Yamato and Musashi vs. Missouri and Iowa

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Thorsten Wahl
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Re: Yamato and Musashi vs. Missouri and Iowa

Postby Thorsten Wahl » Tue May 13, 2014 8:09 am

with regards to general quality of german armor grade steels
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Re: Yamato and Musashi vs. Missouri and Iowa

Postby Dave Saxton » Wed May 14, 2014 2:45 pm

To elaborate a bit on the document posted by Thorsten; The use of cutting edge electric arc furnace smelting technology in Germany allowed them to consistently produce higher quality armour. The main advantage is much lower levels of impurities in the steel as well as more tightly controlled chemical composition. The inferior smelting technology in France resulted in significantly higher levels of sulfer impurities, for example.


The superior smelting technology also allowed the Germans to produce a unique type of steel alloy for homogenous armour. Conventional homogenous armour is a nickel based alloy, combined with some chromium. Nickel being the chief alloying agent. The German homogenous armour such as Wotan Harte does not use nickel hardly at all. It is chromium/molybdenum alloy. A different type of steel all together. Any nickel amounts will be very low. The advantage of using Chrom/moly steel for homogenous armour is that it can be treated with special heat and mechanical treatments to higher levels of hardness (and therefore greater tensile strength) without decreasing the ductility to unacceptable levels. This means it can consume more ballistic energy and deform more before tearing apart instead of breaking apart compared to conventional homogenous armour types.
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Re: Yamato and Musashi vs. Missouri and Iowa

Postby Dave Saxton » Wed May 14, 2014 3:04 pm

Getting back to the question of the quality of the armour plates in Yamato and Musashi; the Japanese copied British metallurgy exactly. Indeed the Tech Mission to Japan revealed that the MNC plates was exactly the same chemical composition to the latest British NCA plates. The VH armour plates was the same as Vickers cemented plates, and the construction steel was Ducol, or D Steel, the same as in British construction. D steel is not weldable, however.

The question of quality boils down to the thickness. The problem of making homogenous armour of high quality at greater than about 150 mm thickness is the disparate rate of cooling between the outer portions and inner portions of thick homogenous plates. This makes it impossible to properly treat the plates with special heat treatments. The USN Research Lab found that the inner portions of thick homogenous plates were always brittle. It is also questionable of how the inner portions of thick plates could be properly treated by mechanical treatments used to align the micro structure.
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.

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Re: Yamato and Musashi vs. Missouri and Iowa

Postby LeopardTooth » Sun Jun 29, 2014 9:16 am

This info comes from the book "The Pacific War Encyclopedia” by James F. Dunnigan and Albert A. Nofi:

“A true test would have pitted a squadron of Iowas against a squadron of Yamatos. The differences between the two classes of battleships are interesting. Since speed in a ship is partially a factor of hull length and fineness, her more powerful engines made Iowa about twenty percent faster than Yamato. In addition, Iowa’s deeper draft made for greater stability, making her a better “gun platform” than her rival. Both of these factors would have been important in an engagement at sea. Moreover, Iowa was a handier ship, responding to helm more rapidly, with a smaller tactical diameter (The minimum diameter necessary to make a full circle), which made her more maneuverable.

On paper, of course, Yamato’s thicker armor suggests a better protected ship, but this is rather deceptive. Thickness of plate must make an allowance for quality. In the years before World War Two, the U.S. Navy had made considerable strides in armor technology. As a result, the protection offered by its new armor plate was equivalent to about twenty five percent more thickness in terms of the older type of armor carried by the Yamato.

An additional important factor was that Iowa appears to have been better constructed than Yamato. On December 25, 1943, for example, Yamato took a torpedo that demonstrated that the jointing between the hull and her armor belt was faulty. As a full repair would have entailed the addition of over 5,000 tons to the ships displacement, the Imperial Navy merely patched up the damaged section, and pretended there was no problem. When a similar incident occurred to Musashi in March 1944, the Imperial Navy continued to pretend.

Of course the big difference was in the main batteries, Yamato’s 18.11 inch rifles (as battleship guns were traditionally called) making Iowa’s 16 inchers seem puny by comparison, what with the Japanese armor piercing shell weighing nearly twenty percent more and having almost seven percent more range. But this is a superficial comparison. A deeper look proves more interesting.

Gun caliber is given in inches and barrel length, so if a piece is described as 18.11”/45 the bore is 18.11 inches in diameter and barrel is 45 times that in length, or slightly less than 70 feet. The 16”/50 was about 66.6 feet long. Longer barrel length lends stability to the shell in flight, which increases range, which is one reason why, although the Japanese gun had a bore diameter thirteen percent greater than the American piece, its maximum range was only seven percent greater.

Other factors of importance were the propellant used (the “Gun powder”) and shell aerodynamics. On this score, the U.S. piece was better, with a slightly higher muzzle velocity (the speed with which the shell leaves the barrel, measured in feet per second, or fps).

Incidentally, the marginally greater maximum range of the Japanese gun would have been of no consequence. The greatest range at which a land-based heavy artillery piece ever hit a target deliberately aimed at appears to have been about 17.4 nautical miles (roughly 35,200 yards, 20 land miles) a feat accomplished by a U.S. Army model 16"/45 coast defense gun at Fort Weaver, Hawaii, in August 1938, under absolutely wonderful conditions of weather and sea. The longest range deliberate hit at sea in naval combat occurred on July 9, 1940, off Calabria, Italy, in the Mediterranean, when the British Battleship Warspite put a single 15 inch round into the Italian battleship Giulio Cesare at 26,000 yards, about 12.8 nautical miles.

It may seem odd to measure the penetrability of a gun at zero range (i.e., at the instant the projectile leaves the barrel), but it actually is of some value for comparison purposes. The number of rounds per minute that the pieces were capable of firing is a rather optimistic figure, since it was dangerous and exhausting to attempt to sustain maximum rates of fire for more than a few minutes. Of course, this still gave the U.S. gun a higher rate of fire.

In effect, on technical grounds, the U.S. 16”/50 battleship rifle was by no means inferior in performance to the Japanese 18.11”/45. And in action that performance would have been enhanced by fire control radar, a development with which the Japanese had very little success.

Below is the table for Main battery Gun Performance Comparison

Japanese 18.11”/45 American 16”/50
Muzzle velocity 2,559fps 2,600fps
Penetration at:
0 yards 34” 32.62”
20,000 yds about 20.4” 20.04”
30,000 yds about 14.7” 14.97”
Rounds per minute 1 2"

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Re: Yamato and Musashi vs. Missouri and Iowa

Postby alecsandros » Sun Jun 29, 2014 12:46 pm

... most of the opinions in that encyclpoedia are wrong.

Steve Crandell
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Re: Yamato and Musashi vs. Missouri and Iowa

Postby Steve Crandell » Sun Jun 29, 2014 6:54 pm

alecsandros wrote:... most of the opinions in that encyclpoedia are wrong.


I agree. A lot of incorrect stuff there.

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Re: Yamato and Musashi vs. Missouri and Iowa

Postby tameraire01 » Mon Jun 30, 2014 8:08 pm

Out of the two classes which has :
1.The best rate of fire
2.Range
3.Fear Factor
4.Speed
5. The amount of damage it is capable of sustaining
6.How many crew on board
7.The amount of AA on board

The only way of settling these sort of things.
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Re: Yamato and Musashi vs. Missouri and Iowa

Postby Steve Crandell » Mon Jun 30, 2014 9:43 pm

tameraire01 wrote:Out of the two classes which has :
1.The best rate of fire
2.Range
3.Fear Factor
4.Speed
5. The amount of damage it is capable of sustaining
6.How many crew on board
7.The amount of AA on board

The only way of settling these sort of things.


My opinion:

5. Favors Yamato by a wide margin.

The others are similar between the two or don't count for much in a battleship gunnery engagement. What you didn't mention is the ability to hit their target, where Iowa would have a significant advantage. In excellent visibility that advantage might not be decisive, but in less than that it might be.

7. I don't know about "amount" of AA (how do you measure that?), but overall Iowa's was much better than Yamato's.

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Dave Saxton
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Re: Yamato and Musashi vs. Missouri and Iowa

Postby Dave Saxton » Tue Jul 01, 2014 1:35 am

In 44 chances are it will be a night battle for such a match up to come off. Something like the Iowa's being sent in to attack Japanese shipping after dark in bad weather precluding much air activity, and hence using the Iowa's because of their speed and firepower instead. And Y&M rushing in from a cover position based on a submarine contact or something.
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.

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Re: Yamato and Musashi vs. Missouri and Iowa

Postby alecsandros » Tue Jul 01, 2014 5:37 am

Steve Crandell wrote:
tameraire01 wrote:Out of the two classes which has :
1.The best rate of fire
2.Range
3.Fear Factor
4.Speed
5. The amount of damage it is capable of sustaining
6.How many crew on board
7.The amount of AA on board

The only way of settling these sort of things.


My opinion:

5. Favors Yamato by a wide margin.

The others are similar between the two or don't count for much in a battleship gunnery engagement. What you didn't mention is the ability to hit their target, where Iowa would have a significant advantage. In excellent visibility that advantage might not be decisive, but in less than that it might be.

7. I don't know about "amount" of AA (how do you measure that?), but overall Iowa's was much better than Yamato's.


I would add Yamato's armor belt was 410mm thick declined at 20*, vs Iowa's 305mm belt declined at 19*, while their shells had comparable perforations.

The turrets were also substantialy better protected in Yamato, as were the decks.

Still I would favor the Iowa, as she would probably hit first, and more often afterwards...

Donald

Re: Yamato and Musashi vs. Missouri and Iowa

Postby Donald » Thu Dec 24, 2015 11:15 pm

The Iowa class could rapidly change course and maintain a firing solution even firing "over the shoulder". Mushashi and Yamato could do one or the other not both. The fire control radar was so good it could detect misses not so with the IJN. In a night fight with rain or smoke or fog IJN would not be able to use their optics and would be firing blindly (sea battle Guadalcanal). IJN had issues with armor and they did not want to risk their largest ships. IJN battleships were designed for fighting USN BBs. Iowas were designed to provide protection for US Carriers. No IJN battleships survived the war. All the Iowas did as well as several earlier classes ( North Carolina and South Dakota).


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