The 18.1 inch Naval Gun - Origins and Development

[Music] [Music] the story of Japan's manufacturer of massive guns actually goes back a lot further than the initial planning for the yam class or even the number 13s back in the late 1910s Japan was considering what gun to adopt for the future ships of their 88 Fleet plan bearing in mind this is roughly contemporaneous where their designs for the nagato most dis discussion was centering on whether they should go for even more 14in guns or less numerous but more powerful 16-in guns as is usually the case in these kinds of Naval discussions maximalist and minimalist approaches were also looked at and one of the maximalist approaches called for simply the biggest guns Japan could manufacture the slight issue was that no one was entirely sure exactly what the biggest gun the foundaries could actually make was so it was decided to order one to see how it performed and what the challenges would be for secrecy much as the British had named the 15in 42 development program publicly as a new variant of the 13.5 in weapon the new gun would be designated for the public record at least the 45 caliber fifth year type 36 CM gun which translates to a gun that with a barrel diameter just a fraction over 14 in this would suggest again to General Public observers that perhaps they were triing some novel technology to see if you could get an approximately 14-in gun up to the penetration power of a 16-in weapon which was as a general principle at least something that various navies periodically had tried to do in the early 20th century not specifically with 14 to 16inch weapons but trying to see if they could get a smaller gun to match the performance of a larger one and thus benefit from the lighter weight of the smaller one but the greater hitting power of the larger one in actual fact the gun was a massive 48 CM or 18.9 in weapon ultimately ending up being almost 47 calibers long it turned out that the idea of what is the biggest gun we can physically build had managed to hit right on the margin of capability initial attempts to assemble it saw impurities in the steel caus cracking and excess shrinking in the various Barrel layers which resulted in their replacement in part with wire winding thus it was a hybrid gun because the broken sections were removed and replaced with set wires this increased the overall weight of the gun but even these stop Gap measures weren't enough when the gun was finally judged ready in 1920 and taken out for testing it self-destructed after nine shots destroying much of the after section of the gun although it would later be repaired and used for preliminary testing for the yam project between this failure and the Washington treaty limiting guns to 16 in the brief foray into giant gun construction was abandoned and the gun itself as well as its mounting were left where they lay in the kamashi gun testing range until the 1930s fast forward a dozen years to early early 1934 and the Genesis of the Yamato project it was clear that if a new Battleship supremely more powerful than any foreign vessel was going to be built it would need to have an extremely heavy Armament but this involved more than just what the hull could support the Imperial Japanese Navy also had to consider what rival navies would have the capacity to build in response to their Su ship along with the capabilities of the guns that the various treaty Nations could actually build at the moment given the treaty restrictions but they also had to consider as they had over a decade ago what Japan could actually manufacture without suffering major failures this was also actually a discussion that dominated armor manufacturer in Many Nations essentially the size of the gun or the thickness of armor plate that you could make was governed in large part by how large a block of consistent steel your foundaries could produce if the size of any one major component of what you wanted to make needed more material than that in a single Mass once you counted for Milling finishing and in Gun Barrel cases boring out then you would very likely fail or not be able to construct the gun in question and the loss of material when you were boring out various tubes for a major Battleship gun could be as high as 80 to 90 % the then current upper limitations of Japanese steel manufacturers meant that a 20in gun the favored choice of some officers was ruled out almost immediately for the initial run of battleships although investment into the steel industry might allow for such a gun to be made at a later date this along with the failures of the 18.9 in gun in the previous decade led to the selection of the 46 CM or 18.1 in gun as the maximum immediately available weapon and this gun would dominate most yam design plans as we've seen in the video on yam's design history the next argument was over the length of the barrel theoretical calculations and a few scaled up practical tests indicated that a 50 caliber length gun would have approximately 12 1 12% better armor penetration compared to a 45 caliber length weapon all else being equal behind that averaged figure lies quite a range of figures for both horizontal and vertical armor penetration across the expected battle range and this indicates as low as a mere 7% Improvement in belt penetration closer in increasing as the distance went up in benefit of the 50 caliber gun to a massive 24% increase in deck penetration at closer ranges for the 50 caliber weapon but this dropped off although it would constantly remain superior to the 45 caliber weapon as the range increased however the limitations of Steel manufacturer and ship design would come in again a 45 caliber gun would weigh about 165 tons per barrel whilst a 50 caliber gun would weigh over 200 tons per barrel the latter requiring component which were just beyond the reach of Japanese steel makers to reliably guarantee the end result and it would also Force the overall size of the am to be increased to accommodate them as the simple weight of the guns themselves doesn't tell the full story The their effect on stability the placement of the turrets and barbets and as a result of their guns length and the effect that that would have on the ship were also multiplying factors along of course with the heavier Machinery that we needed to rotate and Elevate these guns it would take a little bit of time however before the precise limitations of Industry with regards to producing a reliable 50 caliber option were realized eventually the 18.1 in 45 caliber gun would be chosen as the primary Armament of the am although it was once again incorrectly officially listed as the type 94 40 cm 45 caliber type I.E claiming that its actual Cal caliber was just under 16 in for security purposes the choice of this gun wasn't universally popular or seen as ideal as it was known that the British had already built an 18in gun back during World War I on HMS Furious and they'd been planning an 18in 45 caliber weapon of their own for the N3 battleships in the early 1920s given that the appearance of increasingly heavier guns in both the American and British fleets in that time period had been approximately contemporaneous it could reasonably be supposed that when the true nature of the OS was discovered both the US and British fleets would be able to match this Armament in relatively short order which is part of the reason why work on future successes to the am class were looking at even larger guns along of course with the appropriate investments in upgrading the Japanese steel industry so they could actually build them having selected the gun the Japanese Navy now actually had to get some of them built a tentative order to start the program was thus placed in mid 1934 shortly after the final decision by the Japanese government to sabotage the outcome of the second London Naval treaty however how to construct this new gun was something that needed to be determined very briefly large Naval guns in this time period were generally either what is sometimes called monolock construction or of wire wound Construction in either case a series of tubes of increasing size and varying length were placed over the barrel liner which is the bit the shell goes through in monolock or more properly speaking builtup block construction as strictly speaking monolock implies the gun is made from a single piece of Steel like an old school Cannon but in the time period monoblock was sometimes used to denote a gun that was made up of a series of tubes the inner tube or liner which had a series of larger tubes heated because metal expands when it's heated and then dropped over it and cooled down usually this would consist of a ful length jacket or potentially multiple of these and then a series of what are usually termed Hoops which are basically tubes that don't run the full length of the gun and these are all built up in layers with more towards the breach end where the pressures are higher in wire wound guns many of these Hoops are replaced with extremely high tension steel wire which is wound around the gun although a solid outer hoop for the relevant section is placed over them both construction methods have advantages and disadvantages but the fine details of Battleship gun manufacturer are best left to their own video the three candidates for the 18.1 in guns Construction in this case were a fully wire wound gun and two different options of half wire W half monolock or builtup hybrid types with have different numbers of wire layers and the wire layers in different positions in the guns Construction in 1935 as we mentioned earlier both the 45 and 50 caliber options were still notionally on the table but apart from the issues we mentioned earlier with a 50 cal further examination of 45 and 50 caliber versions of weapons of the same bore diameter in previous Imperial Japanese Navy service had revealed that the 45 caliber versions were often more accurate as greater length in the 50 caliber versions often meant more whip in the guns when they fired especially in the case of wire wound guns in the end a hybrid approach was chosen trying to combine the relative cheapness and speed of builtup guns with the longevity of wire wound guns and again incorporating the easier liner changes of builtup guns with the more precise quality control that was possible with the wire wound option one of the final deciding factors actually occurred when somebody bothered to check the relevant armor penetration calculations and suddenly realized that even at the edge of expected battle range the penetration values for the 45 caliber gun exceeded practically all known armor schemes and certainly anything that could be afforded on a 35,000 ton treaty compliant Hull and things only got worse for the Target as you moved from the extreme Edge into more realistic battle ranges two test guns were then ordered along with a Turret to mount them in now that they knew that they were definitely getting a 45 caliber version the turret itself was a complex and radical item since all previous Japanese Navy dreadnut and later turrets had either been British built twin mountings with the Congos or der ations thereof whereas this new three gun turret was an entirely Japanese designed and built aair the first gun would be ready in March 1938 and whilst the second test gun and the turret were being completed they'd be ready in 1939 the first gun was test fired it didn't blow up which made everyone quite happy and so further test firings were done incorporating the second gun and turret when they were ready these tests would result in a number of slight modifications and improvements which would be incorporated into the main production Run for the battleships themselves the final specifications of the 18.1 in gun at least at the time of the first of yam's guns being manufactured were as follows caliber was 460 mm or if you want to be really nitpicky 18.11 in the barrel length was 21.13 M or 69' 4 in which is equivalent to 45.94 calibers although this length is from the face of the breach to the muzzle the weight was 167 tons the rifling involved 72 individual grooves which had a one rotation every 28 calibers in terms of twist the charge was made up of six charge bags Each of which weighed 60 k kilos or £ 132 for a full charge although some sources claim that the charge bags weighed 55 kilos per bag the muzzle velocity varied According to which shell was being used but was between 20560 and 2,640 ft per second assuming the gun was in relatively good condition and they were using a full charge and range was around 46,000 yard at maximum elevation although quite how you were supposed to spot and hit anything at that range was not ever quite stated the elevation was 45° and this was more useful for the anti-aircraft shell use which will come to a bit later Barrel life was around 200 rounds but possibly slightly more depending on your Source four types of charges were listed in Imperial Japanese Navy records a service charge consisted of a full charge a reduced charge used 75% of the propellant and a weak charge used half the propellant there was also a testing only strong charge with 120% of standard full charge propellant you might call that supercharge a full charge firing was held to reduce Barrel Life by One A reduced charge counted as half and a weak charge as 116th if the gun had been tested with a strong charge then that firing counted for two against its expected Barrel life in theory the hybrid nature meant that the gun liner could be easily removed and replaced when the gun reached the end of its service life but in the event neither the guns on yam or moushi ever actually got this point there is however another conflict of sources as what Japanese documents and testimony survive largely indicate that replacement of the barrel liner should have been possible whilst the US technical Mission conducted after the war asserts that the liner could only be replaced after being bored out with Machinery a process so lengthy and destructive that it would actually just be easier and faster to build a new gun and discard the old one after testing it was determined that a delay coil to the firing of the center gun of point 08 seconds was needed to prevent interference in Shell flight paths although there is once again conflict here 08 seconds being the figure that the US technical Mission reported whilst some Japanese sources claim a much longer 3 second delay unfortunately there is only one known photo of a yam class in this case moushi firing a salvo and whilst the difference in Fireballs from the center and left guns is is quite marked as that's the one you can see from this particular view a single photo doesn't strictly allow us to calculate the actual delay without a fair degree of supposition being involved when the fall turret was constructed the weight breakdown consisted notionally of 495 tons for the three guns 228 tons for the elevation mechanisms 350 tons for the rotating turntable that the gunhouse sat on 647 tons for the rest of the rotation Machinery needed to make the gunhouse rotate around the turntable and 790 tons for the gunhouse armor plating a grand total of 2,510 tons per turret which is famously considerably more than most World War II destroyers although this might be a pattern once again the exact quoted figures will vary depending on your source course anything between 2,200 and 2774 tons some of that disagreement comes from how you account for the ammunition which was stored in the rotating portion of the overall turret mechanism some was in the Shell rooms but some was in the rotating mechanism and I said occasionally people count all of it some of it or none of it towards the overall weights plus there's a bit of disagreement on the precise figures for the weights themselves but 2510 is roughly the middle and so is a pretty good guide due to the weight of the shell and the charges it was not considered practical to invest in even heavier and more powerful Machinery which would be required for all angle or even partial angle loading I.E being able to load the gun whilst it was elevated to a greater or lesser extent instead the guns would have a fixed loading angle so they had to lower themselves down to a 3° elevation each time they needed to reload thus the rate of fire was largely dependent on the distance to the Target as the time needed to raise and lower the guns could add considerably to the overall firing cycle time the 1.5 rounds per minute that's often quoted as the gun's maximum rate of fire was for if the gun was firing at 45° elevation each time and so represent something of a worst case scenario although a worst case ideal scenario since as we know in most Battleship engagements even 1.5 rounds per minute is a somewhat brisk rate of fire in practice a total of 100 rounds would be supplied for each gun and accuracy was noted as being quite good with a relatively minimal spread although the high density of the rounds being fired likely helped with that as much or more than anything particular to the gun design in general now without deviating too much into turret design there there are two final things to note this video you might notice is a little bit shorter than some others you see on Wednesdays but that's because much of the data on these particular guns was either destroyed by bombing or deliberately burnt by the Japanese before the end of World War II and of what's left as you all have noted various sources often disagree on the details the penultimate item of interest is of course the blast effects when tested it was found that the pressure generated was twice as strong as that which was caused by nagato's 16in guns when you put test items at equivalent distances for example one test found that if you were 15 M or around 50 ft in front of the muzzle when two of the guns were fired you'd be subjected to an over pressure that was just a fraction under 100 PSI about six times what you'd need to knock somebody out and well past the Fatal threshold as this is the equivalent of somebody suddenly dropping a column of water 60 M tall on top of you literal guinea pig tests ran into some complications when one blast utterly destroyed a number of the cages and then swept the contents and the cage Parts out into the ocean leaving them with nothing to study other than you really don't want to be guinea pig standing on the deck of a yam class when the guns fire the net result of all of this was a policy that no one was to be allowed to be left exposed anywhere on a yam class's open deck when the main guns were fired blast shields were fitted to some anti-aircraft weapons but anyone Manning an anti-aircraft weapon that didn't have a blast Shield was supposed to be notified of the guns firing by a two-tone buzzer the first tone told you to grab anything that was breakable such as yourself and the gun sights on on your gun that might have prisms in them and get into cover ASAP as the main guns would be firing at the end of the second tone in battle it's actually reported that this procedure was not followed for some reason during at least part of the battle of cbanc and thus Masashi accidentally incapacitated a good portion of her own anti-aircraft Gunners whilst firing her main guns in anti-aircraft mode there is the possibility that this also happened in yam's Final Stand during operation Tango this massive overpressure was also the reason why all of the am class's aircraft and boats had to be stored in enclosed hangers as otherwise the first time they fired their main guns they'd also be wrecking every single exposed boat and aircraft on the ship even men who were stationed up on the bridge or even higher above weren't entirely immune with one report from someone who was in such a position stating that when the main guns were fired the the shock wave was strong enough that he had to hold onto his hat to avoid it being blown away or if you want to put it in a more modern context Fireball and radiation injuries aside you would be able to stand about a mile away from the detonation of the average submarine launched ballistic missile Warhead and you'd only be subject to about 1/5 the over pressure although that's still enough that you almost certainly suffer fatal consequences and lastly we have the ammunition for most battleships the main ammunition types are of course an armor piercing round and a slightly more explosive one variously called high explosive or high capacity or some variant thereof depending on which particular Navy you're in for the 18.1 in gun however there were three kinds of ammunition the type 91 armor piercing round which was specifically designed to incorporate the features of a diving shell ever since tests conducted against the incomplete of the Japanese battleship TSA back in the 1920s had shown the potential benefits of getting a shell to dive underwater and strike below the armor belt and the specific design features of the type 91 allowed it to maintain its heading so that it could Pierce an enemy's hole underwater if it fell short and still explode this shell weighed 3,219 just under 1 and 1/2 tons and came with a rather substantial bursting charge of almost 75 lb which is about 34 kilos of explosive on paper the slight changes made to the type 91 to allow for this diving Behavior did reduce its overall armor piercing capability a bit but given the overall power of the 18.1 in gun that moved the armor penetration from hilariously ridiculous to just ridiculous in any case the high explosive round was a little bit like lighter than the armor piercing round at a m 2,998 lb and interestingly enough its bursting charge was just under twice that of the armor piercing round at 136 lound of explosive a ratio that's actually well below other ships armor piercing to high explosive round bursting charge ratios in fact the high capacity round of an Iowa class Battleship has a bit more explosive in it than the Japanese 18.1 in high explosive round for whatever reason the Third Kind of ammunition carried was the type 3 San Shiki or anti-aircraft round a unique round found only in the Imperial Japanese Navy at least as far as battleships of World War II went this was supposed to exploit the 45° elevation of the main guns to allow them to engage in long-distance barrage work against incoming aircraft at a preset distance using a timed fuse the shells would explode and then project a column of burning incendiary fragments ahead of them in theory this should break up incoming aircraft formations and potentially even set one or two of them on fire but as it turned out the py Technics were generally seen by incoming Allied Pilots as more of an interesting you are definitely attacking a Japanese battleship type of thing rather than anything that posed any significant Danger and as we've seen the use of the main guns probably overall negatively affected the am class's anti-aircraft defenses a lot more than it helped if you absolutely had to use the main guns for anti-aircraft work I suspect that a gigantic multi-layered fragmentation round that just spread a lot of shrapnel in a 360° sphere would probably have been marginally more effective if admittedly a little less spectacular in the end 2 seven guns would be built two test guns 18 which were installed on yam and moushi and went down with them and seven more intended for shinano before her conversion into a carrier were in various stages of completion at the time that Japan surrendered two of these were taken back to the US for testing but they appear to have been scrapped at some point before 1960 which means that the only way you'll see an 18.1 in Japanese battleship gun these days is if you happen to have access to a deep water submersible and a license from the Japanese government to go and look at one of the wrecks that's it for this video thanks for watching if you have a comment or suggestion for a ship to review let us know in the comments below don't forget to comment on the pined post for dry do questions

Channel: Drachinifel

Views: 234,654

Keywords: wows, world of warships, 18.1, Yamato class, Admiral Yamamoto, WW2, USN, IJN, Musashi

Id: Kk1RNdINavg

Length: 28min 48sec (1728 seconds)

Published: Wed Feb 28 2024