15in Up Gunned Gneisenau v 1939 Modernized Renown

[dunmunro]

The 11" could also have defeated the thin armour, both belt and/or deck of the British battle cruisers at most battle ranges.

Renown's magazine protection is 4+1 inch in a single layer plus additional layers above. By keeping a 30 deg target angle, for example, Renown can achieve an immune zone down to about 14K yds.

[José M. Rico]

Here is the deck penetration of the German 38cm according to Gkdos100.

25,000 meters (27,340 yards) = 100 mm
26,000 meters (28,434 yards) = 105 mm

4 inches = 101 mm.

http://www.kbismarck.com/38cm.html

[Dave Saxton]

I come up with a reading closer to Thorsten's original estimate Jose. At 23km, the angle is about 22.5* and the velocity is just shy of 500. This gives ~100mm penetration. At 25km the angle is ~24* and the V is about 475 m/s. This gives about 105-110mm.

[Karl Heidenreich]

This is odd, really. If Bismarck did achieve to disintegrate HMS Hood, which was an improved battlecruiser over Renown and Repulse (much bigger too) at 14,5 km, how is it that now, those same guns need to be at 23 km plus of distance of Renown to perform the same feat? Renown lacks of the IZ against the theoretical 15" of Gneisenau (as with Bismarck) at the same distances. If we change Hood for Renown at DS (at the exact same circumstances) she will become a celestial body too. So, how is it that it cames now that we are having an argument that was solved by fact on May 24th, 1941`s morning?

[yellowtail3]

This is odd, really.

not all that odd

If Bismarck did achieve to disintegrate HMS Hood, which was an improved battlecruiser over Renown and Repulse (much bigger too) at 14,5 km....[./quote]well, I think she did from just a little further, didn't she?
[quote="Karl Heidenreich"...how is it that now, those same guns need to be at 23 km plus of distance of Renown to perform the same feat?

because of the diff between side and deck penetration - you've got to get out a ways for Bismarck's relatively flat shells to be effective on Renown's (or any other) deck. Some say it's more likely that Hood got it through the side, not the deck.

[Karl Heidenreich]

yellowtail3:

because of the diff between side and deck penetration - you've got to get out a ways for Bismarck's relatively flat shells to be effective on Renown's (or any other) deck. Some say it's more likely that Hood got it through the side, not the deck.

This means that, then, Renown`s belt was vulnerable too, so the IZ is inexistent against the 15" at close ranges, and, when the ranges increase the deck is the one that will be vulnerable.

[Dave Saxton]

The Renown's belt was only 230mm at the waterline. Although inclined 12* it can be penetrated at virtually any battle range by the German 38cm -until the terminal velocity drops to ~425 m/s. Which it never does. As Thorsten stated above, the thin, steeply angled, splinter slope behind the belt will not be of much good until the range is so great that there is little residual energy after penetrating the outer belt in this case.

Were not giving the Hood 4" effective deck protection are we? In the case of the Hood we are not talking about a homogenous material of comparitive quality to RHA. Also the arrangement and thickness of each protective plate in series is such that each plate is unlikely to to be very effective in terms of removing the cap from the shell, or by being able to consume significant energy.

[Thorsten Wahl]

Here are some official british Armour Efficiency drawsheets

http://picasaweb.google.com/urudofsky/A ... NelsonQE02#

http://www.admirals.org.uk/records/adm/ ... 1-9387.php

They offer another sight then the german material

Against own horizontal armor there is good agreement to the pentration data offered by
http://www.navweaps.com/
but any vertical protection seems very optimistic in every approach
Its my thinking that they know everything about own firepower and protection

[lwd]

A bit OT but ...

...But the USN proceeded with arming their 14" designed BBs with 16", using the escalator clause of the Treaties, but when doing so the overall defensive scheme become compromised. ..,

How does changeing the armament compromise the defensive scheme?

[lwd]

...Now, the HMS Hood had zero IZ against the German 15" and, for that same matter, neither would have the Renown, which makes your previous statement invalid. The 11" could also have defeated the thin armour, both belt and/or deck of the British battle cruisers at most battle ranges....

Zero immune zone does not mean that the deck could be "defeated at most battle ranges" indeed at the angles we are talking about above even hitting the deck is problematic. If the deck is hit there is a good chance the shell glances off and/or is destroyed due to exceeding the design limits. At those ranges belt hits are by far the more likely result.

[yellowtail3]

A bit OT but ...

...But the USN proceeded with arming their 14" designed BBs with 16", using the escalator clause of the Treaties, but when doing so the overall defensive scheme become compromised. ..,

How does changeing the armament compromise the defensive scheme?

it doesn't, of course. The North Carolinas were like a light-heavyweight boxer with a super-heavyweight punch; what's not to like? I'll tell you: fans of a heavyweight boxer with a mediocre punch.

[Kyler]

A bit OT but ...

...But the USN proceeded with arming their 14" designed BBs with 16", using the escalator clause of the Treaties, but when doing so the overall defensive scheme become compromised. ..,

How does changeing the armament compromise the defensive scheme?

it doesn't, of course. The North Carolinas were like a light-heavyweight boxer with a super-heavyweight punch; what's not to like? I'll tell you: fans of a heavyweight boxer with a mediocre punch.

Very true

I would rather have a lighter armored ship with big guns that could duel with anything, than and heavily armored ship with smaller guns that couldn't match smaller ships

[dunmunro]

Here are some official british Armour Efficiency drawsheets

http://picasaweb.google.com/urudofsky/A ... NelsonQE02#

http://www.admirals.org.uk/records/adm/ ... 1-9387.php

They offer another sight then the german material

Against own horizontal armor there is good agreement to the pentration data offered by
http://www.navweaps.com/
but any vertical protection seems very optimistic in every approach
Its my thinking that they know everything about own firepower and protection

Thanks for the 1st link, which I hadn't seen before. It shows the KGV magazine protection very clearly. It also shows that the 1.5" splinter protection was directly over and along the magazines rather than the shell rooms as shown in Allied Battleships. It also shows the SPS and SPS armoured bulkhead very clearly and it shows that it retains its full thickness over its full height, where Allied Battleships shows it reducing in thickness above the SPS V-L-V layers.

[Karl Heidenreich]

lwd:

How does changeing the armament compromise the defensive scheme?

You know how and has been discussed at lenght in other threads. However it is important to point out that 35,000 tons were, by the 1930ies, not an ideal displacement for a battleship. The British came to that conclusion when they built the Rodney Class vessels, with 16" guns.

If you are in a straight jacket and the greatest displacement to come with is 35 K tons, but other nations are not abiding that, then you are in a compromised situation. The USN came with two designs that were escalated: North Carolinas and South Dakotas. In order to design and built them with 16" guns, armor had to be sacrificied. Armor that maintains the ship safe when under attack. And that attack could came not only from 16" armed ships but from those with even a smaller caliber. In the case of North Carolina, she was designed to withstand up to 14" guns. South Dakota was the same. Bottom line, the 15" shells of Bismarck, if they hit the deck of any of those ships, would have come down into the vitals, hence the upper deck was very thin and unable to initiate fuzing, decapping or yaw enough to make them explode before penetrating the armoured deck. Of course, in order to avoid any discussion on this everybody get`s entagled in hypothetical arguments of RDFC and Super Heavies, anything in order not to analyse, even, this.
In the Bismarck and her Contemporaries thead I brought up no pretty photos but information from recognized authors as Friedman, as Raven and Roberts, Garzke and Dullin, Skulsky, Mullenheim Rechberg, etc. etc. that points very much in that direction (and others as the design mistake on South Dakota and Iowa of having internal sloped belts with a restricted beam). However, when this is brought the issue is deviated to other latitudes with the sole exception, granted, of boreatwork.

Good night.

[lwd]

lwd:

How does changeing the armament compromise the defensive scheme?

You know how and has been discussed at lenght in other threads.

It may have been discussed but I've never seen it stated so and it is obviously fallacious.

However it is important to point out that 35,000 tons were, by the 1930ies, not an ideal displacement for a battleship.

Important? I'd say irrelevant.

...The USN came with two designs that were escalated: North Carolinas and South Dakotas. In order to design and built them with 16" guns, armor had to be sacrificied.

What armor was sacraficed? My understanding was that the armor they were built with was what was planned. The only difference being the armament was upgraded.

Bottom line, the 15" shells of Bismarck, if they hit the deck of any of those ships, would have come down into the vitals,

Possibly and possibly not. Of course the opposite is also true. So what's the difference.