On the use of the 10-dm/45 gun model 1892 as the main caliber of Russian battleships
Some errors
В previous article I pointed out that the armored cruiser "Azuma" was protected by Krupp armor. In all honesty, I had serious doubts about this, but Russian-language sources talk specifically about Krupp, and I had no refuting data. Thanks to the respected Igor, writing under the nickname "27091965i", such data appeared - "Azuma" was protected by "Garvey" armor, apparently of improved quality. Thus, we can say that the only armored cruiser of Japan that could carry Krupp armor (and, most likely, did carry it) was "Yakumo".
My second mistake is that I completely forgot to point out an important nuance regarding the turret-like protection of the barbettes of the Fuji-class battleships. They were covered by comparatively light 152 mm armor, which, however, was positioned at a significant angle to the horizon. At close range, 12-inch shells would ricochet off such armor, but as it increased, the deviation from the normal would gradually decrease by the angle of incidence of the shell. Therefore, if in other cases the distances indicated in the tables should be interpreted as "the armor of this ship will be penetrated at this distance or less", then for turret-like protection a different interpretation would be correct - "the armor is penetrated at the specified distance or greater". That is, for example, if for the 12-inch/40 gun mod. 1895 indicates 10 cables, then the Fuji “tower” can be penetrated at any distance, up to a distance of 10 cables, and if you approach closer, there is a risk of ricochet.
"Ten-inch" main caliber
Of course, the 10-inch gun as the main caliber of domestic battleships in the 1890s looks extremely strange. It is well known that before the appearance of the 10-inch/45 gun model 1892, the Russian imperial fleet was not inclined to "smaller". In 1872, the construction of "Pyotr Velikiy" was started, which received 12-inch guns, and it was this caliber that became classic for our battleships. Since the early 80s of the XIX century, Russia was looking for the optimal type of armored ship for squadron combat, the projects were very different. There were "six-barreled" "Ekaterina II" for storming the Straits, there were Baltic battleships-rams of the "Emperor Alexander II" type, there was "Navarin", whose four pipes resembled an inverted stool, as well as relatively small battleships "Twelve Apostles" and "Sisoy Velikiy".
After a decade of searching in the Baltic, the Poltava-class squadron battleships and the Black Sea Tri Svyatitelya were laid down, which at that time could rightfully be considered, if not the strongest, then one of the strongest battleships in the world. And all of them carried 12-inch guns as their main caliber, which were constantly being improved: not even counting the guns of the Pyotr Velikiy, from the 12-inch/30 artillery system of 1877, capable of accelerating a 331,7 kg projectile to 570 m/s, to the 12-inch/40 gun of 1895, capable of giving the same projectile an initial velocity of 792 m/s.
And suddenly - an incomprehensible decision about unification with the land forces artillery and the move to a 10-inch caliber, which was justified by the army's requirement to retain the ability to manually load the gun. I didn't dig deep history creation of the 10-inch gun model 1892, but I can assume that the main leitmotif of its adoption into service was banal savings combined with the desire of the fleet to obtain battleships that, at the cost of a certain weakening of combat power, would receive relatively high speed and the ability to conduct cruising operations.
The economy, as it usually happens, led to the fact that the ten-inch guns did not work out from the start. As follows from the Journal of the Artillery Committee No. 401, Lieutenant Colonel Brink drew up two projects for a 10-inch gun 45 calibers long. In one project, the gun consisted of 5 layers, and the "elastic limit in the shell" was to be 2500 atmospheres. In the second project, the gun consisted of only 4 layers, and the corresponding elastic limit was to reach 3100 atmospheres. The MTK was satisfied with both options, leaving the final choice to the Artillery Committee of the Main Artillery Directorate. The latter, of course, chose the "four-layer" artillery system, because it was cheaper, and recommended that the fleet order it. As for the greater strength of steel required for a "four-layer" gun, AK GAU took this into account, but considered that the Obukhov plant was well equipped and would easily meet the required parameters. And if something went wrong, a solution was immediately proposed: drill out the casing and add a fifth layer.
The result is well known: the 10-dm/45 gun mod. 1892 was over-lightened, which required reducing the charge and muzzle velocity of the projectile. As a result, three coastal defense battleships and the Peresvet with the Oslyabya received guns capable of accelerating a 225,2 kg projectile only to 693 m/s, and only the Pobeda received heavier and more powerful guns capable of sending a projectile of the same weight into flight with an muzzle velocity of 777 m/s.
However, it cannot be said that interaction with land forces had only a negative impact on the fleet. In those years, our sailors were sure of the need to use lightweight shells, but the 10-inch/45 gun mod. 1892 received quite hefty shells for its caliber of 225,2 kg. But, perhaps, the most important difference from the 12-inch shells (in addition to the caliber, of course) was that the armor-piercing and high-explosive shells of domestic 10-inch/45 guns by the beginning of the Russo-Japanese War were equipped with pyroxylin, and not smokeless powder.
This led to the fact that in terms of explosive content, the Russian 10-inch high-explosive shells were more explosive than the 12-inch shells. It is reliably known that the 10-inch high explosive shell contained 16,39 pounds of pyroxylin (apparently, we are talking about wet pyroxylin), and the 12-inch shell only 14,62 pounds of smokeless powder, which, when converted to the metric system, gives 6 g and 712 g, respectively. However, this advantage was largely offset by the longer fuse action time - the 5-inch high explosive shell was equipped with a Brink tube with a longer action time compared to the 987 model tube.
As for the 10-inch armor-piercing shell, I, unfortunately, do not know the explosive content in it. But the "Album of Naval Artillery Shells" indicates that after the Russo-Japanese War, the 10-inch armor-piercing shell, equipped with an armor-piercing tip, was equipped with 3,89 kg of TNT. It should be said that large-caliber shells with such tips were only slightly short of being ready for the battles at Shantung and Tsushima, despite the fact that the 2nd Pacific Squadron managed to receive a certain number of 6-inch shells with tips. It is also known that the drawing of a 12-inch shell with an armor-piercing tip differed from that without a tip. The body of the "tipless" projectile was longer: 807,7 mm versus 751,8 mm (another 77,5 mm of length was "chosen" by the tip), but the explosive content, oddly enough, was less. The projectile with a tip contained 6 kg of TNT, and without a tip only 5,3 kg.
Assuming that a similar proportion existed for 10-inch shells, and using the data on the conversion of the explosive mass from TNT to pyroxylin, which I used earlier, we find that the armor-piercing "tipless" shell of the "Tsushima" model contained 2,79 kg of wet pyroxylin versus 4,3 kg of pyroxylin, which could be supplied with an armor-piercing 12-inch shell. If the explosive content of the "capless" 10-inch shell corresponded to that of the "capped" shell, then the armor-piercing 10-inch shell contained approximately 3,16 kg of pyroxylin.
I cannot know which of the above figures is more accurate. But I think we will not be mistaken in assuming that the mass of pyroxylin in a 10-inch armor-piercing shell was in the range of 2,79–3,16 kg. At the same time, a 12-inch armor-piercing shell contained about 2,6 kg of smokeless powder. From which it follows that the 10-inch armor-piercing shell, equipped with pyroxylin, also turned out to be more powerful than its 12-inch counterpart, equipped with smokeless powder.
Is it possible to assert on this basis that it was the 10-inch/45 guns of the 1892 model (or at least their version, which the squadron battleship Pobeda was armed with) that better met the tasks of squadron combat than the 12-inch/40 guns of the 1895 model, whose shells were equipped with smokeless powder? Let's take a look.
Mikasa
"Asahi", type "Shikishima"
Fuji type
"Yakumo"
Azuma, Izumo type and Tokiwa type
"Nisshin" and "Kasuga"
Conclusions
As can be seen from the calculations presented above, the 12-inch/40 gun model 1895, when using projectiles with pyroxylin filling and a Brink tube, has obvious advantages over the 10-inch/45 gun model 1892. Moreover, this advantage is significant even in comparison with the improved model with an increased muzzle velocity of the projectile to 777 m/s. When compared with the original version of the ten-inch gun with an muzzle velocity of 693 m/s, it is almost absolute.
Firstly, the better armor penetration of the 12-inch artillery system is obvious. Thus, the citadel of the "Mikasa" in the area of coal pits could be hit by a twelve-inch shell from 20-25 cables, and a 10-inch shell with an initial velocity of 777 m/s - only from 15-21 cables. The barbette of the "Mikasa" with a thickness of 345 mm was penetrated by a twelve-inch shell from 4-11 cables, and a 10-inch shell - with a deviation from the normal of 25 degrees was not penetrated at all, and with an ideal hit - only from 6 cables.
It would seem that 4-5 cables - is there much difference? But in the realities of the Russo-Japanese War, it turned out to be a lot. Let's take, for example, the Asahi, Shikishima and Hatsuse with their 356 mm barbettes made of "improved Harvey" armor. According to calculations, their barbettes could be penetrated by 12-inch Russian shells from a distance of 9-15 cables, but if we assume that the armor was weakened due to the bending of the plate, then at 12-18 cables. Such distances, at least as an exception, were still possible. But up to 8-13 cables, at which in the best case for us we could count on hitting these same barbettes with 10-inch shells - no longer. The Japanese could only get so close to a completely battered battleship, whose main caliber was no longer effective. Thus, the 10-inch armor-piercing shells had virtually no real chance of hitting the barbettes of the Japanese battleships.
The situation could have been improved by armor-piercing tips, thanks to which it was quite possible to increase the destruction zone of the barbette of the same "Shikishima" with a 10-inch shell to 16-19 cables. But, as was said earlier, in 1904-1905 our large-caliber shells were not equipped with them.
All of the above shows that the 12-inch/40 guns of the 1895 model were significantly superior to even the improved 10-inch/45 guns of the 1892 model, which were only issued to the Pobeda. As for the Peresvet, Oslyabya and the coastal defense battleships, the armor-piercing shells of their 10-inch guns could not count on hitting the citadels, turrets and barbettes of the Japanese battleships. In order to have a chance of hitting the Shikishima citadel, these ships had to get closer to the Japanese battleship by no more than 10-15 cables, but even closer would be better.
All of the above was "firstly", now let's move on to "secondly". Even at distances where, according to armor penetration formulas, a 10-inch shell would penetrate the armor belt, the coal, and the bevel, it still had a much smaller chance of hitting the citadel of a Japanese battleship than its 12-inch "brother". This is due to the extremely thick (in comparison with domestic) bevels of Japanese battleships.
As was already described in the previous article, 12-inch shells, hitting with a deviation from the normal of 55 degrees, could penetrate 110-111 mm of armor, while the Mikasa outside the coal pits had a bevel thickness of 114,3 mm. Asahi, Shikishima and Hatsuse were no worse protected: although their bevel was 101,6 mm, it was located at an angle of 30 degrees to the surface, and not 35 degrees, as on the flagship of H. Togo. Accordingly, the deviation from the normal was 60 degrees, and not 55, and the maximum armor penetration for 12-inch shells was 95-96 mm.
In other words, 12-inch shells should have ricocheted off the Japanese battleships' bevels in theory. But given the probabilistic nature of armor penetration and the fact that the tabular armor penetration, although not quite up to par, was still close to the actual bevel thickness, it was quite possible to count on the fact that if not the first, then the second shell that hit the bevel would still penetrate it. But in the case of a 10-inch shell, its caliber plays a cruel joke on it, since the thickness of the armor penetrated in this case directly depends on the caliber of the shell. Thus, if a 12-inch shell could penetrate a 55-110 mm bevel at a 111-degree deviation from the normal, then a 10-inch shell could only penetrate 93-94 mm at a 114,3 mm bevel on the Mikasa. At a 60-degree deviation from the normal, A 10-inch shell could “overcome” 79-80 mm of Japanese battleships with slopes of 101,6 mm.
Not only did a Russian ship armed with 254 mm artillery have to approach at a closer distance to hit the citadel of a Japanese battleship than a battleship with 12-inch guns, but even in this case, hitting the citadel with 10-inch shells was less likely than with 12-inch shells.
Thirdly, a 12-inch armor-piercing shell could carry approximately 1,5 times more pyroxylin than a 10-inch shell.
But not only armor-piercing shells... High-explosive 12-inch shells with pyroxylin filling would also have had a significant advantage over 10-inch shells. As I have said many times before, domestic high-explosive 12-inch shells could well be considered semi-armor-piercing. Their thick bodies, although made of relatively cheap steel, were still capable of penetrating armor half the thickness of their own caliber.
I do not know exactly what kind of steel was used to produce the 10-inch high-explosive shells, but the 12-inch high-explosive shell weighed (roughly) one and a half times more than the 10-inch shell. At the same time, according to “Calculation No. 1 of the cost of shells and other items in the amount of half of the second combat set for ships going to the Pacific Ocean,” attached to the testimony of the assistant to the head of the construction department of the main directorate of shipbuilding and supply, Major General Ivanov, the cost of a 12-inch high-explosive shell was 155 rubles, while a 10-inch high-explosive shell was 100 rubles.
That is, a twelve-inch projectile cost one and a half times more than a 10-inch projectile, but it also weighed more in the same proportion, from which we can conclude that the steel used to make both was approximately equivalent. And this, in turn, means that the armor-piercing capabilities of a 10-inch high-explosive shell were limited to armor half the caliber of the projectile.
But the half-caliber of a 12-inch shell is 152,4 mm, while the half-caliber of a 10-inch shell is only 127 mm. At the same time, the upper armor belt and casemates of Japanese battleships were protected by 148–152 mm of armor, which 12-inch high-explosive shells could easily penetrate, but 10-inch shells should not. Again, due to the probabilistic nature of armor penetration, anything is possible, but in general, a 12-inch high-explosive shell had a much better chance of causing a full-fledged rupture in a casemate than a 10-inch shell.
Thus, the 10-inch gun model 1892 was inferior to the 12-inch/40 gun model 1895 in all respects, but if only the fleet had received 12-inch armor-piercing shells with pyroxylin filling. Unfortunately, our ships did not have such shells in their ammunition, and with “gunpowder” shells everything was not so clear-cut.
In the battle with Japanese battleships, in terms of high-explosive shells, in my opinion, the 12-inch caliber had an advantage, even despite the slightly smaller quantity (and quality) of explosives. Firstly, the 12-inch shell had a much better chance of giving a timely explosion due to an adequate fuse for a high-explosive shell - a tube model 1894. And secondly, the 12-inch shell won due to the ability to penetrate armor up to 152 mm inclusive.
But it would be quite difficult to award the palm in terms of armor-piercing shells. At distances of 20-25 cables, from which, according to the instructions, our ships switched to armor-piercing shells and which sometimes occurred in battles of the Russo-Japanese War, neither 12-inch shells with gunpowder filling, nor 10-inch shells with pyroxylin could ensure the destruction of the citadels and barbettes of Japanese battleships. On the other hand, even 222-229 mm armor belts were quite penetrable for them, not to mention 148-152 mm casemates, and here the 10-inch shell with its more powerful filling could have an advantage. Therefore, I would risk claiming that 10-inch armor-piercing shells were still superior to 12-inch gunpowder shells, but this superiority was insignificant, since neither one nor the other ensured the infliction of decisive damage on Japanese battleships.
Another matter is the Japanese armored cruisers. Despite the fact that for their class they were superbly protected, their armor was absolutely unable to withstand 10-inch armor-piercing shells with an initial velocity of 777 m/s at 25-30 cable lengths (except for the 14-inch conning tower, of course). Here even the weaker guns of the Peresvet and Oslyabya could show themselves very well, since they had a good chance of penetrating the citadel (except for the Yakumo) at 20-25 cable lengths.
This leads to a very obvious conclusion: the 10-inch guns of the 1892 model were a bad solution for a squadron battleship, but an excellent option for an armored cruiser. Not as heavy as the 12-inch/40 guns of the 1895 model, they, taking into account the smaller weight of the turret mounts and ammunition, freed up hundreds of tons of displacement, which could be spent on increasing speed, but at the same time they perfectly solved the problem of confronting armored cruisers and were not at all useless in combat with enemy battleships.
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