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The Weird and Wonderful World of North Carolina Designs (also general ship design stuff)

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So I got goaded into writing posts about the North Carolina class.

 

For additional reading about warship design:

http://navweaps.com/index_tech/tech-035.htm (I moved this up to the front because it's good and I'm angling for a general thing here).

 

The weird and wonderful world of North Carolina sketches

So the US found itself in the mid 1930s with a need for a new battleship with a treaty in place limiting it to 35k tons displacement and 14 inch guns. The first and most important thing about this design process is that they were in the middle of figuring out what a modern navy was and how it should work. They'd traditionally prioritized protection at the expense of speed and slightly less so firepower, giving them a battle line of slow football shaped things that could take a pounding and dish one out.

Problem was those damnable carrier things. The first US carrier, the Langley, was a slow collier conversion, but the next two were conversions of the battlecruisers Lexington and Saratoga, (which were a lot like the mad, flammable fever dreams of Jackie Fisher in terms of protection, so it was probably a good thing in the end). The reason for this was the negotiations for the treaty. Unlike in RtW there was a lot of quid pro quo. The US had just finished the Colorado, Maryland and West Virginia, and the Japanese had just finished the Nagato and Mutsu. The British had the Courageous, Glorious, and Furious, which were in severe danger of starting to make sense. So the UK got to build the Nelsons so they could have nice modern battleships armed with and against 16" guns, and the US and Japan could get some carriers.

So the US built the Lexingtons, which promptly showed the supremacy of the big fast carrier. Not only could they get places really quick to do important carrier things, they could also operate planes in larger numbers much more easily and in much worse weather. So the treaty carrier force was decided on being hulls as big as they could make them and 30+ knots. Suddenly that 21 knot battleship speed looks like a massive operational and strategic liability if they want to not have their carriers run in fright at sight of a battleship (This is still the time of the Lexington class carrying a heavy 8" armament to fight off cruisers, air power just couldn't be expected to head off heavy surface attack and conceding the sea wasn't necessarily a winner).

The sum of all this was that they knew they were going to be making a major departure to what had gone before but they really weren't sure what that would be. To this end they tried a lot of ideas to see what they could get. These ideas are A, A1, B, B1, C, C1, D, E, F, G, H, I, J, J1, K, L, 1, 3, 4, I, II, II-A, III, IV, IV-A, IV-B, IX-C, IX-D, IX-E, X-A, X-B, XI-A, XI-B, IV-C, V, VI-A, VI-B, VII, VIII, IX-A, IX-B, XII, XIII, XIII-A, XIII-B, XIV, XV, XV-A, XV-B, XV-C, XV-E, XVI, XVI-A, XVI-B, XVI-C, XVI-D (Word says that list has 55 commas so that's 56 sets of specs considered).

For obvious reasons I'm going to talk more about the fun designs.

Scheme A had 3 triple 14" turrets forward and 30 knots speed with a thin 11.5" belt. A1 added to the belt with 13.5" and the same 9x14".

B and C tried for more protection and a more conventional layout. BuOrd introduced a super-heavy 14" shell that made their targets for immune zone unattainable, (that's where A1 comes from).

The CNO asked for ideas for a minimum displacement ship emphasizing defensive features. They didn't get dignified with an actual name on that list (Preliminary design called the worst, with 8x12" and 23 knots a deathtrap).

D and E were armed with the shiny new 16" rifle to see what a ship armed with and armored against it would look like. However after a thorough search of their couch cushions, they couldn't turn up the 5,000 tons to make them fit the treaty limits.

F makes me cry. 8 guns in two rear mounted quads. Wait, rear? They needed to free up the front for the three aircraft catapults. FDR apparently liked this demented battleship version of what the Tone class did better.

G and H were slow 23 knot designs. They were nice, reasonable, balanced battleships and the spiritual successors of the standards. They also didn't fit the fleet's needs.

So that left them looking at a 30 knot ship or a slower, better armed ship. Yes, this is the USN that previously considered a battleship to be a football made of armor.

J tried to go with four turrets. It turns out that getting an idea and hammering the belt armor down to 8" to make it work is frowned upon.

K made the belt narrower over A1 to make it thicker, but was considered too tight to the treaty limit.

L is where we get to the good stuff and bring back the noble quadruple turret, which would have been 12 guns forward and crazy fun to play in WoWS.

After that we get the thirty five (that we know of) sketch designs elaborating on those ideas. I through V show the development of the brilliant feature of fitting the ship for but not with 100 rounds more than the 100 per gun to save weight by careful manipulation of paper. I and II moved a turret aft to see if they could save weight there.

Anyway, this is dragging on, I'll just post this and add a part 2 so we can get further adventures of people trying desperately trying to fit 40k+ tons of battleship that people can't even decide on the shape of into 35k tons.
 

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The weird and wonderful world of North Carolina sketches: Part 2

Honestly the roman numerals are just a whole bunch of small things to save weight to try and jam the ship into the displacement limit. Not weighing it with all the ammo, sloping the belt (the bottom is the narrower part because plunging fire is a concern, this isn't a tank), making the barbettes conical even, making the hull longer (which meant that the ship needed less power to make the same speed and the armored area could be shortened). That last one saved 47 tons by shortening the armor belt 8 feet, on a ship they were trying to fit in 35,000 tons that had just grown to 725 feet. Ship design is a thing. They then started trying to fit 16 inch guns in, trying eight in both two triples front and a twin aft as well as two quads forward, but they decided against the sacrifices that meant.

Scheme IV seemed to be pretty good if a bit tight, which meant that of course they immediately demanded a bunch more stuff be slapped on. Twelve 5 inch guns became twenty, and a frankly quaint setup of two quadruple 1.1" AA guns and at least eight .50 caliber machine guns.

Next the board tried a few four turret designs which followed the example of earlier four turret designs and didn't work.

The main line of development kept finding weight for desired features in such things as the ability to take two torpedoes to the same part of the torpedo defense system and the ability to take more than one torpedo on a side before the deck went below the waterline. Even then they just couldn't make the numbers. Next up was IXA, B and C, where they tried out two quadruple turrets up front. At that point they were at 30 knots and they realized that just had to give. XA was 27 knots and had a quad up front as well as the triple and an aft triple for ten guns, XIA traded belt for length and thus speed (length makes a ship faster by reducing drag). They also tried a small cut in speed to 26.6 knots for more armor (XII), they tried nine guns and a bit more power, and so on. Next they tried adding length to XII for some more speed to see if that would be cheaper than more power, they finally gave up on the requirement that the frontmost turret be able to fire at 0 degrees forwards so they could drop the front turrets and conning tower (a big savings). They removed a second conning tower that had caused much heartache all the way back in scheme I to see what they could get for it.

After a whole bunch of rearrangements new requirements were issued, asking for a ship that could do 28.5 knots with eleven 14 inch guns and sixteen 5 inch guns. Both firepower and speed were on the relatively high end of what they'd been considering, and the proposal noted that weight savings could be made by trimming a gun or if refinements freed up weight another gun could be added (BuOrd still wanted the 16" gun, but treaty conditions were still in effect).

At that point they realized the waves the ship made would reveal the lower edge of the belt right over the magazine, that they probably couldn't taper the transverse bulkhead like the belt (because going through the bow wouldn't slow a shell like going through water), and underwater hits were a major menace in the longer range brackets.

The next alternatives considered were all moves towards a fast and well protected ship with relatively light armament, and was again considered as a carrier escort. This proposal was being seriously considered when Admiral Reeves on the General Board poked in and said the design was still too slow to work with the carriers and wasn't worth the high cost. He recommended thinning the belt to strengthen it and provide underwater protection over the magazines, and the board also recommended provision for replacing quadruple 14" with triple 16" if the escalator clause was invoked. This was just about what got made. Next up was a request to add four more secondaries, a bit more belt armor to get a uniform inner edge on the immunity zone, and to raise the second turret so it could fire over the first a bit more easily and move forward a bit for a bit more machinery room. Surely that would be minor tweaks. Right?

And now we understand Old George in that link I posted earlier and his plight. Those changes would lower the speed to 24 knots by gutting the weight budget for machinery, and even then cost too much stability. The turret change just wasn't going to happen, the secondaries could get stuffed in unprotected twin turrets that would replace the singles in the design, and the belt could get thickened mainly by angling it more sharply. 8 quadruple 1.1" guns were requested (apparently to fend off small torpedo boats at close range as well which is a bit odd).

With a bit more work the North Carolina emerged. One big fight was the adoption of high pressure, high temperature steam plants, which were more efficient. What they were not, however, was well proven, but engineering won, and adopted 565 psi at 850 F compared to 400/648 in recently completed carriers. Naturally they won late enough that the turbines were designed for lower pressure and lost some of the efficiency. Two skegs outboard were adopted to keep the stern wide for better torpedo protection of the aft magazine, and calculations were done to reassure the designers that the form wouldn't cause transverse vibration. It didn't, instead the ships had bad longitudinal vibration.

Finally after the first ship was laid down the escalator clause was invoked and the US was saved from the shame of quadruple turrets and the North Carolina as we know it was finalized (until they put AA guns on every flat surface they could find). It was reasonably balanced against 14" fire, but the 16" guns especially firing the superheavy shell were just beyond its armor, and they still needed to make weight. The result was another flat 2 percent cut to the armor. However, a special advisory board was able to shave weight from paper so they didn't have to shave it from the steel, including a 10 ton reduction to the 30 tons of stores carried for sale to the sailors as well as more pedestrian water and stores reductions. Those got cashed right back into armor, which actually got a bit thicker.

Finally, the ships were made to the plans for which so much had been sacrificed at the altar of meeting the 35k ton treaty limit. According to the BuShips standard figures from 1941, they displaced 36,600 tons (ssh).

And then they started to move and tried to shake themselves apart.

Tune in next time for a very special episode, My battleship is full of bees!

 

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The weird and wonderful world of North Carolina sketches Part 3: There's no business like show(boat) business

So last time we checked in, they'd just finished the North Carolina and gotten her up to speed when the rear end of the ship started shaking like it was a crime against ship design and wanted to die.

The Navy was rightly pretty worried. After all, the stern of the North Carolina looked something like this:

D1NB0ku.png

And that kind of stern was a feature of all their new battleships, with the next class looking like this:

tRu46hA.jpg

If the new and unconventional stern they'd made was actually a crime against hydrodynamics and incompatible with actually moving at high speed, then the USN was screwed because that would be their entire lineup of modern battleships (and also their entire lineup of battleships that could do more than 23 or so knots) unable to actually do their job. The vibration was some sort of resonance in the incredibly complex (and at high speed, very energetic, just ask the Prince of Wales) system of shafts, propellers, machinery and hull, and the proposed fixes off the bat were new propellers, stiffer foundations for the machinery and restraining blocks for the shafts. Interestingly the Atlanta class had a similar problem, having a similar hull structure. The first fix tried was using propellers with one more blade on the inner shafts than on the outer, eventually moving from three blade propellers on the outboard shafts and four bladed inboard to four and five respectively by December 41, which provided a noticeable improvement, although the after range-finder vibrated excessively, and it got external braces, as well as braces on the turbine and gear casings. By 1943 the ships were using reduced diameter three bladed propellers inboard with four bladed propellers outboard and a scheduled change of the inboard propellers to five bladed ones in a continual effort to reduce the vibration. The eventual solution was a set of four bladed propellers outboard and five bladed inboard. They didn't actually fix the problem but moved it so that the vibration between 17 and 20 knots was unacceptable, which was likely between cruising and flank speed and thus less of an issue (I'm guessing here, because it says elsewhere that the class was most efficient between 18 and 25 knots).

The vibration saga was only part of the history of the class though, and much of that is far happier. The huge compliment of secondary optics was slowly replaced by radar and by AA guns. Navigational rangefinders were replaced by 20mm cannon, and the auxiliary main battery rangefinder was replaced by a microwave radar in 44 after being supplemented by a third Mark 3 fire control radar in 42. This sort of pattern continued, with huge numbers of radars being added, with a CXAM air search unit, two Mark 3 main battery sets and three Mark 4 secondary battery sets (not four to match the compliment of directors because of interference concerns). Upgrading and adding radars on an ongoing basis was just a fact of life for WWII US battleships.

The other huge configuration change was four quadruple 1.1" guns (Actually a pretty nifty gun with the abilty to rotate, elevate and also yaw to track dive bombers at high angle, but overcomplicated and too small to really warrant the more complex mounts) giving way to four quadruple 40mm Bofors (a superlative gun with good fire rate and range, a good amount of firepower for a director controlled mount, and a design that could be kept topped up without needing a break in firing). The number of quadruple 40mm mounts just spiralled upward through the war. By June 1943 the NC was carrying fifteen 40mm mounts, and Washington followed in August. Similarly, the planned twelve .50 caliber machine guns became forty 20mm cannon and twenty-eight .50 caliber by June 1942, and NC got forty-six 20mm cannon after her major refit. By August 1945, the Washington was carrying 63x1, 8x2 and 1x4 20mm guns (the NC was only carrying 36 20mm guns total at that point)

By 1945, the North Carolina class, which they had fought so hard to fit inside 35,000 tons, was now displacing 46,800 tons and assigned a maximum desirable displacement of 48,000 tons.

The main combat record of the class was two major events. First was the night battle of Guadalcanal, where Kirishima started opening up on the South Dakota as the latter was crippled by teething flaws and accumulating damage to the superstructure. The Washington took the opportunity to get in perfect firing position on the Kirishima using radar, and once the Kirishima lit her searchlights to get a firing solution on the South Dakota, Washington promptly showed her what a difference twenty-five years makes in ship design. The other was the North Carolina being an unlucky participant in the most successful torpedo spread in history. While patrolling in south of the Solomons on September 15 1942, I-19 fired off six torpedoes at the Wasp. For those who don't know US carriers, a brief aside. I mentioned the Langley, Lexington, and Saratoga. After that the US built the Ranger, after which they realized that large carriers were really the way of the future. They decommissioned the Langley and had enough space in the treaty tonnage limit for three and significant change carriers at the maximum tonnage allowed for a carrier. Once they realized they could either have four mediocre carriers or three good ones and one compromised one, they built three Yorktowns and the Wasp, a smaller Yorktown that saved weight by skipping out on having a sufficient torpedo defense system. Anyways, back to the Wasp on September 15, sitting downrange of a torpedo spread it doesn't have real protection against.

Whoooops.

Three torpedoes hit the Wasp and knocked out her power, so she couldn't fight the fires. Bye, Wasp. The remaining three kept going. One hit the destroyer O'Brien, which sank on the way home. Finally one more hit the North Carolina, which wound up needing repairs that took her out of the fight for two months. The armor above the hole cracked, the second and third decks buckled, 970 tons of water was let in, and although the ship was able to get back up to 24 knots within a few minutes but had to slow back down to 18 because of strain to the shoring. Worryingly, the damage below the first turret basically took it out of action, and the shock disabled the main search radar. The General Board wanted a redesign on the last two Iowas for more protection, but BuShips said the system performed as designed, made no change and the US wound up not making the ships anyway.

In contrast to the following South Dakotas, which managed to kind of properly protect against 16" fire (same scheme as the Iowas, which at 10,000 tons heavier than the South Dakota class shows just how expensive going from 27 to 33+ knots is), the North Carolinas weren't incredibly cramped for their crew, which gave them a bit of a career postwar, but nothing too major.

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I immediately imagined a Hoover and then a Roosevelt looking over these, and saying "Fuck this noise, Build me a proper Navy"..

 

And then, December 7, 1941 ending verry differently.... The very absurd and evil bit sees F7F's and L133's rising to meet early A6M's, etsc... The really dark bit sees a long range patrol of Lockheed L-133"s intercepting the Japanese fleet with 1000 pound bombs, and scaring them back to Yokohama.

 

From there, shit gets very pear shaped.

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Great stuff here, this was a fun read.

 

 

 

L is where we get to the good stuff and bring back the noble quadruple turret, which would have been 12 guns forward and crazy fun to play in WoWS.
 

 

Three four gun turrets in a superfiring configuration?  Oh boy, I bet that is going to cause some stability issues.

 

On the other hand, it sounds hilarious.

 

By 1945, the North Carolina class, which they had fought so hard to fit inside 45,000 tons, was now displacing 46,800 tons and assigned a maximum desirable displacement of 48,000 tons.
 

 

I thought they were trying to cram it inside 35,000 tons?

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Great stuff here, this was a fun read.

 

 

 

Three four gun turrets in a superfiring configuration?  Oh boy, I bet that is going to cause some stability issues.

 

On the other hand, it sounds hilarious.

 

 

I thought they were trying to cram it inside 35,000 tons?

I can type good.

 

Yeah, 35,000 tons, and then they finished it and put things into it, stopped the enron tier accounting for what the ship actually weighed when set up for war. Then they scabbed radars and AA on everything flattish.

 

As far as I can tell, none of the three turret up front designs had all guns superfiring. The idea they looked at before starting work on the NCs that did have three forward superfiring triples looked badly compromised. So more of a Nelson arrangement or one, one non-superfiring, and one superfiring in order from front to back than this:

 

OejgxJQ.png

 

That cut in the front to basically let the front turret rest its guns on the forecastle would cause a hellish stress concentration right where you don't want one. And I'm pretty sure those aren't triple 16s or quad 14s.

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In contrast to the following South Dakotas, which managed to kind of properly protect against 16" fire (same scheme as the Iowas, which at 10,000 tons heavier than the South Dakota class shows just how expensive going from 27 to 33+ knots is), the North Carolinas weren't incredibly cramped for their crew, which gave them a bit of a career postwar, but nothing too major.

 

This is an interesting point that deserves some attention.  What is the approximate relationship between ship speed and power consumed?  I was under the impression that it was a square relationship.

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You need more power to do that (to overcome energy lost to drag). Exactly how much depends on your displacement, hull form, surface roughness, and other shit.

 

I read a book from the work library that had a nifty equation for estimating a submerged sub's top speed from reactor output and displacement, I'll see if I can find it in somewhere generally available. I'm about 99.9% sure it was a good bit more complex than the KE equation though.

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This is an interesting point that deserves some attention.  What is the approximate relationship between ship speed and power consumed?  I was under the impression that it was a square relationship.

NavWeaps is a really good site and has the best info on the subject I've seen:

 

http://navweaps.com/index_tech/tech-029.htm

 

For more:

 

http://navweaps.com/index_tech/index_tech.php#Ship_Design_and_Construction

 

I recommend the one on prismatic coefficient at the very least, it's about hull form.

 

Anyway, I was swinging by to post this.

 

Fun topics in ship design: The Superposed Turret

hU37t1i.jpg

I'm not saying it's the cake for the wedding between the US and Mahan's ideas, but it's a pretty likely explanation.

The first US battleship was the Texas, authorized in 1886, and already obsolete when completed in 1895. The US built up to the second strongest naval power in terms of battle line strength in the twenty years after 1886. They did this in two major bursts between 1890 and 1896 and 1900 and 1902. These bursts followed each other so quickly that they couldn't incorporate experience with actually using the things. The only war experience they got was the Spanish-American war of 1898, which was in time for the latter group of ships. The result was a bunch of ships that got some things right, some things wrong, and some things so different that without them going to war we still don't know if they were actually a good idea or not. One which was definitely not in the first category was the superposed turret. In classic old timey racism manner with a dash of timeless hyperbole, William S. Sims claimed that (at least as far as the Kearsarges went), the setup was "The greatest crime ever perpetrated against the white race".

So what exactly are superposed turrets?

They're what happens when a daddy ship designer loves a mommy place to put a turret a bit too much. It's also what happens when a nation is backwards technologically and trying to match more sophisticated weapons with innovation. Describing what a design feature is is only part of what matters, the trade-off it means are vital to a ship as a whole, and the US had a problem with a different toolkit to solve it than other nations. The US had a problem in being unable to make proper 5-inch rapid fire guns (IE firing a shell from a metal cartridge that seals the breech), while foreign ships were armed with 6 inch guns of the type. The solution decided upon was to mount a slower firing secondary that could defeat protection against the 6 inch rapid fire guns. That meant an 8 inch gun, with the serious problems that meant. The guns were heavy and cumbersome, the 6 inch guns could devote much more of a similar amount of weight to ammunition, and blast interference would be severe, particularly on the relatively short and light US ships. The first class of US battleship with such guns, the Indiana was a mess. It took four twin turrets to get four 8 inch guns on a side, and the small ships were incredibly crowded with guns, which made for serious issues with blast interference.

JyEFKCn.jpg

Just look at this. I'm pretty sure some of those firing arcs would be grounds for an evacuation or failing that a court martial.

The ships were simultaneously badly cramped and undermanned (only nine line officers, with none for the torpedoes, main deck battery, secondary battery or replacements for those killed in action(!)), could only use 400 tons of coal if they wanted to have their design freeboard (or to have their belt line up with the waterline, at maximum draft the belt would be submerged). Naturally foreign observers were very impressed, since the US had clearly solved the problem of fitting a very heavy weight of ordnance into a very compact hull, and they neatly missed the statements made in Navy Department publications that they couldn't make an RF 6 inch. The next design down the line (Iowa) was a very similar design that traded in 13 inch main guns for very effective 12s and 6 inch BLR (breech loading rifled) for 4 inch RF in order to get a longer hull with a long forecastle and a greater coal load at normal displacement. This step from "coastline battleship" to "seagoing coastline battleship" was a major improvement. There were still problems though, that the following Kearsarge class sought to improve.

The high 8 inch turrets were troublesome, especially since BuOrd had finally figured out a 5-inch RF gun, and designs showed a long casemate for them, which pushed the 8 inch turrets out torward the ends. The turrets didn't have protection for their support structures all the way up, with only light armor (4" vs and 18" belt) covering half the way up to the turret itself, leaving the potential problem of being undermined by rapid firing guns.

The superposed turret was a replacement for all these problems. The 8 inch turret would be placed on top of the main caliber turret. The unprotected barbette and structure would be replaced by a thickly armored main caliber turret, the 8 inch turrets would be moved over away from the RF battery, and better yet, put them on the centerline so broadside firepower could be maintained with half the turrets. The ideas considered before this design were:

-two centerline turrets and two more on the waist

-two turrets on the beam forward and one superfiring aft

-two superfiring turrets on the centerline

-two turrets in the waist

BuOrd didn't like any of the designs, and an ensign who would later become its chief (Joseph Strauss) came up with the idea of a double-story turret. The immediate objection that the 8 inch guns and 12 inch guns might not want to shoot the same thing was "solved" by even a large ship being a pretty small target at battle range, while at shorter range, the 8 inch guns could take advantage of their 2 to 3 times faster reload to train back and forth. The turret would take "only" 30 seconds (at a point where the main battery fired once in five minutes and the 8 inch once in two) to train from one side to another so in theory fire could be maintained against a weaker target to one side while the main battery engaged a heavier target. Justifications aside, the blast interference situation was markedly improved, and that was a serious improvement over a lot of contemporaries. For example, the French Brennus' crew had worked out a system of bugle calls by which crews could leave their guns to get shelter from the blast of the heavy guns.

The two ships of the Kearsarge class weren't commissioned before 1900, so two more classes were laid down before any operational experience could be gained, but gunnery trials were successful, even though the 8 and 13 inch guns carried by the design were obsolete at that point. Amusingly the merits of the superposed design weren't the most notable features of the gunnery design of the ships. The 13 inch mount was flawed in a way that made the main battery guns be mounted too far back in the turret, which made for huge ports for the guns and potentially enemy fire (this failure, and a possibly contrived scenario by which a lit match (rather than a more likely ember) could be thrown straight through that gap into the magazine was the foundation of Sims' criticism of the design). The 5 inch battery wasn't subdivided by splinter bulkheads, which raised the possibility of a single hitting wiping out the entire battery of 7 guns on the side. Foreign observers didn't seem to hate the design, but nobody copied it, and it was considered to be a typical American overgunning of a ship.

The superposed turret was sidelined after the Kearsarge class, with the advent of a new rapid firing 6 inch gun. Since the 6 inch drastically outpaced the 8 inch in rate of fire and the 8 inch could penetrate enemy secondary protection but only with AP ammunition without HE, the 8 inch gun was rendered dubious in terms of value.

The Spanish-American war rolled around when the Texas, Indiana, and Iowa were the only battleship classes in service, and the 8 inch received favorable reviews for its decent rate of fire, flat trajectory, and actually scoring hits (13 of 319) at Santiago (unlike the 13s). Somehow nobody seems to have noticed that the weapons present for the battle were a generation old, and the rapid fire 6 inch (or even 5 inch) gun wasn't even present. The Virginia class was designed in a period where the 8 inch had a renewed cachet, and they were given two double turrets like the Kearsarge and two more 8 inch turrets in the waist for a broadside of four 12 inch and six 8 inch at the behest of seagoing officers in the Board on Construction (a design similar to the Indiana was favored until the objections of one of the officers meant a second board, which the chief of BuOrd still wasn't included in). It actually took two years to figure out what they wanted to build, and there were later claims that some of the votes in favor of the design built were to spoil a BuOrd proposal for replacing the wing 8" turrets with four additional 6-inch guns.

Unfortunately, while the Virginia class fixed the mounting, they weren't able to fix the passage of time. Heavy guns fired faster by that point in time, enough so that the concussion and smoke from the 12 inch guns alternating fire every 20 seconds, the 8 inch would only have 10 seconds to fire, and would likely interrupt the next 12 inch salvo. A variety of salvo techniques were tried, single barreled, double barreled, double barreled 8 inch combined with single 12 inch, and so on. Nothing really worked for that problem.

On the plus side, they had plenty of experience shooting guns over other turrets. That turned out to be nice to have as they entered the all big gun era. The South Carolina class was able to fit an equal broadside to the Dreadnought under better armor on about 3,000 tons less displacement (it's worth noting the US gave a damn about displacement and the UK didn't).

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Yes?

 

And you need to move all that water at higher speeds, thus you need more energy to do that?

 

Like LC said, you would need more power.  Dimensional analysis is important bro.

 

I suspect that a simple equation like that would suffice over a small range.  Even Issac Newton thought that drag force would be equal to some sort of coefficient multiplied by velocity raised to some power.

 

But if you take that sort of simple model too far, you end up with planes going into unrecoverable dives when the elevators suddenly become unresponsive and the plane starts shuddering above some critical airspeed.

 

NavWeaps is a really good site and has the best info on the subject I've seen:

 

http://navweaps.com/index_tech/tech-029.htm

 

For more:

 

http://navweaps.com/index_tech/index_tech.php#Ship_Design_and_Construction

 

I recommend the one on prismatic coefficient at the very least, it's about hull form.

 

 

Speed thrills I had read, but not the other article.  Thanks.

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Yeah, anything by Stuart is liquid gold when it's about ship design, all of the articles there especially.

The speed thrills article is good for illustrating partially how power and speed relate and also how things can fall apart fast if you push a hull hard enough that previously manageable effects start devouring your power.

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You need more power to do that (to overcome energy lost to drag). Exactly how much depends on your displacement, hull form, surface roughness, and other shit.

 

I read a book from the work library that had a nifty equation for estimating a submerged sub's top speed from reactor output and displacement, I'll see if I can find it in somewhere generally available. I'm about 99.9% sure it was a good bit more complex than the KE equation though.

 

To expand on this, I managed to find the equation in the work library's copy of Strategic Antisubmarine Warfare and Naval Strategy, I believe top speed was proportional to the third root of power (so doubling your power only gets you a 26% increase). There were a bunch of other parameters, but power and hull diameter were the most important.

 

My copy of the book just shipped, so in a few days, I should be able to get the exact numbers (unfortunately, all the book is Imperial units).

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So, all of this is from Appendix 1 of Strategic Antisubmarine Warfare and Naval Strategy;

 

First, there's two components to drag on a submerged submarine; form drag (dependent on the shape), and surface drag. Apparently, with how hydrodynamic subs are, form drag on contributes about 5% of the total (I was surprised too, Stepanick cites pg. 313 of Principles of Naval Architecture by Comstock). Surface drag is given by the following formula;

WNZPju4.png

 

where F is the drag,rho is seawater density, Cf is the coefficient of friction for the sub, U is the speed, and A is the surface area. Setting the maximum propulsive power equal to the drag gives the max speed of the sub (in units of horsepower/knots);

 

dwq5EY0.png

 

Ps is the shaft power, eta is the efficiency.

 

Stepanick gives Cf for submarines at 25-40 knots as ~.0002, with about a 10% variation between hulls.

 

The surface area is dependent on the exact shape, but can be approximated by the formula

 

A = BLD

 

L is length, D is diameter, and B is a number that approaches pi the closer you get to a cylindrical hull. Stepanick lists it as 2.8 for 1960s subs and a bit higher for more modern boats, probably not more than 3.

 

Combining all of these together gives

 

f9xNjED.png

 

which relates the speed to length, diameter, and power. K is 25 for a single shaft and 24 for two shafts.

 

For reference, here's what the book gives for various subs;

 

mPhkHRcl.jpg?1

 

If for some bizarre reason you stuck a second reactor in an Alfa (assuming the hull is lengthened by 30 feet but stays the same diameter), you'd get a predicted top speed of
 

25*(80000/(290*29))^(1/3) ~= 53 knots.

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Speaking of things that carry a lot of torpedoes and go under the water:

 

Fun concepts in ship design: The Torpedo Battleship

The US laid down a whole bunch of dreadnoughts that were on the whole pretty similar in concept. Big armor, big guns, and a low speed. This is not about them. This is about an idea that got seriously considered and wargamed as a supplement to them.

The US had a bit of a love-hate relationship with torpedoes on large ships, putting them on and then taking the above water tubes off their early battleships following the Spanish-American War. However torpedoes kept getting better and by late 1903 the General board was recommending them on every armored vessel of the Navy under construction, one or preferably two as they started proving decisive in war games at ranges of 3,000 yards or even more.

But if one was good, why not more? In 1903, that was answered by advances in fire control taking gunnery out to considerably longer ranges. In 1907 a Lieutenant Commander Schofield proposed a 23 knot ship that used weight that would otherwise go to guns to become essentially proof to shellfire, above a 16 21-inch torpedo tubes, with only 12 5 inch guns to cover from torpedo ships. A torpedo hit was reasoned to probably sink and certainly cripple its target, and such a ship would be able to launch an entire school of fish at once. While battleships would be firing at longer ranges and unlikely to be able to fire their torpedoes and lighter torpedo ships could be held at bay, such a ship could fire torpedoes into an 18-knot fleet with ease, with armor to deal with the shellfire that represented the only major threat. Gaming showed that a fleet with two such ships could always attack an enemy line with torpedoes.

So the idea went on to the main games, where the ships were given a charitable rating of equivalence in underwater resistance to damage (charitable in that a university system of torpedo rooms like that would've meant the TDS would be a torpedo detonation syndrome rather than a torpedo defense system, but this wasn't realized until years later, when it led to the removal of submerged torpedo tubes). The ship was given a 50% greater life than a usual battleship, since it would still be vulnerable to conning tower and smoke pipe hits even if it wasn't actually sunk. In games with such ships replacing battleships 1-1, one such ship could never succeed but two nearly always resulted in victory. There were other unconventional ships being touted however, and the battlecruiser as represented by HMS Invincible and a more heavily armored example the Naval War College had devised in 1904 offered a serious problem, since the design depended on a surfeit of speed. The Invincible was already faster by two knots, and could carry a significant torpedo load as well as a battery superior to any battleship except the Dreadnought. By the time a reworked torpedo battleship was submitted, gunnery had gained ground yet again, and an enemy fleet with battlecruisers was able to wipe them out before they entered torpedo range. Further attempts to gain sufficient speed led towards unsustainable sacrifices. Late drafts could hit 31 knots, with four 14 inch guns and a very large number of 6 inch guns, with a protected cruiser armor scheme, and it took mounting all four guns in a single thin turret to get a belt. It just wasn't going to work.

However, the torpedo was still considered very strongly as a battleship weapon even in 1914, when the General Board wanted four tubes a side, and when C&R started screeching about how the torpedo bulkheads would be compromised and structural bulkheads near No. 1 turret would have to be cut, they accepted a cut of half a knot. Thankfully war experience showed soon that it turned out that firing the things at speeds over 16 knots was pretty much impossible, damage showed they were a weakness, and in the end they were omitted. In 1921 the above water tube was set to make a comeback with the South Dakota class (not that one, the one that got canceled by treaty), but by the end of the treaty era the battleship torpedo tube was not in the US' design ideas.

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Were torp tubes on battleships a worldwide fad at the time?  I note that the Germans and Italians ended up slapping some on theirs.

 

Honestly I'd be surprised to see anybody without torp tubes on their battleships through most of the dreadnought era through till the treaty. The biggest divergence I can think of is the US not putting forward or aft tubes on even early on, which goes with their general disdain for concerns about end-on fire.

 

They seem to have been universal up until the treaty. Japan had some really heavy layouts, with the Nagato class carrying eight a side (two of four per side were above water, which is interesting).

 

Germany, UK, Japan, France, Italy, Austria-Hungary, Russia, Argentina, Chile, the only navy I can think of to have battleships without any tubes are the Brazilians (I definitely had to look that one up).

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I didn't realize that torps on battleships were so common.

 

What happened?  Did fire control get good enough that they were inferior to large-caliber guns, or do torps drive weight up for reasons that aren't obvious?

 

Fire control got good enough that they didn't overlap with battleship engagement ranges any more. When I mentioned that in 1903, they were talking about torpedoes being decisive at 3,000 yards, those were ranges that gunnery was being exchanged at as well. Later on, torpedoes weren't able to keep up with the rapid realization of big guns' potential driven by fire control systems. Plus, you'd have to slow down, which kept becoming more of an imposition as speeds grew. Range was the main driver though, in 1911, the torpedo could reach 6,000 yards, but gun range had quadrupled to 12,000 yards. The 1913 specification for Battleship 1915 that was enthusiastic about torpedoes was shortly following a 10,000 yard torpedo.

 

Torps are more expensive in terms of room than in terms of weight, although in some designs they may cost room in such a way that you need to spend weight on ship structure to offset that. The other big problem is that they take room that you can't put a torpedo defense system in and that you can't carry structural bulkheads through. Worse, through WWI and the destructive testing that followed the treaty, they started to realize just what happened when a shell fell short and what happened when such a room was hit (that was more WWI experience). Suddenly people weren't feeling so smug about those unprotected rooms full of torpedo. The main reason they lasted as long as the final pre-treaty designs was likely inertia driven partly by just how long it took to design ships (see also that 1913 spec for Battleship 1915). There's still some wiggle room in the timeframe I should go over WWI history again to cover.

 

Edit for clarification: By wiggle room, I'm surprised the Nelsons got built with torpedoes. I can easily see the Colorado class being in the pipes, the Nagato class wasn't from a nation that would've had much first hand experience with underwater damage, but the British surprise me. At a guess, the Nelsons were quite long ships (reducing drag by lengthening the hull was a lighter way to gain speed than adding more machinery and its protection), so the room wasn't a big deal.

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Regarding the US adopting triple turrets much later than some other nations:

 

The US' first ships that could have really benefitted from triples are the Delaware class, and it appears that for them (and the Floridas when the 14" wasn't ready in time) that weight at the aft end of the ship was very limited, to the point they accepted only one turret able to fire straight backwards to avoid even the extra weight that making the number 4 turret superfiring would have added. Unfortunately I don't know what was up with the Wyomings. The New Yorks ended up like that just because they were designed before the triple was really finished, the Delawares are the real mystery and I don't know why.

The US went with triples because they'd seen just how clumsy the five and six turret layouts that resulted otherwise were. They were still concerned about excessive weight aft it seems, the first draft of what became the Nevada was based on the New York with the number 4 turret eliminated and number 3 raised before all turrets were turned into triples rather than eliminating number 3. It's also worth a quick note that all this is with 14" guns rather than the 12s on previous triples, which makes the weight on the ends a much bigger problem. Only after Delaware's magazine cooling was reported a failure did they push the turrets all the way out on the ends. The triple was actually adopted after the New York class as a weight and length saving measure. The USN was actually very tightly limited in ship cost by its political setup, with a lot of repeat ship classes out of a desire to not raise costs. That translated into a direct limit on armor and machinery weight.

The US had previously considered triples (and they'd had de facto quads with the Virginias) all the way back in 1905 (I don't want to know what "semisuperposed" means incidentally) for the South Carolina. The biggest problem for them seems to have been getting the turret working the way they ran things, since each gun was elevated by a single pointer per and they weren't sure where the middle gun's pointer would go. The solution was a single pointer per turret with the guns elevating as a unit, but that left concerns about a single blow knocking out the entire turret and the alignment of the guns in the unit. They also used a very strong front plate to make up for three holes, and tried to get a turret prototyped (it took until two classes with it had been contracted though). Incidentally this is where the US got a lot of their information on gun interference. They hedged their bets by considering twin 15 inch turrets.

Later on BuOrd wanted to avoid working on twin and triple turrets at once when going to 16 inch turrets, preferring a New York style layout (BuEng wanted to keep the machinery the same and go with four turrets). General Board went with five doubles based on fleet experience with doubles and inexperience with triples, as well as theorycrafting that another double would be pretty cheap weight-wise and turboelectric machinery would allow a layout that wouldn't heat the middle turret's magazine. Josephus Daniels said fuck this noise we're building a repeat of last class, pick the caliber you want and that became the Colorado.

I'll point out that the Dante Aligheri and Gangut classes both had two midsection turrets, while the US seemed to have sought to minimize the amount of turrets there. The Tegetthoff class was the familiar ABXY layout, but I don't know if they had any issues with the layout. Frankly I don't take inclusion on that class to be an automatic sign that something doesn't have significant problems, and I'm sure you'd agree there.

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