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Subject: ww2 Yamato vs Iowa class
capt soap    9/17/2005 12:55:11 PM
How would this fight turn out? the Iowa's 16 inch guns against the Yamato 18 guns? The iowa had radar,which one would sink the other 1 on 1.
 
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elclip1       11/3/2009 11:02:59 PM
 
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Lars    Flight times and gunnery   1/31/2010 1:39:06 PM
Hi guys! I'm new here. I would like to pitch in my 2c on this very important topic. :)

I would like to add some thoughts on gunnery control. The flight time of a shell to a target about 20-25 km away is about a minute or more. A fast moving battleship will travel about half a mile during that time. There is considerable uncertainty as to where it will elect to go during that time. Assuming violent evasive maneuvering, the uncertainty becomes so large that the odds of scoring a hit drops to somewhere in the order of 1% (target area of ship divided by area of possible location), still assuming perfect gunnery control and perfect knowledge of where the target was when the gun was fired. These ships had about 90 shells per gun so theoretically you could shoot everything you had at that range and not score a hit, this despite perfect gunnery control and perfect range estimation etc. This is all assuming radical evasive action at all times. That's actually not very realistic, for various tactical reasons the path of a ship can often be much more predictable, for example when steaming in a line ahead. You don't want your teammates to all do a random walk, it kind of messes things up, but for the sake of this discussion let's pretend they can.

A shell travels about 100-150 times faster than a ship, in the horizontal plane and when shooting at long ranges. Therefore, if the ship is doing violent evasive maneuvers, any accuracy beyond about 1 part in 100 is therefore simply wasted (at least in the absence of clairvoyance). Just for curiosity, you can compare this to a sniper rifle which can have an accuracy of better than 1 minute of arc (moa) or an Olympic match air gun which can hit a target to about 1 mm at a range of 10 m, both corresponding to an accuracy of about 1 part in 10 000, this with gunnery control provided by a Mk. 1 eyeball.

This is what happened off Samar. There was nothing wrong with Japanese gunnery control, just simple statistics. If you are trying to hit a small and agile target like a destroyer, going through the calculations, you find that you will have to wait until the range has dropped to about 10-15 km before you have a reasonable chance of hitting it, assuming the destroyer is doing all it can to dodge the shells. Swatting destroyers is a frustrating business and destroyer captains intent on a torpedo attack know that and used it many times during the war. This is why many battleships of the time had 6? secondary artillery. A 6" shell will probably disable a destroyer almost as effectively as 14"/16? shell but the 6" gun will be able to maintain a much higher rate of fire which is what you need to beat the statistics. American battleships gave up 6? guns for better AA and it might be that the USN compensated for this by having a larger proportion of cruisers with 6? guns and thus a high rate of fire. The Yamato's had good secondary artillery, they could fend for themselves and their cruiser where mostly armed with 8? guns, optimized for fighting other cruisers.

You can compare this to what happened with the Norden bomb sight and high-level bombing of moving targets. The time for the bomb to reach a moving target tended to make that type of bombing pretty ineffective regardless of how excellent the bomb sight was. There were other basic problems with high-level bombing but we can leave that out.

My hunch is that much of what has been said about better gunnery control on the US battleships is probably true in a sense but possibly also irrelevant in that it didn't actually produce more hits on target. It would be great if somebody could explain in what way US gunnery control led to more hits on target, not just being "better" in the sense of "more sophisticated" or "more automated" or whatever.  After all, salvo based long range gunnery was pretty old technology and very well understood by everybody by the 40's.

According to NavWeaps.com, the muzzle velocity of the Yamato's 18.1? gun is significantly higher than that of Iowa's 16? but Yamato's shell is only slightly heavier. Iowa selected a relatively heavy shell and paid the price in muzzle velocity. At close range the Yamato's guns should be considerably more destructive, despite similar shell weights. At longer ranges the muzzle velocity has bled off due to friction with the air and destructiveness is mostly related to shell weight and there the two guns are about equal. Please note that at longer ranges the Yamato still has an advantage in that the shorter flight time to target makes gunnery control easier, Iowa has to have better gunnery control just to compensate for facing a somewhat more difficult gunnery control problem. Yamato is optimized for night combat, according to IJN doctrine, and Iowa is optimized for longer ranges. Looking at how battleships actually fought each other during the war, the Japanese choice was probably the correct
 
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StobieWan       1/31/2010 2:27:29 PM
One thing I've not seen referenced in this thread was the calibre and state of readiness of the crews - the Yamato was at a relatively low state of readiness throughout much of the latter part of the war, spent little time under steam and presumably her gunnery drills were not frequent - whereas the Iowa's were at sea, worked up and with good supplies. 

I suspect that the Iowa's would have been able to apply a consistently higher rate of better aimed fire and ground the Yamato down. However, it'd be a difficult affair - with the end results very possibly being dictated by a single lucky hit (the Bismark had two turrets disabled by a single 16 inch hit for instance, despite proving to be almost impossible to sink via gunfire)


Ian


 
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ker       2/1/2010 3:32:53 PM
StobieWan       1/31/2010 2:27:29 PM
".... However, it'd be a difficult affair - with the end results very possibly being dictated by a single lucky hit...."
 
Rather than answering the question I would like to sujest a form in which the answer could be communicated.  Rather than predicting a winner imagine 2000 repetitions of the same battle.  Then order the battles by the decisiveness of the battle infavor of the Japanes.  The first outcome would be the total distrution of the Iowa with no dammage to the Japanes.  Then moving through the list the damage done to the Japanes increases.  At some point the battle becomes a effective draw with neather ship capeble of future service.  The incedence of the Japanes taking sufficent damage to there guns that they would try to escape and then succeding in the escape would be the least likely outcome.  Cases where the Iowa lost use of two thirds of her main guns and successfuly ran would occure enough to deserve discusion.  Then moving further down the list of outcomes (from japanes victorys towards increasingly severe Japanes defeats) we find battles where the Yamamoto is distroyed and the Iowa takes heavy damage.  Then at the far extream of the list are the battles where the Iowa distroyes the enemy with less and less damage to her self.  Then the outcomes can be clustered into catigorys and asighned presentage chances. 
 
Chance would play a roll in the outcome.  In total the success curve would favor the Iowa.
 
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bartrat       2/1/2010 5:58:59 PM












StobieWan       1/31/2010 2:27:29 PM



".... However, it'd be a difficult affair - with the end results very possibly being dictated by a single lucky hit...."


 

Rather than answering the question I would like to sujest a form in which the answer could be communicated.  Rather than predicting a winner imagine 2000 repetitions of the same battle.  Then order the battles by the decisiveness of the battle infavor of the Japanes.  The first outcome would be the total distrution of the Iowa with no dammage to the Japanes.  Then moving through the list the damage done to the Japanes increases.  At some point the battle becomes a effective draw with neather ship capeble of future service.  The incedence of the Japanes taking sufficent damage to there guns that they would try to escape and then succeding in the escape would be the least likely outcome.  Cases where the Iowa lost use of two thirds of her main guns and successfuly ran would occure enough to deserve discusion.  Then moving further down the list of outcomes (from japanes victorys towards increasingly severe Japanes defeats) we find battles where the Yamamoto is distroyed and the Iowa takes heavy damage.  Then at the far extream of the list are the battles where the Iowa distroyes the enemy with less and less damage to her self.  Then the outcomes can be clustered into catigorys and asighned presentage chances. 

 

Chance would play a roll in the outcome.  In total the success curve would favor the Iowa.

I suggest that someone wargame this out using a computer program with a decent AI for both sides. Play 10000 times or so with various variables and then post the results. I don't have a program to do that, but maybe someone does.
My guess is that the Yamato would lose more than win (but that is a guess).
 
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Hamilcar    Your numbers are wrong.   2/2/2010 11:40:36 AM

Hi guys! I'm new here. I would like to pitch in my 2c on this very important topic. :)



I would like to add some thoughts on gunnery control. The flight time of a shell to a target about 20-25 km away is about a minute or more. A fast moving battleship will travel about half a mile during that time. There is considerable uncertainty as to where it will elect to go during that time. Assuming violent evasive maneuvering, the uncertainty becomes so large that the odds of scoring a hit drops to somewhere in the order of 1% (target area of ship divided by area of possible location), still assuming perfect gunnery control and perfect knowledge of where the target was when the gun was fired. These ships had about 90 shells per gun so theoretically you could shoot everything you had at that range and not score a hit, this despite perfect gunnery control and perfect range estimation etc. This is all assuming radical evasive action at all times. That's actually not very realistic, for various tactical reasons the path of a ship can often be much more predictable, for example when steaming in a line ahead. You don't want your teammates to all do a random walk, it kind of messes things up, but for the sake of this discussion let's pretend they can.



A shell travels about 100-150 times faster than a ship, in the horizontal plane and when shooting at long ranges. Therefore, if the ship is doing violent evasive maneuvers, any accuracy beyond about 1 part in 100 is therefore simply wasted (at least in the absence of clairvoyance). Just for curiosity, you can compare this to a sniper rifle which can have an accuracy of better than 1 minute of arc (moa) or an Olympic match air gun which can hit a target to about 1 mm at a range of 10 m, both corresponding to an accuracy of about 1 part in 10 000, this with gunnery control provided by a Mk. 1 eyeball.



This is what happened off Samar. There was nothing wrong with Japanese gunnery control, just simple statistics. If you are trying to hit a small and agile target like a destroyer, going through the calculations, you find that you will have to wait until the range has dropped to about 10-15 km before you have a reasonable chance of hitting it, assuming the destroyer is doing all it can to dodge the shells. Swatting destroyers is a frustrating business and destroyer captains intent on a torpedo attack know that and used it many times during the war. This is why many battleships of the time had 6? secondary artillery. A 6" shell will probably disable a destroyer almost as effectively as 14"/16? shell but the 6" gun will be able to maintain a much higher rate of fire which is what you need to beat the statistics. American battleships gave up 6? guns for better AA and it might be that the USN compensated for this by having a larger proportion of cruisers with 6? guns and thus a high rate of fire. The Yamato's had good secondary artillery, they could fend for themselves and their cruiser where mostly armed with 8? guns, optimized for fighting other cruisers.



You can compare this to what happened with the Norden bomb sight and high-level bombing of moving targets. The time for the bomb to reach a moving target tended to make that type of bombing pretty ineffective regardless of how excellent the bomb sight was. There were other basic problems with high-level bombing but we can leave that out.



My hunch is that much of what has been said about better gunnery control on the US battleships is probably true in a sense but possibly also irrelevant in that it didn't actually produce more hits on target. It would be great if somebody could explain in what way US gunnery control led to more hits on target, not just being "better" in the sense of "more sophisticated" or "more automated" or whatever.  After all, salvo based long range gunnery was pretty old technology and very well understood by everybody by the 40's.



According to NavWeaps.com, the muzzle velocity of the Yamato's 18.1? gun is significantly higher than that of Iowa's 16? but Yamato's shell is only slightly heavier. Iowa selected a relatively heavy shell and paid the price in muzzle velocity. At close range the Yamato's guns should be considerably more destructive, despite similar shell weights. At longer ranges the muzzle velocity has bled off due to friction with the air and destructiveness is mostly related to shell weight and there the two guns are about equal. Please note that at longer ranges the Yamato still has an advantage in that the shorter flight time to target makes gunnery control easier, Iowa has to have better gunnery control just to compensate for facing a somewhat more difficult gunnery control problem. Yamato is optimized for night c
 
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JFKY       2/2/2010 1:02:13 PM


My hunch is that much of what has been said about better gunnery control on the US battleships is probably true in a sense but possibly also irrelevant in that it didn't actually produce more hits on target. It would be great if somebody could explain in what way US gunnery control led to more hits on target, not just being "better" in the sense of "more sophisticated" or "more automated" or whatever.  After all, salvo based long range gunnery was pretty old technology and very well understood by everybody by the 40's.

American naval artillery had superior fire control....its radar allowed for the computation of range AND bearing, whereas the Yamato had range only and had to develop bearing from OPTICAL observation.
 
The US had a better stable vertical and better computation for fire control...
 
It comes down to this, the Yamato could "dodge" or "shoot", it could not do both....if it "dodged" it lost its fire control solution.  US vessels could both "dodge" AND "shoot".  USS North Carolina, IIRC, completed a 450 degree turn, and several 135 degree turns back-to-back and never lost the solution on its target. 
 
Yamato would be trying to hit a moving target, whereas the US vessels would be able to maneuver and engage a non-evading target...advantage US, plus the US is going to be firing at 30K yards, the Japanese at less than 27 K yards...longest hit was a 26.5 K hit by Scharnhorst on the HMS Glorious.
 
US shells were better, achieving penetration on ALL portions of the Yamato...Japanese shells less effective...the US armour would De-Cap any AP shell up to 18.5 ", meaning that the shell would penetrate one layer of armour, but would be inhibited from penetrating further.  Battleships had multiple levels of armour, making it difficult for the Yamato to severely damage the say the Iowa, with one shot.
 
Bottom-line: the Yamato were a waste of resources, overall for Japan, but I'm not saying they were bad vessels in and of themselves.  However, I am saying they were over-matched by US fast battleships, the Iowas in particular.
 
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Hamilcar    Ford Mark !A    2/2/2010 2:17:37 PM
My hunch is that much of what has been said about better gunnery control on the US battleships is probably true in a sense but possibly also irrelevant in that it didn't actually produce more hits on target. It would be great if somebody could explain in what way US gunnery control led to more hits on target, not just being "better" in the sense of "more sophisticated" or "more automated" or whatever.  After all, salvo based long range gunnery was pretty old technology and very well understood by everybody by the 40's.
 
 
1. The US computers were able to handle Magnus effect and compare time of flight to measured enemy rate of advance between salvoes incrementally using time solutions(shoot solutions were FAST.). Foreign fire control had to recompute each salvo.  
2. US gunnery tables were built into the computers. The enemies or allies had their tables printed in books that had to have values literally cranked in.  
3. US computers were clocked. That last is important, because once the US tracking parties achieved time straddles, the next three salvoes would inevitably hit as the shell ladders would fall into the enemy battleship track every thirty seconds. Even if the Yamato dodged at its best gunnery speed (12 meters per second), then it could only run 360 meters between ladder splashes. The Yamato was 250 meters long and could only turn into a circle radius at 15 times its length at SLOW speed. The American fire control could creep chase such a target and hit repeatedly under those conditions optically at ANY effective range while the US ship dodged. The Iowas could turn circle at 10 times their length radius at high speed (>12 meters per second)    
 
Average US battleship gunnery PK was 3-5% not 1% therefore, the gunnery massacre at Surigao Strait reflects this. The two Japanese battleships missed the American line entirely with their main guns. The 5 of 6 US battleships present scored at least one straddle each for the very brief time  they shot. The one shell one cave ridiculous accuracy of the USS New Mexico at Saipan is also explained. It just sat there and shot by map coodinates after it had the absolute range to the Marine FO's dialed in. 
 
In the case of the USS Washington, it was actually a staggering 8% or greater of all main gun shells fired against Kirishima despite violent evasive maneuvering by both ships.at very close ranges that made it almost impossible for Kirishima to hit Washington at all when she, Kirishima, shifted off South Dakota.        
 
Germans, French, Japanese, and even a few unlucky Russians who were hit by it in the Aleutians...ALL agreed that US naval gunnery was DEADLY.
 
H.   
 

 
 
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skimmer    Battleship weapons & mission   6/24/2010 8:32:20 PM
To cowboyp97dc       10/13/2009 12:01:38 AM
 
"The Iowa Class did exactly what it was built to do - bombard shore defenses and provide superior AA cover for the capital ships- the aircraft carriers."
 
Your statement is only partly correct, inadvertently. No battleship is designed for shore bombardment, nor to provide AA coverage for "capital" ships. "Capital ships", as a term, includes battlecruisers, battleships, and (later) aircraft carriers.
 
You might benefit from doing a little more reading on the Navy's design requirements. Battleships were designed to face-off against the opponents' battleships. The unending competition over armament and armor is testiment to this. You must remember that just prior to World War II aircraft carriers made their debut as serious implements of fleet actions - the preponderance of senior naval officers had grown up with the theory of paired battle lines opposing each other in force (e.g. Jutland). Design and construction of battleships continued, though at a diminished rate, only after aircraft carriers had shown themselves capable of distinct advantages in range for exchange of fleet actions. Aircraft had been considered ineffective against naval ships because of the targeting problem. Relative motion, with no stabilized fire control system, is very problematic.
 
The aircraft carriers were capable of much greater speeds than the battleships of the inter-war period. Heavy and light cruisers were beefed up in AA weaponry, and assigned to escort the carriers because they had the required speed. As Japan continued the quest for the "super-battleship", the U.S. had to rethink its escort lineup. The problem with aircraft carriers is that when they launch their air-wing (strikers and escort fighters) nothing is left to defend it - no major caliber weapon. Oh, the carriers still have the cruisers (to keep pesky destroyers and submarines at bay), but if confronted by a single or pair of battleships is dead. The U.S. had bet the farm on the carriers after Pearl Harbor's losses. The Iowa-class was designed as "fast battleships", to keep up with carrier task groups. The addition of AA armament was welcome in ANY task group - but it isn't the reason for the battleship design. The battleship defensive armament is meant (because of ranges for secondary arms) as point-defense. The task group is always faced with a paradox problem in combat - if you tighten the formation (to maximize AA coverage) you open the door to submarines (if you aren't running at flank speed and zigzagging). If you open the formation to compensate for submarines, then you diminish your AA coverage.
 
As for shore-bombardment, that was a side-line capability. The preponderence of shells normally carried aboard battleships was armor-piercing (AP). High-capacity (HC) shells were developed to provide capability against ships who weren't (or lightly) armored - an AP shell will pass right through a light cruiser without detonating. The shell is there to maximize damage - pick the shell appropriate to the target. The Navy found that HC was good in beach gunfire support when Marines went ashore (since the Marine artillery is still aboard the amphibious shipping during the beach preparation phase). When you can choose between saturating an enemy artillery position with cruiser fire or wiping it from the map with a battlehip salvo, which would you choose? Hands down, the battlehip fills the bill - but not designed for it (unless you also count cruisers and destroyers as designed for it). The Navy uses what it has. It adapts as it waits for new weaponry developments. The amphibious rocket ships were another development, but didn't supplant the battleship rifle. It was superior in so many ways.
 
[Retired Naval Surface Warfare Officer]
 
(BTW, I said naval *rifle* because a naval *gun* is smooth-bored (e.g. cannon). U.S. naval ship main armament weapons are *rifled*, for better shell control, longer range, and better bore wear.)
 
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cowboyp97dc       7/8/2010 2:54:53 PM
In reply to the previous post- I have done my research.  When you say "You might benefit from doing a little more reading on the Navy's design requirements. Battleships were designed to face-off against the opponents' battleships. The unending competition over armament and armor is testiment to this." I would agree with you if we were talking about pre December 7 1941.  December 7th taught us very important lessons- 1. the battleships were no longer the "capitol" ships of the MODERN navy and 2. there were going to be no more battleship face-offs in this new era of warefare.  I would totally agree with all of your post if we were talking about the design and implementation of the South Dakota Class Battleship- but we are not we are talking about the design, and modification of the Iowa Class Battleship.  The Iowa class battleships were designed to keep up with the fast aircraft carriers which is why they were faster than the South Dakota they were replacing.  The Iowa Class battleship was designed to keep up with the new capitol ships the aircraft carriers and provide the capitol ships with AA fire to protect them from planes.  Most Iowa Class battleships only fired their impressive main guns at shore targets to "soften" the beaches for Marine landing zones.  "In their World War II configuration, each of the had a main battery of 16-inch (406 mm) guns that could hit targets nearly 20 statute miles (32 km) away with a variety of artillery shells designed for anti-ship or bombardment work." and "When brought into service during the final years of World War II, the Iowa-class battleships were assigned to operate in the Pacific Theatre. By this point in the war aircraft carriers had displaced battleships as the primary striking arm of the both United States Navy and the Imperial Japanese Navy. As a result of this shift in tactics U.S. battleships of all classes were relegated to the secondary role of carrier escorts, and were assigned to the Fast Carrier Task Force to provide anti-aircraft screening for U.S. aircraft carriers and perform shore bombardment." are both direct quotes from Wikipedia.  The South Dakota was designed to be the capitol ship and engage other battleships in old style line combat and crossing the "T" dating back to the ship of the line.  The Iowa was a modern battleship to fight a modern war- they were no longer the capitol ships but played important support roles.  They were built tough enough to engage any of the Imperial Navy's battleships however if a IJN battleship was spotted they would send out dive bombers and latter torpedo planes (once we had a good torpedo and torpedo plane) to engage it.  A battleship would only engage such a target if it somehow got too close to the task group which would never happen when you consider planes (even of that day) had ranges of hundreds of miles.  Iowa Class Battleships more resembled floating Anti-Aircraft platforms when compared to earlier battleships.  Earlier battleships only had AA to protect themselves- Iowa's had every spare inch bristling with a AA gun to protect the aircraft carriers of the task group.  Still I think that the superior training, 16in guns (that were actually superior to the 18.1 in Jap guns and had radar directed fire control), and superior armor design of the Iowa would have carried the day vs a Yamato Class battleship.
 
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