Bismarck vs. Iowa

Historical what if discussions, hypothetical operations, battleship vs. battleship engagements, design your own warship, etc.
User avatar
tommy303
Senior Member
Posts: 1528
Joined: Mon Oct 18, 2004 4:19 pm
Location: Arizona
Contact:

Re: Bismarck vs. Iowa

Post by tommy303 »

RDX by itself is much more powerful than TNT, but it is not an ideal explosive for torpedo and mine applications, as the explosive pulse is of very short duration and the explosive is both expensive and susceptible to shock. In this respect, straight TNT is probably better; however, by blending RDX and TNT one comes up with an explosive that is 20% or so more powerful than straight TNT. Adding aluminium powder acts as an oxidant and increases both the heat of the explosion and the duration of the explosive pulse (in much the same way as the Germans achieved with aluminized TNT/HND warheads).

Their shoulders held the sky suspended;
They stood and Earth's foundations stay;
What God abandoned these defended;
And saved the sum of things for pay.
Thorsten Wahl
Senior Member
Posts: 919
Joined: Mon Apr 27, 2009 4:17 pm

Re: Bismarck vs. Iowa

Post by Thorsten Wahl »

ballistic mortar of Schießwolle 36 was about 130 with TNT =100

similar compositions were also used in german bombs like Fritz X
Meine Herren, es kann ein siebenjähriger, es kann ein dreißigjähriger Krieg werden – und wehe dem, der zuerst die Lunte in das Pulverfaß schleudert!
User avatar
tommy303
Senior Member
Posts: 1528
Joined: Mon Oct 18, 2004 4:19 pm
Location: Arizona
Contact:

Re: Bismarck vs. Iowa

Post by tommy303 »

Some Luftwaffe bombs, particularly those used for attacks on merchant ships, used Trialen, which was similar to Torpex. It consisted of a combination RDX, TNT, and aluminium.

Their shoulders held the sky suspended;
They stood and Earth's foundations stay;
What God abandoned these defended;
And saved the sum of things for pay.
dunmunro
Senior Member
Posts: 4394
Joined: Sat Oct 22, 2005 1:25 am
Location: Langley BC Canada

Re: Bismarck vs. Iowa

Post by dunmunro »

lwd wrote:
RobertsonN wrote:...The only modern US battleship torpedeod was NC. The main sources differ: Dulin and Garzke say the charge was over 900 lb TNT and that the SPS was defeated. Friedman says the charge was 660 lb and that the system just held. Flooding was a comparatively modest 970 tons. More serious was structural damage that all but put the foremost main turret out of action and limited sustained speed to 18 knots. Anybody know what the charge really was and whether there was flooding inboard of the HB? The performance of Iowa to a hit in this position would have likely been similar.
From http://www.navweaps.com/Weapons/WTJAP_WWII.htm
I suspect either a Type-95 mod 1 or a Type-96 the former has a 405Kg (~900 lbs) charge the latter a 550kg (~1200lbs) charge. The charge is given as being type 97 which http://www.navweaps.com/Weapons/WTJAP_Notes.htm suggest is 107% as powerful as TNT.
The TROM at http://www.combinedfleet.com/I-19.htm states it was a Type-95.

The detailed report is not at http://www.ibiblio.org/hyperwar/USN/rep/WDR/index.html but the summary report says:
Struck by a deep-running torpedo at frame 55 port side holding bulkhead failed along a vertical butt permitting some flooding. After damage, speed was increased from 19 to 25 knots.

NC's TDS was defeated by the hit, as flooding and flash occurred inboard of the holding bulkhead., OTOH, it seems from the damage report, that the flooding was fairly minor and the flash effect was unlikely to have endangered the ship. There was some shock damage to the main armament but this was easily repaired by the ships company. However, I suspect that Iowa or SoDak would have faired less well, due to the differences in their TDS design, over that used in NC.
RobertsonN
Member
Posts: 199
Joined: Wed Jan 05, 2011 9:47 am

Re: Bismarck vs. Iowa

Post by RobertsonN »

From the gist of all this information, it appears that the torpedo had by the late war period become a much greater threat to the battleship, if not to the same extent as the most powerful bombs. It would seem to follow that damage control and good compartmention became relatively more important. Perhaps this is why the Montana had much better compartmentation than Iowa, similar (if not better) to that of the Bismarck.
On the other hand, the British appeared to think that the long range threat of the shell had actually decreased. The early designs for the Lion (Dulin and Garzke) give the 16 in gun penetrating nearly 6 in (5.73 in) at 30000 yards. But ADM Supp 6-481 of Jan. 1946 gives the 16 in (2393 lb shell) penetrating a 6 in deck at 34000 yds (a 2375 lb shell is given as 34200 yds and a 2240 lb shell at 35400 yds). This may be why the later, much larger, Lion variants still had 6 in decks (only 4 in over machinery). On the other hand, underwater protection was much improved with a much wider beam (120 ft).
User avatar
Dave Saxton
Supporter
Posts: 3148
Joined: Sat Nov 27, 2004 9:02 pm
Location: Rocky Mountains USA

Re: Bismarck vs. Iowa

Post by Dave Saxton »

RobertsonN wrote:......On the other hand, the British appeared to think that the long range threat of the shell had actually decreased. The early designs for the Lion (Dulin and Garzke) give the 16 in gun penetrating nearly 6 in (5.73 in) at 30000 yards. But ADM Supp 6-481 of Jan. 1946 gives the 16 in (2393 lb shell) penetrating a 6 in deck at 34000 yds (a 2375 lb shell is given as 34200 yds and a 2240 lb shell at 35400 yds). This may be why the later, much larger, Lion variants still had 6 in decks (only 4 in over machinery). On the other hand, underwater protection was much improved with a much wider beam (120 ft).
This came from new, more extensive, live fire, testing data which indicated that earlier estimates had been rather optomistic.
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.
paul.mercer
Senior Member
Posts: 1224
Joined: Fri Mar 26, 2010 10:25 pm

Re: Bismarck vs. Iowa

Post by paul.mercer »

Gentlemen,
I think we have rather strayed from the original question, Bismarck v Iowa.
My view is that we are talking about two ships of two different eras, Bismarck was probably the finest ship of her time, but I believe that design and firepower improved considerably by the time Iowa was ready to put to sea and that would have given her a considerable (and winning edge) even without radar. It is all very well saying that Bismarck SHOULD have been outgunned at Denmark Strait, but remember what she sank was an elderly and not very well protected Battlecruiser and severly damaged a modern but ill prepared and not worked up Battleship which only had a fraction of her guns working at any time - yet a couple of 14" shell hits were enough to put paid to Bismarcks foray into the Atlantic. I also believe that in a one to one fight a fully operational KGv class would have also given Bismarck a very hard time. In any case, with Iowa, Bismark or a KGv, I do not think there would have been a case of any of them being actually sunk by one anothers gunfire alone and given that the US and RN seldom sent their capital ships out without an escort it would have been up to them to finish the job with torpedoes as the RN did with Bismarck.
As I have already said, Bismarck was a fine ship, but she would have been outclassed by an Iowa.
RobertsonN
Member
Posts: 199
Joined: Wed Jan 05, 2011 9:47 am

Re: Bismarck vs. Iowa

Post by RobertsonN »

The Iowa was distinctly larger than the Bismarck: Tirpitz's maximum displacement was about 52700 metric tons (no doubt Bismarck would have grown to about this too with extra AA) and Iowa went to 59331 tons at war overload. And, other things being equal, the bigger ship should have won. However, much would have likely depended on chance: what the sea state and light were, who scored the first telling hits. Bismarck was more weatherly, Iowa faster. The Iowa has fine lines forward, an advantage in the Pacific, but similar ships had their foremost turret washed out in the Atlantic and in that case Bismarck would have had the advantage. Either would have found the other difficult to actually sink on their own (at least 769 heavy shells (excluding those from the Hood) and over 20 torpedoes were fired at Bismarck).
Speculation knows few bounds though and such evaluations often tell more about the preferences of the evaluator than of the ships concerned. I was just thinking this yesterday evening when I looked up what D. Brown had to say about Vanguard in From Nelson to Vanguard. He started off by saying Vanguard, whose guns could range to 36500 yds, would not be outranged by Iowa (but this assumed Vanguard had the supercharges which her mountings were strengthened for but which she never carried) and he goes on to say that Vanguard's guns would have easily penetrated Iowa's "thin belt of inferior armor" (from the 1930s on the RN saw little advantage in inclined armor, perhaps they took the roll of the ship into account in their calculations so that there was a range of inclinations for a given range and sea state (roll range) and state of manoeuvre). He then went on "I would have even given her a good chance against Yamato". Brown was an expert but he was also (like most of us) biased.
Byron Angel
Senior Member
Posts: 1655
Joined: Sun Mar 06, 2011 1:06 am

Re: Bismarck vs. Iowa

Post by Byron Angel »

RobertsonN wrote: Speculation knows few bounds
True words indeed. ;-)
User avatar
Dave Saxton
Supporter
Posts: 3148
Joined: Sat Nov 27, 2004 9:02 pm
Location: Rocky Mountains USA

Re: Bismarck vs. Iowa

Post by Dave Saxton »

RobertsonN wrote:.....when I looked up what D. Brown had to say about Vanguard in From Nelson to Vanguard. He started off by saying Vanguard, whose guns could range to 36500 yds, would not be outranged by Iowa (but this assumed Vanguard had the supercharges which her mountings were strengthened for but which she never carried) and he goes on to say that Vanguard's guns would have easily penetrated Iowa's "thin belt of inferior armor" (from the 1930s on the RN saw little advantage in inclined armor, perhaps they took the roll of the ship into account in their calculations so that there was a range of inclinations for a given range and sea state (roll range) and state of manoeuvre). He then went on "I would have even given her a good chance against Yamato". Brown was an expert but he was also (like most of us) biased.

Interesting commentary by Brown considering the original theme of this thread and considering the relative power of the Bismarck's 38cm guns and the oblique perfomance of its AP shells, to those of the Vanguard.
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.
RobertsonN
Member
Posts: 199
Joined: Wed Jan 05, 2011 9:47 am

Re: Bismarck vs. Iowa

Post by RobertsonN »

Brown also said regarding Vanguard v Iowa that "the heavy American shells would have done much damage, and much would depend on who hit first." Hence the importance of the supercharges and 36500 yds range. Brown doubted (and I do too) whether the Iowa could hit at over that range. The Bismarck's 15 in ranged to 36200 m so it had more margin than the Vanguard here.
The comparison of vertical penetrating power is harder. The German 15 in gun was superior to the British 15 in with standard charges (1938 lb, 2458 ft/s (new gun)/2400 ft/s (average)). With supercharges the new gun MV was 2638 ft/s and the average 2575 ft/s against the German 1760 lb and new gun 2690 ft/s. So the British gun might have had the edge in vertical penetration in theory. As the British shell carried a larger charge than the German one, it might have been less robust and not been able to attain its theoretical penetration with supercharges. What do you think on these matters of relative penetration?
Regarding horizontal penetration things are clearer. The figures usually accepted favour the British shell. However ADM Supp 6-481 shows that by 1946 the Admiralty realized that the deck penetration of the new 16 in gun was inferior to the till then accepted figure for the 15 in (6 in at 34000 yds for the 16 in gun v 32000 yds (est.) for the 15 in). The real deck penetration of the 15 in (standard charge) was almost certainly less than that of the 16 in. With the flatter trajectory of the supercharged shells, the deck penetration would have been lower still, so that the German 15 in actually had the better deck performance, which would be expected on account of their different head shapes.
The German gun probably also had an advantage in flight times, given its higher MV, an obvious advantage in hitting at very long ranges where the flight time is over 50 or 60 s, although the British gun was good too even at the average 2575 ft/s MV.
So, yes, if Brown's comments have any truth in them at all regarding Vanguard and Iowa (I am more sceptical about Yamato), they would seem to hold for Bismarck too. As I say, the main unknown is the vertical penetrative power of Bismarck's guns relative to the supercharged British guns.
lwd
Senior Member
Posts: 3822
Joined: Sat Jun 17, 2006 2:15 am
Location: Southfield, USA

Re: Bismarck vs. Iowa

Post by lwd »

Shorter time of flight implies the shell isn't coming down at as steep of angle so will have more problems penetrating Horizontal armor. If it actually hits the steeper descending shell is more likely to make it to vital areas as well. Of course it is less likelly to hit.

As for hiting at over 36,000 yards I think the shoot vs the Nowaki is pretty strong proof that the ships would have been capable of it. Now whether they would actually try is another matter. Rather than go into this again if you are not familiar with it most of the pros and cons are discussed at length on several other threads on these boards and there were several posters who did/do not agree with me on this.
User avatar
Dave Saxton
Supporter
Posts: 3148
Joined: Sat Nov 27, 2004 9:02 pm
Location: Rocky Mountains USA

Re: Bismarck vs. Iowa

Post by Dave Saxton »

The comparison of vertical penetrating power is harder. The German 15 in gun was superior to the British 15 in with standard charges (1938 lb, 2458 ft/s (new gun)/2400 ft/s (average)). With supercharges the new gun MV was 2638 ft/s and the average 2575 ft/s against the German 1760 lb and new gun 2690 ft/s. So the British gun might have had the edge in vertical penetration in theory. As the British shell carried a larger charge than the German one, it might have been less robust and not been able to attain its theoretical penetration with supercharges. What do you think on these matters of relative penetration
The difference in weight isn't going to make much difference vs cemented armour as the more important factor is velocity. The British found post war that the 1.4 CRH became detrimental for belt penetration after about 12,000 yards battle range due to the increasing striking obliquity. Whith SC the British gun may have the edge inside of 12,00 yards but not at more normal battle ranges.

The question of penetrating intact is more difficult. The British found post war that smaller, shorter, burster cavities relative to caliber were actually counter productive to remaining intact. A greater problem was found by the fact that the only mass produced shells pulled at random from stock which normaly penetrated CA intact were the short body Nelson class 16". Custom built 14" and 15" shells from ROF would remain intact better but these were not the stadard shells which would be used in action.
With the flatter trajectory of the supercharged shells, the deck penetration would have been lower still, so that the German 15 actually had the better deck performance, which would be expected on account of their different head shapes.


Another factor here is the heavier weight shell will retain more momentum down range. The German shell will likely have steeper angles of fall vs horizontal armour at the more extreme battle ranges.
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.
Thorsten Wahl
Senior Member
Posts: 919
Joined: Mon Apr 27, 2009 4:17 pm

Re: Bismarck vs. Iowa

Post by Thorsten Wahl »

The difference in weight isn't going to make much difference vs cemented armour as the more important factor is velocity.
dave do you have a source?
Seems to me the formula used for Unterlagen zur Bestimmung Hauptkampfentfernung was using the energy aproach.
Meine Herren, es kann ein siebenjähriger, es kann ein dreißigjähriger Krieg werden – und wehe dem, der zuerst die Lunte in das Pulverfaß schleudert!
lwd
Senior Member
Posts: 3822
Joined: Sat Jun 17, 2006 2:15 am
Location: Southfield, USA

Re: Bismarck vs. Iowa

Post by lwd »

Dave Saxton wrote: ... Another factor here is the heavier weight shell will retain more momentum down range. The German shell will likely have steeper angles of fall vs horizontal armour at the more extreme battle ranges.
Not sure that's correct. The lower velocity (the charts at http://www.navweaps.com/Weapons/WNGER_15-52_skc34.htm and http://www.navweaps.com/Weapons/WNBR_15-42_mk1.htm) show the German gun as having a slightly higher muzzle velocity will tend to be flatter shooting and some of velocity comes back due to gravity. The above tables show the British weapon as decending at 40.9 degrees at 36,500 yards and the German at 40.3 at 38,280 yards which implies at pretty much all ranges the British round will have a steeper angle of fall.
Post Reply