Prinz Eugen's Performance at DS Battle

Discussions about the history of the ship, technical details, etc.

Moderator: Bill Jurens

Tiornu
Supporter
Posts: 1222
Joined: Mon Oct 25, 2004 6:13 am
Location: Ex Utero

Post by Tiornu » Thu Jun 15, 2006 3:07 pm

By "wrong," I think Phil means that it is tilted back and consequently gives a more accommodating angle to incoming shells. For example, at a range of 30,000 yards, a Bismarck shell would strike a US faceplate at an angle of roughly 7deg from the perpendicualr while a perfectly vertical plate would give an angle 28deg from the perpendicular. Whether or not such long-range hits are an important design consideration, that's a matter of opinion. My advanced mathematical skills tell me that the incoming angle has to exceed 17.5deg before the 35deg American plate has a disadvantage compared to a vertical plate. For a new Bismarck gun, that puts things around 23,000 yards. I suppose a similar factor would apply to the target area of the faceplate. It would be much harder to hit a KGV faceplate than a US facepalte at 23,000 yards.
Bismarck's Bruno turret took a direct hit on the faceplate or on the angled facet above the faceplate. The turret was blasted so thoroughly that the back was blown off.
Cruisers give us a broader sample pool. Quincy, Vincennes, and Astoria all took faceplate hits at Savo, as did the Japanese flagship. Boise took a faceplate hit at short range at Cape Esperance, and suffered no turret damage worth mentioning.

User avatar
nwhdarkwolf
Member
Posts: 55
Joined: Fri Jun 02, 2006 4:42 pm
Location: Appleton, USA

Post by nwhdarkwolf » Thu Jun 15, 2006 5:29 pm

Tiornu wrote:Bismarck's Bruno turret took a direct hit on the faceplate or on the angled facet above the faceplate. The turret was blasted so thoroughly that the back was blown off.
Cruisers give us a broader sample pool. Quincy, Vincennes, and Astoria all took faceplate hits at Savo, as did the Japanese flagship. Boise took a faceplate hit at short range at Cape Esperance, and suffered no turret damage worth mentioning.
The angled facet above makes more sense to me, but I have no data to support either theory. The roofs of the turrets were less armored, thinner, than the face plate, thus giving any justice to my opinion.

Cruisers were, obviously, less armored, but that aside...The Boise example would lead me to believe that a point blank, essentially, shot should do less damage, based upon the fact that the angle of shell entry would be considerably less than a high angle shot.

Bgile
Senior Member
Posts: 3658
Joined: Wed Mar 09, 2005 7:33 pm
Location: Portland, OR, USA

Post by Bgile » Thu Jun 15, 2006 8:50 pm

nwhdarkwolf wrote:
Tiornu wrote:The larger gun port is a inescapable result of the more vertical faceplates. For mounts with only low elevation, it might not make much of a difference. For a gun with 45deg elevation, I wonder if the smallest gunport would be for a faceplate mounted at 22.5deg.
That, certainly, makes sense to me. You might be able to get away with less.

I'm not convinced that the US face angle was wrong, does anyone have any proof of this?

Most hits on Battleships weren't on the faceplates of turrets, even though most of the turrets were armored as such. I'm in the process of reading Whitney's Encyclopedia on WWII Battleships. Even though I am only 1/4 of the way through, he does mention faceplate armor being very thick, but I have yet to see a hit of this type.
I believe the British report of the sinking of Bismarck mentions a hit from Rodney which penetrated the front of one of Bismarck's forward turrets and blew the back plate of the turret overboard.

Tiornu
Supporter
Posts: 1222
Joined: Mon Oct 25, 2004 6:13 am
Location: Ex Utero

Post by Tiornu » Thu Jun 15, 2006 11:27 pm

I've looked very closely at Boise's experience as it gives us the ONLY examples of Japanese AP shells hitting face-hardened armor, apart from the debatable hit on SoDak's barbette the follwoing November.
Three 8in shells hit Boise's armor. All failed. I think there are two factors that limit the value of these examples as a basis for understanding other shell hits. First, the 8in Type 91 shell differed from the battleship-caliber models in not having a true AP cap; instead it had only a "cap head" which, apart from being redundant, gave greatly inferior performance against face-hardened armor. (No Japanese cruisers had face-hardened armor. No American cruisers had face-hardened armor until the Brooklyn class was under construction; Boise was one of the first--lucky for her.) Second, the Japanese were still using an explosive that was significantly more sensitive than TNT. The hit to the faceplate merely left the imprint of its cap head on the armor, yet it exploded powerfully, causing extensive fragment damage. A hit to Boise's belt acted in a similar way. I think both those hits exploded prematurely, triggered by the impact without waiting for the fuzes to do their job.

User avatar
nwhdarkwolf
Member
Posts: 55
Joined: Fri Jun 02, 2006 4:42 pm
Location: Appleton, USA

Post by nwhdarkwolf » Fri Jun 16, 2006 12:49 pm

Bgile, yes...I understand that. I'm trying to figure out where that shell would have entered the turrett. I have a hard time believing that it was faceplate shot. I have an easier time, based upon the relative thinness of the roof armor, accepting the fact that the shell entered through the roof.

Tiornu, That makes sense. I would tend to believe, based upon what you have said, that the fuse was intended to work against lesser armored targets.

User avatar
tommy303
Senior Member
Posts: 1528
Joined: Mon Oct 18, 2004 4:19 pm
Location: Arizona
Contact:

Post by tommy303 » Fri Jun 16, 2006 5:27 pm

The fuze would work against any armour thickness and in any AP or SAP type shell so long as the shell did its part. The problem was not the fuze detonating the shell early, but the explosive undergoing concussive detonation. I believe the Japanese used TNA (trinitroanisol) as an explosive instead of the less sensitive TNT(Trinitrotoluol). This could and sometimes did detonate on impact before the fuze had time to work, particularly if poorly manufactured.

Their shoulders held the sky suspended;
They stood and Earth's foundations stay;
What God abandoned these defended;
And saved the sum of things for pay.

Tiornu
Supporter
Posts: 1222
Joined: Mon Oct 25, 2004 6:13 am
Location: Ex Utero

Post by Tiornu » Fri Jun 16, 2006 8:05 pm

The Japanese were reluctant to give up their picric acid, but the obvious oversensitivity finally forced them into it. TNA was a slight improvement. To prevent prematures, the Japanese inserted a very large cushion around the burster. The cavity could have accommodated something like a 2.5% charge, but the cushion reduced it to about 1.5%. They would have done better to accept the less powerful TNT. This would have given more reliable performance, while actually increasing the power of the exposive since they could have reduced the cushioning.

Bgile
Senior Member
Posts: 3658
Joined: Wed Mar 09, 2005 7:33 pm
Location: Portland, OR, USA

Post by Bgile » Fri Jun 16, 2006 10:54 pm

nwhdarkwolf wrote:Bgile, yes...I understand that. I'm trying to figure out where that shell would have entered the turrett. I have a hard time believing that it was faceplate shot. I have an easier time, based upon the relative thinness of the roof armor, accepting the fact that the shell entered through the roof.

Tiornu, That makes sense. I would tend to believe, based upon what you have said, that the fuse was intended to work against lesser armored targets.
Why do you have a hard time believing it? According to navweaps, Rodney can penetrate 14" of armor at about 15k yds. The impact would be straight on, since the turret was pointed at Rodney. The 5" turret top can't be penetrated until about 30k yds, so that's unlikely.

It would be nice to be able to examine the turrets.

Tiornu
Supporter
Posts: 1222
Joined: Mon Oct 25, 2004 6:13 am
Location: Ex Utero

Post by Tiornu » Fri Jun 16, 2006 11:29 pm

The angled facet above the faceplate, which I believe is the surface nwhdarkwolf refers to, is 180mm, which makes it vulnerable to EVERY battleship gun at ALL ranges. I think the best way to guess at the initial point of impact would be to find the possible paths from front to back that don't hit any heavy intervening material.

Bgile
Senior Member
Posts: 3658
Joined: Wed Mar 09, 2005 7:33 pm
Location: Portland, OR, USA

Post by Bgile » Sat Jun 17, 2006 12:54 am

Tiornu wrote:The angled facet above the faceplate, which I believe is the surface nwhdarkwolf refers to, is 180mm, which makes it vulnerable to EVERY battleship gun at ALL ranges. I think the best way to guess at the initial point of impact would be to find the possible paths from front to back that don't hit any heavy intervening material.
Thinking of it that way, it seems to me that if a shell penetrated the 14" faceplate it would be likely to hit the interior of the barbette and not the turret backplate. Maybe it is likely that that shell did hit the slope.

User avatar
tommy303
Senior Member
Posts: 1528
Joined: Mon Oct 18, 2004 4:19 pm
Location: Arizona
Contact:

Post by tommy303 » Sat Jun 17, 2006 2:04 am

I could be completely wrong or misinterpreting the gist of the thread, but it seems to me we are talking about two different hits--the hit at 0902 which initially put Bruno out of action whilst on a forward bearing, and a subsequent hit which caused the rear of the gun house armour to be blown off at 0940. Photographic evidence shows the top edge of the barbette was hit and holed by a shell which possibly jammed the turret on a bearing pointing towards the port bow. A hit through the nearly vertical face plate of the turret would have a difficult time finding its way to the rear of the gun house, there was considerable machinery in the way not to mention the two guns themselves. However, a subsequent shell through the side of the turret could have reached the rear of the turret and burst in the ready use shell stowage behind the loading platform and caused a sympathetic detonation of the shells there. This could easily have blown off the rear of the gunhouse armour. The hit through the thinner side armour could have come from either KGV or Rodney.

Their shoulders held the sky suspended;
They stood and Earth's foundations stay;
What God abandoned these defended;
And saved the sum of things for pay.

User avatar
nwhdarkwolf
Member
Posts: 55
Joined: Fri Jun 02, 2006 4:42 pm
Location: Appleton, USA

Post by nwhdarkwolf » Wed Jun 21, 2006 12:40 pm

The angled portion is much more believable.

My thinking is that unless the angle of impact were, relatively, flat, a shell would have had a hard time blowing out back of the turret. Whereas, a hit closer to the roof, at any trajectory, would have had much more of a chance of penetraiting a point in the turret where it could have done that amount of damage.

I would like to see the turret myself. I think, with modern forensics being what they are, we could figure out the exact point of impact and detenation.

User avatar
nwhdarkwolf
Member
Posts: 55
Joined: Fri Jun 02, 2006 4:42 pm
Location: Appleton, USA

Post by nwhdarkwolf » Wed Jun 21, 2006 3:01 pm

http://www.navweaps.com/index_nathan/metalprp2002.htm

http://www.navweaps.com/index_nathan/Hstfrmla.htm

Here's something that I am reading, but hardly understanding. So, I post it here so that someone might make sense of it. LOL

I'm not a Math guy, more of an artist type actually. :stubborn:

User avatar
tommy303
Senior Member
Posts: 1528
Joined: Mon Oct 18, 2004 4:19 pm
Location: Arizona
Contact:

Post by tommy303 » Wed Jun 21, 2006 7:12 pm

I would like to see the turret myself. I think, with modern forensics being what they are, we could figure out the exact point of impact and detenation.
Unfortunately the main battery turrets are all upside down in the mud and impacts against the armour are pretty much obscurred.

Their shoulders held the sky suspended;
They stood and Earth's foundations stay;
What God abandoned these defended;
And saved the sum of things for pay.

Post Reply