Richelieu vs. South Dakota

[lwd]

lwd - A slight correction. You wrote that "If dispersion a has CEP is twice as big as b, then your chance of hitting a ship anywhere in the CEP area for a is ~half what it would be for b". This is wrong; a CEP is a radius but you will be scattering shells over an area. Therefore, if you double the radius, the area will increase by a factor of 2 squared. Thus, you will get one quarter of hits, not one half.

You are correct. I meant to refer to the area defined by the CEP rather than the CEP but got a bit sloppy.

[Thorsten Wahl]

Yes, it's intriguing how a shell could defeat so much armor given the circumstances...
There was also another 406mm shell (the 5th strike) which perforated 16 + 18 + 8 + 13 + 15 + 100mm of steel on Jean Bart's stern, allthough I don't know if the steel was armor grade.

the problem were the very thin plates in series
"16 + 18 + 8 + 13 + 15 "

using german calculations the energy required for pentration of one 18 mm plate at 70 degrees obliquity (0 degrees = perpendicular to plate) was only 3 MJ. So the 5 plates may absorb max 15 MJ, this is roughly 10% of the incoming energy at 20 kyard (489 m/s impact speed)
this 15 MJ energy loss reduces speed of projectile probably by less then 5 m/s
as the impact on the thin plates probably did not affect projectile, the very thin plates in this case seem negligible.

..Therefore, if you double the radius, the area will increase by a factor of 2 squared. Thus, you will get one quarter of hits, not one half...

Impact areas for artillery shells are long stretched ellipses. As long as you consider broadsise targets, side dispersion is negligible, as it is usually less than a fourth of shiplenght for single shots.

[Dave Saxton]

One question that puzzles me is why Massachusetts' 16” shell could get through Jean Bart's 150 mm armoured deck without even being slowed enough to explode before it passed through the 40 mm armoured deck into the (empty) 155 mm magazine......

It's not really that puzzling considering a possible list and/or the very poor French armour quality alluded to by the German engineers. The hit in question was scored at about 24,000-yards battle range. (there is no evidence of BB59 shooting at extreme ranges must less scoring any extreme range hits). The deck penetration at that range was about 124mm. If the effective thickness was 155mm (square root 150 +40 = 155(Splinter decks are wasted tonnage)) and if the armour quality was about 80% of standard it comes out 120-125mm. The armour proved to have a effective thickness of about 5" not 6" of standard.

Could the armour quality be only 80% of standard? Yes it could. It was actually quite common with homogenous armour, even keeping impurities within limits. For example, extremely thick US Class B plates of 16"-18" consistently only provided 80% the ballistic resistance to standard. Extensive studies by the US Naval Research Lab determined that this was an intractable problem. Nothing could be done. This was due mainly to the problems of proper cooling of thick homogenous armour plates when the center of the plate retained heat for too long. The Germans considered that homogenous Wh plates should be not much thicker than about 150mm to maintain high quality standards, and thinner homogenous plates were calculated to higher quality constants than thicker homogenous plates. The JB plates were only 150mm thick but this was nearing the limit of maintaining acceptable quality and if they had additional problems such as impurities and backwards smelting technology they could have easily been sub -standard.

[Keith Enge]

alecsandros - Sorry, I missed seeing your question about my database's power calculations. These are algorithms that use the raw data to obtain a rating for the ship in gunnery/torpedo battles. Besides evaluating a ship, it is used to evaluate groups of ships to get the probable winner of historical battles whose order of battles are in the database. Besides the power rating, there are AA and ASW ratings, among others, for other types of battles. Briefly, to answer your question, the power rating is the square root of the product of the offensive rating and the defensive rating. Of course, this merely answers one question by posing two others so I'll discuss them now.

The offensive rating evaluates the various sized guns and torpedoes. For guns, among the factors considered are shell weight, range, penetration, number of guns, shells in magazine, rate of fire, and directors. The algorithm that combines these is fairly sophisticated. For example, the shells in magazine are prorated by the product of the number of guns and the rate of fire. Therefore, a large number of shells is modified downward if it is paired with a low number of guns and low rate of fire. The rationale is that, if that ship was sunk, she probably would take a lot of unfired shells down with her. Excessive shells aren't useful if it would take forever to fire them off. The torpedo calculation is similarly complicated. The factors include warhead weight, range, speed, number of tubes, and number of reloads. Once again, the number of reloads is prorated downward by a large reload time. You might as well not carry reloads without quick reloading gear; otherwise, you are unlikely to have the time to reload during the same battle.

The defensive rating is, if anything, even more complicated. Among the factors are the ship's displacement, the various armors (thickness, placement, and extent), TDS (depth, height, and liquid/void distribution), damage control, and age (to a limited extent). Damage control is an exception to my algorithm design philosophy. Generally, I wanted to eliminate my own personal prejudices from the ratings generation. Of course, they inevitably did influence the design of the algorithms and the weightings given to the various factors. However, the final results for all of the ships provided feedback on the viability of an algorithm. If any questionable results emerged, the algorithms were tweaked until acceptable results across the whole range of ships were obtained. Damage control, on the other hand, required a personal value judgement. Just counting things like damage control stations, counter-flooding pipes, pumping capacity, emergency pumps, emergency diesel generators, firefighting gear, etc doesn't provide adequate grist to create a useable algorithm. Therefore, I had to make a value judgement and insert it into the database as "data". Besides the result of all of the factors mentioned at the top of this paragraph, I added speed and ship dimensions too; a fast ship that presents a small target is harder to hit and thus has a greater defensive rating.

That completes my rather long-winded explanation of the power rating. If carriers are evaluated, it gets even more convoluted. All ships have their ratings change as they undergo modifications in refits; carriers have their ratings change as the mix of their carrier planes change. To support this, besides the 22,000 ships in the database, there are over 700 planes or different versions of planes. They have their calculated ratings also. I have found these are more controversial than the ship ratings. People generally tend to agree with relative ratings of the ships that the database produces. However, some disagree strongly with the aircraft ratings. The problem is basically that I'm concerned mainly with aircraft in a naval setting. Therefore, I emphasize range; if your enemy can reach you but you can't reach him, you are in trouble. In addition, fighters used for CAP need endurance (proportional to range) so they don't have to land frequently to refuel and so disrupt flight deck operations. This emphasis on range means that planes like the Seafire fair poorly in some ratings. The Seafire, unfortunately, is a Spitfire variant and, for a lot of people, criticizing something about the Spitfire seems to be equivalent to criticizing their mother. Flame wars have resulted.

Anyway, alecsandros, I hope that answers your question. If you want to test the ratings, give me groups of ships and I will provide the power rating ratios. We'll see if you too find the results acceptable; feedback is always helpful. If the groups of ships are those of some historical battle, it is likely that it is already in the database, I have over 300 of them. If, on the other hand, they are groups from a hypothetical battle, I can get that result quickly too because the whole database has a "point and click" interface. For custom groups, make sure that you include the date of the proposed battle.

[lwd]

It's OT here but since you brought it up.
The following statement is clearly incorrect.

...there is no evidence of BB59 shooting at extreme ranges must less scoring any extreme range hits....

There is considerable evidence presented at:
http://warships1discussionboards.yuku.c ... 942?page=1
and
http://warships1discussionboards.yuku.c ... nca?page=2
not conclusive as far as hits goes IMO but not "no" evidence and very strong evidence she was firing at ranges well over 26,000 yards.

[Byron Angel]

It's OT here but since you brought it up.
The following statement is clearly incorrect.

...there is no evidence of BB59 shooting at extreme ranges must less scoring any extreme range hits....

There is considerable evidence presented at:
http://warships1discussionboards.yuku.c ... 942?page=1
and
http://warships1discussionboards.yuku.c ... nca?page=2
not conclusive as far as hits goes IMO but not "no" evidence and very strong evidence she was firing at ranges well over 26,000 yards.

..... I suppose the term "extreme range" needs to be quantified.

French inspection of the physical damage to JEAN BART @ Casablance put the angles of fall of the two deck hits scored by MASSACHUSETTS at 33 and 35 degrees ["French Battleships", Jordan & Dumas], which would put the range somewhere between 25.000 and 30,000 yards if the Navweaps range tables are to be believed.

A stationary target to be sure, but .....

B

[alecsandros]

@ KEITH
My messages don't work anymore. It maybe that my storage is full; I don't know.
I'm posting my reply here; I hope it doesn't upset you...

By "Garzke and Dulin", I assume that you are referring to their book "Battleships: Axis and neutral battleships of World War II". On page 229, the authors say that the torpedo was a surface runner. I used that book for much of the information in this series of messages.

Yes, this is the book I was refering to. It's a great encyclopedia of events for battleships in WW2, and I use it very often also.
There are some aspects in that series of books that need to be re-assessed, as lots of information has surfaced in the 30 years passed from their initial publication.

For instance, the authors make an interesting hypothesis: the first torpedo hit (in the armored belt) probably bent the armored belt inwards by 50cm. They make this assumption because one of the BBs sunk at Pearl Harbor (I think it was USS Oklahoma, but I'm not sure) received a torpedo hit directly in the armored belt, which was displaced inwards by 50cm.

I haven't found any primary source, either British or German that would support this hypothesis. The idea is interesting, but I would have several objections on it:
- first of all, the main armored belt of Bismarck was much heavier than the one used in the old US battleships (because it was longer and slightly wider).
- behind it there was a 60mm layer of teak wood, specificaly put there to absorb shocks and stop splinters
- the metallurgical properties of the KC n/A face-hardened armor were much better than the ones had by 1916-age face-hardened armor, and thus had the capability of absorbing bigger shocks.

It's stuff like this that make me skeptical, sometimes, about some information presented by G&D. Of course their books are landmarks in the historiography of WW2 naval warfare, but a slight caution in reading them isn't off-placed...

The Japanese report is interesting but I think that there is a problem. The way I read it, I don't think that they constructed models and made physical tests. It seems that it was only a "thought experiment" based on the designs. As such, it is suspect, especially since they got some of the design details wrong.

I don't know much else about the Japanese report. Maybe following the links the other members of the forum posted you could find more info... Anyway, it's an interesting perspective... As the Germans rated BS TDS as resistant against 250kg warheads and Tirpitz against 300kg warheads.

Another piece of the puzzle may come from an assesment of Scharnhorst's battle of North Cape. That's because Scharnhorst's TDS was very similar to Bismarck's...
If you can find the discussion between "dunmuro" and "david saxton" here on the forum, you would see a great debate about the capabilities of Duke of York and Scharnhorst... There is a passage that I can't find right now, from which it would seem that Scharnhorst received "3-4 torpedo" hits coming from the 4 destroyers accompanying Duke of York. The speed of the German battleship dropped "to 20-22kts", if I remember correctly. And the ship retained manouvreing capability...

I'll be out of internet reach for a week or so, so don't hurry with your reply

Regards,
Alex

[Dave Saxton]

It's OT here but since you brought it up.
The following statement is clearly incorrect.

...there is no evidence of BB59 shooting at extreme ranges must less scoring any extreme range hits....

There is considerable evidence presented at:
http://warships1discussionboards.yuku.c ... 942?page=1
and
http://warships1discussionboards.yuku.c ... nca?page=2
not conclusive as far as hits goes IMO but not "no" evidence and very strong evidence she was firing at ranges well over 26,000 yards.

Warships 1???

The track charts show BB59 ceasing fire beyond 26,000 yards and waiting until the range came back down before commencing to fire again. Furthermore, the chronology of the action records the time points when the hits were scored and they occurred at times when the range was no more than 25k according to the track charts.

French inspection of the physical damage to JEAN BART @ Casablance put the angles of fall of the two deck hits scored by MASSACHUSETTS at 33 and 35 degrees ["French Battleships", Jordan & Dumas], which would put the range somewhere between 25.000 and 30,000 yards if the Navweaps range tables are to be believed.

I have seen that the accuracy of these reports is called into question.

[Dave Saxton]

....However, offensively, South Dakota has a large advantage. Her shells are almost 40% heavier and she carries more of them. ...... At the inner edge of the immune zone, South Dakota has about a 3000 yard advantage but that is probably too small to be consistently usable....

Shell weight is not necessarly of great meaning to fire power, unless it's being used to infer greater penetration and/or a more destructive warhead after penetration. In the case of the 16"/45 vs the French 15"/45 it doesn't translate. The French gun had better belt penetration and a more destructive warhead than the 16"/45 with the super heavy.

Assuming the Rich can hit anything, this doesn't bode well to a US fast battleship, because of the weak belt protection and poor quality of US Class-A armor.

I think SD would hold an offensive advantage, due to other factors, such as firecontrol, though.

[tommy303]

The standard USN AP shell filler from shortly before the First World War to well after the Second was Explosive D (ammonium picrate); it was at the lower end of the high explosive scale in terms of power, being considerably less powerful than TNT, TNA, TNN, Shellite, or picric acid as used elsewhere. In addition, it produced corrosive fumes which could and often did corrode fuze parts until steps were taken to properly seal the fuzes. It was, however completely resistant to the shock generated by high velocity impacts against armour. Overall yield, weight for weight or volume for volume was less than foreign shells, but the USN preferred getting a smaller, low yield payload past the armour rather than a larger more powerful explosive that might not.

[lwd]

It's OT here but since you brought it up.
The following statement is clearly incorrect.

...there is no evidence of BB59 shooting at extreme ranges must less scoring any extreme range hits....

There is considerable evidence presented at:
http://warships1discussionboards.yuku.c ... 942?page=1
and
http://warships1discussionboards.yuku.c ... nca?page=2
not conclusive as far as hits goes IMO but not "no" evidence and very strong evidence she was firing at ranges well over 26,000 yards.

Warships 1???

That amounts to attacking the messenger rather than the message. Information was posted there that indicates firing over the ranges you state. Indeed there is a quote about opening up on one of the French DD's at 30,000 yards I believe. What do you have to counter that?

The track charts show BB59 ceasing fire beyond 26,000 yards and waiting until the range came back down before commencing to fire again. Furthermore, the chronology of the action records the time points when the hits were scored and they occurred at times when the range was no more than 25k according to the track charts.

Given the history of some of the posters there I would assume that they are familiar with the track charts and have reason to doubt them. Certainly they seem to be in conflict with some other information presented on that site. I'm not familiar enough with it all to judge which is most likely to be valid.

French inspection of the physical damage to JEAN BART @ Casablance put the angles of fall of the two deck hits scored by MASSACHUSETTS at 33 and 35 degrees ["French Battleships", Jordan & Dumas], which would put the range somewhere between 25.000 and 30,000 yards if the Navweaps range tables are to be believed.

I have seen that the accuracy of these reports is called into question.

Indeed. However it still represents some data supporting BB59 firing at over 26,000 yards and possibly hitting at said ranges. I will note that you have hardly refuted any of the arguments there.

[Dave Saxton]

What do you have to counter that?

I don't need any. Mine is the established position on this matter. Now if there is credible evidence to revise the established history here, I'm all for examining it and bringing forth a revision, but posting a link to an opinion thread doesn't do it.

[lwd]

What do you have to counter that?

I don't need any. Mine is the established position on this matter. Now if there is credible evidence to revise the established history here, I'm all for examining it and bringing forth a revision, but posting a link to an opinion thread doesn't do it.

Contained with in that thread was considerable evidence (on both sides) dismissing it as an "opinion" thread is unwarrented. Your position was that there was no evidence. I pointed out that it's there in the thread. I could try and summarize it but as I stated I'm not all that familiar with some of it and there are arguments and evidence on both sides. Somthing I could hardly do justice to here and which would be OT in any case. As was your original jibe.

[Dave Saxton]

.......and which would be OT in any case. As was your original jibe.

Not really. The question being alluded to was how could the JB's heavy deck protection perform so poorly. One possibility of course was that the range was extreme. I simply pointed out that there's no credible evidence that the range was extreme. Therefore, the possibility that the deck armour quality was sub par is the more likely possibility.

[19kilo]

Sabatage? French politics were pretty extreme in the 30s..........