WWII Battlecruiser matchup

[hojutsuka]

Originally posted by Ol Paint:

Friedman indicates that the 205,000shp Essex plant was discarded because it would have required eliminating all underwater protection.  The final design was rated at 150,000shp, although it made 173,808shp for 32.75kts at 33,148 tons displacement on trials.  The 150,000shp plant may have been made up of 5 standard 30,000shp units, but the description would seem to indicate that the 150,000shp plant was not directly modular to the earlier plant.

 

Douglas

 

Douglas,

 

Can you tell me where in Friedman (what book and page) you found that? I did a quick scan in my "U.S. Cruisers" and found nothing about a 205,000shp Essex plant. The Essex plant is in fact 150,000shp as designed, and IMHO is almost certainly the basis for the Alaska class propulsion. Since the Alaska used geared turbines, there is no way that BuEng would have gone for 5x30,000shp units (5 shafts? no way!) especially when there was a 150,000shp system in full production. In fact, a look at the data in Appendix C of "U.S. Cruisers" shows that the Alaska class had 8 boilers, i.e. could not be 5x30,000shp. Incidently, the Essex plant is actually based on a pair of 75,000shp plants originally developed for the Atlanta class light cruisers (Friedman, "U.S. Aircraft Carriers", page 140).

 

Hojutsuka

[Tiornu]

The primary downside to the diving shell appears to have been a loss in performance against face-hardened armor, especially for the 8in shell which had no AP cap. Penetration of homogenous armor was actually very good. The problem is that combat offered few examples, and we (I) can't distinguish the cap form's poor performance from the filler's poor performance. I cannot cite even one effective penetration of face-hardened armor for a diving shell during the entire war.

[Guest Sargent]

Originally posted by Tiornu:

I cannot cite even one effective penetration of face-hardened armor for a diving shell during the entire war.

 

Well, you aren't going to know about the ones that worked, unless there is evidence tape, "Diving Shell Did This" over the hole.

 

That's like there's not one single recorded case of a wolf pack killing and eating a lone man... who's going to report it?

[Tiornu]

Really? Haven't you ever read a damage report? It will go into painful details of what each shell did.

The closest that a Type 91 ever came to effective penetration of FH armor was the barbette hit on Boise at Cape Esperance.

"The projectile was defeated by being broken open and stopped with its base just inside the outer surface of the armor...." The face-hardening "separated in large flakes and the tough back flowed with the projectile as would be expected. Apparently the projectile was cracked open by the impact as there was no explosion, only a fizzing or burning action which was heard for several seconds and filled the turret with smoke." The shell had what looks to me to be a spiral fracture through its lower half. "Aside from the hole the nose made in the circular bulkhead and a crushed vertical web outboard of the gun girder there was no damage inside the barbette." Despite its failure to explode, it jammed the turret. This obviously was a failure of the shell form rather than the filler, which didn't explode at all, let alone prematurely.

[Guest Sargent]

Originally posted by Tiornu:

Really? Haven't you ever read a damage report? It will go into painful details of what each shell did.

The closest that a Type 91 ever came to effective penetration of FH armor was the barbette hit on Boise at Cape Esperance.

"The projectile was defeated by being broken open and stopped with its base just inside the outer surface of the armor...." The face-hardening "separated in large flakes and the tough back flowed with the projectile as would be expected. Apparently the projectile was cracked open by the impact as there was no explosion, only a fizzing or burning action which was heard for several seconds and filled the turret with smoke." The shell had what looks to me to be a spiral fracture through its lower half. "Aside from the hole the nose made in the circular bulkhead and a crushed vertical web outboard of the gun girder there was no damage inside the barbette." Despite its failure to explode, it jammed the turret. This obviously was a failure of the shell form rather than the filler, which didn't explode at all, let alone prematurely.

 

 

Like I said, that one didn't work. If it had, would anyone be able to tell from the hole? Especially if the ship was on the bottom?

 

An analogy would be the received wisdom that artillery was the most lethal killing agent in WW1. This is based on wound records.

 

Howsomever, out of approximately 30,000 British wounded treated on and after July 1, 1916, NOT ONE was treated for a rifle-caliber wound in the head or torso. Which sorta inclines me to the belief that the guys shot with MGs and rifles didn't make it treatment areas....

[Tiornu]

The ship was not on the bottom, and it would not have been on the bottom if the shell had exploded. (Boise survived a shell that exploded directly inside a magazine in that battle, so one exploding in a barbette overhead would not have made much difference.) Shells penetrate and explode all the time in a war. They show up repeatedly in damage reports. Your analogies about dead soldiers seem to imply that ships sink whenever they are hit, bringing their crews with them to the bottom and leaving no witness to their wounds. Do you know how many ships with face-hardened armor were sunk by the Japanese in WWII?

[Mobius]

Originally posted by Dan Robertson:

On a similar note has anyone ever produced a decent battleship simulator which doesn't work on hit point, but actually models the shell/armour combinations.

 

Yes, I have.

Its on paper with charts and tables.

 

Scharnhorst-class had 12.6" belt armor tapering to 6.7" at the bottom, and 1.9" and 5.9" decks. The Alaskas carried less armor with a 9.5" 10-deg sloped belt, 1.4" STS bomb deck, 3.25" and 2.8" armor decks on 1" STS.

 

The Scharnhorst side armor was backed up by 4" sloped deck giving it a total protection of something like 17".

 

One book I have lists the 12/50 penetrating 18.2" at 10,000 yds and the 11/54.5 penetrating 17.1" at 10,000 yds.

 

 

[Edited by Mobius (20 Nov 2004).]

[Guest Sargent]

Originally posted by Tiornu:

The ship was not on the bottom, and it would not have been on the bottom if the shell had exploded. (Boise survived a shell that exploded directly inside a magazine in that battle, so one exploding in a barbette overhead would not have made much difference.) Shells penetrate and explode all the time in a war. They show up repeatedly in damage reports. Your analogies about dead soldiers seem to imply that ships sink whenever they are hit, bringing their crews with them to the bottom and leaving no witness to their wounds. Do you know how many ships with face-hardened armor were sunk by the Japanese in WWII?

 

 

My point is that if the shell functions, is there going to be enough of it left to conduct an investigation on?

 

I know Boise took a magazine hit. What did the investigation conclude about that shell? AIUI, the shell went in under the armor belt, which suggests it might have been a diving shell.

 

The analogy about the soldiers is to be careful what conclusions you draw from evidence in the study. Determining what caused the wound of a man who survived to reach hospital and not determining what killed the man dead on the field is going to give you a skewed conclusion on what the most effective battlefield weapons are.

 

By the same token, your evidence shows that the Type 91 shell performed poorly, especially on face-hardened armor. The evidence is taken from examinations of shells that failed. But is there any evidence that one ever performed well? IOW, were they able to determine the type of shell if it functioned properly?

 

If all the Japanese shells fired were diving shells, then some of them worked - there were holes in Allied ships to prove it. If there was a mixture of shells fired, we are back to trying to determine what the shell that caused the damage was.

[celtredleg]

I cant speak of naval projectiles, but I spent a lot of time doing what the US Army calls crater anylisis. Everything from 81mm morters, to 8" artillery. There is almost always enough left of a given round to tell what it was.

 

Big rounds break into much larger pieces than you might expect. Sometimes you have to hunt around a bit to find what you need, but its there. I cant see there not being a similar situation for naval rounds

[Tiornu]

If an armor-piercing shell performs properly, it will not destroy the evidence of its success since it will be well beyond its point of entry when it explodes.

All Japanese AP shells in WWII were of the diving sort. The standard AP shell was the Type 91. If there was some need to clean out the surplus warehouses, the next older shell was the Type 88, but it was a diving model as well. It may be that there was no Type 91 for the 200mm gun, but the only two Japanese ships carrying that were Akagi and Kaga.

Yes, the hit on Boise's magazine went diving under her forward "belt" (such as it was). This is the one acknowledged success of a diving peformance. However, here we do have a problem with destroyed evidence, as Gambier Bay took some underwater hits that may have been true diving hits (as opposed to shells that merely land a bit short and continue their downward path into the hull--Salt Lake City appears to have had such a hit at the Komandorskis). And there may have been others like Gambier Bay. I have been looking.

"But is there any evidence that one ever performed well?" No. The question is, does this fact result from the limited sampling. I've been trying to answer my own question from before, how many ships with face-hardened armor did the Japanese sink? Apart from those sunk entirely by air attack and/or torpedoes, I can think of only one such ship--Exeter. The hits that crippled her were both deck hits, and if there are details of subsequent hits to her face-hardened armor, I have never seen them. Wait! Another one, Canberra. I do have a diagram of the hits she suffered, and none of them appear on surfaces with face-hardened armor. Since the only areas covered by FH armor were the ammo spaces, we likely would know about a shell's succes there. Now we're faced by some irony. Canberra was the only member of her class not to be modernized with a face-hardened belt amidships. Since she was disabled by low-trajectory gunfire to her midships, this singular failure to upgrade may have led directly to her loss. In the exact same circumstances, Australia would likely have survived.

What other ships with FH armor were subjected to Japanese AP shells? I can think of only a couple more besides Boise. There was Denver at Empress Augusta Bay, and I don't think her hits were on her FH armor. And there was SoDak at Guadalcanal. The 8in hits against her belt did not penetrate; it's hard to draw conclusions there, but at that close range, even an 8in shell might have a chance against BB armor. The big question is the 14in hit to her barbette. The shell got through her bomb deck, so one might suspect AP; but the blast damage was dramatic, hinting at HE. My personal opinion is that it was AP. In any case, it failed miserably to penetrate the barbette.

Can anyone recall other examples I've overlooked?

[Tiornu]

"There is almost always enough left of a given round to tell what it was."

You're right. The official reports do get into the type of shell that caused the damage. The only difficulty here resulted from the USN's unfamiliarity with Japan's weird shells. The 8in AP rounds were described as common (like an SAP round) probably because they had no AP cap. Even worse for the experts were the hits from Type 3 IS shells, which didn't look like anything in the USN inventory (or anyone else's inventory). The comments on the shell that hit SoDak's barbette are specifically noncommittal regarding the shell type. That frustrated me a lot when I read it.

[Tiornu]

The Scharnhorst side armor was backed up by 4" sloped deck giving it a total protection of something like 17".

I would caution against assigning any such equivalence. Depending on the sort of shell, the angle of the hit, and numerous other factors, the result of the two-plate system could equal significantly more or less than 17 inches worth of protection.

We have a set of penetration tables posted at http://www.geocities.com/kop_mic/ .

You can expect the low-trajectory 28cm shells to do disproportionally well against vertical armor, especially at short range, while the 12in shell is a dedicated deck-penetrater.

[gewing]

Tiornu, I have asked before, I believe the response was "not really" but...

 

WOuld HEAT rounds for naval guns have been better in WWII? At least in place of some of the HE?

 

I would think that the blast would still be pretty effective from a 6 or 8" heat round, and they might have a better chance of lucky damage against the really heavy targets.

 

Though WWII heat rounds were not exactly highly advanced.

 

HMM, 16" heat round? oh well. silly late night ideas.

[Scott Cunningham]

HEAT rounds would be poor for naval fighting.

 

I think HE shells (instead of AP) would probably been far more effective.

 

By WWII the concept of mission kill was becoming a reality. HE shells have far more destructive power, but less penetration. They are more likely to destroy something critical when they go off. They won't take out a turret, or blst open a barbette, but you can bet they will wreck optics, and anything else topsides, as well as start decent fires.

 

I wish they would release a naval surface warfare game like the old "Fighting Steel" that would let me test something like that out.

[gewing]

Wouldn't the blast effect from HEAT be fairly effective at that, and have a somewhat greater chance of penetrating pinprick hits setting fires/detonating ammo, etc? Though since a ship is basically spaced armor... maybe not.

 

 

HMMM EFP?

 

 

Originally posted by Scott Cunningham:

HEAT rounds would be poor for naval fighting.

 

I think HE shells (instead of AP) would probably been far more effective.

 

By WWII the concept of mission kill was becoming a reality. HE shells have far more destructive power, but less penetration. They are more likely to destroy something critical when they go off. They won't take out a turret, or blst open a barbette, but you can bet they will wreck optics, and anything else topsides, as well as start decent fires.

 

I wish they would release a naval surface warfare game like the old "Fighting Steel" that would let me test something like that out.

[Scott Cunningham]

You need to reduce the shell HE content by 50% to make a shaped charge. Even then, since it is shaped, much of the blast effect goes in one precise direction.

 

It might penetrate, but then what. All you would have is a small hole poked in.

 

AP shells get in, then explode to do their damage. Getting in is just half of the effect. It is important enough to sacrifice 75% of the explosive effect to achiee it, but it still needs terminal results.

[Guest Sargent]

The British doctrine before WW1 was to fire mainly HE, to set the target on fire, kill crew, and mess up communications and fire control. The AP was reserved for "finishing off" the cripple by penetrating her armor belt at close range. This is one reason why the British AP shells performed poorly at long range, they were specifically designed to function as vertical hits at short range.

 

It also explains the "secondary belts" of thinner armor spread over the ship. They were not intended to defeat AP, they were intended to keep the HE out.

[Mobius]

Since ships are such a large object there is need to make substantial damage to it. Not just to penetrate it.

The larger shell do this. If the shell stays together is can do considerable damage no matter what it hits. Didn't one 16" hit on the French battleship at Casablanca chink off the barbette side and thrash most of the cabins on the superstructure?

 

[Edited by Mobius (21 Nov 2004).]

[Mobius]

repeat

 

[Edited by Mobius (21 Nov 2004).]

[Tiornu]

WOuld HEAT rounds for naval guns have been better in WWII? 

I don't know all that much about HEAT rounds, but I tend to think that they would have been used if they offered something practical. The only ones to used shaped charges in anti-ship ammo were (I believe) the Germans who used them only in coast defense rocket-mortars promising an extreme angle of descent. Did they know how to combine shaped charges with rifled weaponry back then?

[Tiornu]

Yes, at Casablanca one 16in dud rattled its way along the top of the armor deck. Damage wasn't extensive, but it did kill the ship's XO. The other dud disabled JB's only turret by deforming the armor and shorting out the electrical training gear.

[Guest Sargent]

Originally posted by Tiornu:

  Did they know how to combine shaped charges with rifled weaponry back then?

 

If you mean did they have something like the ball-bearing ammo that takes the rifling but does not spin the shaped charge, no.

 

If you mean did they fire HEAT from rifled guns, yes. Generally at fairly low velocity because the shell would deform before a mechanical or powder fuze could ignite the charge at an MV over ca. 1300fps. It took the development of piezo-electric fuzes post-war before HEAT could function at high velocity.

 

Which, now that I think about it, answers the question of HEAT in naval guns during WW2. The fuzes available then would not have functioned at the striking velocity of naval shell, so HEAT wouldn't work in naval guns.

[Mobius]

Taking a closer look at the Scharnhorst armor scheme it looks like the tapering only starts below the joint with the armored sloped deck. That would mean to penetrate the vitals at closer ranges the full 12.625" belt would have to be penetrated. I measured the angle of the drawing of sloped deck in the Friedman Battleship book and the Beyer Battleship book. One is 67° and the other is 63°. So let's say its 65°. The 12"/50 impacts at 12.2° at 16,000 yds. The LOS of this angle through the armor would be a total of 19.7". And that's not counting 1" torpedo bulkhead.

 

One thing I did notice is that the Breyer book barely shows that shot-trap like step in the horizontal deck but the Friedman drawing clearly shows it. A shell penetrating the side but above the sloped deck might have an easy entry point into the vitals.

 

[Edited by Mobius (21 Nov 2004).]

[Tiornu]

Scharnhorst's belt is not 12.6in but 13.8in.

That step over the boilers is where DoY put the 14in shell that slowed Scharnhorst at North Cape, allowing her to be torpedoed.

[Mobius]

Originally posted by Tiornu:

Scharnhorst's belt is not 12.6in but 13.8in.

That step over the boilers is where DoY put the 14in shell that slowed Scharnhorst at North Cape, allowing her to be torpedoed.

 

You're right. The Friedman schematic is wrong. In another book it has the armor at various frames and all main belts are 350mm. The angled deck is @ 67°.