American militarism pre-WW2 and the Ultimate Battleship

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TheMarcksPlan
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Re: American militarism pre-WW2 and the Ultimate Battleship

Post by TheMarcksPlan » 24 Feb 2021 22:13

Richard Anderson wrote:So why don't they spend a billion more for a fusion reactor as power source?
About as serious a response as shells falling out of chambers (despite this never happening in thousands of high-level guns) and America building plane-less aircraft carriers.

We get it. You don't like What If's. What If you found something you enjoyed?
https://medium.com/counterfactualww2
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Re: American militarism pre-WW2 and the Ultimate Battleship

Post by Terry Duncan » 25 Feb 2021 09:41

Shells have slipped out of the chamber in heavy guns when loading at high angles, which is why most navies fell back on limited angle or even fixed angle loading after spending a lot of cash chasing the all angle loading heavy gun - the 15" guns on Hood were capable of this but it was found to be wasteful being just one example.

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Re: American militarism pre-WW2 and the Ultimate Battleship

Post by T. A. Gardner » 25 Feb 2021 16:03

You also have to consider there will be a cooling problem here. Lots of rounds fired will heat the gun. You really can't load a hot gun with bagged powder in any case without the very real possibility it will cook off the powdered during loading and wipe out the gun crew and turret.

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Re: American militarism pre-WW2 and the Ultimate Battleship

Post by Carl Schwamberger » 25 Feb 2021 16:13

T. A. Gardner wrote:
25 Feb 2021 16:03
You also have to consider there will be a cooling problem here. Lots of rounds fired will heat the gun. You really can't load a hot gun with bagged powder in any case without the very real possibility it will cook off the powdered during loading and wipe out the gun crew and turret.
Swabing the breach interior with water helps a lot, but there are limits. Im trying to imagine sloshing liters of water around a confined breech space in a turret. It must have been done by some, but theres a point where it sounds impractical.

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Re: American militarism pre-WW2 and the Ultimate Battleship

Post by T. A. Gardner » 25 Feb 2021 17:04

Carl Schwamberger wrote:
25 Feb 2021 16:13
T. A. Gardner wrote:
25 Feb 2021 16:03
You also have to consider there will be a cooling problem here. Lots of rounds fired will heat the gun. You really can't load a hot gun with bagged powder in any case without the very real possibility it will cook off the powdered during loading and wipe out the gun crew and turret.
Swabing the breach interior with water helps a lot, but there are limits. Im trying to imagine sloshing liters of water around a confined breech space in a turret. It must have been done by some, but theres a point where it sounds impractical.
That would require sponging the breech then swabbing it to remove any remaining water. In turn, that adds more gun crew and time between rounds. And, it'd be one big sponge too!

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Re: American militarism pre-WW2 and the Ultimate Battleship

Post by Richard Anderson » 25 Feb 2021 17:26

Terry Duncan wrote:
25 Feb 2021 09:41
Shells have slipped out of the chamber in heavy guns when loading at high angles, which is why most navies fell back on limited angle or even fixed angle loading after spending a lot of cash chasing the all angle loading heavy gun - the 15" guns on Hood were capable of this but it was found to be wasteful being just one example.
Not just that, but failure to seat properly results in excessive dispersion, i.e., loss of accuracy, and excessive barrel wear, especially at the chamber. Add to that the possibilities of damage from broken driving bands and you have an excellent recipe for reducing wear from c. 300 rounds per replacement to something less...not too great an idea when you only have a single such vessel.
"Is all this pretentious pseudo intellectual citing of sources REALLY necessary? It gets in the way of a good, spirited debate, destroys the cadence." POD, 6 October 2018

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Re: American militarism pre-WW2 and the Ultimate Battleship

Post by Richard Anderson » 25 Feb 2021 17:31

T. A. Gardner wrote:
25 Feb 2021 17:04
Carl Schwamberger wrote:
25 Feb 2021 16:13
T. A. Gardner wrote:
25 Feb 2021 16:03
You also have to consider there will be a cooling problem here. Lots of rounds fired will heat the gun. You really can't load a hot gun with bagged powder in any case without the very real possibility it will cook off the powdered during loading and wipe out the gun crew and turret.
Swabing the breach interior with water helps a lot, but there are limits. Im trying to imagine sloshing liters of water around a confined breech space in a turret. It must have been done by some, but theres a point where it sounds impractical.
That would require sponging the breech then swabbing it to remove any remaining water. In turn, that adds more gun crew and time between rounds. And, it'd be one big sponge too!
Its simple and you obviously don't understand the true genius of this design. Since USS Behometh is a behemoth, you can simply add a lake in the center for cooling water and build water-cooled 18-inch guns. Then all you need is the compressed air system for clearing the barrel and chamber after each round. That might require a separate power-plant just to drive the compressors, and then you need room for the 1,000-odd compressed air tanks, but again, if you need space, USS Behemoth just needs to be bigger. Problem solved.
"Is all this pretentious pseudo intellectual citing of sources REALLY necessary? It gets in the way of a good, spirited debate, destroys the cadence." POD, 6 October 2018

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Re: American militarism pre-WW2 and the Ultimate Battleship

Post by TheMarcksPlan » 25 Feb 2021 19:52

T. A. Gardner wrote:
25 Feb 2021 16:03
You also have to consider there will be a cooling problem here. Lots of rounds fired will heat the gun. You really can't load a hot gun with bagged powder in any case without the very real possibility it will cook off the powdered during loading and wipe out the gun crew and turret.
Yeah I've considered a cooling system. At least for the outer barrels, shroud it in a foot-thick (or so) sheathing and pump water through it. The ship will have a massive pumping apparatus for damage control, should be possible to divert some of that to cooling hoses unless/until it's needed for damage control.

I'd guess there's barrel degradation issues for pumping seawater through the barrels. If so, you could pump freshwater through. Tanking 100k tons of freshwater is no biggie. Plus even when cruising at 33kn you have 2mil extra HP and/or boilers with which to power a distillation plant. So it'd be easy to regenerate a freshwater cooling supply. For the outer barrels, water could just go through a heat exchanger with seawater as for the condensers.

Other point about cooling is the ship's speed and tactics. As the ship engages at super-long range and can do 40+kn, it can disengage to cool the barrels if necessary. Enemy isn't going anywhere not wanted, relative to the ship.

Of course if cooling is needed after 50 rds/gun, that's 50,000 rounds fired and at 1% accuracy 500 hits. Not sure there's any Axis fleet left after eating 500 plunging/penetrating 18in shells.
https://medium.com/counterfactualww2
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Re: American militarism pre-WW2 and the Ultimate Battleship

Post by TheMarcksPlan » 25 Feb 2021 20:23

Re firing cycle time, here's what happens at the gun face when elevating from 45 to 70 degrees per round:

Image

Again the tray loading operations happen simultaneously behind a partition, which is what enables a dramatically faster cycle (that and the automatic breach/primer).

Separate cycle for the tray-loading operations. It's probably a two-stage hoist system.

As you can see, achieving 5 rds/min is easily doable at the gun face once its operations are physically (and therefore temporally) separated from tray loading. We can probably do short bursts of higher-rate firing depending on how much machinery we want tray-side. For reasons of labor economy, the primary (first stage) shell hoists will probably be limited to 5 rds/min max. To go higher would add thousands of shell/powder schleppers in the magazines and would probably be precluded by cooling issues anyway for longer-term operation.
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"The whole question of whether we win or lose the war depends on the Russians." - FDR, June 1942

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Re: American militarism pre-WW2 and the Ultimate Battleship

Post by TheMarcksPlan » 25 Feb 2021 21:45

Re the shells falling out issue... Again, many feasible solutions IF that's actually a problem. One is to add rubber/plastic around the shell base forward and aft of the bourellete and rotating bands.

Image

As these rub/burn off upon firing, they shouldn't change ballistic characteristics significantly.

Again, same type of solution with the powder bags: aft bag (or two) has a rubber/plastic/foam compressible exterior.

Intriguing possibility: if plastic is used, perhaps USN discovers the barrel-wear saving effects of plastic long before OTL. This practically eliminated barrel wear as a factor; the life limitation became 1,500 cycles on the combustion chamber instead.

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TheMarcksPlan wrote:As you can see, achieving 5 rds/min is easily doable
The cycle times in the spreadsheet are approximate, if we need an extra second or two for ramming, we're still well within the 12 sec cycle required.
https://medium.com/counterfactualww2
"The whole question of whether we win or lose the war depends on the Russians." - FDR, June 1942

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Re: American militarism pre-WW2 and the Ultimate Battleship

Post by TheMarcksPlan » 26 Feb 2021 04:59

TheMarcksPlan wrote:
25 Feb 2021 20:23
Re firing cycle time, here's what happens at the gun face
The rest is pretty straightforward. We need the second-stage hoists go from first stage pickup to tray (and back) in <12 seconds. That's easily doable.

Second Stage Hoists

The turret cross looks something like this drawing I did a while back and posted far upthread:

Image

Shells ascend ~10 feet, powder ~17feet. To make the roundtrip journey in 12 seconds, minus a second for transfer, requires ~2 ft/s and ~3 fts/s for shells and powder respectively (~1.4- 2.1 mph). On the same HP we could speed up the descent - when the hoist is unloaded and working with gravity - and thereby slow down the ascent. Or we could specify a shorter cycle time.

We'll probably want to specify a shorter cycle time of, say, 7.5 seconds for the second-stage hoists. This will enable the ship to do short bursts at up to 8 rds/min when firing from near the loading angle of 45 degrees - which is around where the guns will fire at max range engagements and when doing long-range AA barrages against approach high-altitude aircraft.

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First stage hoists

I envision the first-stage hoists being outside the rotating structure, feeding the turrets via at least two independently-rotating rings that would periodically mate to the rotating structure. Again this is something only possible due to the absence of barbette - otherwise there's space for this solution. I'm not gonna redo the drawing completely (maybe I will if someone is earnestly interested); here's a 30sec sketch via Paint:

Image

Red arrows for shell flows, black for powder.

It's not fully drawn, but each row of guns in the turret is 6-7ft higher than preceding one. On the three-row turret, the upper two horizontal areas would feed shell and powder decks devoted to third-row guns. Thus we can have 4-5 levels of stacked rotating rings around the turret circle, each feeding turret levels that service different rows of guns.

I've put another set of black arrows with question marks on the diagram. This represents the option of using a level(s) below the first-row powder floor for intermediate hoists to the second-row powder floors. If space on the floors becomes a problem or if we want more room to stow ready rounds (for high-rate bursts), this is an option. Otherwise the bottom two layers on the above drawing are superfluous.

[I realize this is not a great drawing so if somebody's really interested in the schematics, which make perfect sense in my head, I'll post a better version.]

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It might be possible to do a single-hoist system if we specify shell & powder magazines up around the turrets. Two good reasons not do so, though perhaps it's a worthwhile saving of machinery and generating plant:
  • Powder we usually want as far low as possible for safety reasons. If we're sufficiently confident in our deck armor's impenetrability, however, maybe.
  • Because the megaship carries so much shell weight (~800k tons probably), and because the hull is so deep, shell storage has a big impact on vertical CoG. With shell storage near the bottom of the hull, full-draft (ballasted) CoG is ~35ft below the waterline. If shells are stored abreast the turrets, ballasted CoG moves up to around the waterline. Most BB's had CoG above the waterline, however, so maybe we move the shells up - they're safer up there than powder. That removes a lot of first-stage hoist machinery.



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Tactical implications for surface engagements: The ship can dart in and out of maximum practical range for adversaries, firing short bursts at 8 rds/min then maneuvering back out of range using her 40kn speed. Typical shell flight time at >40k yards is >80 seconds, megaship might fire 7 rounds in 45 secs (one in the chamber at t=0) then maneuver hard, exiting the enemy's target point at 22.5 yards/sec. By the time enemy shells start landing 35 seconds later, she's quite far from the aiming point (depending on turning radius specifications - as discussed upthread, this can be surprisingly low due to megaship's multiplicity of shafts and availability of reverse).

Of course the enemy can maneuver too but megaship will presumably be firing against a battle line, barrage style. Enemy maneuvers during shell flight time will only shift which ships get hit. [If the megaship is fighting only one ship, that's either a very unlucky ship or Japan has spent everything on its own megaship].
https://medium.com/counterfactualww2
"The whole question of whether we win or lose the war depends on the Russians." - FDR, June 1942

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