Bismarck vs. Iowa

Historical what if discussions, hypothetical operations, battleship vs. battleship engagements, design your own warship, etc.
Saltheart
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Re: Bismarck vs. Iowa

Post by Saltheart » Sat Jun 18, 2011 6:54 pm

Hi, thanks for the welcome.
A lot of what you said I agree with. I was also thinking Tirpitz would have a higher rate of fire, probably in the order of 3 salvos for every 2 by Iowa and that that could play a major role in the outcome. I was also thinking that even if Tirpitz couldn't cleanly penetrate an Iowa turret face the impact energy alone would put it out of action pretty comprehensively. When the South Dakota's barbette took a partial hit at it's base by a 14 inch shell in the Pacific it was enough to hinder the above turret for some time. A direct face hit would disable an Iowa turret. So even though Iowa could destroy Tirpitz's armament Tirpitz could still also knock out Iowa's. What's more it only has to get rid of 3 turrets not 4.
I didn't know Iowa's magazines were very deep in the ship, I thought like South Dakota's they could be accesed through the main belt. Hmmm, it does make it harder to get a kill.
But it would be an unbelievable pounding match. Both ships would be fighting for their lives. Every man in both crews would know they were in a battle with an enemy more than capable of killing them. The reputation of Tirpitz would be there because of Bismarck's exploits while the Germans would be acutely aware of the massive American 16 inch guns. The sweating going on on both ships would be serious. The concentration levels, attention to every detail, quest for more speed in everything attempted would be total. in some ways it would be almost like a Napoleonic naval struggle. Instead of running out the guns it would be the fire control director stations, radar rooms and massive gun turrets full of men desperate not to make a mistake and preying for the accuracy of their gunfire. Down in the boiler rooms and magazines and in fact throughout the hull a thousand or more men would be constantly looking up every time the guns fired or the countdown was on to receive the enemie's shells. The stress would be on everyone's faces.
I'd sell my car for a ticket to getting a full multi angle view of that fight live!
Anyway, something I thought of yesterday after my post was underwater protection. Prince of Wales penetrated Bismarck's engine room and ultimately it had to be abandoned. I was thinking if a 16 inch 45 calibre made that hit it might not do any more damage. The fact it would be much heavier would be countered by it's lower velocity. But a 16 inch 50 calibre? It might punch into that room and keep on going. if so I wonder if there was another watertight room after that one or whether it would mean uncontrollable flooding into a much larger space. If so underwater hits could be potentially lethal for Tirpitz in such a fight. I don't know if Tirpitz could penetrate Iowa's ups but I've heard it wasn't so good as the American's hoped so maybe it would. Certainly as you said the bow could be flooded.
I agree Tirpitz upperworks would be demolished. 2700 pound shells would remove the superstructure and secondary turrets and destroy the main turrets. I wonder if complete explosions in Tirpitz turrets and barbettes would wreck the whole ship or whether the damage though terrible would be localised to that immediate area of the ship. If it had the capacity to wreck the whole ship then Tirpitz would be in a very dangerous position.
Personally having said that I think Tirpitz would win. The broader hull I think would help in absorbing punishment in general and the higher rate of fire would I think see Iowa getting hit more. Maybe a hit on Iowa's middle turret if the range closed would penetrate and knock out both forward turrets. We know from what happened with Bismarck that it doesn't seem to take all that much to disable turrets even if only temporarily.
I think the range between the two would close relentlessly as both sought more and more hits and Tirpitz would come out of it even maybe with just one turret still firing but that one turret hammering Iowa's belt at 8000 yards. I think it would be a knock down drag out and Tirpitz's scarp and faster fire would see it win.

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Re: Bismarck vs. Iowa

Post by Saltheart » Sat Jun 18, 2011 7:47 pm

"according german general tactics no enemy firing on own ship was left unresponsed. The 1st AO decide to shot mixed HE shell and semi AP shell to deal with the large unprotected areas and slightly armored structural parts and waterline of the US ship."

I get that HE and semi AP could do damage to Iowa but if they fired it they would leave themselves more open to being hit by Iowa. If the Tirpitz captain obeyed German doctrine and traded fire using HE at long range then I think Tirpitz would lose. If he fully understould the danger from Iowa and disregarded doctrine in favor of common sense survival and went solely for evasive action then I think he'd have a chance.
But thanks for letting me know their rule of engagement there, I wasn't aware of it.
It seems limiting though, as you'd think they'd consider that in some situations or at least time periods not returning fire might be better and that the Captain be allowed to exercise his discretion on that.

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Re: Bismarck vs. Iowa

Post by delcyros » Sat Jun 18, 2011 7:49 pm

In the case of the 14" round hitting the SoDak it was rejected by the barbet armor and still detonated high order. My point was that just because it was rejected by the armor doesn't mean that it won't explode high order or even that it will shatter. I've seen battleship projectiles that have partially penetrated armor for instance and while obviously damaged they were a long way from shattering.
Here two things need to be adressed seperately:

[+] was the projectile rendered inert during impact
[+] did the projectile went up high order?
[+] what do You conclude out of this?

In fact it appears that the 14in type 91 APC indeed impacted the 17in thick barbette highly obliquily. It cannot be said it was rejected (it exploded while still in contact with the barbette with the projectile´s base), though. From Rob Lundgren´s and my disussion with him about the rational of the impact it appears that the projectile is not a standart one.

Japanese APC had a shock sensitive, highly powerful TNA filler (Q= 1.05 compared to 1.0 for TNT and 0.95 for US explosive D) which required a wooden plug to be substituted in the nose of the cavity to protect the charge from premature explosion during impact shock. However, from the description of Mr. Lundgren (if we follow him on this despite the concerns raised by Bill Jurens in the same discussion, which need to be kept in mind) it appears that the projectile impacted the barbette, and the nose pressed down the 1.5in STS armoured weatherdeck while the base jammed against the barbette laterally hard.
This lateral shock and not nominal fuse delay touched off the main charge because the TNA filler wasn´t protected against sideways directed lateral shock.
The projectile may be shattered at this point or broken up badly, it doesn´t matter at all, the sideimpact would have triggered the explosive charge very similarely to british lyddite fillers at Jutland.

The technical answer is that yes, the projectile inerted after impact with the barbette but no it doesn´t rendered a dud because of the very sensitive filler present in japanese APC and the sideways impact shock. This wouldn´t have been the case for more save fillers like US explosive D which were so resistent to premature detonation that they got completely rid of protective wooden plugs. These projectiles would have been blinded in the same condition with no detonation at all.

The answer to the second question is more difficult to find. You have lot´s of projectile fragmentation above and below the weatherdeck suggesting that the projectile completely burst. Did it burst high order? Here I think Mr. Lundgrens argumentation is weaker. It appears that the weatherdeck wasn´t holed at all by any of the fragments nor even badly rippled or cracked -both of which should have happened against type 0 high explosive impacts. BUT: True is that it would also happen with type 91 APC exploding in near contact conditions like the very impact mentioned here. Note that the projectile is in contact condition with the 1.5in STS weatherdeck in the areas encircled under (1) and (2) in the drawing below:

Image

If impact condition applies then the 14in APC should be able to defeat 0.112 cal thick STS / class B plating with lateral fragments according to Nathan Okun (=1.57 in STS for the 14in). This is most likely conservative because the filler is more powerful than the reference filler (TNT) used by Nathan Okun and late 30´s + ww2 STS plating below 2.0 in thickness was not as powerful in stopping power than thicker plates (Q=0.95 ac. to Nathan Okun). Thus a high order AP burst would still see a few calibre sized holes in 1.5in STS plating even if spaced less than one calibre away from the burst as a lower limit. The upper limit for bulges and cracks created but no complete hole is 0.135 cal. thickness STS plating or 1.9 in STS for the japanese type 91 APC. In between both values sub calibre sized holes are formed in the plating growing constantly until reaching ca. calibre size at 1.6in STS latest.

No holes were shown in the plating nor cracks caused by fragmentation damage and this makes me believe it was not a high order burst but kind of a low order detonation caused by touching off the charge of a broken / shattered projectile. This kind of detonation is much less powerful than a high order burst (typically one third as powerful).

delcyros
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Re: Bismarck vs. Iowa

Post by delcyros » Sat Jun 18, 2011 8:42 pm

Byron Angel wrote: ..... For what it's worth, British WW1 investigation (Final Report of the President of the Projectile Commission - 1917) observed some interesting differences in effect among different projectile types -

Lyddite charged HE projectiles produced a cloud of very small fast moving fragments in all directions, which generally were able to pierce one unarmored internal bulkhead or deck, but were stopped by a second.

Black powder charged common projectiles dispersed in a forward cone axial to projectile path a limited number of heavy slow moving heavy fragments (one might call them 'slabs' perhaps) able to smash through several such unarmored internal bulkheads in succession before exhausting their energy.

So it does indeed seem that overall projectile damage effect (outside of pure blast effect) is indeed a function of both fragment velocity AND size.

B
Dear Byron,

I think You both are right without necessarily contradicting each other. The Trials in the RN show that high explosives (such as lyddite and TNT related fillers) create high order detonations with fragmentes traveling at very high speeds, capable to destroy much thicker plating than slower and larger projectiles but in the same time loosing up their energy more quickly with distance.

Low explosives such as Black powder or gunpowder fillers commonly used before ww1 tend to break up the projectile in fewer, albeit larger fragments and create a more inward directed zone of destruction but are uncapable of penetrating armoured bulkheads, generally. The british black-powder filled ultra large cavity CPC projectile mentioned by You falls in this category.

The RN Bellisle trials show the relative merits with regard to 6in hits. Lyddite filled shells had the potential of complete pulverization of the spaces hit but the many fragments also meant a more sideways directed fragment pattern shielded by the heavier nose (AP only) and base pieces. The rational of high eplosives was to put them as close to the centerline of the ship as possible (narrow path of destrution formed y the projetile passing through the bulkheads) followed by the complete pulverization of the space hit (the projectile at this time was in within the sensible parts of the ship and forward directed fragmentation wasn´t required anymore) while the rational of black powder filled low explosive shells was to fragmentate on the outer surface and direct damage from outside to the inside with the hope expressed to induce waterplan related flooding damage.
Low explosives were rejected in favour of high explosives in all nations in the interwar period. RN ww2 period trials suggest that the capability of a projectile to cause inboard destruction was much more related to the size of the HE filler than to the weight of the projectile if the projectile went up high order (the rational behind the comparably large british HE fillers in AP ammunition by ww2) and that the momentum of the projetile (it´s kinetic energy) was important if the projectile ended up as a dud or a very low order detonation.
Larger, more powerful bursters directly relate to thicker splinterproof plating ruptured and holed by the lateral, sideways directed fragmentation of the projectile. Thicker slower fragments started with much less fragment penetration ability but kept that ability for a longer distance. However if it can´t penetrate in the first place a bulkhead this "keeping" advantage of the thicker fragments are of no use at all.

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Re: Bismarck vs. Iowa

Post by Byron Angel » Sun Jun 19, 2011 2:04 pm

delcyros wrote: Dear Byron,

I think You both are right without necessarily contradicting each other. The Trials in the RN show that high explosives (such as lyddite and TNT related fillers) create high order detonations with fragmentes traveling at very high speeds, capable to destroy much thicker plating than slower and larger projectiles but in the same time loosing up their energy more quickly with distance.

Low explosives such as Black powder or gunpowder fillers commonly used before ww1 tend to break up the projectile in fewer, albeit larger fragments and create a more inward directed zone of destruction but are uncapable of penetrating armoured bulkheads, generally. The british black-powder filled ultra large cavity CPC projectile mentioned by You falls in this category.

The RN Bellisle trials show the relative merits with regard to 6in hits. Lyddite filled shells had the potential of complete pulverization of the spaces hit but the many fragments also meant a more sideways directed fragment pattern shielded by the heavier nose (AP only) and base pieces. The rational of high eplosives was to put them as close to the centerline of the ship as possible (narrow path of destrution formed y the projetile passing through the bulkheads) followed by the complete pulverization of the space hit (the projectile at this time was in within the sensible parts of the ship and forward directed fragmentation wasn´t required anymore) while the rational of black powder filled low explosive shells was to fragmentate on the outer surface and direct damage from outside to the inside with the hope expressed to induce waterplan related flooding damage.
Low explosives were rejected in favour of high explosives in all nations in the interwar period. RN ww2 period trials suggest that the capability of a projectile to cause inboard destruction was much more related to the size of the HE filler than to the weight of the projectile if the projectile went up high order (the rational behind the comparably large british HE fillers in AP ammunition by ww2) and that the momentum of the projetile (it´s kinetic energy) was important if the projectile ended up as a dud or a very low order detonation.
Larger, more powerful bursters directly relate to thicker splinterproof plating ruptured and holed by the lateral, sideways directed fragmentation of the projectile. Thicker slower fragments started with much less fragment penetration ability but kept that ability for a longer distance. However if it can´t penetrate in the first place a bulkhead this "keeping" advantage of the thicker fragments are of no use at all.

...... I hope I did not create the impression that I disagreed with the original post. I was only seeking to expand on the topic and provide some further data.

B

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Re: Bismarck vs. Iowa

Post by alecsandros » Sun Jun 19, 2011 6:08 pm

Hello Byron,
I'll try to adress your comments in order; I hope you don't mind I've split them.
Byron Angel wrote:

IOWA will not be doing any ranging fire. In a late 1943 daylight engagement at 18,000 yards she will open with rapid fire full broadsides under radar ranging and optical train and will straddle on the first or second broadside (official doctrine at the time)...
My guess is that the first 3-4salvos for each turret woudl be to bring the tubes to the correct firing temperature; prior to that the guns woudl be "cold". IF Tirpitz woudl respond with 4-gun salvos (that would also straddle on the first semi-salvo - see what Hipper done to Achates at 18000y), both captains may decide hard evasive actions and/or speed altering, so that they may have a chance of disrupting the others flow of plotting solutions. Depending on how "hard" the evasive actions woudl be, the firing solutions would be 1) still accurate (for small changes in bearing/speed) 2) somewhat accurate (for mdoerate changes) and 3) completely innacurate and useless (for hard changes). In 1943, this woudl affect both ships...

Based upon some previous notes I had taken for an exchange of fire at 22,000 yds (if the Navweap stats for the respective guns are valid), the ballistic differences in gun performance at 22,000 yds range are largely inconsequential -
> ToF difference is < 1 second.
At 18000m:
38cm L52: 28sec time of flight, 13,9* angle of fall, 532mps
40,6cm L50: 29,5 sec tof , 14,9* angle of fall, 530mps
> AoF/danger space advantage to Bismarck for a 30 ft tall target is about 10 ft in range. But Bismarck is 10 feet wider in beam, which makes their overall target footprints equal for all practical purposes.
But also the Iowa is 30ft longer, and it's a little bit "taller", on average, IIRC. Thsu the projected strikable surface from the respective shells is larger for Bismarck's shells than for Iowa's.
> True mean dispersion for the 16in/50 ~20,000 yards is approx 165-200 yards.
That's the dispersion for 1 single gun, I suppose ? The dispersion of the L52 38cm at 20km was 104m.
The dispersion for a 3-gun turret at that distance was about 250-300y; Tirpitz underwent firing trials in which showed about 150-200y dispersion of 4-gun salvos beyond 20000y.

As regards Rof, the proven rate of fire of the 16in/50 under actual battle conditions was ~1.5 rpm;
But the Iowa's never had a chance to deliver full rapid-fire in battle. Why waste precious ammo when the target isn't clearly plotted and/or isn;t a real threat ?
In trials in 1940, South Dakota averaged 2,5 rpmpg (actualy fired shells, not only ordered) against a target 1000y away.

The stated rate of fire of the 38cm/L52 is said to have been 3 rpm,
At ranges of ~ 20km and probably for short periods of time, the rof was > 3,3 rpm. There's a movie showing just that: teh aft turrets fire at 18sec intervals... at elevation of about 15*... corresponding to a range of about 22-23km.
So ...... IMO ..... the ship that hits first andhardest will likely win such an engagement.
Agreed :D

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Re: Bismarck vs. Iowa

Post by Thorsten Wahl » Sun Jun 19, 2011 7:31 pm

But Bismarck is 10 feet wider in beam, which makes their overall target footprints equal for all practical purposes.
ther is a little comment I have to made. even bismark was 36 m wide it doesnt mean that you are able to in every case of potential deck perforations to hit something important about this whole width.

there are roughly 11 m of width below the scarp,
to achieve a potentially devastating hit into the magazines or machinery its necessary mostly to hit the flat part of the armored deck, except for steep fall so that a projectile perforates upper deck-> scarp -> torpedobulkhead ----boom.
Meine Herren, es kann ein siebenjähriger, es kann ein dreißigjähriger Krieg werden – und wehe dem, der zuerst die Lunte in das Pulverfaß schleudert!

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Re: Bismarck vs. Iowa

Post by alecsandros » Sun Jun 19, 2011 8:04 pm

Saltheart wrote: ..But a 16 inch 50 calibre? It might punch into that room and keep on going. if so I wonder if there was another watertight room after that one or whether it would mean uncontrollable flooding into a much larger space.
Well, the 12 boilers were grouped into 6 different watertight compartments, and the turbines were divided into 3 turbine rooms. The internal subdivision was very good...
I wonder if complete explosions in Tirpitz turrets and barbettes would wreck the whole ship or whether the damage though terrible would be localised to that immediate area of the ship.
Well, an explosion of the main magazine or in the handling room may have been disastrous. But I doubt that were possible, as the magazines were relatively high in the ship (exactly below the panzer deck) a a hit at 18-20km couldn't have been obtained unless the main belt and scarp were defeated, which is difficult to demonstrate. (it's exactly the opposite of Iowa's magazine protection :) )

The handling rooms were inside the barbettes, which were 220mm thick beneath the upper-deck. A shell coming from Iowa would have been de-caped adn badly yawed by the 145mm or 320mm KC n/A belt armor, and then it would shatter against the 220mm thick armored walls of the internal barbette.

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Re: Bismarck vs. Iowa

Post by Saltheart » Sun Jun 19, 2011 8:43 pm

"Well, the 12 boilers were grouped into 6 different watertight compartments, and the turbines were divided into 3 turbine rooms. The internal subdivision was very good..."

Oh okay, that does make things a lot better then. It gives the Tirpitz far more of a fighting chance than I actually feared in the face of underwater hits.

"Well, an explosion of the main magazine or in the handling room may have been disastrous. But I doubt that were possible, as the magazines were relatively high in the ship (exactly below the panzer deck) a a hit at 18-20km couldn't have been obtained unless the main belt and scarp were defeated, which is difficult to demonstrate. (it's exactly the opposite of Iowa's magazine protection :) )"

When I was thinking of a hit through the belt and on into a magazine I was actually thinking of Iowa if it was vulnerable like South Dakota.

My worry for Tirpitz was whether a 16 inch shell blowing up inside a Tirpitz turret could spread the destruction down through the barbette to the magazines and destroy the ship. I agree hits on the magazine via the belt and scarp would have been near impossible. Also defenately hits on the barbettes beneath the deck would have been useless as the shell would have already come through to much armor by the time it hit it.

My only concerns really for Tirpitz as far as total defeat of the ship is concerned were based on turret destruction resulting in ship destruction, if that's possible, and underwater hits causing uncontrollable flooding. If neither of those is likely then I think Tirpitz will win precisely because getting to it's own magazine through the scarp is near impossible.
Iowa would lose because if the range just kept on closing the Tirpitz, minus a couple of turrets and most of it's superstructure, could fire it's surviving guns straight into Iowa's belt and detonate the magazines.

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Re: Bismarck vs. Iowa

Post by dunmunro » Sun Jun 19, 2011 9:26 pm

alecsandros wrote:
In trials in 1940, South Dakota averaged 2,5 rpmpg (actualy fired shells, not only ordered) against a target 1000y away.
No triple turret 16" USN BBs were in commission in 1940.

The max rate of fire of the USN 16"/45 was less than 2 RPM even at ~8400 yds:
www.usswashington.com/washingtonguadalcanal.pdf
which is only about 5 degrees elevation.

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Re: Bismarck vs. Iowa

Post by Byron Angel » Mon Jun 20, 2011 4:59 am

Hi Alex,
alecsandros wrote: My guess is that the first 3-4salvos for each turret woudl be to bring the tubes to the correct firing temperature; prior to that the guns woudl be "cold". IF Tirpitz woudl respond with 4-gun salvos (that would also straddle on the first semi-salvo - see what Hipper done to Achates at 18000y), both captains may decide hard evasive actions and/or speed altering, so that they may have a chance of disrupting the others flow of plotting solutions. Depending on how "hard" the evasive actions woudl be, the firing solutions would be 1) still accurate (for small changes in bearing/speed) 2) somewhat accurate (for mdoerate changes) and 3) completely innacurate and useless (for hard changes). In 1943, this woudl affect both ships...
..... Any "cold gun" issue was resolved on the opening discharge and actually involved clearing the bore of any oil residue remaining from the last tube swabbing rather than gun temperature. Corrections in elevation/range (not to say "perfect" corrections by any means) for this first discharge were a standard feature of capital ship gunnery.

At 18000m:
38cm L52: 28sec time of flight, 13,9* angle of fall, 532mps
40,6cm L50: 29,5 sec tof , 14,9* angle of fall, 530mps
..... Sounds reasonable. I think you'll agree that the differences are not dramatic.

But also the Iowa is 30ft longer, and it's a little bit "taller", on average, IIRC. Thus the projected strikable surface from the respective shells is larger for Bismarck's shells than for Iowa's.
..... The following is worth consideration:
BISMARCK versus IOWA (approximated from respective ship plans and profiles found in Dulin & Gartzke and Sumrall) -
> Length on the waterline - 792 ft versus 859 ft
> Length of machinery spaces - 267 ft versus 247 ft
> Length of main battery spaces - 290 ft versus 206 ft
> Overall length of vitals - 557 ft versus 453 ft

The question of target height depaned upon how one wishes to calculate it. A cursory glance as a profile plan suggests IOWA to be a taller target amidships by two deck levels. But a closer examination of the profile plan indicates that the heights of both BISMARCK and IOWA from keel to uppermost load bearing deck (i.e. - bearing the weight of a main battery turret) are both approx 60 feet. It remains a matter of debate how essential the light superstructures above these load-bearing decks would have been to the structural integrity and overall survivability of either ship.

> True mean dispersion for the 16in/50 ~20,000 yards is approx 165-200 yards.
That's the dispersion for 1 single gun, I suppose ? The dispersion of the L52 38cm at 20km was 104m.
The dispersion for a 3-gun turret at that distance was about 250-300y; Tirpitz underwent firing trials in which showed about 150-200y dispersion of 4-gun salvos beyond 20000y.
..... I cited an incorrect TMD value in my previous post, so re-state as follows. Re data provenance, TMD values were computed by the USN from results of BB gunnery practices at sea between Jan 42 and Dec 43, using the "new service AP projectiles". Ships of both the 16in/50 IOWA class and the preceding triple turret 16in/45 class participated. I selected the seven practices where average firing range was given as reasonably proximate to 18,00 meters. All told, this involved 42 salvoes. The great majority of these tests involved the simultaneous discharge of all three guns of a firing turret, with one or more turrets participating in any given salvo - therefore replicating shooting under action conditions as closely as practicable. Average TMD for these tests at ~18,000 meters range was 126 yards, which according to the USN analysis equated to a 9 gun salvo pattern of ~465 yds. On the other hand, I think it is dangerous to put too much faith in these tests as predictors of events on any given day - some really capricious variations in results appear in the data I've seen - with the same ship shooting at the same range on consecutive days getting widely different results; I've even seen better TMD results being obtained at longer ranges.


But the Iowa's never had a chance to deliver full rapid-fire in battle. Why waste precious ammo when the target isn't clearly plotted and/or isn;t a real threat ?
In trials in 1940, South Dakota averaged 2,5 rpmpg (actualy fired shells, not only ordered) against a target 1000y away.
..... Are you sure on the SODAK data? She was not launched until 1941. As for the 1.5 rpmpg figure "in action" (it was actually about 1.6 rpmpg) I took that from the performance data of USS WASHINGTON's engagement of KIRISHIMA, which did allow for a two minute cease fire when sight of the target was lost momentarily. I don't think WASHINGTON's gun crews were dawdling along in that engagement.


The stated rate of fire of the 38cm/L52 is said to have been 3 rpm,
At ranges of ~ 20km and probably for short periods of time, the rof was > 3,3 rpm. There's a movie showing just that: teh aft turrets fire at 18sec intervals... at elevation of about 15*... corresponding to a range of about 22-23km.
..... Can I view this film clip on the web?

So ...... IMO ..... the ship that hits first and hardest will likely win such an engagement.
Agreed :D

B

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Re: Bismarck vs. Iowa

Post by Byron Angel » Mon Jun 20, 2011 5:18 am

Interesting find on ibiblio-hyperwar site - US Bureau of Ordnance report on the 16in/50cal -

" Firing cycle was 20 seconds with the gun at the loading position."

Note - loading position was 5 degrees elevation.


B

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Re: Bismarck vs. Iowa

Post by alecsandros » Mon Jun 20, 2011 8:04 am

Byron Angel wrote:

.. The following is worth consideration:
BISMARCK versus IOWA (approximated from respective ship plans and profiles found in Dulin & Gartzke and Sumrall) -
> Length on the waterline - 792 ft versus 859 ft
> Length of machinery spaces - 267 ft versus 247 ft
> Length of main battery spaces - 290 ft versus 206 ft
> Overall length of vitals - 557 ft versus 453 ft
That's very interesting. One further addition would be that the un-protected portion of Iowa was vulnerable to HE fire. A couple of 38cm HE hits on the bow or stern could trigger a big flood.

Byron Angel wrote:
..... Are you sure on the SODAK data?
Nope; I'm still searching for the Jurens INRO article with the 2.5rpmpg figure.

Byron Angel wrote: As for the 1.5 rpmpg figure "in action" (it was actually about 1.6 rpmpg) I took that from the performance data of USS WASHINGTON's engagement of KIRISHIMA, which did allow for a two minute cease fire when sight of the target was lost momentarily.
Ok, but Washington's engagement was to short to draw any conclusions on the 3 x 3 16" arrangement rte of fire...

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Re: Bismarck vs. Iowa

Post by Byron Angel » Mon Jun 20, 2011 12:57 pm

alecsandros wrote: Ok, but Washington's engagement was to short to draw any conclusions on the 3 x 3 16" arrangement rte of fire...

..... Hi Alex,

I'm not sure I undestand your argument here. WASHINGTON knocked out and crippled KIRISHIMA in approximately 5.5 minutes, firing 25 salvoes and scoring 20 hits (Lundgren). That seems pretty conclusive to me, even at 8,000 - 12,000 yards range.

B

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Re: Bismarck vs. Iowa

Post by alecsandros » Mon Jun 20, 2011 1:09 pm

Byron Angel wrote:
alecsandros wrote: Ok, but Washington's engagement was to short to draw any conclusions on the 3 x 3 16" arrangement rte of fire...

..... Hi Alex,

I'm not sure I undestand your argument here. WASHINGTON knocked out and crippled KIRISHIMA in approximately 5.5 minutes, firing 25 salvoes and scoring 20 hits (Lundgren). That seems pretty conclusive to me, even at 8,000 - 12,000 yards range.

B
I wannted to say that it needs a longer engagement, and preferably during the day, to extrapolate a more accurate rof. My belief is that, had the engagement occurd in daylight, the rof would have been > 2 rpmpg.

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