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Bismarck vs USS Iowa

Discussion in 'Ships & Shipborne Weaponry' started by JimboHarrigan2010, Aug 29, 2011.

  1. lwd

    lwd Ace

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    Not sure why you think the sea state would eliminate the advantage of long range shooting. From some of what I've read over on kbismack the German radar was actually pretty good. There was also some pretty good shooting at long range in the North Atlantic. The problem for the Germans is that the US practiced long range engagements and their doctrine was to keep the engagement at long range. The redundant radars would also be a factor as even shorter range engagements might require or at least significantly benefit from radar fire control due to visibility issues. As for taking damage the German ship might be able to take more and stay afloat the question though is how much could it take and keep fighting in comparison with an Iowa.

    Looking at Nathan Okun's tables Bismarck's turret faces can be penetrated out to over 28,000 yards by Iowa's guns. The upper facet looks to be penetrable at any range and the turret roofs at anything over 26,000 yards. The barbets are vulnerable out to around 30,000 yards as well at over that hits are unlikely in any case. In comparison the Bismarck has to get under 18,000 yards to penetrate Iowa's faceplates and only starts penetrating the turret roofs at ranges in excess of 38,000 yards. Nathan Okun has a fairly detailed comparison of Bismarck's armor scheme to that of several contemporary battleships (SoDak is used rather than Iowa for the US). It doesn't inspire confidence in the ability of Bismarck to soak up more damage than Iowa.
     
  2. Dave55

    Dave55 Member

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    In addition to having a big speed advantage the Iowas were great sea boats so they'd be able to open and close the range at will in rough seas. No contest under any conditions.
     
  3. lwd

    lwd Ace

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    I disagree. If it came down to a knife fight such as Washington vs Kiroshima it's pretty much a toss up. Or perhaps more accurately crew training and luck will be more important than the hardware differences.
     
  4. mac_bolan00

    mac_bolan00 Member

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    to hit something accurately past 10,000 meters, you have to stay on an even keel, steady at less than 20 knots i think. a tossing prow? i doubt if you'll hit anything that far, no matter how good your radar, or how accurate your guns are.
     
  5. Dave55

    Dave55 Member

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    Maybe true but the Iowas outgunned Bismarck with more numerous and more powerful main armament with better ammo.
    They also had, if I remember correctly, thicker turret, barrette, deck and conning tower armor, equal belt armor and the armor deck was several levels higher so that communication and fire control systems were protected by it.

    Seems to me Iowas would have big advantage no matter how close the range was.
     
  6. mac_bolan00

    mac_bolan00 Member

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    not meaning to belittle the wealth of technical information given out here, but they're just that: numbers. what items in the tale of the tape do you look at to guess with certainty who will win the boxing match? number of wins? knockouts? weight? reach? height? any of those could make a decisive difference but you'll never be sure. remember, joe luis got his ass kicked by a light heavyweight (though he won the bout.) jack johnson got floored by a middleweight.
     
  7. Dave55

    Dave55 Member

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    Sure, I agree. I was just trying to emphasize that the Iowas were the top dog of battleships, and I think, by a pretty good margin.
    At first I thought your Louis vs Billy Conn was a pretty good analogy but I think a flash knockdown by a heavy underdog might be a better one. Like Hammering Henry Cooper knocking down Clay (or Two Ton Tony Galento vs Louis) instead of long match with with Billy Conn. Iowa could follow Conn's plan if it wanted to and hit Bismarck from long range and stay away with speed.

    If you ever see Conn's interview about the fight it is really good. He's was very well spoken and talks about how confident and happy he was in the final rounds until that big hit. He was smiling when he said "And that was the end of me." :)
     
  8. lwd

    lwd Ace

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    ???
    So if you hit anything over 10Km you are hitting it inaccurately?

    Bismark, POW, and Eugen all scored hits at well over that range in rough seas traveling at well over 20 knots. Yamato likely scored a hit at 3 times that distance while moving at over 20 knots. New Jersey and Iowa repeatedly straddled a wildly maneuvering destroyer at well over 30,000 yards (and may have inflicted splinter damage) while well in excess of 20 knots. Your opinion doesn't seam to conform to the reality of naval combat in WWII.
     
  9. lwd

    lwd Ace

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    I think there's a pretty good argument for the Yamatos at least being close.
     
  10. mac_bolan00

    mac_bolan00 Member

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    well, i have to qualify myself. if it's a long-range shooting match with both sides keeping a distance, my assumptions stay. but if it was like in denmark strait, or between washington and kirishima, it doesn't. in the second premise, you two are racing at each other at top speed, and the distance between you is shrinking at the rate of your combined speeds. in that case your shooting accuracy improves every second, and you two will invariably switch to visual sighting.
     
  11. Takao

    Takao Ace

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  12. mac_bolan00

    mac_bolan00 Member

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    one wins at the ring toss every once in a while.
     
  13. Takao

    Takao Ace

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    It's not like there are a lot of big gun actions that fit the bill.

    To get the kind of radar interference, you would need a hurricane/typhoon.
    [​IMG]
     
  14. the_diego

    the_diego Active Member

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    Wars like to spring surprises, especially to "experts." The Kirishima, a WWI vintage battle cruiser, was sunk by a modern Washington. That's what people like to write about. What they don't like writing about is, minutes before, the Kirishima battered the South Dakota which was supposed to have the most modern armor at the time. Four hits with main battery fire to nothing. Not bad for a WWI vintage warship.
     
  15. Takao

    Takao Ace

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    Like the US OBBs, the Kongos were upgraded a few times over the years, so there was little left that was WW1 vintage.

    Also, I have never seen conclusive proof that the Kirishima was targeted by the South Dakota's main battery, except for the last few salvos from Turret 3(the after turret). The number of Kirishima hits has also been disputed - IIRC, only one was attributed to Kirishima's main battery by USN damage assessment. Robert Ludgren(sp?) has disputed this over on NAVWEAPS. He attributes a few more hits to 14-inch San-Shiki shells. But, none were very damaging. Further, most of the shells that hit SoDak were in the unarmored superstructure.
     
  16. Carronade

    Carronade Ace

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    Let's not forget that SoDak suffered a series of electrical problems which disabled her radar among other things. Otherwise she would have been as effective as Washington, and whoever she shot at just as unhappy.

    Radar is the wild card in comparisons like this. A few hundred pounds of electronics may be more significant than thousands of tons of guns or armor.
     
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  17. Thoddy

    Thoddy Member

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    With regard to protection for vital areas (Magazines, machinery)

    To defeat Bismarcks side protection any incoming shell has to defeat
    1-Main belt 320 mm mainly vertical vertical-->inclined up to 15 degrees at the turrets
    2-slope 110 mm at machinery--> 120 mm at magazines
    3-torpedobulkhead 45 mm (this ads relatively few to ballistic protection what was sufficent to catch debris and splinters
    depending on angle of fall
    any shell has to penetrate
    at 0 degrees AOF ~650 mm armor grade steel in flight direction
    at 10 degreed AOF ~575mm
    at 20 degrees AOF ~550 mm
    (this is much more raw thickness in flight direction compared to any other battleship)
    AND after penetration of the main belt any shell loses its cap and was likely damaged so the vertical pretection system was likely to defeat most shells at any distance.

    horizontal protection
    To reach magazines any shell has to perforate
    the first deck 50 mm
    battery deck 20 mm <----> splinter bulkhead 30 mm - 75 mm
    main armor deck 80 mm /100 mm over magazines

    The Germans testet the arrangement fullsize against own 38 cm and 40,6 cm projectiles

    In the context of the evaluation of the horizontal protection "Battleship H", fears were expressed, that the horizontal protection consisting of a 50 mm upper deck and 100 mm armored deck could already penetrated at angles of fall of 15 ° - 25 ° (corresponding to a distance of at least around 20 km).

    The Navy Weapons Office(Marinewaffenamt) therefore carried out fullsize ballistic tests with 40.6 cm armor piercing shells, which were able to dispel the fears.

    It is confirmed that there is a risk to the horizontal protection with regard to penetration through the armored deck (penetration whole), but requires a angle of fall of about 27 ° corresponding to a distance of >30 km.
    [​IMG]
    Hauptgefährdung Panzerdeck Schlachschiff H.jpg (85.21 KiB)
    (Bundesarchiv BA-MA RM 20/1913 Akte Oberkommando Kriegsmarine AV Allgemeine Typfragen für Schlachtschiffe, Panzerschiffe und Kreuzer (02/1939- 12/1939) Schreiben Marinewaffenamt M WA Ia 759/39 g-Kdos. vom 6. April 1939)


    Not every splitted arrangement of deck protection may reach the same or better results of ballistic protection as a single plate of same total thickness.

    British ballistic research gave requirements for the positive case

    1) detachment of armor piercing cap (ADM 281-37 The ballistic performance of Non-Cemented, Cemented and Face Hardened Deck Armour (200+240 lbssqft) under attack by decapped APC)

    at 60 degrees angle of incidence, the speed required for perforation of single armor plate for usual decapped armor piercing projectiles was increased by about 15 - 20 % percent compared to the same capped armor piercing projectile ADM 281-37 The ballistic performance of Non-Cemented, Cemented and Face Hardened Deck Armour (200+240 lbs/sqft) under attack by decapped APC
    report shows degradation of penetration of high obliquity attack of deck targets full caliber size tests.
    Ballistic limit of 200 lb plate vs 15" APC
    .............capped shell (1938 lb) vs decapped shell (1712 lb)
    at 60°..980 ft/sec...........................1160 ft/sec
    at 65°..1030 ft/sec.........................1285 ft/sec

    these are the numbers without considering yaw


    2) sufficent distance between first deck and armor deck to develop sufficent yaw., (DEFE 15-490 High Obliquity Attack of Deck Targets. Part III, it was a series of three reports describing high angle attack of deck targets.)


    [​IMG]



    Yaw is a double edged sword. It may assist or prevent perforation, depending on development of yaw.
    -The yaw increases steadily after perforating the first plate.
    -Decapped projectiles develop yaw faster.

    With so called "Optimum Yaw" a shell may perforate a plate of given thickness far below its expected ballistic limit ( 20-40%).
    The "Optimum Yaw" region lies for Armour piercing projectiles in the region of about 15 degrees projectile tilt towards armor plate compared to the line of flight.
    But if yaw was sufficent, the projectiles usually failed to perforate by topple. It makes a somersault on impact of the main armour plate.

    The german armour scheme is the only one possessing a first deck with sufficent thickness for potentially decapping incoming projectiles and it was also the only one wich includes a distance of two decks until the main armour deck.

    Further explanation see also SUPP 6-910 THE PENETRATION OF ARMOUR PLATE Summarized report of all british ballistic research up to 1951
    Chapter four "Complex Targets.

    British post WW2 research uprated Tirpitz horizontal protection to an equivalent of 6" single plate against british projectiles compared to earlier assessments.
    In SUPP 6-481 Underwater performance of shells they described the target
    "a target similar to the Tirpitz with dimensions as follow
    -Beam 125 feet deck armour 6 inches
    -vertical side armour 12 inches extending to 8 feet above waterline
    -vertical underwater target equivalent to 2 inches extending from 8 feet below WL to 22 feet below WL.
    .....
    Chance of an effective hit .. against deck armour
    ...range 30000 yard; Nil..."

    ---------------------------------------------------------------------------------------------------------------
    with regard to firecontrol facilities and wiring
    apart from the 3 independend control rooms and sensors in the superstructure all firecontrol equipment and wiring was situated below the main armour deck
    Bismarck has two independent plotting rooms for main artillery, wich consist of the firecontrolcomputers and switchinng positions as well as two independent plotting rooms for AA-firecontrol

    Main wiring above the main armor deck was protected by a 220 mm KC cable duct (forward facilities) 100 mm cable duct (rear facility)
    and any command line/firecontrol wiring was doubled.

    The protection for vital parts sacrifices the area between the upper deck and the main armour deck.
     
    Last edited: May 18, 2021
    Kai-Petri likes this.

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