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#1 alberto ricart

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Posted 30 April 2007 - 11:45 PM

I have multiple questions and could not decide where to place theses.first the website for naval weapons posted at this site is very usefull and showed as I had seen in other places that the japanese 6 inch guns of the agano and the 5 inch guns had no armour piercing shells. should the armour penetration for japanese guns be capped at cs.also the 5.5 inch gun has rate of fire reported up to 10 rounds per minute. should the 5.5 gun be allowed rapid fire?also the japanese 6.1 inch gun does not have its own site. although few ships carried it, it is my understanding that due to high caliber it had better penetration and was still used in a few ships.the american 16 inch gun is given the same penetration as the british 16 inch gun. it is my understanding that the new american 16 inch gun firing a 2700 pound shell had better penetration. is this the case? will there be a new section for those 16 inch guns caliber 45 and 50.?the italian 8 inch gun is given a similar accuracy as the japanese 8 inch gun, but it is my understanding that the italian gun had significant dispersion problems, while the japanese did achieve some long distance hits like at the battle of java sea and the komandorskies. is this accurate? should the accuracy of the italian 8 inch gun be downgraded?

#2 Cpt M

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Posted 02 May 2007 - 12:57 AM

'first the website for naval weapons posted at this site is very usefull and showed as I had seen in other places that the japanese 6 inch guns of the agano and the 5 inch guns had no armour piercing shells. should the armour penetration for japanese guns be capped at cs."According to such sources as Nathan Okun, the IJN 5" was capable of penetrating the equivalent of CA armor at close range. So the provision of such penetration is appropriate."also the 5.5 inch gun has rate of fire reported up to 10 rounds per minute. should the 5.5 gun be allowed rapid fire?'The majority of the IJN 5.5" guns in service during WWII were hand operated pedastal mounts (such as those mounted on Sendai) with limited ammunition supply arrangements. Given these limitations, the rate of fire for these weapons would be towards the lower value of 6 rounds per minute. The only modern power operated mounts capable of the higher rate of fire were those on Yubari."also the japanese 6.1 inch gun does not have its own site. although few ships carried it, it is my understanding that due to high caliber it had better penetration and was still used in a few ships."The 6.1" (properly known as the 155mm/60 3rd Year Type) was only mounted on the Yamato class (as a secondary), and the Oyodo. The 6.1" was originally mounted on the Mogami but was replaced with 8" weapons prewar. While it had impressive range, it was not any more powerful than the other modern 6" guns (such as the US 6"/47 or the UK 6"/50). "the american 16 inch gun is given the same penetration as the british 16 inch gun. it is my understanding that the new american 16 inch gun firing a 2700 pound shell had better penetration. is this the case? will there be a new section for those 16 inch guns caliber 45 and 50.?"According to available data, the UK 16" gun's performance is on par with the US 16" firing the 2700lb shell (even a little better, at some ranges; that surprised me, as well). Whether an additional table with the US 16"/45 is added is up to Lonnie and ODGW. "the italian 8 inch gun is given a similar accuracy as the japanese 8 inch gun, but it is my understanding that the italian gun had significant dispersion problems, while the japanese did achieve some long distance hits like at the battle of java sea and the komandorskies. is this accurate? should the accuracy of the italian 8 inch gun be downgraded?"The Italians, and others, had the same problem with dispersion brought about by the close mounting of the guns. The solution, arrived at prewar, was to stagger the firing of the guns by a fraction of a second. This effectively eliminated the problem.

#3 alberto ricart

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Posted 05 May 2007 - 09:49 AM

thanks for your reply

#4 Radek Gozdek

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Posted 07 May 2007 - 05:16 AM

You have no right about "UK 16" gun's performance" . Please compare http://www.navweaps....45_mk6.htmArmor Penetration: 12.2" vs 17.6" at 20 000y. Even 15" funs was much better: Italy (20"), Germany (16,5") anf France (15.5" at 24 000y). Also IMHO a_ricart has a right with Italian 8" guns. Please look at ROF - worst of 8" guns. Together with shell dispersion problems shuold have penalty.

#5 gregoryk

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Posted 07 May 2007 - 10:02 AM

Mike,Is it possible to say from where you obtained your information? I am always suspicious of formula-driven derivations of penetration data, such as found on the website Ragozd mentioned.Gregory

#6 Cpt M

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Posted 07 May 2007 - 11:43 PM

"Is it possible to say from where you obtained your information? I am always suspicious of formula-driven derivations of penetration data, such as found on the website Ragozd mentioned."The information is from an extensive tabular listing based on Nathan Okun's Facehard formula. The penetratons listed in Campbell's are the US Navy's empirically derived calculations made during or just after war and have been brought into considerable question since. Given the amount of information uncovered in the interim and the level of research involved, I'm inclined to place more credence with Okun's results."Also IMHO a_ricart has a right with Italian 8" guns. Please look at ROF - worst of 8" guns. Together with shell dispersion problems shuold have penalty."The rate of fire for the majority of modern mounts ranged from 4 to 5 rounds per minute. The Italians, according to Campbell's and other sources managed up to 3.8 rounds per minute, which made theirs one of the slowest. It is also largely irrelevant. To accurately gauge fire requires waiting for the shot to fall. At any range of length, this wait imposes a considerably slower rate of fire, often down to 2 rounds per minute. Consequently, the Italians would not be at any more disadvantage than any other nation. As previously stated, the dispersion problem was resolved by staggering the firing circuits of the guns. This was arrived at pre-war and was not a problem during combat. (This is from a Warship article form the '80s; unfortunately I do not recall the exact issue.)

#7 gregoryk

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Posted 08 May 2007 - 11:31 AM

Interestingly, even Nathan Okun's work has been called into question, and found to contain some errors of up to 10-15%. One should always be aware of what happens in real life, i.e., empirically, for which there never seems to be sufficient testing or after-the-fact formulŠ. Given that caveat, Okun still is about the best ballistics work available.Mike's information matches what I have read concerning the Italians.Cheers,Gregory

#8 Jim O'Neil

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Posted 08 May 2007 - 10:01 PM

Very interesting... who perchance proved him off by 10% ? ...He is maniacal about accuracy and as a Terminal Ballistician for the Navy, rather well placed to have good data.

#9 Radek Gozdek

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Posted 10 May 2007 - 05:46 AM

But even Okun change his mind about decapp. Nobody is perfect ;)

#10 Jim O'Neil

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Posted 10 May 2007 - 07:57 PM

In which sense ? I know he has found new data, and thus corrected his views (Lord knows, I wish more researchers did that).He found written evidence that the Italian Navy intentionally planned for de-capping, but there seems little to support the knowledge in the USN... the Iowa class benefited from a lucky decision it woud seem, and the South Dakota's less so, as the outer hull was thinner.Is there something else I have missed?

#11 alberto ricart

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Posted 12 May 2007 - 09:01 PM

thanks again for the information




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