Starting with the smashing of Dunkirk

Chapter 103 Paving the Way for Dual Use of Gaoping
Whether to produce 16 more potentially surplus cannon barrels was not a decision Lelouch could make; naturally, he looked to Gustav.
Faced with the eager looks from the Minister of the Navy and Lelouch, Gustav immediately patted his chest in assurance:

"Krupp is willing to take this risk! After all, it's an insurance policy for the construction cycle of the Imperial Navy. At worst, we'll just have to build 16 more pipes that we don't know what to do with and end up with unused stock."

In fact, Gustav had already slipped up a little when answering this question—

He didn't need to make any extra sacrifices, because eight of the 16 pipes were almost finished, and those were originally intended for the "Baden". As for the eight for the "Baria", they had been completed long ago and were even repurposed for railway guns, with eight more ordered later. Although this batch wasn't finished yet, the steel billets had already been forged.

In other words, regardless of whether Tirpitz made this request or not, Krupp had to complete the production of those 16 pipes. He was simply saying this to make the customer feel indebted to him.

However, Tirpitz and Lelouch were unaware of this, so Lelouch generously offered Gustav advice on finding a new employer:
"Don't worry about that. If the old cannons don't sell well in the end, I'll find you another buyer. Whether you continue to develop railway cannons or coastal defense cannons, I'm sure every heavy cannon from Krupp will play its due role."

Gustav smiled slightly embarrassedly upon hearing this. He had only intended to play the victim to gain some sympathy, but he hadn't expected Lelouch to be so honest.

He quickly replied, "With Director Lelouch's words, what else could I possibly worry about? The use you've come up with is definitely the best."

"You converted those eight main guns of the 'Balya' into railway guns, which ultimately played a crucial role in sinking the 'Warspite' and severely damaging the 'Queen Elizabeth.' Without those large guns, the Empire would have been helpless against the Queen Elizabeth-class ships."

This topic was temporarily put aside, and all parties formally agreed to use new three-phase electric arc furnace gun steel forged main guns for the "Barria-class" battleships and even the "Mackenson-class" battlecruisers that followed.

After discussing the main gun issue, Lelouch pressed on, continuing to help Gustav sell more secondary/cruiser guns made with electric arc furnace gun steel.

Lelouch then said, "Your Excellency Marshal, I believe that the Imperial Navy's 150mm cruiser guns, and even the secondary guns of battleships, can be completely redesigned and replanned. We can make sure that all new ships use a brand-new gun made of high-quality gun steel, and we can even develop a new caliber."

As soon as Lelouch uttered those words, Tirpitz and Gustav immediately frowned: Changing the gun steel was one thing, but they also wanted to change the caliber? Wouldn't that increase logistical complexity and increase the stockpile of military equipment?
Warfare is all about logistics. The simpler the supply, the better. Why should the caliber of artillery shells be increased arbitrarily if there is no need for it?
However, considering that Lelouch's previous suggestions had been quite good and that he had a history of credibility, Marshal Tirpitz patiently gave him a chance to finish speaking:

"Then tell me, what caliber of gun do you want to add? Why do you have to save on barrel weight and use new gun steel for such secondary/cruiser guns?"

Lelouch immediately produced a set of ideas that he had repeatedly pondered during his previous life as a military enthusiast, and began to speak eloquently:
“I think the Empire could take inspiration from the 140mm secondary guns used on the Franks’ latest ‘Brittany-class’ battleships and develop a similar one.”

Of course, the 140 of the Franks is just a nominal designation. I measured the actual diameter precisely using the finished product that was seized from the Dunkirk shipyard and it was 138.6 mm, which is exactly 1% smaller than the nominal value.

We now have readily available captured samples, as well as other production equipment and materials seized during the Northern French campaign. Based on imitation, reverse engineering should be easily achievable, given Krupp's technological capabilities, or even if we bring Rheinmetall into the mix.

Upon hearing this, Marshal Tirpitz waved his hand, signaling the other party to stop: "You don't need to tell me 'how fast or easy it is to develop this thing' first. What I care about first is the necessity and benefits of developing it! If something is useless, no matter how easy it is to develop, it is still useless!"

Lelouch immediately adjusted his analysis: "In terms of use, 138.6 mm or 140 mm guns are certainly very valuable, mainly in the following aspects: The reason why the Franks painstakingly spent a long time developing such an odd caliber as 138.6 mm was to repeatedly test the 'sweet spot' of the limits of manual loading of complete shells."

A 127mm or 5-inch gun can be fitted with a complete set of shells and propellant charges, not to mention the smaller 105mm gun. This is why, whether it is naval guns or land guns, the rate of fire of 105mm or 127mm guns is much faster than that of heavy guns of 150mm or more, at least twice as fast.

At the 150 level, the weight of the shells themselves, excluding the propellant charge, is around 60 kilograms or even heavier. With the propellant charge and packaging materials, it may approach 80 kilograms. We cannot recruit strong enough sailors who can repeatedly carry 80-kilogram weights on their own and operate continuously without errors.

The caliber of around 140 mm was the 'sweet spot' determined by the Franks after repeated testing; that is, the 'maximum caliber that allows a strong sailor to repeatedly move the entire shell, including the warhead and propellant.'

Previously, when various countries manufactured artillery, they used calibers like 105/127/152 simply to round up to whole inches; it was for convenience, not for greater physical rationality.

Tirpitz and Gustav understood these principles, after all, the Franks had been thinking about this for many years, and as adversaries, they would generally study the enemy's naval weapon planning ideas.

But the Demacian navy has always been known for its efficiency and precision, and Tirpitz has never liked rapid water splashing, so he frowned and said:
"But is it necessary to pursue such an extreme rate of fire? The current rate of fire of the secondary guns is already sufficient, as is their maneuverability. Reducing the rate of fire from 150 to 140 will result in a loss of power, armor penetration, and maximum range. Moreover, the Empire's 150 is the best 150 in the world, and there is no reason to give up its existing advantages."

The Empire's 150 secondary guns were designed to long-range sniping of enemy light, high-speed torpedo boats at distances exceeding 10,000 meters. However, it takes over ten seconds for a shell to travel 10,000 meters. For artillery with a firing rate exceeding six rounds per minute, this is largely ineffective at this distance; the next round fires before the previous one has even landed, leaving no time for correction of any errors.

Lelouch, of course, knew that Marshal Tirpitz was right, so he didn't intend to refute him directly. Instead, he offered another application scenario to broaden everyone's thinking:

"However, Your Excellency Marshal, have you considered that the application scenarios for secondary guns and cruiser guns in the future will be different from those now? Airplanes have already appeared, although they do not yet have strong ground and sea attack capabilities, but their long-term development trend should not be underestimated."

Six months ago, airplanes couldn't even engage in aerial combat with machine guns, but now they can. Pilots can also manually drop single bombs weighing around 5 kilograms below the plane. With the addition of a simple escapement mechanism in the future, dropping bombs weighing tens of kilograms or even heavier will be no problem.

The Empire's airship force, in the Battle of de Panne, annihilated two Britannian pre-dreadnoughts that had sunk on the beach with 2000 kilograms of aerial bombs. All of this foreshadowed the increasingly serious aerial threats that future battleships would face.

The 150mm secondary gun, due to the excessive weight of its shells, had to be loaded with separate warheads and propellant charges, which limited its rate of fire and made it difficult to rotate, thus making it ineffective for air defense.

However, by scaling down to the 140mm caliber and using specialized anti-aircraft shot/fragmentation rounds, the effective fragmentation count could be increased by another 50% compared to a 127mm cannon, and the kill radius would be increased by more than 20%. Combined with altitude-fixed fuse anti-aircraft defense, this would certainly be much more effective.

Lelouch, drawing on his understanding of future anti-aircraft guns from his time-traveling perspective, described the "dual-purpose" concept to Tirpitz and the others, which indeed prompted deep thought among them. "Is this for the needs of facing future air defense threats? That makes some sense. Long-range air defense should definitely be taken seriously..." Tirpitz muttered to himself, quite moved.

In fact, Lelouch had another consideration hidden—he knew that if he focused on radio technology in the future, miniaturizing and reducing the cost of passive radio detection devices would make it possible to create the VT radio proximity fuse.

Historically, one important reason why the Demania series of secondary guns was not suitable for both anti-aircraft and anti-tank purposes was that the 105mm caliber was too small. After the radio proximity fuse was packed into the shell, it took up too much space, leaving little volume for fragments and explosives, resulting in extremely poor anti-aircraft efficiency.

The 150mm gun, due to its separate loading mechanism, also couldn't be used for rapid-fire against air targets. Ultimately, this led to the US 127mm dual-purpose gun becoming the king of the radio proximity fuse era.

Historically, the Demacian army did not prioritize 127mm cannons; their land artillery jumped directly from 105mm to 150mm, unlike their infantry which had 60-pounder cannons around 127mm, or the Lussa army on the Eastern Front which had 122mm cannons.

In terms of the navy, Demania did not have destroyers based on the Burghers concept during World War I. They only had so-called destroyers that resembled "large torpedo boats," which used 88mm main guns, the same as those used on submarines. Moving up to light cruisers, they directly used 150mm guns. While light cruisers did have 105mm secondary guns, the "large torpedo boats" did not use them.

So much so that during World War II, some "destroyers" equipped with a small number of 150mm main guns were created. If we were to strictly classify them according to the caliber of the main guns, these would hardly be considered destroyers; they would be considered light cruisers, only lacking the endurance and combat range of light cruisers.

Therefore, from this perspective, Lelouch's suggestion that Marshal Tirpitz should now make up his mind to develop a 140mm or 138.6mm gun based on existing French guns is actually very worthwhile.

If it were any other country, they would already have a 127mm gun, so building a 140mm gun would be redundant. But Demand didn't even have a 127mm gun, so there was no waste. (The German 127mm gun was actually later upgraded to a 128mm gun; there were twin 128mm heavy anti-aircraft guns and Jagdtiger 128mm anti-tank guns.)

From now on, let's never work with 127/128mm or anything like that again. Let's just add another 10mm to 140mm and get it close to the "sweet spot" of "maximum weight of manually loaded ammunition".

The future navy's 150mm and 105mm guns can be absorbed by the 140mm guns. Alternatively, one of the 105mm and 88mm guns can be retained specifically to deal with high-speed torpedo boats, or as supplementary firepower for medium-range air defense. However, once the Bofors 40mm gun is available in the future, the 88mm gun will not be of much value on warships.

……

Lelouch's vision of merging calibers and combining high-altitude and low-altitude defense with air defense capabilities finally persuaded Marshal Tirpitz.

After much deliberation, he finally made this epoch-making decision: not to be ashamed to learn from the Franks, but to start with the 138.6mm physical objects and data that the Franks had already captured, and to develop Demania's own 140mm guns!
From now on, we will not build new 150mm frigates, and we will never develop 128mm frigates again.

If, in the future, we want to emulate the Britannians and build large, conventional destroyers, we can directly equip them with 140mm main guns. The difference between destroyers and light cruisers doesn't necessarily lie in the main gun caliber; it could simply be in terms of protection, combat radius, and firepower density.

Large destroyers have short ranges and small hulls, and are equipped with only two 140mm gun turrets, one forward and one aft, but their torpedo attack capabilities are roughly the same.

With its long range, long hull, and slightly stronger protection, the light cruiser can be equipped with several 140mm turrets, serving as the main force for sweeping away enemy torpedo formations in outpost battles.

Seeing that he had finally persuaded Marshal Tirpitz, Lelouch took the opportunity to add some more details:
"Your Excellency Marshal, I believe that since the Empire has decided to develop 140mm secondary/cruiser guns, perhaps some minor adjustments can be made to the battleships currently under construction and even those designed for the future."

Currently, all secondary guns are caseback guns, mounted on a dedicated gun deck, which can only rotate left and right, while elevation is greatly restricted.

If we want to make them suitable for both high-altitude and low-altitude use in the future, then all secondary guns must be turreted. If we directly build 150mm secondary guns, converting them to turreted configurations will be very troublesome, because turreted guns of the same caliber will definitely take up more space and tonnage than casement guns, and are more difficult to adjust.

However, we deliberately reduced the cannon caliber by at least 10 millimeters, greatly reducing the tonnage and volume of the cannons themselves. I estimate that replacing the original two single-mounted 150mm guns with one twin-mounted 140mm turret would allow for significant adjustments in size and weight. If a decision needs to be made, it should be made now to avoid major modifications to other battleships in the future.

After listening, Tirpitz first looked at Gustav, who immediately stated: "Krupp is confident that it can build a 140 twin-mounted gun within the reserved volume and weight of the original two 150 single-mounted guns. However, the design and construction of the hull are not something we can decide; it depends on the Wilhelm Shipyard and the relevant design bureau."

Tirpitz was very knowledgeable about this and could accurately assess the design capabilities of those organizations. After some deliberation, he ultimately offered a prudent compromise:

"Then the 'Barria' and 'Baden' will remain stationary for now, as there's definitely not enough time. They can be modernized later if needed after the war ends, leaving room for future modernization."

The last three ships of the 'Baria-class' haven't even been completely finished yet. You can remove the uppermost galley gun deck to free up space for the 140mm twin secondary gun turrets. But Krupp, don't mess things up. Remember to estimate the size and tonnage of the 140mm twin dual-purpose gun turrets in advance, leave some margin, and inform the design bureau at Wilhelm Shipyard so that the project can proceed in parallel.

The tonnage and size specifications you reported will be strictly enforced; the actual manufactured product must be smaller, not larger. Otherwise, if it exceeds the specifications and cannot be installed, you will be held responsible.

Gustav readily agreed, saying he would take care of everything.

-

P.S.: I was originally going to post the second update after class this afternoon, but I ended up finishing it before class this morning. That's all for now.

(End of this chapter)