被俾斯麦完爆的偷工减料纳尔逊镇楼

底图：南达，来自warship international第43辑3期
按Freeman的说法，南达级在战争中主装平均仅露出水平6尺。
从左到右：黎塞留、俾斯麦

上图中南达的吃水是加强放空之后的，而黎塞留和KGV是加强放空前的原装吃水情况。改造之后吃水都增加了0.5米，相应的水下装甲带高度也要提高，实际的水下弹防护要更深一些。

水下弹防护分为三种情况：


1-御敌于TDS之外，这是上等。
2-御敌于核心舱之外，这是中等。
3-水下裸奔，这是下等。



防御过程一般是渐进的。


KGV主装延伸极大，如果来袭炮弹相对高一些，是足以御敌于TDS之外的，这样不进水漏油，不牺牲储备浮力，效果是最好的。如果来袭炮弹很低，像俾斯麦打POW那一发，由于在水中前进距离远，动能衰减，可以被防雷隔舱挡住，也就实现了御敌于核心舱之外。KGV的水下防护是相对理想的。


黎塞留的情况比较特殊。内置倾斜主装，虽然绝对高度较大（3.5米），但弹道高度比起KGV是较低的，和2.2米的俾斯麦的差距也相对有限。他的TDS设计特殊，即便侵入TDS外层也不会进水漏油，因此如果打到主装下缘，也不过是穿过泡沫橡胶弹出去了，防御效果也是较好的。但如果来袭炮弹较低，主装拦不住，进入了TDS，由于最后的隔板较薄，是存在着一定危险的。但TDS纵深较大，很可能炸在外面。


俾斯麦垂直外置，弹道高度相对来说是不小的，但绝对高度毕竟有限。如果炮弹较高，御敌于TDS之外也是可能的，效果也是较好的。但如果炮弹较低的打进来，由于TDS设计不合理，炸在液舱里也是比较危险的。


南达的内置倾斜装甲带，要起作用就必然要让炮弹砸进TDS，进水漏油避免不了。相对好一些的是对核心舱的保护。但如果炮弹位置较深，穿透下沿变得很薄的装甲进入核心舱，也是有一定危险的。从弹道高度和TDS布局来看，他对核心舱的水下保护和KGV差不多是同等的。但KGV可以避免进水漏油，这点上南达是比较差的。

顺便吐槽一下鸡贼的美国人。


看南达的吨位注水是怎么来的？
一，内置装甲，33米的最大舰宽，最大甲板宽度也就30米。
二，皮带装甲。Class A高度不到10尺，约3米，下面全是Class B来凑。


代价：
需要额外的设计来补足储备浮力和燃油的可能损失。
同等深度，别国表面硬化装甲的水下防护效果当然强于他家均值甲。对亏美国船个个超重超载，CB压在水下较深，这才没构成明显的防护弱点。

——但衣阿华超重过分，满载主装干舷仅剩2尺，简直比沙恩还要感人

看看文盲现眼是怎么现的


“御敌于TDS之外”是指，对水中弹的防护不以牺牲TDS隔舱中的燃油和储备浮力为前提。上面的论述已经说的很清楚了很明确了。
楼上这莫名其妙来指控我“靠着那点船壳想挡住水中弹”，简直不知道小学修没修过语文。

南达衣阿华等船的水中弹问题：


1-按照美国海军联合委员会提出的设计要求，北卡级的主装在战时应露出水面6尺以上。将此推到南达和衣阿华身上作为设计的预计指标，是很合理的。


2-南达和衣阿华的主装仅高10尺，在这种情况下，水下仅高4尺，且内置于舰壳内两米以上。也就是说，在设计预想的作战情况下，其CA主装的防御面积是连纳尔逊都比不上的。


3-比纳尔逊好是下面接了CB的板子。但对比同等弹道高度下的满载状态的KGV，虽然有倾斜加成，还是存在明显不足的，尤其是逐渐削弱的部分。

搞了半天一堆人拜神教是因为有人说CB装甲下沿作用不逊于CA。


首先，他原文里只提到了30度入射角的测试，至于是30度以内优于还是30度以外优于是没明说的。
其次，目前现有的Okun对这个问题的阐释，是相当清楚的：



http://www.zhanliejian.com/navweaps/metalprpsept2009.htm


Armor still manufactured by the same three steel makers (Carnegie was now Carnegie-Illinois Steel Corp.), but now all armor of a given type was made by the same manufacturer on a given single ship, with no more mix-and-match. Significantly improved steel, but only a slight improvement in ballistic protection, since this form of armor had always had plenty of toughness (CLASS "A" armor (see below) benefitted much more from these improvements). The use of homogeneous Class "B" armor in turret faces (either as a single thick plate or as a not-quite-so-thick plate laminated to a 2-2.5" (5.08-6.35cm) Class "B" support plate) was an extension of the results of the 1921 tests of 13" (33cm) STS (see above), where the even more indestructible World War II U.S. armor-piercing projectiles made the situation even worse for Class "A" armor compared to Class "B" armor. (It turned out that most foreign projectiles were not nearly as good as U.S. designs at oblique impact, but this was not known at the time and might not have made enough of a difference in any event to alter the turret face plate material.) The thinner face plates used on U.S. cruiser turrets had less of a resistance difference between Class "A" and "B" against the smaller projectiles used against them and much more chance of being hit by uncapped projectiles that might be able to penetrate if the hard face was not there to shatter them, so Class "A" armor was retained for turret faces when U.S. Navy cruisers switched to Class "A" armor for new ships circa 1937. Also, Class "A" armor was retained on the sides and rear of the all turrets and on the cylindrical barbettes under the turrets, where the armor was somewhat thinner--but still thicker than in most non-US Navy World War II battleships--and was much more likely to be hit at a medium-to-high obliquity (30o and up) where the face could destroy even a high-quality projectile, though at over about 55o obliquity a ductile Class "B" armor plate would again be desirable because a ricocheting projectile might punch out a very dangerous, cork-like armor plug from a Class "A" plate, which rarely happens with good Class "B" armor, especially at high obliquity. Post-1930 U.S. warship armored conning towers used Class "B" armor so that they could be welded, riveted, and bolted into the surrounding superstructure to save weight--the rigid face of face-hardened armor could not be welded or drilled without weakening it or allowing it to tear itself free upon any substantial impact shock. As a result, U.S. Class "B" armor on new battleships was the thickest homogeneous Krupp-type armor ever used. The Midvale Company used 0.2-0.3% by weight Molybdenum in this armor under 15" (38.1cm) thick and Bethlehem Steel Corp. used 0.18-0.2% Carbon (the lowest amount of Carbon in any Krupp-type armor, to my knowledge), 0.3-0.4% Molybdenum, and 0.1-0.14% Vanadium (the sole use of this element in any U.S. Krupp-type armor; to my knowledge, only Terni of Italy also used it extensively, but only in its AOD and POV homogeneous armors (see above) to any significant amount) in plates under 7&qout; (17.78cm) thick.


ssvcrtfi79网友的翻译：


二战时期美国海军标准Class B装甲
用途：炮塔顶部装甲。5英寸以下的炮座装甲和指挥仪装甲。指挥塔装甲。主炮正面装甲16英寸及以上厚度
生产公司：三大制造商
时间：1933-1955
该装甲仍然有这三家钢铁公司制造（卡耐基已改称卡耐基---伊利诺斯钢铁公司）。但是现在这三家公司制造的指定类型的装甲都规定用于特定的单艘战舰上，结束了以前那种混乱的装甲搭配。这种装甲是在原先的基础上做了较大的改进，但在防弹效果上的进步并不是很大。这种装甲始终保持着非常大的韧性。他被用于炮塔表面的装甲（单块厚的的装甲板或者不是很厚的层压到2英寸的支撑板），这个用法是由于1921年13英寸受到STS装甲板测试反馈的结果。二战时美国人使用的穿甲弹的弹头更加坚固，使得class a装甲在与class b装甲的对比中处境更糟糕（大部分国外设计的穿甲弹在倾斜击中装甲时远没有美国设计的穿甲弹好，在那时没有明显的证据表明改变炮塔面用钢材料会带来什么区别）。但是美国巡洋舰炮塔上薄的面板使用class a或class b在抵抗力方面差别不大，更何况偶尔被命中时如果穿甲弹弹头没有被击碎，那么来自穿甲弹的威力足够穿透装甲。所以当美国海军大约在1937年新造的巡洋舰转用class a装甲的时候，巡洋舰炮塔表面装甲也仍然保留使用class a装甲。【并且class a装甲被保留用在战列舰舷侧装甲和所有炮塔后部以及炮塔下面的圆筒形炮座。这些地方的装甲稍微有点薄，但是比二战中大部分战列舰的要厚。这些地方被命中时大都可能在从中到高的角度（30度以上），class a能破坏高质量的穿甲弹。当超过大约55度时延展性好的class b装甲恢复性就比较好的多了，因为弹飞中的炮弹威力的打击还是非常危险的。在高角度class b要比class a更好的充当软木塞堵塞似的装甲。所以1930年后美国海军战舰装甲指挥塔使用class b装甲。】在安装方面class b可以使用焊接、铆接、螺钉的方法安装在上层建筑，这样能节省重量。刚性的表面硬化装甲不能使用焊接或者钻孔只会弱化防护效果或者在任何打击下撕裂装甲。鉴于以上结果class b装甲在美国战列舰上使用了最厚的均质Krupp-type装甲。米德维尔公司生产的厚度15英寸以下class b装甲的钼含量达0.2%-0.3%，伯利恒钢铁公司生产的7英寸以下class b装甲的碳含量0.18%-0.2%（估计是Krupp-type装甲里面碳含量最低的）、钼含量0.3%-0.4%、钒含量0.1%-0.14%（所有美国Krupp-type装甲里唯一使用这一元素的。另外只有意大利Terni生产的装甲同样使用这一元素，但只在AOD 和 POV均质装甲上）。




另一篇文章：


The use was originally justified by the improved performance of US Navy late 1930 AP ammo that was essentially impervious to the hard face of Class "A" armor at low obliquity (near right-angles) impact. Thus the hard face, which was expensive to make and which caused some plate weakening due to its brittleness, lost all of its previous advantages (breaking up the shell so that the shell had a more difficult time penetrating the armor) when used in the turret face that, by necessity, was always pointing directly at the enemy and thus could expect near right-angles impacts at all times.
Turret side armor and barbette armor would usually be hit at a more oblique angle, usually circa 30-45 degrees or more, though the very center of the barbette could be hit at near right angles. Using face-hardened armor to destroy the shell was more effective in these areas.
However, when extremely high oblique impacts occurred (55 degrees or more), as on turret roofs and decks, face-hardened armor, due to its brittleness, was a very poor choice since it could break and throw pieces into the region behind it even if the shell glanced off. DUNKERQUE's face-hardened turret roof, designed to maximize resistance to AP bombs from aircraft, was hit by HOOD and is a perfect example of this problem.

一句话，30度或30多度可能是个临界点，小于30度，或者大于55度，都是CB占优。这是Okun的结论，而且和他举例的测试并不不矛盾。