Bismarck vs USS Iowa coass

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alecsandros
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Re: Bismarck vs USS Iowa coass

Post by alecsandros » 18 Nov 2017 22:06

T. A. Gardner wrote:
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.
.
According to Bismarck's reconstructed War Diary, and in agreement with Prinz Eugen's war diary,
both ships were actively using their radar sets on May 24th, to scan the horizon for enemy ships. The rear sector was covered by Bismarck and the forward sector by Prinz Eugen (as Bismarck's main foretop radar set broke down while firing with the aft guns agaisnt HMS Norfolk on May 23rd).

The same radar sets were used to aquire the target and to produce continous ranges to the main fire control computers. This is in agreement with AVKS-700 Bismarck firing trials document, of March - April 1941.

Fumo27 BB detection range was approx 30km in 1941.

Fumo26 BB detection range was approx 40km in 1944.

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T. A. Gardner
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Re: Bismarck vs USS Iowa coass

Post by T. A. Gardner » 18 Nov 2017 22:37

alecsandros wrote: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.
The Mk 8 was streets ahead of the Fumo 26, or late war version of Seetakt. Seetakt continued to use an A and B scope for range and bearing. The Mk 8 uses a modified PPI type display. There is really no comparison in between the two. Mk 8 was also Track While Scan. That is you could switch between general sweep and precision sweep to get a target then to get a precise range and bearing on it.

Image

Image

http://www.navsource.org/archives/01/57r.htm
That was demonstrated as well by German Fumo-radar direction batteries firing at night against Channel Convoys as early as 1940.
I severely doubt that those batteries were getting first salvo straddles on their targets the way W. Virginia, Tennessee, and California did at Suigao Straight. FC radar in 1940 was nowhere near accurate enough for that, be it German, British, or US.
At North Cape, Scharnhorst was exercising complete radio and radar silence, in accordance with Adm. Bey's orders.
And, Scharnhorst got repeatedly surprised by British ships opening fire on her as a result. Scharnhorst did reasonably well returning fire using Seetakt radar against British cruisers attacking her until the forward set was destroyed leaving her for all intents blind in the near blizzard weather conditions prevailing. When Duke of York opened fire on her it was a total surprise due to her (now) lack of radar, and return fire was completely worthless.
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.
I doubt that the RoF would make a serious difference, any more than any differences in penetration of the rounds. Now, that US shells go off virtually every time, while the German ones were optimized for serious penetration and rarely went off if that wasn't achieved, is a big defect against the Germans much like the Japanese optimizing their rounds to follow a reliable underwater trajectory. On the rare instance where the necessary conditions are met, such shells do greater damage. But, for the other more common cases, they do far less.

There is no knowing for sure what the US might choose for ranging salvos. They may go with a 5 - 4 salvo rather than a 3 gun. There's no reason the turrets have to fire all their guns at the same time. The big point here is who hits first. There's no way to know that for sure. But, given historical evidence, in 1944 it's likely going to be the US ship.
The odds are long against the German battleship winning.

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Re: Bismarck vs USS Iowa coass

Post by paulrward » 19 Nov 2017 04:02

Hello All ;

To Mr. Gardner:

I thought we went over this once before. OK, let's try it again ( I will be quoting myself, as apparently you didn't read it the first time.) The equation :

E = (58.2R^2)/BM Where:

E = the error in range in yards
R = range to target in yards
B = base length in yards
M = magnifying power of the instrument.

Is NOT a calculation of the intrinsic error of a rangefinder, rather it is the equation for determining the amount of what was called a 'Unit of Error". or the amount of error created by a 12 second arc error in the range determination. This is important, as this is what was used to determine if it was necessary to do a correction of the optical system using the soft wedges. By careful adjustment, it was possible to correct that range finding system so that at 10,000 yards, the read error was within 20 yards of the true range.

In addition, by careful training, and using techniques such as only approaching the range reading from one direction to eliminate the hysteresis ( or backlash ) of the adjusting unit, skilled operators with experience and exceptional eyesight could get VERY accurate readings, even at long ranges.


You can read all about the Mk58 optical rangefinder at

https://maritime.org/doc/rangefinder/index.htm


As for the Mk8, According to the Manual, which you can read at

http://www.researcheratlarge.com/Ships/Misc/FCR-Mk8/


The minimum distance between gradations on the CRT screen was the equivalent to 200 yards, and, what is further of importance, that the stated maximum range accuracy was +/- 15 yards + 0.1% of the measured range. Thus, at 10,000 yards, the maximum error was as much as +/- 25 yards.

However, to this must be added a caveat: The 'pip' that was being measured manually on the screen was between 15 and 18 mils in width, and, with the flickering of the system, could introduce an additional error of as much as +/- 50 yards, and this was independant of range. Thus, at 10,000 yards, the error in range as read on the Mk8 at 10,000 yards could be as much as +/- 75 yards, or 150 yards total.


Which brings us to another point. The calibration of the Mk8 Radar itself. WW2 radar relied on Cavity Magnetrons, which, being made under wartime conditions, were shipped with only the most rudimentry calibration by the factory. It was required, when they were installed, that they be calibrated in the radar system itself. This was done on board ship, and, interestingly enough, when it came time to do the range calibration, the technique was to point the mount, which had both the optical and radar range units mounted to it, and, using a distant ship as a target, use the optical system to supply the range figure to which the radar was calibrated to.

In effect, the radar could NEVER be more accurate than the optical system, because it was calibrated from it.

Finally, a good summary of some of the issues afflicting USN wartime radars are mentioned in the following article, ' Automation's Finest Hour: Radar and System Integration in World War II ' , by David A. Mindell, which you can find at

https://mitpress.mit.edu/sites/default/ ... h_0001.pdf



To Mr. M. Falcon :
Probably poking the bear but humans were not even around 600 million years ago. Even red herrings hadn't evolved by then. :lol: 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.
According to the latest theories relating to evolution on our planet, the first micro organisms with what are believed to be a visual receptor that we could describe as a predecessor to the eye developed approximately 550 million years ago. I don't know about you, but I can trace my family tree all the back to that time .....

As for landing aircraft, Mr. Falcon, exactly HOW MANY aircraft have you personally landed ? In
ANY weather ? Me ? A lot. Of different types, under a lot of conditions. And here is a kicker for you. When you are landing on IFR, at night, in fog, you ARE NOT landing with radar. There is a radar operator on the ground that may be watching you crash, but when you are on short final, you are using the Mk 1 Eyeball to pick up the runway lights and the threshold so you can land.

Which brings us to another point: Which would you think is more accurate for a landing in CAVU conditions: A pair of eyeballs or a radar? Let me give you a hint: Its the ones that can blink, and distinguish different colors. Something radars can't do yet.



And now I am going to tee off on several of the posters in this thread: You insist on pitting the Iowa of 1944 against the Bismarck of 1941. This is like pitting a 1944 P-51D against a 1941 P-51A. Not much of a contest.

I propose a different matchup: Let us pit the Bismarck of 1941 against the USS Iowa of 1941. OOOH - Wait ! HMMMMMMMMM..... That's not gonna work, is it....

OK - Instead, let's pit the Bismarck of 1941 against the USS Washington of 1941. That's right. Let's see if the Showboat, with her vibrating turbines and prop shafts that mess up the fire control at any speed over about 25 knots could go up against the Kriegsmarine's finest.


If we compare apples to apples, we find that the applesauce is considerably different.


Respectfully ;

Paul R. Ward

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Terry Duncan
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Re: Bismarck vs USS Iowa coass

Post by Terry Duncan » 19 Nov 2017 04:25

paulrward wrote:OK - Instead, let's pit the Bismarck of 1941 against the USS Washington of 1941. That's right. Let's see if the Showboat, with her vibrating turbines and prop shafts that mess up the fire control at any speed over about 25 knots could go up against the Kriegsmarine's finest.


If we compare apples to apples, we find that the applesauce is considerably different.


Respectfully ;

Paul R. Ward
Now that is just plain unfair! In every one of this sort of debate the US ship gets to be in the 1944/45 configuration whilst everyone else must stick to 'as designed' or 'a few years earlier' rather than a direct comparison, not that even this would help a Washington moving anywhere above 24.5kts (effectively a sort of enlarged and partially-sighted Queen Elizabeth) as she would still shake a hell of a lot due to the problem never really being fully fixed!

The only real answer to the question is still that the ship that gets in the first hit on a critical area will most likely win.

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Re: Bismarck vs USS Iowa coass

Post by maltesefalcon » 19 Nov 2017 05:58

Bear successfully poked I would say. :lol:

alecsandros
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Re: Bismarck vs USS Iowa coass

Post by alecsandros » 19 Nov 2017 10:18

T. A. Gardner wrote: The Mk 8 was streets ahead of the Fumo 26, or late war version of Seetakt. Seetakt continued to use an A and B scope for range and bearing. The Mk 8 uses a modified PPI type display. There is really no comparison in between the two. Mk 8 was also Track While Scan. That is you could switch between general sweep and precision sweep to get a target then to get a precise range and bearing on it.
AFAIK, late-1944 Fumo26 adn Fumo81 radars mounted on Tirpitz did have PPI and could track shells while in flight.

More info here:
http://www.kbismarck.org/forum/viewtopi ... 724#p18602

However, there is so little that we actualy know about late-war German radar technology that anything is possible. Prinz Eugen actualy was captured by US forces, and her main battery actualy tested by US engineers and technicians. BUT there is no real documentation to be found on the results of those tests. [it would be important for battleships as well, as Hipper-class heavy cruisers were equipped and considered in a parallel way to the German battleships]
I severely doubt that those batteries were getting first salvo straddles on their targets the way W. Virginia, Tennessee, and California did at Suigao Straight. FC radar in 1940 was nowhere near accurate enough for that, be it German, British, or US.
They did, but firing against 9-kts merchant ships moving in a straight course was simpler then firing against a 15-20kts manouvreing target.

In terms of battery accuracy, Admiral Scheer straddled HMS Jervis Bay from her first 3 x 283mm gun salvo in Nov 1940. Range about 20km, poor visibility. Bismarck straddled HMS Prince of Wales from first salvo on May 24th 6:01 (but with good info priorly existing from the firing on Hood); Bismarck also straddled HMS Sheffield from first salvo on May 26th 21:00, etc. Hipper straddled HMS Achates from 18km in Dec 1942, from first salvo.

That is NOT to compare West Virginia's continous (correct) firing solution with the variating firing solutions of early war German capital ships. However, German fire control of 1940 to 1942 was excellent and produced remarkable results IMHO.
Comparing it to USN fire control and results of 1941-1942 would be more fair.

For 1944, as I said above, we have very little documentary evidence on German advances to work with. It's clear though that they abandoned investing resources in the Kriegsmarine (after battle for Barents Sea), but some advances may have been obtained nonetheless.

And, Scharnhorst got repeatedly surprised by British ships opening fire on her as a result.
Yes she was, but that wasn't a failure of the radars installed, but of doctrine and tactics.
Some sources mention that the same radio silence was in play at Battle for Barents Sea, thus robbing Hipper and Lutzow of their combined weight to crush the convoy escort. If that is true, all the hits on Barents Sea must have been obtained on optical-range finding alone, which is all the more remarkable.
Now, that US shells go off virtually every time, while the German ones were optimized for serious penetration and rarely went off if that wasn't achieved
German typical fuze delay was 0.050 sec long, American typical fuze delay was 0.033 sec long.

Practical defects of fuzes were noted in both navies, but consistent and battle-changing defects of fuzes were not noted. The often quoted case of Bismarck's shell fuzes is a result of popular books being written and published on the subject , but which do not correctly depict the mechanical parts of the shells and fuzes.
There's no way to know that for sure. But, given historical evidence, in 1944 it's likely going to be the US ship.
The odds are long against the German battleship winning.
I agree there is no way of knowing for sure, but Bismarck (Tirpitz) wouldn't be the dead meat that they are usualy are being portrayed as being. With identical officers and crews and doctrine, and fully functioning systems, I'd give Iowa 60-40 chances of winning a "normal battle" (starting at long range, decreasing to medium range and possibly ending at short range), but I'd favor Bismarck/Tirpitz (60 to 40) if, by some reason, the battle would start and develop at short range (below 15km).

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Re: Bismarck vs USS Iowa coass

Post by paulrward » 20 Nov 2017 08:24

Hello All ;

To Mr. M. Falcon :
Bear successfully poked I would say. :lol:
There is a word for people who poke bears:

Bearshit


Respectfully ;

Paul R. Ward

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Re: Bismarck vs USS Iowa coass

Post by Plain Old Dave » 21 Nov 2017 02:25

Bears mentioning, too that both the Iowa and Essex class were still in service in the 1990s.

Iowa decommissioned in 1990; Turret Two was deemed uneconomical to repair.
New Jersey, February 1991
Missouri, March 1992
Wisconsin, September 1991
Lexington (AVT-16, formerly CV/CVA/CVS/CVT), November 1991

A 1930s-40s design advanced enough to be in active service in memory of Sailors serving currently speaks volumes to its superiority. I served with Sailors that served on all five of these ships.

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Re: Bismarck vs USS Iowa coass

Post by Terry Duncan » 21 Nov 2017 15:10

Plain Old Dave wrote:Bears mentioning, too that both the Iowa and Essex class were still in service in the 1990s.
My grandfather was still alive at 92, but he was no longer a regimental boxing champion, so a ship that was long since obsolete remaining in service as a prestige unit means nothing, HMS Victory is still a commisioned ship at coming up to 250 years since her launch.
Plain Old Dave wrote:A 1930s-40s design advanced enough to be in active service in memory of Sailors serving currently speaks volumes to its superiority. I served with Sailors that served on all five of these ships.
They were a design that was obsolete the moment torpedoes were able to be targeted to detonate underneath the keel the battleships were nothing but death traps. The reason they stayed in service was to show the flag, and they were decommissioned earlier too but reactivated when a president decided he liked them. Most nations scrapped such ships because missiles, airpower, and submarines made such ships far too expensive for their worth and better value as scrap metal, newer ships with better-designed hulls could do the same job for far less cost, the only possible exception being shore bombardment, and even that was only practical against targets that had no means of self-defence.

The Essex design was only viable because it could carry more modern weapon systems, as in aircraft, but even then it suffered from not being able to carry the most modern aeroplanes due to weight restrictions on the flight deck. Even then the USN didn't exactly consider them frontline units by the end of the 1950's, they were just handy to keep around because they existed and money was not a problem.

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Re: Bismarck vs USS Iowa coass

Post by Plain Old Dave » 22 Nov 2017 01:59

Re: the Iowa BBs. Considerably more surviveable than the Perry FFGs or the Sheffield. An Exocet on an Iowa just meant that First Division (deck seamen; painters) would have more work to do.

Re: The Essexes. The most numerous capital ship in history as well as the most preserved aircraft carrier with four museum ships (two of which I have visited), The 27 Charlie (steam catapults and the angled deck among other things)upgrade kept the US in the war in Vietnam; the F-8 Crusader and A-4 Skyhawk were first-line aircraft. CDR Jim Stockdale and LCDR John McCain both were deployed onboard Essex CVAs (attack carriers). As to "frontline units', as the supercarriers came online the Essexes became CVSs (antisubmarine warfare, what nearly licked the Allies in WW1) and the last 27C Essex, USS Oriskany, decommissioned in September 1976.

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Re: Bismarck vs USS Iowa coass

Post by Aber » 22 Nov 2017 09:37

Plain Old Dave wrote:The 27 Charlie (steam catapults and the angled deck among other things)upgrade kept the US in the war in Vietnam; .
Upgrades developed by "one of the least military inventive nations on Earth"? :D

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Re: Bismarck vs USS Iowa coass

Post by Plain Old Dave » 22 Nov 2017 12:12

Blind hogs find acorns on occasion.

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Re: Bismarck vs USS Iowa coass

Post by Terry Duncan » 22 Nov 2017 12:45

Plain Old Dave wrote:Re: the Iowa BBs. Considerably more survivable than the Perry FFGs or the Sheffield. An Exocet on an Iowa just meant that First Division (deck seamen; painters) would have more work to do.
Sheffield was not sunk by a modern torpedo or any other type of weapon that explodes beneath the keel in such a manner. I agree there would be little point targetting an Iowa with an Exocet, so did the Russians, who had sensibly sized missiles to deal with larger ships. A Perry will not take the best part of 2000 men with it though now will it or cost anywhere close as much to run and keep in service. These are a couple of the reasons why the Iowa's were decommissioned first time around, and why nobody else has bothered with the type for well over half a century now.
Plain Old Dave wrote:Re: The Essexes. The most numerous capital ship in history as well as the most preserved aircraft carrier with four museum ships (two of which I have visited), The 27 Charlie (steam catapults and the angled deck among other things)upgrade kept the US in the war in Vietnam; the F-8 Crusader and A-4 Skyhawk were first-line aircraft. CDR Jim Stockdale and LCDR John McCain both were deployed onboard Essex CVAs (attack carriers). As to "frontline units', as the supercarriers came online the Essexes became CVSs (antisubmarine warfare, what nearly licked the Allies in WW1) and the last 27C Essex, USS Oriskany, decommissioned in September 1976.
Patton sat in an FT-17 tank in WWI, it no more makes it a viable Cold War tank than two named people serving on Essex class ships make them modern carriers. I am not sure why you would even bother to mention it, or how many were built in what was effectively a war emergency program? Neither says anything about the viability of the design.

There were certainly panics in WWI about the submarine menace, though given rationing wasnt introduced in the UK until April 1918 and no troop ships were lost to them, the scale of the threat is often overestimated. The German belief they could knock the UK out was based on an underestimate of how much they would need to sink to do so, and it was not carriers that solved the problem, it was the availability of small escort craft and the introduction of the convoy system - only avoided as it was felt 'too passive' and impossible with undisciplined merchant sailors. Carriers tend not to be too good at anti-submarine work, Churchill tried them at it in WWII and the loss of Courageous was the result, the role is better performed by smaller craft even today. Carriers can do it, but they are a very expensive solution to the problem.

None of this has the slightest thing to do with comparing the Bismarck to the Iowa or Washington though, let alone justifying any reason we should not compare them as designed or laid down, rather than with several years of additional technology being added that was not invented when they were designed, just because it favours one side to do so. Bismarck is far from perfect but the Iowa has its own faults too, and other than in its ability to escort the carrier groups is no real improvement over the South Dakota class when it comes to ship to ship combat. Bismarck wasted a lot of tonnage due to an od armour layout and not having DP secondaries, whilst Iowa is not too well protected for its size as all the extra tonnage over South Dakota went on speed.

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Re: Bismarck vs USS Iowa coass

Post by alecsandros » 22 Nov 2017 13:05

Terry Duncan wrote: Bismarck wasted a lot of tonnage due to an od armour layout and not having DP secondaries, whilst Iowa is not too well protected for its size as all the extra tonnage over South Dakota went on speed.
With all due respect,
Bismarck had DP secondaries and tertiaries - allthough not in the USN sense.

Iowa had thicker main turrets armor then SD had, and also thicker armored decks.

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Re: Bismarck vs USS Iowa coass

Post by Terry Duncan » 22 Nov 2017 13:33

alecsandros wrote:
Terry Duncan wrote: Bismarck wasted a lot of tonnage due to an od armour layout and not having DP secondaries, whilst Iowa is not too well protected for its size as all the extra tonnage over South Dakota went on speed.
With all due respect,
Bismarck had DP secondaries and tertiaries - allthough not in the USN sense.

Iowa had thicker main turrets armor then SD had, and also thicker armored decks.
Bismarck certainly had secondaries and tertiary armamants, but they do not fit any nations definition of dual purpose, not just the US one. The 5.9" guns cannot engage aircraft, and iirc there was to real provision for the 4.1" to engage surface targets in action (as opposed to being able to sink merchant ships that had been caught or as a barrage fire type defence). It is not a problem, but the tonnage could have been better used elsewhere.

The hull is the main area that needs protecting on the Iowa, the bow is quite vulnerable to flooding right back to the forward bulkhead (the one that went rusty right away!) due to its length and fine profile needed for the high speed. The deck armour is mostly only important against bombs, the long expected gunnery dual at extreme ranges that would lead to 'long-range hits' never materialised and at ranges where hits are realistically going to occur the deck armour on both South Dakota and Iowa are invulnerableto almost all shells. With regards the turret faces, the USN had always had a strange predilection for very heavy armour there, but then oddly angled the turret face backwards, allowing incoming rounds to strike at a far better angle and thus negate the purpose of heavier armour in the first place! Compare the KGV turret faces to those on US ships and you can see the British ship is offering a tougher target per inch/ton of armour enployed on this subject as the impact angle will increase on the British ship, rather than decrease closer to 'normal' as in the US ship.

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