Two KGV's vs. Yamato

[Bgile]

If the conning tower hits occurred at very close range, it is possible the impact velocity exceeded the structural integrity of the shell.

Yes, that is one plausible explanation, particularly if the hit was from Rodney at less than 6km.

[dunmunro]

Just looked at the penetration tables something funny is happening between 32,000 and 35,000 yards. The velocity is increasing slightly which is reasonable and the angle is improving some (~9 degrees) but penetration is almost doubling! This seams to be independent of gun. Could be real I just don't understand what's going on.

I think this has to do with the design of AP shells, which typically have difficulty with high target angles but then become disproportionately effective as the target angle begins to fall. The RN 14/45 for example had a more rapid decline in performance with armour plate at 40 degs, than scaling results taken at 30degs would suggest. AFAIK, Nathan Okun has taken this into account with his penetration formulas, by fine tuning them to agree with the actual test results. For example if you download NAab 1.0 and play aroud with it, you will note that the USN 16/45 performs relatively better than the RN 14/45 at high target angles, which was reflected in actual proofing trials, and then incorporated into Okun's pentration formulas.

[RNfanDan]

The KGVs...would have to split up so they had a chance to hit Yamato's turrets on the back or side armor. They might be able to silence her before they ran out of ammo.

With the characteristic mechanical failures known to have plagued the quad turrets of the KGVs, it is not unreasonable to assume the two ships' firing efficiency would not exceed 60 to 70 percent, overall.

Thus reduced, the level of ammunition expenditure would therefore be unlikely to become critical at any point before they embarked on their respective seafloor trials.

[dunmunro]

The KGVs...would have to split up so they had a chance to hit Yamato's turrets on the back or side armor. They might be able to silence her before they ran out of ammo.

With the characteristic mechanical failures known to have plagued the quad turrets of the KGVs, it is not unreasonable to assume the two ships' firing efficiency would not exceed 60 to 70 percent, overall.

Thus reduced, the level of ammunition expenditure would therefore be unlikely to become critical at any point before they embarked on their respective seafloor trials.

If the weather conditions equal a force 8-10 gale, then the output might fall to that level, but in that case,the reduced visibility would probably serve to increase KGV's radar advantages.

[lwd]

Just looked at the penetration tables something funny is happening between 32,000 and 35,000 yards. The velocity is increasing slightly which is reasonable and the angle is improving some (~9 degrees) but penetration is almost doubling! This seams to be independent of gun. Could be real I just don't understand what's going on.

I think this has to do with the design of AP shells, which typically have difficulty with high target angles but then become disproportionately effective as the target angle begins to fall. The RN 14/45 for example had a more rapid decline in performance with armour plate at 40 degs, than scaling results taken at 30degs would suggest. AFAIK, Nathan Okun has taken this into account with his penetration formulas, by fine tuning them to agree with the actual test results. For example if you download NAab 1.0 and play aroud with it, you will note that the USN 16/45 performs relatively better than the RN 14/45 at high target angles, which was reflected in actual proofing trials, and then incorporated into Okun's pentration formulas.

That was the only thing I could think of as well. Interesting.

[Karl Heidenreich]

lwd:

That's not what he says at:
http://www.navweaps.com/index_tech/tech-040.htm

PROJECTILE USED:

U.S. Navy 2700-lb 16" Mark 8 Mod 6 AP with inert filler ("BL&P") (last version of this projectile manufactured during WWII)

OBLIQUITY: Near-normal (0°)

TEST #1 on 16 October 1946 (IMPACT #33443):
...RESULT: Complete penetration ...
TEST #2 on 23 October 1946 (IMPACT #33459):
... Projectile nose tip only penetrated 21" (53.34cm) into the plate, though punching a hole entirely through. Projectile was completely undamaged ... Plate had exactly the same thing happen to it as with the first test, with numerous small cracks, many laminations, and a complete break through hole between left edge and curved gun port cutout.

Yeah, that´s right. I just checked the page and the quote it´s right. Sorry. But , the conclusions are pertinent to the fact that KGV could not have (and neither Iowa) defeated that armour.

Best regards.

[Legend]

I agree. The only thing I can see the 14in guns of the KGV class damaging that is important on the Yamato is the superstructure... bridge, fire directors, control centers, AA... perhaps an extremely lucky hit to the propeller or rudder? (He he, but not likely)

On the flip side, Yamato's 18in guns vs KGv class armor... I seem to recall a certain German BB causing damage to PoW with only 15inches of lead. I am willing to believe that if a KGV caught herself trying to shrug off 18in shells she wouldn't last long... especially if they needed to stay at long range to make the trajectory of their shells steep enough to penetrate the Yamato's armor!

In a daytime scenario I see KGV1 getting sunk, Yamato with a damaged superstructure, and KGV2 with (major?) damage. The only reason KGV2 didn't get blown up like her auntie Hood is because the sheer number of shells fired managed to take out the bridge or the fire director's periscope thing (can't remember the word at the moment, on the tip of my tongue). At that point being virtually blind the Yamato had to back off, unless KGV2 kept persuing. Then she would have to close the range with no commander and finish off KGV2 with nothing but the individual gun's directors (assuming Yamato had those).

(a minute of pause)

I might be able to see KGV1 and KGV2 closing in fast enough to decimate Yamato's superstructure, then keep pounding her until the fires spread until... BOOM!!! One of her numerous magazines blew. But I still give my chances to the above theory during the day, while the two would do the latter during the night (although I think we already agreed on that earlier due to superior radar).

[lwd]

.. But , the conclusions are pertinent to the fact that KGV could not have (and neither Iowa) defeated that armour....

Indeed they clearly point out that such conclusions are wrong. Note that in the case where the 15" round did not penetrate the face plate that had it impacted a turret face in such a manor the turret would almost assuredly not been functional afterwards. Furthermore the turret faces were the thickest parts of Yamato's armor. The test did suggest that a single round from a 16"/50 wasn't going to penetrate the Yamato's face plate beyond that it suggest that said rounds could still do considerable damage by implication a KGV's 14" rounds would do lesser but still considerable damage.

[Dave Saxton]

I think this has to do with the design of AP shells, which typically have difficulty with high target angles but then become disproportionately effective as the target angle begins to fall....

This is why somewhat lighter and smaller battleships caliber shells can attain surprizing deck penetration at the ranges around 30,000 meters (~33,000 yards). At these ranges the lighter weight BB shells such as the KGV 14" have relatively steep angles of fall, where heavier projectiles will retain more velocity and these steeper angles of fall are delayed until the range becomes greater.

[Bgile]

.. But , the conclusions are pertinent to the fact that KGV could not have (and neither Iowa) defeated that armour....

Indeed they clearly point out that such conclusions are wrong. Note that in the case where the 15" round did not penetrate the face plate that had it impacted a turret face in such a manor the turret would almost assuredly not been functional afterwards. Furthermore the turret faces were the thickest parts of Yamato's armor. The test did suggest that a single round from a 16"/50 wasn't going to penetrate the Yamato's face plate beyond that it suggest that said rounds could still do considerable damage by implication a KGV's 14" rounds would do lesser but still considerable damage.

Where is the article that mentions the 14" and 15" guns? The only one I'm aware of is the test with the 16"/50.

[Karl Heidenreich]

If the 16" didn´t penetrate (and we are talking the Iowa´s 16") then why worry about the other, lesser ones. They can´t.

[Bgile]

If the 16" didn´t penetrate (and we are talking the Iowa´s 16") then why worry about the other, lesser ones. They can´t.

As I read the passage, Okun was stating his opinion that if you hit one at point blank range with a 16"/50 it might jam the turret. Dave was opining that 14" shell would be almost as effective, and I was wondering where that came from.

[dunmunro]

If the 16" didn´t penetrate (and we are talking the Iowa´s 16") then why worry about the other, lesser ones. They can´t.

As I read the passage, Okun was stating his opinion that if you hit one at point blank range with a 16"/50 it might jam the turret. Dave was opining that 14" shell would be almost as effective, and I was wondering where that came from.

Depending on the turret design a direct 14" hit might cause spalling inside the turret. A hit on the gun port would probably damage the elevating mechanism for that gun, at least, but the turret faces represent a fairly small surface area compared to the rest of the ship, and hits might be rare.

[lwd]

...
Where is the article that mentions the 14" and 15" guns? The only one I'm aware of is the test with the 16"/50.

The 15" was a typo on my part. 14" because we are talking about KGVs. Not sure what they would do to the faceplate of a Yamato the physics of partial penetrations is really messy. My guess is no plug but possible spalling. Whether or not the plate cracked would be another matter.

[lwd]

If the 16" didn´t penetrate (and we are talking the Iowa´s 16") then why worry about the other, lesser ones. They can´t.

Because, while the lower velocity 16" didn't penetrate, a hit like that would have taken the turret out of commission especially if the round detonated which we have every reason to expect it would. Now whether or not lesser rounds would do the same is another question.