40 cm/45 Type 94 vs 16"/50 caliber Mark 7

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BlackBirdZGTR
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40 cm/45 Type 94 vs 16"/50 caliber Mark 7

Post by BlackBirdZGTR » Sat May 16, 2009 10:41 pm

Does anyone have any information on the performance of each gun and how they compared to one another? I know the 16"/50 guns had comparable penetration to the 18.1 inch guns of the Yamato at long ranges but by just how much were they?

dunmunro
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Re: 40 cm/45 Type 94 vs 16"/50 caliber Mark 7

Post by dunmunro » Sat May 16, 2009 11:02 pm

Here's a set of penetration tables that I created for various WW2 BB guns:

http://www.sfu.ca/~dmunro/BB_Gun_pen.html

Using NAaB 1.0, which can be found here:

http://www.panzer-war.com/Naab/NAaB.html

NAaB uses Nathan Okun's armour penetration formulas to estimate armour penetration with almost all WW2 era rifled naval guns.

JtD
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Re: 40 cm/45 Type 94 vs 16"/50 caliber Mark 7

Post by JtD » Sat May 16, 2009 11:31 pm

You're aware that the 40cm Type 94 are just a cover name for the 46cm Type 94?

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Re: 40 cm/45 Type 94 vs 16"/50 caliber Mark 7

Post by BlackBirdZGTR » Sun May 17, 2009 12:13 am

JtD wrote:You're aware that the 40cm Type 94 are just a cover name for the 46cm Type 94?
Yes just thought i should of used its offical name to prevent confusion. :?

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Re: 40 cm/45 Type 94 vs 16"/50 caliber Mark 7

Post by JtD » Sun May 17, 2009 6:58 am

It certainly confused me! :)

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Re: 40 cm/45 Type 94 vs 16"/50 caliber Mark 7

Post by nathanokun » Mon Oct 26, 2009 10:30 am

Note: The homogeneous armor penetration formulae/data set of M79APCALC is only partly mine. It is based on the major, long-duration work at the US Naval Proving Ground, Dahlgren, Virginia, during and after WWII by Dr. Allen V. Hershey and associates in the Ballistic Division. It is EXTREMELY accurate for a blunt-point, non-deforming, uncapped AP projectile (the 15-lb US Army 3" M79 AP SHOT was the primary test projectile, but others had inputs in the final formulae and data set used). It should replace the old DeMarre Formula, since the M79APCALC data works at all obliquities up to 80 degrees and against plates from 0.01-2.0 times the projectile diameter or up to 3500 ft/sec penetration velocity, whichever maximum is reached first with intact projectiles.

My contribution to the formula and data set was the observation that the Krupp Wh n/A (Odin Hardened New Type) armor of WWII, which had a reduced Percent Elongation of only 18% in the spec, compared to US and British 25% or more, had a rather large scaling effect in its armor penetration tables for large shells over 8" in diameter of identical design (Krupp 15-40.6cm Psgr.m.K. L/4,4 scale-model projectiles), though the US and British armors did not. There is a small universal scaling effect for these more ductile armors, but it is fixed. SInce the tests by the US and Britain after WWII confirm these results, there had to be a reason and onlly the Percent Elongation seems to be different.

My theory is simply that to make a hole, one can assume that the projectile in a ductile plate has to stretch the opening sideways enough to make a hole big enough to let the projectile through (actually, it is bending the plate forwards along the projectile path as well as sideways, but this is just a detail). The Percent Elongation is how much the metal can stretch prior to snapping in two in a test. 25% or more allows armor steel to stretch enough first that there does not seem to be any problem, regardless of the size of the plate and projectile. If the Percent Elongation gets under this for large shells, hence the 8" minimum size limit, as the center of the hole is stretched sideways, it reaches this "snap apart" limit prior to opening up all the way to allow the projectile through, creating cracks and tears, which greatly reduce the resistance from that point on. The lower this Percent Elongation value is, the earlier this weakening effect sets in and with larger and larger shells, the cracking and tearing begins closer and closer to the center, relative to the size of the final hole. This makes the larger shells penetrate easier and eaiser as their size goes up. QED

This is my only significant addition to the Dr. Hershey results, other than turning them virbotim into a computer program.

The computer program FACEHARD, on the other hand, is ALL MINE -- every formula and every data set value is from my personal data analysis efforts. There are NO other sources for face-hardened armor theory (at least correct theory) that I know of, though others have done work that gives the same results that I have, going back to the 19th Century, but these were not for armor (at least not their main aim in doing the research). The fact that I found that I had reached the same conclusions as they had from totally different data (projectile/armor test results) was and is of great satisfaction to me, as it confirms that I have found true rules, not just imaginary patterns. FACEHARD has given EXACT duplicates of test results (and I do not mean the tests I used to create it, which of course it matches).

Nathan Okun

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Re: 40 cm/45 Type 94 vs 16"/50 caliber Mark 7

Post by alecsandros » Wed Jun 02, 2010 1:11 pm

As I understand it, the penetrative performance of the 2 shells isn't all that different at normal battle ranges (up to 25km).
The difference becomes substantial afterwards, and it concerns homogenous armor penetration.
Yamato's 460mm shells have a bigger penetrative performance against decks than Iowa's 406mm shells. The difference comes from the bigger weight of the Japanese shell (1460kg versus 1225kg).

That's one difference.

The second, more important, in my opinion, is the expected internal damage delivered by the shell. After all, that is all about: delivering damage inside the enemy ship.
In this aspect, Yamato's double-sized bursting charge (35 vs 18 kg) would make a big differnce.

The third aspect is shell reliability: Japanese type 91 "diving" shells had multiple problems in actual combat, and this is atested in numerous Pacific battles. American mark 7 and mark 8's, on the other hand, were thoroughly tested and delivered very good results in actual combat.

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Re: 40 cm/45 Type 94 vs 16"/50 caliber Mark 7

Post by lwd » Wed Jun 02, 2010 4:01 pm

Actually I've read of some problems (on this board I believe) with some of the early war US fuses. On the other hand didn't the nose desing on the Japanese 18.1" rounds have a problem with "biteing" if the angle got to far from verticle?

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Re: 40 cm/45 Type 94 vs 16"/50 caliber Mark 7

Post by tommy303 » Wed Jun 02, 2010 4:04 pm

American mark 7 and mark 8's, on the other hand, were thoroughly tested and delivered very good results in actual combat.
This is not necessarily true, as during the period of 1942-43 the USN had considerable trouble with their Mk21 Mod 0 base fuzes. These proved highly unreliable leading to an extraordinarily high number of duds in action. The problem was eventually traced to fumes from the Explosive D corroding the internal moving parts of the fuze. This fuze was highly complex and with numerous close tolerance working parts which needed to interact with eachother to arm, meant that any failure of one caused the failure of all. This was corrected successfully in 1943-44 with the introduction of the Mk21 Mod 1 base fuze which used bakelite resin to seal the fuze. The Mk 21 mod 1 nevertheless still had problems when impacting at high oblique angles which tended to jam or damage the internal parts and prevent proper functioning.

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Re: 40 cm/45 Type 94 vs 16"/50 caliber Mark 7

Post by alecsandros » Wed Jun 02, 2010 5:18 pm

@Lee - the question regarding 460mm actual combat performance remains opened, for my part, as there are to few informations to draw from in this aspect. Much of the performance of the heavy 460mm shell is extrapolated starting from US 16"/45 and Us 16"/50 "super-heavies" performances, as real, Japanese, firing-trials data are missing.
It's behavior at oblique angles is also approximated starting from 8" and 6" Japanese type 91 shell performances with similar windscreens.

SOmeting which has always puzzled me is the extra-long fuze delay - 0.4 sec for the giant shells. This means that, in normal combat (say 20km range, good sea, weather), a shell striking the deck would have ~ 17* obliquity, and ~ 520mps speed (~ 1560ft/s). Given the fact that the thickest non-Japanese armored deck in existence in WW2 was 152mm thick, the exit velocity of the shell would be ~ 400mps. So, in the 0.4 sec needed to explode, it would still travel 160 meters, most likely passing below the armored belt on the opposite side of the target ship and exploding harmlessly into the sea.
Now, think about this shell striking not a 152mm, but a 38mm or 50mm plate! It would pass through it and go far, far into the ocean, away with the fairies :D

So, without the decelaration provided by water (that is for diving shells only) I don't know how usefull those delays would be. Even against FH armor, it would take some luck for the exit velocity to be big enough for the shell to fully penetrate, but small enough for the shell not to pass the ship from side to side.

@Thomas - thanks again for some great info

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Re: 40 cm/45 Type 94 vs 16"/50 caliber Mark 7

Post by Bgile » Wed Jun 02, 2010 5:34 pm

I would think that if the shell passed all the way through the ship and exploded underwater, that might cause some serious flooding, with numerous flooding boundaries compromised.

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Re: 40 cm/45 Type 94 vs 16"/50 caliber Mark 7

Post by lwd » Wed Jun 02, 2010 6:13 pm

Even with a shell of that size and performance I'm not sure how likely you are to get a through and through penetration at least if there is significant armor encountered in both passages. On the otherhand this could increase the probabilty that the shell breaks up. If you get a through and through with the exit penetration being below the armored belt if we assume a decent angle of 45 degrees and the 160 meter of travel suggested below then even if it hits the widest part of Iowa it's going to be over 110m from the ship when it explodes (neglecting velocity loss). Of course you will have a hole that's open at both top and bottom with the latter open to the sea.

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Re: 40 cm/45 Type 94 vs 16"/50 caliber Mark 7

Post by alecsandros » Wed Jun 02, 2010 6:38 pm

If the shell strikes the deck at, let's say, 20 degrees, asuming the shell's trajectory as perpendicular to the target ship's direction of movement, then it will pass through the ship and try to "get out" on the other side. There, it has 2 choices: passing throguh the vertical armor belt or beneath it.
SOme shells, striking the deck at the right point (more closer to the opposite side) will strike the armor belt; some won't.

Asuming the above example, with a shell exit velocity of 400mps, cap and windscreen destroyed (leaving ~ 2600pds of body weight), 12" class A US armor, and neglecting internal speed loss, we get "complete penetration achieved, exit velocity 518ft/s".

So it will go THROUGH the armor belt, and still retain ~ 170mps speed. So, it could still travel 53 meters, far enough for the explosion (asuming it will still take place) to further damage the target ship...

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Re: 40 cm/45 Type 94 vs 16"/50 caliber Mark 7

Post by lwd » Thu Jun 03, 2010 12:43 pm

The burster of the Japanese 18.1" gun is listed as 32.8 lbs at: http://www.navweaps.com/Weapons/WNJAP_161-45_3ns.htm
This is less than the explosive in a 100 lb bomb. For instance if I'm reading it right from:
http://www.fischer-tropsch.org/primary_ ... 200-23.pdf
The Japanese Type 97 No.6 bomb weighed in at ~60kg and carried a burster of ~24kg.
More over any fragments are going to loose a lot of energy to even 10m of water much less 50m.

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Re: 40 cm/45 Type 94 vs 16"/50 caliber Mark 7

Post by dunmunro » Thu Jun 03, 2010 1:12 pm

lwd wrote:The burster of the Japanese 18.1" gun is listed as 32.8 lbs at: http://www.navweaps.com/Weapons/WNJAP_161-45_3ns.htm
This is less than the explosive in a 100 lb bomb. For instance if I'm reading it right from:
http://www.fischer-tropsch.org/primary_ ... 200-23.pdf
The Japanese Type 97 No.6 bomb weighed in at ~60kg and carried a burster of ~24kg.
More over any fragments are going to loose a lot of energy to even 10m of water much less 50m.
That's for the 16" 40cm gun. 18.1" is here:
http://www.navweaps.com/Weapons/WNJAP_18-45_t94.htm

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