Battleship Vittorio Veneto

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Dave Saxton
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Re: Battleship Vittorio Veneto

Post by Dave Saxton » Wed Jan 19, 2011 10:43 pm

Mostlyharmless wrote: I am not a statistician but I think :think: that a nine shell salvo will have twice the dispersion of a three shell salvo on average.
This is interesting. Would they be shooting this larger pattern on purpose? It seems that if the pattern is larger than a 3 shot salvo, the hit% would not be significantly greater by adding 3x more shots, but the chance of scoring at least one hit may be greater if the range estimate contains significant error.
Entering a night sea battle is an awesome business.The enveloping darkness, hiding the enemy's.. seems a living thing, malignant and oppressive.Swishing water at the bow and stern mark an inexorable advance toward an unknown destiny.

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Re: Battleship Vittorio Veneto

Post by Bgile » Thu Jan 20, 2011 3:18 am

Dave Saxton wrote:
Mostlyharmless wrote: I am not a statistician but I think :think: that a nine shell salvo will have twice the dispersion of a three shell salvo on average.
This is interesting. Would they be shooting this larger pattern on purpose? It seems that if the pattern is larger than a 3 shot salvo, the hit% would not be significantly greater by adding 3x more shots, but the chance of scoring at least one hit may be greater if the range estimate contains significant error.
The range estimate doesn't need to be in error for the target not to be where the shells hit. I have it on good authority that these extremely precise German guns and extremely precise German FC equipment produced salvoes which actually missed once in a while. Hard to believe, I know. :wink:

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Re: Battleship Vittorio Veneto

Post by RobertsonN » Thu Jan 20, 2011 9:07 am

From this discussion, I can see my knowledge about dispersion was in need of revision.

Mostlyharmless pointed out that salvo dispersion is greater than single gun dispersion and and pointed me to the detailed article by Jurens. In Part II of Jurens article on US gunnery, Graph 3 shows true mean dispersion (a measure of inherent gun accuracy) and this is probably what the German data I mentioned refer to. By the 1940s the US had reduced this to about 0.5% of range (150 m at 30000 m), which is consistent with the German figure. The Italian figure of 420 yards at 24000 yds was for a three gun salvo and so is not to be compared with a single gun dispersion.

Bgile suggested that small dispersion was bad, reducing the chance of a hit. This surprised me because all navies tried to reduce dispersion and most naval writers have gone along with this. However, on looking at Jurens he says that between 1920 and 1945 the US reduced dispersion by 66% while fire control (more specifically, the error in the mean point of impact (MPI)) improved by 23%. The overall end result showed only a modest improvement. Graph 5 of Jurens shows that it is counterproductive to reduce dispersion unless MPI error is correspondingly reduced. At very long ranges there will always be some MPI error so that some dispersion or else salvo spread should increase the chances of an occasional hit.

British ships were repeatedly straddled at 28000 to 30000 yds at the Action off Calabria by the large dispersion Italian 8 in and 12.6 in guns with, I think, no hits. However, the near misses were close enough to damage the machinery of the carrier Eagle to the extent that it was unable to participate in the raid on Taranto. The fact Yamoto could not hit destroyers at long range does not surprise me, these were small targets and, as far as I know, only two destroyers were sunk by battleships during the entire War (by Scharnhorst and Gneisenau when the Glorious was sunk).

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Re: Battleship Vittorio Veneto

Post by lwd » Thu Jan 20, 2011 1:10 pm

RobertsonN wrote:.... The fact Yamoto could not hit destroyers at long range does not surprise me, these were small targets and, as far as I know, only two destroyers were sunk by battleships during the entire War (by Scharnhorst and Gneisenau when the Glorious was sunk).
The Yamato conducted her long range fire against the CVE's I believe. By the time she was firing at the DDs I don't think it was at long range anymore. At least one of the US "Tin Cans" off Samar was hit by a battleship main gun round and subsequently lost. Warspite sunk a numer of German DDs near Norway I believe. Heie and/or Kirishima may have gotten some in the Solomons as well. US BB's also at least helped sink a few Japanese DDs on occasion as well.

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Re: Battleship Vittorio Veneto

Post by RobertsonN » Thu Jan 20, 2011 1:53 pm

Yes, other battleships did sink destroyers in WWII. Warspite at Narvick (three or four) and, along with other RN battleships, two Italian destroyers at Matapan. All these cases were at very short ranges though, under 4000 yds, so here the danger space of the 15 in guns was relatively high. And as lwd points out there were cases in the Pacific.
Also, Eagle I now realize was near missed by high level bombers not gunfire, although several British ships were hit by splinters at Calabria. Again it was the Warspite that scored the one telling hit.

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Re: Battleship Vittorio Veneto

Post by Dave Saxton » Thu Jan 20, 2011 4:28 pm

RobertsonN wrote:... However, on looking at Jurens he says that between 1920 and 1945 the US reduced dispersion by 66% while fire control (more specifically, the error in the mean point of impact (MPI)) improved by 23%. The overall end result showed only a modest improvement. Graph 5 of Jurens shows that it is counterproductive to reduce dispersion unless MPI error is correspondingly reduced. At very long ranges there will always be some MPI error so that some dispersion or else salvo spread should increase the chances of an occasional hit.
Thank you RobertsonN
British ships were repeatedly straddled at 28000 to 30000 yds at the Action off Calabria by the large dispersion Italian 8 in and 12.6 in guns with, I think, no hits.
So although larger salvo patterns increase the likelyhood of attaining straddles it doesn't necessarilly increase the likelyhood of scoring hits. To the contrary, it probably decreases the likelyhood of actually scoring hits. Another factor here is that the 12.6" gun at these battle ranges had relatively steep angles of fall (30* by 25km and 40* by 30km) and a small danger space. The same was probably true of the 8" at these ranges.
Tommy303 wrote:The Royal Navy also sought and achieved very small dispersion patterns, but once achieved, found they had to spread the line to increase the pattern size slightly and thus enhance the possibility of hitting in the face of minor errors in range or with very small targets. If I recall, the British noted Hipper's salvo patterns at the Barents Sea action were very small and commented that the Germans did not appear to be spreading the line. It is possible though, that the Germans, having a high velocity low trajectory gun to work with, did not feel the need to do so at most battle ranges up to about 20,000m as the danger space would have been fairly wide and in some measure would have negated slight errors in range estimate.
At Barents Sea the Hipper scored multiple hits on destroyers at ranges from 14,000 meters to about 18,000 meters battle range in very poor visibility with snow strorms, extreme icing conditions, and polar darkness. The hits that sank the Ashates were scored from about 18,000 meters (~20k yards). This would seem to prove what can be done through the combination of precision ranging, relatively small dispersion, and larger danger space, and without needing to spread the line. The Hipper was shooting from about 50% the max ballistic range of its guns, which seems to be about the optimal though.

Gneisenau scored a hit on the Ardent with its opening salvo from a range of 15,000 meters, but I think it was with the 5.9's, or was it using the 28cm guns? At 15,000 meters the 15cm still has a fairly flat trajectory though.

Note: The IJN battleship which scored hits on the US DDs was I believe the Kongo.
Entering a night sea battle is an awesome business.The enveloping darkness, hiding the enemy's.. seems a living thing, malignant and oppressive.Swishing water at the bow and stern mark an inexorable advance toward an unknown destiny.

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Re: Battleship Vittorio Veneto

Post by Bill Jurens » Thu Jan 20, 2011 5:03 pm

Regarding dispersions, etc., I would recommend reading the lengthy two-part article Brad Fischer and myself did for Warship International about four years ago, which specifically covers the gunnery of the 'fast battleships) (BB-57 onwards). These papers were specifically written to extend my previous paper on battleship gunnery between the wars to cover World War II practices, including the effects of radar ranging, etc. and the introduction of the new 16"/45 and /50 caliber guns. These papers contain an extremely detailed discussion regarding the mathematical characteristics of dispersion, and should clarify many of the issues being discussed here.

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Re: Battleship Vittorio Veneto

Post by Tiornu » Thu Jan 20, 2011 5:42 pm

Note: The IJN battleship which scored hits on the US DDs was I believe the Kongo.
Yamato is the one that hit Johnston.

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Re: Battleship Vittorio Veneto

Post by RobertsonN » Fri Jan 21, 2011 9:02 am

Dave Saxton pointed out that even though a target might be straddled at very long range that the probability of a direct hit is still very low due to the small danger space. Indeed, for the German 38 cm at 25000 m and an angle of fall of 23.7 deg, the danger space was only 51 m and most others, including the Italian ships I mentioned, were less.
I think I prefer the use of nose fuzed HE at this kind of range. The probability of a near miss or hit with one of these is considerably higher than of a hit with an AP round. Fire control gear, especially radar, is vulnerable to splinters from near misses with HE. Some AP 'hits' will go through the superstructure or ends of the ship without exploding, doing little damage. In his classic 1970s book on battleship design, Friedman favoured high velocity 8 in HE to 'blind' superbattleships such as the Yamato and Iowa, and thus make them more vulnerable to attack by more ordinary battleships.

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Re: Battleship Vittorio Veneto

Post by lwd » Fri Jan 21, 2011 2:20 pm

US and Japanese doctrine was to engage with AP rounds at long range. While they acknowledge a drop in P(H) the probability of a truly devestating hit was greater.

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Re: Battleship Vittorio Veneto

Post by Dave Saxton » Fri Jan 21, 2011 3:55 pm

Tiornu wrote:
Note: The IJN battleship which scored hits on the US DDs was I believe the Kongo.
Yamato is the one that hit Johnston.
Thank's Richard. Good to hear from you too.
Entering a night sea battle is an awesome business.The enveloping darkness, hiding the enemy's.. seems a living thing, malignant and oppressive.Swishing water at the bow and stern mark an inexorable advance toward an unknown destiny.

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Re: Battleship Vittorio Veneto

Post by Mostlyharmless » Fri Jan 21, 2011 4:26 pm

One of the more successful battleships shooting at destroyers with their main armament was Littorio at the Second Battle of Sirte. She probably hit Kingston and hit or very near missed Havock as well as damaging Lively with a near miss.

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Re: Battleship Vittorio Veneto

Post by RF » Fri Jan 21, 2011 6:58 pm

But did it have any great impact though? Warspite sank a number of German destroyers at what turned out to be a critical time.... Littorio didn't actually achieve that.
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Re: Battleship Vittorio Veneto

Post by Thorsten Wahl » Fri Jan 21, 2011 8:16 pm

According Unterlagen zu Bestimmung Hauptkampfentfernung bla bla bla :wink:

theoretical hit probability for batteryshootings of SK 38 at a target 30m wide at
25 km 15,5%, flight time 43 sec, 50% zone 120 m lenght ~25m breadth
30 km 11,1%, flight time 55 sec, 50% zone 140 m length ~30m breadth
35 km 8,1 %, flight time 68 sec, 50% zone 170 m lenght ~35 m breadth
if target is straddled

50% zone area of a gaussian distribution with 50% of possible events
the complete 100% zone is approximately 4 times wider than the 50% zone

in reality dispersion of any shooting at long distances must be increased artificially for range and deflection to compensate for expected errors of the firing solution and possible changes of target speed and course. This was standard practice in the KM as well in foreign (i.e. USN) navies.

Tirpitz should have achieved in summer 1941 during artillery testing at the baltic a hitprobability of ~10% at 25 km if I interprete the few available informations this exercise and the usual practice of batteryshootings of the KM correctly.

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The events at Narvik werent suitable to conclude for good shotings as the area for maneuvering was extremely limited.
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Re: Battleship Vittorio Veneto

Post by RobertsonN » Mon Jan 24, 2011 9:03 am

Interesting figures. Does anyone know if it was possible to quantify the effect of rate of fire on accuracy? Friedman in US cruisers says that prewar practice results could not be reproduced in the War against fast maneouvring cruisers at long range because the rate of fire of their 8 in guns (3 rpm) was too slow. The result was the Des Moines class with automatic 8 in guns.
This implies that battleships were in an even worse position with their slower rate of fire (2 rpm was good). It is often said that Prinz Eugen hit the Hood before the Bismarck because of its higher rate of fire (despite a smaller danger space).
The VVs did not compare well, with only 1.3 rpm. Perhaps this is why they fired turret salvos to give 3 salvos per effective boadside, whereas British ships fired alternate 4 and 5 gun salvos for 2 salvos per effective broadside.

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