/338/260/67n.
Notice how close the penetration data at 0 target angle is to the German 15" below:

Range Penetration
18km 442mm
20km 412mm
21km 392mm
22km 378mm
24km 350mm
25km 335mm
26km 320mm
28km 294mm
30km 275mm


That is taking AoF in to account, and at 0 target angle. It is not normalized to a right angle striking angle. Clearly the Italian data is taking AoF into account. For example, the penetration at 20km of 412mm is with about 16* AoF and 0 target angle for the German gun. (about 14* AoF for the Italian gun.)

One can also see from the Italian data that combining target angle and angle of fall/belt inclination is not just a matter of summing all the angles.

The Italian shell penetration will be more degraded by increasing striking angle than the German L/4.4, but from 22,000 meters out to +30,000 meters the Italian gun's AoF is significantly less, which will give it enhanced anti-belt performance at the expense of anti-deck performance. However, what was the Italian AoF data with reduced muzzle velocity?

With the 4" armour over the QE's magazines it would pay for the British to stay beyond 25km battle range.

However, British fighting doctrine up through 1941 was to quickly "close to decisive range." Did they change the fighting range doctrine to a less aggressive one post 1941? Howse, states that the normal maximum practical fighting range in the RN during WW2 was considered 28,000 yards.
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Re: Hood v Vittorio Veneto

Post by Dave Saxton » Tue May 10, 2016 3:42 pm

tommy303 wrote:To the best of my knowledge, the firing trials against Hessen were conducted with nose fuzed shells instead of the much more expensive and difficult to produce base fuzed HE and AP. Consequently, there would be little penetration of armour

As I understand it, the intention was to collect data on how the upper deck affected the velocity and attitudes of the shells and these data were recorded.
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Re: Hood v Vittorio Veneto

Post by Alberto Virtuani » Tue May 10, 2016 5:39 pm

Dave Saxton wrote: "....what was the Italian AoF data with reduced muzzle velocity?"
Hi Dave,
the data reported in the previous posts are obtained with a "reduced" muzzle velocity of 850 m/sec, as well as the maximum range of 42.8 km @ 36° elevation (explicitly mentioned as obtained with a reduced velocity, source is E.Bagnasco, "Littorio class battleships, pag.74 of the Italian version). This book only reports an AoF @ 18.3 km of 11°53' (corresponding to a gun elevation of 9°22') .

However, the "Range" table at this link: http://www.navweaps.com/Weapons/WNIT_15-50_m1934.htm looks as well taken with a reduced muzzle velocity as the max range is the same as per Bagnasco (42800 meters @ 36°). Therefore the AoF with 850 m/sec muzzle velocity should be 13°24' @ 20 km (with a gun elevation of 10°36') and 19°18' @ 25 km (with an elevation of 14°30').

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Re: Hood v Vittorio Veneto

Post by dunmunro » Tue May 10, 2016 7:42 pm

Dave Saxton wrote:
However, British fighting doctrine up through 1941 was to quickly "close to decisive range." Did they change the fighting range doctrine to a less aggressive one post 1941? Howse, states that the normal maximum practical fighting range in the RN during WW2 was considered 28,000 yards.
The RN also issued instructions to present an oblique target to maintain armour effectiveness. The RN was also under no illusions that the rebuilt QEs were equal to modern battleships. The maximum practical range was about 28k yds for any navy as past that range it became increasingly difficult to spot the fall of shot. However, PoW did engage Bismarck at 30-33k yds and claimed a straddle at that range.

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Re: Hood v Vittorio Veneto

Post by dunmunro » Tue May 10, 2016 8:12 pm

Alberto Virtuani wrote:@Dunmunro:
Hi Duncan,
even according to the above data, QE's are anyway not immune at 20 km, 30° target angle and just "slightly" immune at 24km, where our scenario foresees a smaller target angle for the approach, as QE's could not risk to have their fore turrets wooded (see pictures above).....

However, as I have already pointed out in a previous post, the penetration data that you have posted here are the cautionary ones from the RM "fighting instructions" (Direttive e norme per l'impiego della squadra navale), giving to the CO's a distance at which penetration has to be considered sure in any real battle situation.

From the very same page of E.Bagnasco book, here below the results at "balipedio" (gunnery camp) where the 381/50 Italian gun had been actually tested:

range(meters) 90d/deck (90d = 0 target inclination, KC armor)
0k 814/-
18k 510/73
28k 380/130

Therefore much more favorable penetration data that (once interpolated) would mean no immunity at all for QE's even at 26 km distance and 30° target angle....

If we want to compare apples with apples, we should assume at least something intermediate.

Bye, Alberto
The above data is theoretical and assumes 0d target inclination. I don't think it is of much practical use.

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Re: Hood v Vittorio Veneto

Post by Alberto Virtuani » Tue May 10, 2016 8:55 pm

Dunmunro wrote: "The above data is theoretical.... "
Hi Duncan,
no, it's the other way round. The data you posted is theoretical and issued as a guideline in the RM "fighting instructions". The actual data measured is the one I posted, as a result of real tests executed by the manufacturer (OTO) for the acceptance from the RM at the "balipedio" (gunnery camp). If you compare the Od inclination data from the 2 tables, you will realize how much cautionary the fighting instructions are (for very understandable reasons...).

I think something in between is more realistic, thus no immunity for the QE's against the Italian 381/50 under 25 or 26 km, even at 30° target inclination, that would be anyway very difficult to obtain for the slow QE's without risking to wood their fore turrets in our scenario......

Bye, Alberto
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