So, in the last part of the series, we completed the description of the armament of battleships of the "Pennsylvania - it's time to move on."
It would seem that it is a pleasure to describe the armor protection system of American standard battleships, because, unlike their European "counterparts", it should be much simpler and understandable. It is all the more strange that the author of this article probably had the greatest number of questions regarding the booking of battleships of the "Pennsylvania" type. the available information is very contradictory.
Usually, the story about the booking system of American battleships is preceded by the following explanations. US admirals saw Japan as their main adversary, building a very powerful battleship with which the US Navy was to meet in the tropical Pacific Ocean, which is characterized by excellent visibility.
From this, American naval thought drew several fairly obvious conclusions. The battles will take place at distances, until now considered huge, and it will not work to bombard enemy ships with a hail of high-explosive shells in the manner and likeness of what the Japanese Imperial Navy did in Tsushima: no fire control system will be able to provide the required number of hits. If so, preference should be given to the armor-piercing shells of heavy weapons, capable, with a successful hit, of causing decisive damage to an armored target. The Americans believed that the Japanese saw the situation in exactly the same way as they did, and the "Pacific Armageddon" would be reduced to the battle of battleships, showering each other with armor-piercing shells from a distance of 8-9 miles, and maybe more. For protection in such a battle, the all-or-nothing booking scheme was best suited, which made it possible to protect vehicles, boilers and main battery guns with the strongest armor possible. Everything else was worth not booking at all so that the ship had a good chance to "pass through" an enemy shell without causing it to detonate. Indeed, a relatively "tight" fuse of an armor-piercing projectile could not be charged if the latter, having passed from side to side, did not meet armor plates on its way, broke through only a few steel bulkheads.
Accordingly, in the perception of many, the armor protection of American battleships looks like a kind of rectangular box of powerful armor plates, covered from above with a thick armor deck, and leaving the ends unarmored.
But in reality this is not so: if only because the protection of the hull of the battleships of the Oklahoma and Pennsylvania type consisted not of one box, but of two. But first things first.
The backbone of the defense of the Pennsylvania-class battleships was a very long citadel. According to A. V. Mandel and V. V. Skoptsov, the length of the Pennsylvania main armor belt was 125 m., According to the calculations of the author of this article, even slightly longer - 130, 46 m. It began long before the barbette of the bow tower of the main caliber, leaving a little more than 24 meters of the bow end unprotected, and extended much further the edges of the barbet of the 4th tower. Here it is worth noting one important feature of American battleships: their creators considered it necessary to protect the citadel not only machines, boilers and powder magazines for the main caliber guns (as we already know, the Americans kept the main supply of shells in barbets and towers), but also the premises of underwater torpedo tubes. On battleships of the "Oklahoma" type, the project provided for 4 traverse torpedo tubes, they were placed immediately in front of the barbet of the 1st tower of the main caliber and after the barbet of the 4th tower, adjoining them closely. That is why the citadel of "Oklahoma" and "went" behind the barbets of these towers in the stern and in the bow. As for the battleships of the "Pennsylvania" class, it was decided on these ships to abandon the aft pair of torpedo tubes, leaving only the bow, but the citadel was not shortened.
I must say that the citadel of the American battleships had a very long length: taking into account the fact that the length of the "Pennsylvania" at the waterline was 182.9 m, the main armor belt protected 71.3% (68.3%, if relative to the length of the armor belt A. V. Mandel and V. V. Skoptsov were right) the length of the ship!
In addition to the outstanding length, the armor belt of the Pennsylvania-class battleships also had a considerable height: it consisted of a single row of armor plates with a height of 5,337 mm. At the same time, the thickness from the upper edge, and over 3 359 mm downward was 343 mm, and over the next 1 978 mm, it evenly decreased from 343 to 203 mm. Armor plates were located "cut" to the skin of the ship, so from the outside throughout the entire 5,337 mm, the battleship's armor looked monolithic and smooth. The upper edge of the armor plates was at the level of the second deck, and the lower one dropped below the third.
With a normal displacement of the battleship, its armor belt towered above the water by 2,647 mm. Thus, from the constructive waterline downward for 712 mm, the armor belt retained a thickness of 343 mm, and then, over 1 978 mm, it gradually thinned to 203 mm, and in total, the board was protected by 2 690 mm under water. In other words, the Americans positioned the armor belt so that it protected the side about 2, 65 m above and below the waterline. I must say that on the "Arizona" there was a slight difference: usually the Americans laid the armor plates on a teak lining, and they did the same on the "Pennsylvania", but for the "Arizona" they used cement for the same purpose.
Unfortunately, the armor belt within the citadel is hardly the only part of the armor protection of the hull of battleships of the "Pennsylvania" type, the description of which is almost completely the same in all sources. But about everything else, there are discrepancies, and, quite often, very significant.
Analyzing and comparing data from various sources on battleships of the type "Oklahoma" and "Pennsylvania", the author of this article came to the conclusion that, most likely, the most accurate description of the battleship booking system was given by V. Chausov in his monograph "Victims of Pearl Harbor - Battleships "Oklahoma", "Nevada", "Arizona" and "Pennsylvania" ", especially since this book was written later than the others: for example, the work of A. V. Mandel and V. V. Skoptsov was published in 2004, V. Chausov - in 2012. Accordingly, in the future we will give a description of the reservation of battleships of the "Pennsylvania" type specifically according to V. Chausov, and we will note the discrepancies only in cases where the latter are of an extremely significant nature.
Throughout the citadel's armor belt, the main armor deck rested on its upper edge, as if with a cover from above covering the hull space protected by the armor belt. The main armored deck was at the level (and was) the second deck of the battleship, but the data on its thickness vary significantly.
The canonical version is considered that it consisted of two layers of STS armor steel 38.1 mm thick each (76.2 mm in total), laid on a 12.7 mm substrate of ordinary shipbuilding steel. Formally, this allows us to consider the thickness of the main armor deck of battleships of the "Pennsylvania" type as 88.9 mm, but nevertheless it should be understood that its real armor resistance was still lower, since the "three-layer pie" contained the inclusion of ordinary, non-armored steel, and two layers 38.1mm armor plates were not equivalent to monolithic armor.
However, according to V. Chausov, the main armor deck of the Pennsylvania-class battleships was noticeably thinner, because each layer of STS steel was not 38.1 mm thick, but only 31.1 mm thick, and the steel substrate was also thinner - not 12.7, but only 12.5 mm. Accordingly, the total thickness of the battleship's upper deck was not 88.9 mm, but only 74.7 mm, and everything that we said above about its armor resistance naturally remains in effect.
One interdeck space below the main armored deck (in this case it was about 2.3 m) was the third deck, which had bevels connecting to the lower edge of the armored belt. Within the citadel, she had anti-fragmentation armor, but, again, the data on it differ. According to the classic version, it consisted of 12.7 mm of shipbuilding steel, on which 25.4 mm armor plates were laid in the horizontal part, and 38.1 mm on the bevels. Thus, the total thickness of the anti-splinter deck in the horizontal part was 38, 1 mm, and on the bevels - 50, 8 mm. But, according to V. Chausov, its thickness was 37.4 mm in the horizontal part (24.9 mm STS and 12.5 mm of shipbuilding steel) and 49.8 mm on the bevels (37.3 mm STS and 12.5 mm shipbuilding steel).
The bow traverse consisted of three rows of armor plates. In height, it started from the second deck, that is, its upper edge was flush with the upper edges of the armor belt plates, but the lower edge dropped about 2 meters below the armor belt. Thus, the total height of the bow traverse reached 7, 1 - 7, 3 m or so. The first and second tier consisted of armor plates 330 mm thick, the third - only 203 mm. Thus, up to the waterline and, approximately, 2, 2 m below its traverses had a thickness of 330 mm, and below - 203 mm.
But the aft traverse was significantly shorter and reached only the third deck, having a little more than 2.3 m in height. The fact is that outside the citadel, the third deck of the battleship "lost" bevels and was strictly horizontal - well, the traverse extended to it.
However, one should not think that there was some kind of "window" in the protection of the battleship. Not at all - directly to the "box" of the citadel in the stern of the ship was adjoined by the second "box", designed to protect the steering of the ship.
It looked like this. Another armor belt stretched from the main armor belt to the stern for about 22 m. Its main differences from the citadel's armor belt were lower, by about 2, 3 m, height - while the upper edge of the citadel's armor plates was at the level of the 2nd deck, the armor belt that continued to the stern rose only up to the horizontal section of the 3rd deck. Thus, this armored belt adjacent to the citadel protruded only 0.31 m above the waterline, but its lower edge was at the level of the citadel's armor plates.
The height of this armor belt was about 3 m, while during the first meter (to be precise 1,022 mm) its thickness was 330 mm, and then, at the same level where the "break" of the main 343-mm belt began, the thickness of the second armor belt gradually decreased from 330 mm to 203 mm. Thus, along the lower edge, both of them, and the citadel's armor belt, and the second aft armor belt had 203 mm, and, as we already said, this edge was at the same level at both belts.
This armor belt, covering the steering, was closed from the stern with another traverse, which consisted of absolutely the same plates as the armor belt itself - they also had about 3 m in height, also had 330 mm thickness for about one meter, and then gradually thinned to 203 mm and were located at the same level. On the upper edge of the 330-mm belts and the traverse, there was a third deck, which here (unlike the citadel) did not have bevels. But it was very heavily armored: 112 mm of STS armor steel on 43.6 mm "substrate" of ordinary shipbuilding steel gave a total of 155.6 mm protection.
I must say that A. V. Mandel and V. V. Skoptsov, it is argued that in the stern the third armored deck had bevels and was better protected than within the citadel, and the above horizontal protection was "attached" to it in addition: but, apparently, this is a mistake that is not confirmed by any of the known to the author of this article, the protection schemes for battleships of the "Pennsylvania" class. Including those given by A. V. Mandel and V. V. Skoptsov.
In addition to the sides and decks, the hull of the Pennsylvania-class battleships had very powerful chimney protection. On battleships of this type, there was one pipe and chimneys to it from the main armor to the forecastle deck, that is, over two interdeck spaces (over 4.5 m) they were protected by an oval casing 330 mm thick. On the second ship of the series, "Arizona", the casing design was changed - it had a variable thickness from 229 mm in the center plane of the ship, where the casing was maximally covered by other hull structures and barbets of the main caliber turrets, which made a direct hit into it was considered unlikely up to 305 mm closer to the traverse and even 381 mm directly in the area parallel to the side of the ship. Below the main armored deck, between it and the splinterproof deck, the chimneys were covered on four sides with armor plates 31.1 mm thick.
We have already described the protection of artillery before, but we will repeat so that the respected reader does not have the need to look for data on different articles. The main caliber turrets had very powerful defense. The thickness of the frontal plate was 457 mm, the side plates closer to the frontal plate were 254 mm, then 229 mm, the stern plate was 229 mm. The roof was protected by 127 mm armor, the floor of the tower was 50.8 mm. The barbets had 330 mm along the entire length to the main armored deck, and between it and the anti-splinter, where the sides were protected by 343 mm of armor - 114 mm, below the splinter-barbets were not armored. The anti-mine caliber had no armor protection.
The conning tower had a base of STS armor steel 31.1 mm thick, on top of which 406 mm armor plates were installed, that is, the total wall thickness reached 437.1 mm. The roof of the conning tower was covered with two layers of armor protection 102 mm thick each, that is, 204 mm overall thickness, floor - 76, 2 mm. Interestingly, the Pennsylvania, which was built as a flagship, had a two-tiered conning tower, while the Arizona had a single-tiered conning tower.
A communication pipe with a diameter of one and a half meters ran down from the conning tower - up to the main armored deck, the thickness of its armor was 406 mm, from the main deck to the anti-splinter deck - 152 mm.
We will make a detailed comparison of the armor protection of battleships of the Pennsylvania type with European battleships later, but for now we will note two vulnerabilities of American ships: one obvious, and the other not very.
The obvious vulnerability lies in the vicious idea of storing shells in the barbets and towers of battleships. Whatever one may say, but only the frontal plate of the tower had an ultimatum-powerful defense - 457 mm of armor was really almost impossible to master at reasonable distances. But the side walls of the towers with their 229-254 mm, and even the 330 mm barbette, did not provide such protection, and could easily miss an enemy armor-piercing projectile even in its entirety. This was fraught with detonation of more than two hundred shells placed directly in the turret and on the "shell tier" of the 330 mm barbet.
Unobvious vulnerability. We did not mention the 127 mm roof of the Pennsylvania and Arizona turrets, but it also could not protect the main battery from 381 mm shells. The British themselves, installing a similar thickness of protection on the roofs of the towers "Hood", had some doubts about its sufficiency. And so they made the appropriate tests with the latest "greenboys". Two 343 mm rounds of 127 mm did not penetrate the armor, but the 381 mm armor-piercing round "passed" the turret roof without any problems, leaving a smooth hole in it with the edges bent inward. Based on the results of the tests, it was decided that Admiral Beatty (with whose doubts this story began) was absolutely right in recommending that the thickness of the roof of the towers be increased to 152 mm. Since orders had already been placed on the Hood towers, and they were in the manufacturing process, it was decided not to change anything on them, but to provide 152 mm turret roofs for three serial ships, which were supposed to be built after him, but, as you know, Hood”Became the only representative of the series.
But the fact is that the English towers for "Hood", in contrast to the installations of the previous types, had an almost horizontal roof, it only had a slight inclination to the side walls. And if the British 381-mm projectile overcame it without any problems … then in the same way, without any difficulties, it would have pierced the main armored deck of battleships such as "Oklahoma" or "Pennsylvania".
In other words, usually American battleships are perceived as ships with a very heavily defended citadel, which, among other things, had a great advantage over the battleships of other countries in horizontal protection. But in practice, an armored deck with a thickness of at least 74, 7 mm (to which, following Chausov, the author of this article is inclined), even though the canonical 88, 9 mm, and even heterogeneous, and even including a layer of ordinary steel, did not represent much then a serious protection against the impact of heavy projectiles with a caliber of 380-381 mm. And after its penetration, the enemy projectile would be separated from the engine rooms, boiler rooms, cellars with powder supplies and torpedoes, only one inch armor on a half-inch steel substrate, which was not enough even to protect against a fragment that exploded in the interdeck space of the projectile.
It was quite peculiar and unlike the PTZ scheme used on battleships of other countries. "Pennsylvania" and "Arizona" had a double bottom, reaching the lower edge of the armor belt. Behind it were empty compartments, along the citadel, ending in a very powerful anti-torpedo bulkhead, which consisted of two layers of STS armor steel of 37, 35 mm each, that is, the total thickness of the bulkhead was 74, 7 mm! With its upper edge, this boone bulkhead reached the bevel of the lower armored deck, and the lower - the second bottom. Behind it there was still an empty space, and, finally, the last filtration bulkhead with a thickness of 6, 8 mm. According to the logic of the creators, the torpedo that got into the side of the ship wasted energy on a break in the outer skin and double bottom, then the gases freely expanded in empty space, significantly losing their penetrating ability, and the fragments and residual energy of the explosion were delayed by the main protection, which was a thick armor bulkhead of the PTZ. If it also turned out to be partially damaged and a leak occurred, then its consequences should have been localized by the filtration bulkhead.
It is interesting that the empty spaces of the PTZ, the total width of which was 3.58 m, should not have been filled with anything. The water and fuel storages were located directly on the second bottom inside the space protected by the PTZ, and thus, in fact, machines, boilers and cellars from below were protected not even by a double, but by a triple bottom, the "third echelon" of which was precisely the above-mentioned compartments.
It should also be mentioned that the battleship was divided into 23 watertight compartments, with the watertight bulkheads extending to the armored deck, but it is unclear which one. Most likely, we are still talking about a splinterproof deck.
This was a big step forward from the battleships of the previous series. Battleships of the "Nevada" type were two-shaft, and on the "Oklahoma" the Americans managed to heap a steam engine instead of turbines. On ships of the "Pennsylvania" type, finally, the final transition to turbines took place, in addition, both battleships of this type had a four-shaft power plant.
Nevertheless, the desire to put different EIs on ships of the same series was still maintained by the Americans. The boilers on the Pennsylvania and Arizona were identical: 12 Babcock & Wilcox oil boilers were installed on each battleship, but Curtis turbines were installed on Pennsylvania, and Parsons on Arizona. The latter included, in addition to a set of high-pressure turbines for rotating internal shafts and low-external ones, also cruising turbines, thanks to which it was supposed to achieve a hefty gain in range. Alas, these hopes did not come true, since the effect turned out to be much lower than planned, and these turbines (Parsons) themselves turned out to be unsuccessful, and almost the most unsuccessful in the American fleet, since the units turned out to be very capricious and unreliable.
According to the project, battleships of the "Pennsylvania" type were supposed to develop 21 knots with a power of 31,500 hp mechanisms, which was supposed to provide a speed of 21 knots (unfortunately, it is unclear whether we are talking about natural or forced thrust). On tests of "Pennsylvania" it was not possible to reach the contractual power, and it was only 29 366 hp, but the speed, nevertheless, was 21.05 knots. Subsequently, during operation, both battleships easily reached the 31,500 h.p. and even surpassed them: for example, the maximum recorded capacity of the Arizona power plant was 34,000 hp. Of course, this could hardly have greatly increased the speed above 21 knots. The outlines of battleships of the "Pennsylvania" class were distinguished by high completeness, were, apparently, optimized for the above speed and therefore required a large increase in power to increase it.
The normal oil reserve was 1,547 tons, the full one - 2,322 tons. It was assumed that with full reserves the battleships would be able to pass 8,000 miles at a 10-knot speed. In reality, "Pennsylvania" could take 2,305 tons, and, according to calculations made on the basis of actual fuel consumption, the battleship was able to cover 6,070 miles at 12 knots (for some reason, the calculation for a speed of 10 knots is not given). As for the "Arizona", when using cruising turbines at 10 knots, it was able to cover only 6,950 miles and in general we can say that the battleships of the "Pennsylvania" type were somewhat short of their cruising range.
It is noteworthy that the Americans have gone the farthest along the path of "oiling" their fleet. The Germans continued to consider coal as their main fuel, the British as a backup, but only in the United States they abandoned it altogether. However, one should understand the conditions in which this was done. Everybody understood the benefits of oil heating of boilers. But Germany did not have oil deposits on its territory, and could not count on replenishing its reserves in the event of a war with England and a declaration of a blockade. England, although it could count on the delivery of oil by sea, nevertheless, like Germany, did not have oil fields in the metropolis and in the event of any force majeure circumstances, it risked immobilizing its fleet. And only the United States had a sufficient number of fields so as not to fear the depletion of oil reserves at all - and therefore did not risk anything at all, transferring the fleet to oil heating.
This concludes the description of the Pennsylvania-class battleships. The most interesting thing is ahead - a comparison of the three selected "champions" among the "standard" battleships of England, Germany and America.