Bismarck vs USS Iowa coass

[genstab]

I found a comparison of a battle between Bismarck and a US Iowa class: This from wwwlnationalinterest.com

A World War II showdown that never was.
Kyle Mizokami
July 28, 2016
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Despite the vast scope of the Second World War, the navies of the United States and Nazi Germany fought few, if any, direct surface engagements. By the time of America’s entry into the war the Royal Navy had already sunk or neutralized the lion’s share of Hitler’s Kriegsmarine, with only Hitler’s U-boats remaining a substantial German threat.
But what if the UK’s Royal Navy hadn’t been as successful as it was, and the U.S. was forced to hunt down the German Navy’s major surface combatants? What if the Iowa-class fast battleships had been sortied into the Atlantic to square off against their counterparts, the Bismarck-class battleships?
The Bismarck-class battleships were the largest surface ships built by Germany before and during the Second World War. Germany had been prohibited by the Treaty of Versailles to build warships over 10,000 tons, but the Anglo-German Naval Treaty of 1935 implicitly allowed them—though the German Navy was not to exceed thirty five percent the size of the Royal Navy.
With that restriction out of the way, Germany immediately began construction on the Bismarck-class battleships. Two ships, the Bismarck and Tirpitz, were planned. The ships were 821 feet long and displaced up to 50,000 tons fully loaded. Twelve high-pressure boilers powered three turbines, giving the ship a top speed of 30.1 knots. Three FuMo-23 search radars could detect surface targets at more than thirteen miles.
The Bismarck class had eight fifteen-inch guns, each capable of hurling an armor piercing, capped round up to 21.75 miles. The 1,764-pound killer shell traveled at 2,960 feet per second out the bore, faster than the bullet of a high-powered rifle. At 11 miles, it could penetrate 16.5 inches of armor, or roughly to the horizon at sea level, although it could theoretically hit targets much further.
Both battleships were heavily protected, with 12.5 inches of steel at the main belt, 8.7 inch armored bulkheads, and 14.1 inches of armor on the main gun turrets. The eight guns were installed in four turrets of two guns each. This spread the battleship’s main armament out among more protected turrets, increasing their survivability in a gunfight.
Overall, the Bismarck class was an impressive combination of firepower, speed, and protection.
The Iowa-class battleships were the most powerful battleships built for the U.S. Navy. Four ships: Iowa, New Jersey, Missouri, and Wisconsin were built. Each was approximately 861 feet long and weighed 52,000 tons. Eight water boilers connected to General Electric steam turbines propelled the battleships along at a speedy 32.5-knot maximum speed.
Iowa had nine sixteen-inch guns. Each Mark 7 gun could launch a 2,700 pound armor piercing shell 11.36 miles to penetrate 20 inches of steel plate—and even farther to a lesser penetration. In addition to search radar, the Iowas had Mk 13 fire control radars, allowing them to engage targets at extreme ranges and at night. The Mk 13 had a theoretical range out to 45 miles, and could even spot where the Iowa’s errant rounds landed, making aiming corrections much easier.
The Iowas too were heavily armored, with 12.1 inches at the main belt, 11.3-inch bulkheads, and an amazing 19.7 inches of armor on the main turrets. The ship’s vital combat information center and ammunition magazines were buried deep in their armored hulls.
Now, on to the battle. It’s 1942, and the new American battleship Iowa has been rushed into service to hunt the Bismarck. Bismarck, her sister ship Tirpitz, and other large German combatants have made the Atlantic too dangerous to send convoys across, something the United Kingdom desperately needs.
A fast battleship designed to operate alongside aircraft carriers, Iowa can cover a lot of ocean. Operating alone, she detects Bismarck—also operating alone. The duel is on.
Despite the Bismarck’s well-trained crew, good design and powerful weapons, Iowa has one technological innovation the German battlewagon doesn’t: radar-directed main guns. Iowa can fire much more accurately at longer distance targets. This allows Iowa to “out-stick” the Bismarck, which must close to within visual range for its fire control systems and procedures to work effectively. While Bismarck would avoid a nighttime duel, Iowa would welcome it—and its 2.5-knot advantage in speed means it can force a night battle if it wants to, chasing Bismarck down before sunrise.
Iowa’s combination of the Mk 13 fire control radar and Mk 7 shells means it can fire first, hit first, and hurt first. While Bismarck’s armor protection and distributed firepower could help ensure it lasts long enough above the waves to damage Iowa, it’s unlikely could save itself, damaging the American battleship enough to make it break off the attack.
Iowa wins.

[Thoddy]

Bismarck had 3 Funkmess sets in 1941 therof one tactical and two for firecontrol purposes
Mk 13 was introduced in late 1945

Can you provide a source for 32,5 kn (at what shaft RPM) compare with FTP 217 and A215701 First of Class Trials on USS IOWA (BB 61) Class - Past and Present

a 2,700 pound armor piercing shell 11.36 miles to penetrate 20 inches of steel plate—and even farther to a lesser penetration

vertical penetration of 38 cm was the same against the better german KC nA despite a lesser weight of the german projectile
the smaller german projectile had the same amount of explosive but with higher energy content as the american Explosive D.

Both battleships were heavily protected, with 12.5 inches of steel at the main belt

How did you rate the scarp of Bismarck following the main belt?

Vertical protection of Bismarck appears better at any range. the advantage is not even sligth in my opinion.

Iowa held some advantage in horizontal protection. But this advantage was never that great than usually believed. The german horizontal protection scheme used a so called spaced array, for the 50 mm+80 mm parts equivalent to about 150 mm single plate for the 50mm +100 mm over magazines more. The first layer decaps incoming ordnance, cause yaw, and triggers the fuze. The large distance between the first and third deck ensures a reduction of projectile performance against the main armor deck.

Nevertheless the Iowa held also the advantages of being bigger, faster and somwhat greater range of the guns.

[Kingfish]

But what if the UK’s Royal Navy hadn’t been as successful as it was, and the U.S. was forced to hunt down the German Navy’s major surface combatants? What if the Iowa-class fast battleships had been sortied into the Atlantic to square off against their counterparts, the Bismarck-class battleships?

The USN would most likely deploy the North Carolina and/or South Dakota class BBs before sending the Iowa.

Both classes were commissioned ahead of the Iowas, with one of the former (USS Washington) spending time in support of the British home fleet.

[genstab]

The North Carolinas and South Dakotas weren't as fast as the Iowas, about the same speed as Bismarck themselves. Impressive ships though, all with 16-inch guns. I've been on the North Carolina at its memorial in Wilmington and the Massachusetts at Fall River (as well as the New Jersey at Camden, something to do one time if you're on the east Coast (though Wisconsin is at Norfolk). The North Carolinas were longer but the South Dakotas shorter, wider and better armored. Still though, two of them could have done the job but the Admiral King would have been smart enough to send at least one aircraft carrier with them. Until late 1942 though only the USS Ranger was on the east coast as the others were already sunk ILexington, Yorktown, Wasp and Hornet), in service in the Pacific, or in shipyards getting repaired. Then the first of the Essex class attack carriers began coming out of the shipyards and the US Navy never looked back.

Best,
Bill

[maltesefalcon]

Germany sent single capital ships on their own out of necessity. The Allies had more resources and would likely merge any large warship into the convoy it was tasked to protect.

Bismark was detected as it sailed out to open water and was shadowed for much of its short final cruise. I believe it was detected anew by a PBY and of course by Swordfish from Ark Royal.

It would be much harder for two lone vessels in the mid-Atlantic to suddenly bump into one another. But I would give the edge to the US with better fire control.

[Carl Schwamberger]

This analysis: https://www.cnrs-scrn.org/northern_mari ... 91-317.pdf

...discusses the doctrinal basis that influenced US battleship design & some aspects of battle doctrine in WWII. I found it gave some food for thought on what several of the USN admirals were thinking during the surface battles of 1942.

[Markus Becker]

Bismarck had 3 Funkmess sets in 1941 therof one tactical and two for firecontrol purposes
Mk 13 was introduced in late 1945

Germany had radar but it wasn't as good as allied radars. By 1942 allied fire control radar gave one the exact range, a year later centimetric radar gave one the exact bearing too. The latter made allied ships capable of hitting a target in zero visibility and probably with the first salvo too.

German radar never reach this level of performance. Bismarck's radar seems to have had a wavelenght of 81cm, double that of the allied 1942 fire control radar.

[T. A. Gardner]

The US BB by 1944 had Mk 8 fire control radar fitted for the main battery. This set is about 20 times more accurate than the optical rangefinders fitted on either battleship. It will track individual shell splashes. It is also a track-while-scan set. That is, you can use it to find a target then track the target by changing the mode of operation.
The Seetakt sets on Bismarck, served much the same purpose. These were 54 cm versus 3 cm or 10 cm sets on Allied ships. It was accurate in range, but not sufficiently so in bearing, so it could supplement the optical rangefinder(s) by manual range input only.

The US BB also has a significant advantage in search radar. The SG surface search set(s) fitted are 360 degree continuous scan 10 cm. They use a PPI display and are good to about 25 to 30 miles.
Seetakt, which doubles as a surface search set on Bismarck is 54 cm. It uses an A scope display and is fixed to the face of the fire control rangefinder towers. To search on a particular bearing, the rangefinder has to be rotated to the desired bearing. So, there is no true 360 degree search capacity on the Bismarck with radar for surface targets.

The US BB also carries a range of radar jammers like TDY. Both ships have good radar detection gear aboard but this is mostly for warning and gives a general bearing on a potential target.

In poor weather conditions or at night the US BB could have gotten a fire control solution at up to 40,000 yards roughly that would allow out to about 25,000 yards a straddle salvo on the first try. This was demonstrated at Surigao Straight in 1944 where older US BB fitted with Mk 8 sets did exactly that against the Japanese battleship Yamashiro.
As at North Cape with Scharnhorst, the Bismarck in these conditions was likely to be surprised by the fire and would have some difficulty duplicating that sort of accuracy, even as they could fire back.

Exact shell performance would make nearly zero difference. The first ship hit several times loses. This would most likely be Bismarck.

[maltesefalcon]

One other factor which depends more on circumstances than technology. Lets assume both vessels meet in the mid Atlantic. A slugging match occurs where both are heavily damaged enough so that one breaks away to fight another day.

SOS on US ship would draw VLR Liberators and perhaps some surface ships. US ship could flee to Iceland, Greenland, British Isles, Canada or US port. DKM ship is largely on its own for surface or air support. Any UBoats could of course lend a hand if nearby. If not, they would be to slow to make a difference. Plus the German ship would have fewer options as a haven. Sailing to those brings it closer to danger from Allied aircraft.

I'm drawing parallels from IRL situations with Graf Spee and Bismarck. These ships fought well on their own against comparable odds, but were overwhelmed by the inability to draw in help in a crisis.

[T. A. Gardner]

One other factor which depends more on circumstances than technology. Lets assume both vessels meet in the mid Atlantic. A slugging match occurs where both are heavily damaged enough so that one breaks away to fight another day.

SOS on US ship would draw VLR Liberators and perhaps some surface ships. US ship could flee to Iceland, Greenland, British Isles, Canada or US port. DKM ship is largely on its own for surface or air support. Any UBoats could of course lend a hand if nearby. If not, they would be to slow to make a difference. Plus the German ship would have fewer options as a haven. Sailing to those brings it closer to danger from Allied aircraft.

I'm drawing parallels from IRL situations with Graf Spee and Bismarck. These ships fought well on their own against comparable odds, but were overwhelmed by the inability to draw in help in a crisis.

Well, in that sense, if it were a convoy scenario the US would have an ocean going tug with the convoy to assist with salvage and towing if necessary. In addition, the US could send a salvage vessel to assist the ship in staying afloat. These are not options for the KM. Bismarck was on her own to do any sort of damage control resulting from battle. A US ship would receive help from other ships in the form of pumps, firefighting gear, or assistance with towing if the engines were incapacitated. That often makes the difference between the ship being abandoned and scuttled, sinking slowly, or burning out-of-control, and surviving.

Tulagi harbor across from Guadalcanal was the savior of a number of USN ships in the Solomon Island campaign where the IJN could pretty much expect any ship of theirs that was crippled would be doomed come daylight as it couldn't get away and had no friendly harbor nearby to duck into.

[maltesefalcon]

Agreed but I was positing the original but unlikely encounter from the OP, where each vessel was a lone wolf. But of course nearby help would be more likely and more numerous from the US point of view.

[paulrward]

Hello All :

To Mr Gardner:

You stated:

The US BB by 1944 had Mk 8 fire control radar fitted for the main battery. This set is about 20 times more accurate than the optical rangefinders fitted on either battleship. It will track individual shell splashes. It is also a track-while-scan set. That is, you can use it to find a target then track the target by changing the mode of operation.

I thought we had hashed this out in the thread,

Re: Yamato Battleship vs Montana Class BattleShip

You might want to go back and refresh your memory. USN fire control radar, while useful in some circumstances, ( such as night, or poor visibility ) was NOT the omniscient, omnipotent all seeing eye in the pyramid that you seem to believe it to was.



As for the USN Mark 8 Radar being " about 20 times more accurate than the optical rangefinders.... " I have to ask: Exactly WHAT is your source for that figure ? No written source on USN fire control that was contemporaneous with WW2 makes that assertion.

Mr. Gardner, in my career as an engineer, I have worked with a variety of Optical, Electronic, and Electro-mechanical systems and instrumentation. No radar ranging device I have ever worked with can hold a candle in terms of accuracy and precision to a well tuned optical device.

This is why, Mr. Gardner, over the last 600 million years, we evolved with eyes instead of radar screens.


Respectfully ;

Paul R. Ward

[T. A. Gardner]

Hello All :

To Mr Gardner:

You stated:

The US BB by 1944 had Mk 8 fire control radar fitted for the main battery. This set is about 20 times more accurate than the optical rangefinders fitted on either battleship. It will track individual shell splashes. It is also a track-while-scan set. That is, you can use it to find a target then track the target by changing the mode of operation.

I thought we had hashed this out in the thread,

Re: Yamato Battleship vs Montana Class BattleShip

You might want to go back and refresh your memory. USN fire control radar, while useful in some circumstances, ( such as night, or poor visibility ) was NOT the omniscient, omnipotent all seeing eye in the pyramid that you seem to believe it to was.

I never said it was. But, it's a damn sight better than optical rangefinding.

As for the USN Mark 8 Radar being " about 20 times more accurate than the optical rangefinders.... " I have to ask: Exactly WHAT is your source for that figure ? No written source on USN fire control that was contemporaneous with WW2 makes that assertion.

Naval Ordinance and Gunnery Navpers 16116-B.

The accuracy of an optical rangefinder can be calculated as = e = 58.2R^2/BM where R= range in thousands of yards, B = base length of the rangefinder in yards, and M = the magnifying power of the rangefinder.
The accuracy of the Mk 8 mod 3 radar is given on pg 486 as +/- 15 yards + .1 percent of the measured range (example at 30,000 yards it is +/- 45 yards. Accuracy in bearing is +/- .1 degrees (2 mils), or better.

Mr. Gardner, in my career as an engineer, I have worked with a variety of Optical, Electronic, and Electro-mechanical systems and instrumentation. No radar ranging device I have ever worked with can hold a candle in terms of accuracy and precision to a well tuned optical device.

This is why, Mr. Gardner, over the last 600 million years, we evolved with eyes instead of radar screens.


Respectfully ;

Paul R. Ward

Well, I guess you were in the wrong business because the Mk 8 beats the snot out of an optical rangefinder at say 20,000 yards a typical battleship engagement range.
I couldn't find Bismarck's rangefinder maginfication right off hand but at 30,000 yards with a 20 x magnification at a base of 11.5 yards (10.5 meter) the unit has a calculated error of +/- 227 yards, or about 5 times worse than the Mk 8.

That's why today, no navy still uses optical rangefinders of the sort found on WW 2 ships for fire control of guns and has gone to radar instead.

As for evolution, that's just a red herring on your part.

[maltesefalcon]

Probably poking the bear but humans were not even around 600 million years ago. Even red herrings hadn't evolved by then. We didn't evolve radar but that doesn't make it inferior to vision. For example no sane pilot would attempt to land an aircraft in fog at night by Mk1 eyeball alone if radar was available.

We didn't evolve 16 in guns either. But I think I would rather be hit by a fist than a 16" shell.

[alecsandros]

The US BB by 1944 had Mk 8 fire control radar fitted for the main battery. This set is about 20 times more accurate than the optical rangefinders fitted on either battleship. It will track individual shell splashes. It is also a track-while-scan set. That is, you can use it to find a target then track the target by changing the mode of operation.
The Seetakt sets on Bismarck, served much the same purpose. These were 54 cm versus 3 cm or 10 cm sets on Allied ships. It was accurate in range, but not sufficiently so in bearing, so it could supplement the optical rangefinder(s) by manual range input only.

... The Mk8 of 1944 should be compared with the Fumo26 of 1944, and not the Fumo23 and Fumo27 of 1941.
BUT even in 1941, the FUmo27 transmitted data automatically to the main calculator rooms , which calculated the firing solution, which in turn was automatically and continously sent to the main battery turrets.

In poor weather conditions or at night the US BB could have gotten a fire control solution at up to 40,000 yards roughly that would allow out to about 25,000 yards a straddle salvo on the first try. This was demonstrated at Surigao Straight in 1944 where older US BB fitted with Mk 8 sets did exactly that against the Japanese battleship Yamashiro.

That was demonstrated as well by German Fumo-radar direction batteries firing at night against Channel Convoys as early as 1940.

As at North Cape with Scharnhorst, the Bismarck in these conditions was likely to be surprised by the fire and would have some difficulty duplicating that sort of accuracy, even as they could fire back.

At North Cape, Scharnhorst was exercising complete radio and radar silence, in accordance with Adm. Bey's orders.

This would most likely be Bismarck.

Hard to say - German 380mm batteries had faster rate of fire, and shorter shell flight time, giving the probability of an early hit against a larger target rather higher then the other way around.

On the other hand, Iowa could use 9 guns vs 8 to aquire the target - making her likely to open with 3-gun salvos, against 4-gun salvos fired by Bismarck. More salvos = more probability of an early hit or hits.