90th anniversary of Jutland.

[timshatz]

Del, you are the master of this thread. As well as other questions about warships. Great job.

Quick question about the interwar US Cruisers (seem to be in a minority in thinking less of them but that comes with the territory) that you might know the answer to. I hear there was a problem with scatter of the fall of shellfire due to the triple turret design. I am not sure the reason for this (heard it was the closeness of the barrels to each other) but would like to know your thoughts. Also, the same turret design was found on the battleships of the pre-war period. Did they suffer from the same problem if the problem did in fact exist)?

Appologies in advance for putting you on the spot but I think this would be more up your alley and would like to know your thoughts on it.

[delcyros]

Quick question about the interwar US Cruisers (seem to be in a minority in thinking less of them but that comes with the territory) that you might know the answer to. I hear there was a problem with scatter of the fall of shellfire due to the triple turret design. I am not sure the reason for this (heard it was the closeness of the barrels to each other) but would like to know your thoughts. Also, the same turret design was found on the battleships of the pre-war period. Did they suffer from the same problem if the problem did in fact exist)?

That´s a difficult problem You name and I can assure You that there is no overall agreed explenation to it. Perhaps Bill Jurens knows more about that, I will ask him. Much can be read on forums about this topic, but little has to do with the real problem and even less is the progress made by experts.

However, I have assembled some thoughts previously. Sadly nothing about cruiser guns but it would be greatly appreciated if You can send me a link.

To discuss this makes it important to look what happens to the projectile:

The accuracy of a major calibre turret depends on two, fundamentally different occurances, which are often mixed up:

1.) salvo dispersion: The distance from the point of impact of a particular projectile to the statistical mean point of impact of the salvo. Dispersion in range is measured parallel to the line of fire and dispersion in deflection is measured at right angles to the line of fire. A Dispersion Pattern is the combining of all the impact points of a particular salvo. Usually, the error in deflection is less than the error in range, equaling to an ovalized pattern distribution.
2.) gun to gun consistency: The distance from the point of impact of a particular projectile to the point of impact of a preceding projectile under identic circumstances (all factors beeing equal, single rounds firing).

As You see, only the first one includes salvo firing. The latter one just shows what the bottom line error margin of a particular gun / shell / propellant / turret installation is. The latter is necessary to verify the salvo dispersion!


we do have gun consistency figures for:
16/50(Iowa class)
range l standard deviation
yards l in range I in deflection
26000---91-------13
28000---93-------14
30000---95-------16

12/52(Marat class&coast artillery)
range I probable error
yards I in range I in deflection
26000----104-------17
28000----108-------20
30000----116-------23
Note that these are consistency figures and not salvo dispersion figures!

For example, during test shoots off Crete in 1987 (with all recent upgrades in FC), fifteen shells were fired from 34,000 yards (31,900 m), five from the right gun of each turret (this implies no salvo shooting!). The pattern size was 220 yards (200 m), 0.64% of the total range. 14 out of the 15 landed within 250 yards (230 m) of the center of the pattern and 8 were within 150 yards (140 m). Shell-to-shell dispersion was 123 yards (112 m), 0.36% of total range.

Dispersion patterns for full salvos are naturally much higher than these consistency figures:

The highest recorded dispersion patterns do come from
2 row, quad mount 15"/45 of Richelieu (note that all eight guns are positioned close to each other):

5/30/47 :
- projectile : BOF (= HC)
- charge = E3 (practice charge)
- range = 12,000 meters
- dispersion = 1,500 meters
(12.5% seems to be an unrationally high dispersion. But please note that the elevation at 12.000m for this particular gun is only 4.6 deg, so that the max. error in elevation is only +-0.45 deg)

6/6/47 :
- projectile : BOF (= HC)
- charge = E1 (practice charge ?)
- range = 25,000 meters
- dispersion = 1,775 meters
(7.1% at 25.000m still "seems" to be higher than any triple or twin turett designs. At this distance the elevation is 14.9 deg and the max. error in elevation is ~ +-0.5 deg)

(full salvo dispersions of eight gun salvos, fired without delay coil)

The gun consistency for this gun is not published.

So now we do have a big problem, don´t we? Cannot compare different figures on the same base, because the guns are different!
I will throw in some more on that later. Sorry if I cannot present a simple answer, the problems is a complex one and I can only try an aproach to it.

(to be continued later)

[timshatz]

Outstanding post Del. Exactly the line I was thinking down. Good to break it down to Gun and Salvo questions. Good info. Great info.

Do not have a link as all this came from a book I have sitting around my library. It was written by Norman Friedman. Title was "An Illustrated History of US Cruisers". Or something close. Read a while back. Dispersion was a problem he mentioned. It seemed the interwar cruisers had triple turrets with guns packed together. As a consequence, the scatter of the rounds was high enough to be a problem. If I remember right, this lead to the tubes being spaced further apart in later WW2 designs. Going on memory here.

Those gunnery numbers for the Richelieu are almost scary. Must've given the gunnery officer fits. Truthfully, I would not be overly suprised if the dispersion was 1,000 meters at 25,000 yards (even consider that somewhat high) but to have such a spread at 12,000 yards is questionable if the main armament was effective at all.

Question for consideration (given the above numbers). Does the dispersion increase with the number of barrels? If so, at what rate? It looks somewhat higher than an arithmatic increase. More along the lines of a geometric affect. Also, is there a maximum dispersion value beyond which it will not increase.

Thanks again for your post.

Still kicking around your post on Jutland. Plenty to think about. Need to print out the maps and look at them. But just looking at it so far, your arguement has weight. It would be in keeping with Scheer's initial objective of destroying a segment of the GF. Downside is the 2 mile drift in reporting of the CLs. Two miles at sea is nothing much. On the other side of that, the weather conditions were poor at Jutland (for the most part), and that would be a contributing factor. I guess the question that rears it's head at this point:

1. Did Scheer think he was fighting a division of the GFat this point and not the whole thing? That would explain the second turnabout.
2. But if that is the case, why did he turnabout in the first place?

[delcyros]

Dispersion was a problem he mentioned. It seemed the interwar cruisers had triple turrets with guns packed together. As a consequence, the scatter of the rounds was high enough to be a problem. If I remember right, this lead to the tubes being spaced further apart in later WW2 designs.

Yes, that´s what I have read, too. However, I am not sure if that´s the explenation of the phenomena. It´s a multicausal effect, to name some aspects (isn´t complete, I am no ballistic expert):

1.) interior effects:
slight differences in manufacture of shell weight (that might be a good candidate for italian dispersion problems), propellant weight (and even burning temp), gunwear will cause a different spin and initial velocity of the projectile. These errors are usually only fractions but fractions are important in this dispersion analysis. These effects are shortliving. As a rule of thumb, the more chemical energy is used for firing, the larger the consistency error. Do not mix it up with high or low velocity, which is different but might have a comparable effect! F.e. the US 16"/45 is a low velocity gun but used much energy to propel it´s superheavy projectile and vice versa, the german 15"/52 as a high velocity gun but used far less energy to propel its light weighted projectile.

2.) exterior effects:
All the drag related issues in flight of the projectile, differences in the stability, the spin rate and the deceleration. These effects are cumulative. As a rule of thumb, the projectile with a high transverse density will be more resistent to changes and therefore undergo less exterior effects under most (not all!) conditions.

3.) surrounding effects:
The construction and damping of the turret mounting, the delay between rounds, the spacial distribution of the barrels, the energy coupling and my personal dispersion favourite: Recoil. These effects are pulse related.
Firing a salvo contemporarely with other barrels in a load exchanging structure (like a multi barrel turret) will cause slight differences in axes of firing either by blast effects of closely spaced barrels or via recoil (which is without time delay). I believe that the Richelieu had such a bad salvo dispersion pattern because two of the four guns of each turret shared the same gun weige (in order to safe weight), which means that recoil could cause intolerable interferences or trade effects between them by firing. Altough this is purely hypothetical and not quantifyable with the sources on hand.

If talking about gun dispersion patterns, we also make a significant mistake: we do compare it via distance measurement, which is misleading. Better to compare the elevation and deflection error, respectively.
You will notice that the error on our french example doesn´t increase greatly with range (from 0.45% to 0.5% which is a bit, but not beyond effects explained under 2.). That has to do with trajectory and velocity of naval guns: at short range, slight differences in initial elevation and / or deflection will cause a very large metric error (or other measured in any distance), due to the low trajectory and the very high velocity of the projectile, while at long distance, the velocity of the projectile is lower, the angle steeper and it would requirere a larger initial elevation / deflection error to achieve the same metric effect. However, this is only true for labor conditions. The cumulative effects described under 2.) cancel this partly or fully out, esspeccially as range increases. Just wanting to outline that comparably large dispersion patterns at short ranges for low trajectory guns isn´t something fully unexpected.

Does the dispersion increase with the number of barrels? If so, at what rate?

Depending on effects summarized under 3.), yes.
But in how far depends on the individual turret installation. Placing all guns together (Nelson, Richeliue) doesn´t looks good. The introduction of delay coils made things much better post war (Yamato had them from beginning).

Also, is there a maximum dispersion value beyond which it will not increase.

Good question. Hadn´t thought about this earlier.

Concerning Jutland, one must consider the bad visibility condition by this time. From Scheers ship (SMS FRIEDRICH DER GROßE) only WARSPITE was clearly visible. The HERCULES opened from 12.000 yards at 18:25 on the most visible of three ships and had to check firing 6 or seven salvos later. HMS IRON DUKE opened at 18:30 on KÖNIG, which was lit up by the sun at 12600 yards and expanded 43 rounds on her, showing a fine display of her gunnery skills before KÖNIG disappeared. The MARLBOROUGH commenced firing on the leading ships of the KÖNIG-class ( both first believing in KAISERS) on 10.000 yards at 18:34 and checked fire seven rounds later because of intolerable visibility. MARLBOROUGH and other ships (BENBOW, CONQUEROR, COLOSSUS, ST. VINCENT, NEPTUN, ORION, MONARCH, BELLEROPHON) opened later briefly on the german van but all soon lost sight to the enemy. The visibility also was degrading significantly by around 19:00 and only the fleet northwards of the other afterwards had an advantage in this regard. The second turnabout initially could bring the HSF very close to the enemy line (visibility issues?) and more importantly, the enemy would need to turn south of the HSF in order to bring all ships to bear (and thus giving the HSF a bit of an visibility advantage in theory) or to turn north, which would leave half of the RN ships obstructed by other RN ships (again giving a tactical advantage to Scheer).
By 20:07, the sun set down at the given date / latitude and records give a moonless night.

1. Did Scheer think he was fighting a division of the GFat this point and not the whole thing? That would explain the second turnabout.

Given that the german intellegence did not revealed Scheer that Jellicoe had mustered out (he believed the GF was still at harbour), this might be possible. But once he saw the enemy battleline before turn 1 at around 18:30, he undoubtly must got another impression.

2. But if that is the case, why did he turnabout in the first place?

Certainly his situation was unfavourable. Initiating a 8 point turning maneuvre would leave the turning point in the centre of the fire of the enemy battlefleet (while the enemy van itselve was mostly out of sight in the smoke and twilight), while all german ships had to pass that point. The first about turn therefore was the right decision as was the third.

[renrich]

Amazing during that first about turn that there were no collisions. Fine seamanship!

[delcyros]

They had some training for this extra. The RN as the dominating sea power didn´t need to develop this defensive maneuvre.
As far as I can remember, the trick was that the rearmost ships starts to turn first and then the next until the first ship of the line is reached and the about turn acomplished. This prevented that ships had to drop speed to avoid dropping out of the line.
The GF used divisional turn (signal "turning together") as basic maneuvres. The divisional turn is contemporary but cannot be used for more then 90 degrees change. A subsequent second divisional turn will have the same result. According to GF maneuvre lists, a single 90 degrees divisional turn with Jellicoes Battlefleet will take 21 minutes in peacetime (probably less in wartime).

[delcyros]

Does anyone know if Henry Alingham still lives? He is the oldest British male and the only founding member of the RAF living as well as the only remaining survivor of the battle of Jutland. He will turn 111 this year!

BBC NEWS | UK | England | Southern Counties | Fly-past for Britain's oldest man

[timshatz]

Whoa! 111! That is truely impressive. I hope he attributes it to booze, fast cars and alcohol, 'cause I'm working that angle myself.

[renrich]

del, I was thinking last night that the USS Constitution, launched in 1797 may have been the forerunner of the battle cruiser. Her guns were of the sme size as many of the ships of the line although not as numerous since she had only one gun deck. She could outrun anything she could not outfight and she could out fight any ship she could not outrun. As the battle cruiser made the armored cruiser obsolete the Constitution and her sisters would have made the modest sized frigate obsolete if there had been more of them. What do you think?

[timshatz]

[quote=delcyros;227672]They had some training for this extra. The RN as the dominating sea power didn´t need to develop this defensive maneuvre.
As far as I can remember, the trick was that the rearmost ships starts to turn first and then the next until the first ship of the line is reached and the about turn acomplished. This prevented that ships had to drop speed to avoid dropping out of the line.
QUOTE]

That is one slick move. When you think about it, the apposing gun line could very easily not know what is going on until it is over. Since most main fleet actions consisted of lead ship firing at lead ship (it just turns out that way), the side not clued into the turn could possible not know what is going on until it was 3/4ths of the way done. If done fast enough and in succession without any serious battle damage (with some smoke thrown in for good measure), they might know about it all until it was over and the other guy was steaming away, leaving the snookered Admiral to wonder "What the hell just happened".

Starting a major movement, especially when you have torpedo advantage, is one neat trick.

[delcyros]

Dear Renrich,

I have never been well in the good old sail age issues but it indeed looks as You describe. Will have to read something about it but I do think that the similarities between Constitution and Fisherized BC (or PBB) are on a conceptual stage, only. A good friend of mine, Prof. Harald Lohmann, the one who rebuild the 1909 Etrich Taube, has certainly more to say about this as he has expertise about the USS Constituion, I will ask him and post his answer here. Worth a discussion on it´s own!

maneuvreing such huge forces as was done in Jutland must have been horrible! The third about turn was carried out under the most unfavourable conditions and not all HSF ships acted as was thought of (at a critical moment the ships of the König class turned parellel instead of subsequently to avoid staying in the brief but effective aiming point of the whole GF.


BTW, from Tiornu on another board:

If you haven't done so yet, go to Google Books, search the "Full view books," and get some free downloads. I found six complete volumes of old Naval Institute Proceedings. Most of the items I found available in pdf were pre-1930. I understand that those outside the US may not have access to all this stuff. I hope you're not using dial-up because my items ranged as high as 60+MB.

There are some very good sources out in the net!

regards,
delc

[renrich]

Thank you del. To me that is what makes Jutland so fascinating. All of that steel with all of those guns running around in a relatively small area at 20 to 25 knots. No sea battle that I know of approaches Jutland for the intensity and gunpower displayed. Some historians claim that Leyte Gulf was the largest sea battle ever but to me it is not one battle but rather 3 or 4 battles and not particularly well fought at that. Don't get me wrong, I don't think that Constitution was conceptualized as a BC. I think that the US was just trying to build the largest and fastest frigates it could so as to have a material advantage over other navies since they could not hope to have an advantage in numbers. They just happened to have some of the characteristics of Fisher's BCs.

[delcyros]

agreed.
I do prepare some statistics for each major calibre impact at Jutland and will post it here when I finished. Will take some time to get the dataset for all 208 impacts...