Iron Sonata of World War II

But wait a minute, things are not as simple as you think!

On the one hand, before and after World War II in the last plane, the navies of various countries did have many plans to transform large-scale high-speed cruise ships into aircraft carriers (in fact, the sister ship "Europa" of the cruise ship "Bremen" in the previous plane also used to It was one of the objects considered by Mustache to transform into an aircraft carrier).

But on the other hand, if you look at it carefully, of all these carrier modification programs, very few examples were put into practice, even fewer examples were eventually completed, and even fewer examples were successfully applied. few!

What's going on here?

Chapter 54

In World War II in the previous plane, although most countries had plans to transform high-speed cruise ships into aircraft carriers, only Japan was the one that actually built them and achieved good results. And among all the aircraft carriers converted from cruise ships in Japan, only the "Flying Eagle Class" Aircraft carriers were more successful.

In addition to the "Flying Eagle", Japan has several other aircraft carriers converted from cruise ships, such as the "Great Eagle".However, the prototypes of these modified aircraft carriers are not high-speed cruise ships. After the modification is completed, most of them only have a speed of just over 20 knots. As a fleet carrier, it is too slow, so it has not played much role.

There are two "Flying Eagle" aircraft carriers in Japan, namely "Flying Eagle" and "Hayato".Its predecessors were the 24000-ton large high-speed cruise ships "Kashihara Maru" and "Izumo Maru".After the modification is completed, the "Flying Eagle" has a carrying capacity of 58 aircraft and a speed of 25.5 knots.It can be said that apart from the slightly insufficient speed and weak defense ability, the attack ability is not weaker than that of a medium-sized fleet aircraft carrier like "Flying Dragon". The record of the "Flying Eagle" is also remarkable. In the history of the last plane, after Japan lost four fleet aircraft carriers at Midway Island, two "Flying Eagle" and two "Xianghe" "It suddenly became the pillar of the Japanese navy. The highlight moment of the "Flying Eagle" was the naval battle in the Santa Cruz Islands.In this campaign, the carrier-based aircraft on the "Hayato" sank the US fleet aircraft carrier "Hornet". Of course, this was also the last decent victory of the Japanese navy against the United States on the Pacific battlefield.

In addition to Japan's "Flying Eagle", the performance of the modified cruise ship aircraft carrier is relatively close to that of the large and medium-sized fleet aircraft carrier. With a displacement of 23500 tons, it has a carrying capacity of 51-66 aircraft and a speed of 30 knots.The ammunition depot and fuel depot also have 76mm armor coverage, and the overall performance is much higher than that of the Japanese "Flying Eagle".However, it is a pity that due to the large amount of modification work on the "Aquila", coupled with the old tradition of procrastination by the Italians, the transformation of the "Aquila" began in 1941 and was not completed until the end of the war. %, then there is no then.

In short, before and after World War II in the previous plane, many countries and countries were interested in the conversion of high-speed cruise ships to aircraft carriers, but few of them actually completed the modification and played a role, and the relatively successful cases were only the "Flying Eagle-class" sister ships.In stark contrast to the aircraft carrier converted from a cruise ship is the aircraft carrier converted from a cargo ship. In World War II, the three naval powers of China, the United States, Britain and Japan used no less than a hundred aircraft carriers converted from cargo ships!For example, the "Borg-class" light aircraft carrier in the United States was rebuilt from the hull of a C-3 standard cargo ship, and 44 ships were built in one go!

This situation seems unreasonable, because in terms of the potential of being converted into an aircraft carrier, high-speed cruise ships are undoubtedly the most potential of all civilian ships!Most of the high-speed cruise ships have large displacement, slender hull and high speed. Compared with those fat, short and clumsy cargo ships, such basic conditions are not known to be higher.So why, in the game of transforming a civilian ship into an aircraft carrier, the high-end and high-end high-speed cruise ship has been preempted by the cargo ship?There are two main reasons:

The first is the cost and duration of the modification.It is precisely because the high-speed cruise ship has great potential for refitting, it is naturally impossible for the designer to hold back when formulating a refit plan. He must hope that the high-speed cruise ship can play the role of a large and medium-sized fleet carrier after the refit is completed.And if you want to become a large and medium-sized fleet carrier, the range of changes will naturally not be small.On the other hand, when converting a cargo ship to an aircraft carrier, no designer would think of turning a cargo ship into a fleet aircraft carrier. They basically lock in the position of a light escort aircraft carrier. !As a result, compared with the conversion of cargo ships into escort aircraft carriers, the conversion of high-speed cruise ships into fleet aircraft carriers is bound to have high costs and a long construction period.

The second is the value gain of modification.Some people will say that the cost of converting a high-speed cruise ship into a fleet aircraft carrier is high and the construction period is long, but once the conversion is completed, the value of the fleet aircraft carrier is much higher than that of the escort aircraft carrier.This is indeed true, but please don’t forget that when we measure whether the cost-effectiveness of the transformation of existing ships is high, we do not look at the total value after the transformation, but the value increment!The military value of a cheap civilian cargo ship itself is relatively limited, but once it is converted into an escort aircraft carrier, it will immediately turn from a sparrow into a phoenix.The high-speed cruise ship itself is a very valuable and scarce military resource. Even without major modifications, the high-speed cruise ship can also directly serve as a fast transport ship, a high-speed troop carrier, and other roles.As a result, for many countries, the value gain of converting high-speed cruise ships into aircraft carriers is relatively limited, and the cost-effectiveness ratio is not high.

Knowing the above two points, it is easy to understand that in World War II on the last plane, cargo ships were preferred when civilian ships were converted into aircraft carriers.Modifications with high cost, long construction period, and low value gain are indeed not very attractive.But there are exceptions to everything, isn't there a counterexample of "Flying Eagle"? The modification of the "Flying Eagle Class" into an aircraft carrier can be regarded as the most worthwhile sum of money spent in the conversion of Japanese civilian ships to military use in the previous plane.

In this regard, Helena can only say that if things go wrong, there must be demons.In fact, from the time when the predecessors of the "Flying Eagle" aircraft carrier - the "Kashihara Maru" and the "Izumo Maru" cruise ships laid the first keel, the Japanese Navy has been eyeing these two ships. At the beginning, the Japanese did not build these two ships as high-speed cruise ships! In 1938, Japan promulgated the "Large Excellent Ship Construction Assistance System" to encourage private construction of large high-speed merchant ships that can be converted into aircraft carriers.Therefore, the "Kashihara Maru" and "Izumo Maru" were converted into aircraft carriers from the beginning, and the Japanese Navy even provided generous subsidies for the construction of these two ships.It is precisely because the plan to transform into an aircraft carrier was made at the beginning, so the "Flying Eagle" who became a monk halfway through was able to complete the turn in a short time.

However, from Helena's point of view, although Japan's concealment of the "Flying Eagle" was relatively successful, it still left many hidden dangers.The biggest hidden danger is that the design of the parent models "Kashihara Maru" and "Izumo Maru" did not give more overall consideration for future refitting, but only reserved refitting potential in the hull structure.This has led to the fact that although the "Flying Eagle" has good attack capabilities, it has shortcomings in mobility and protection.

Like Japan on the previous plane, the German navy on this plane also focused on the high-speed cruise ships "Bremen" and "Europa".However, under the influence of Helena, the "Bremen" and "Europa" have gone further in integrating the military with the people!

Chapter 55 Torpedo Protection

The reason why the German Navy strongly supported the construction of the "Bremen" and "Europa" high-speed cruise ships is not only because they can be converted into fleet carriers in the future.In fact, the two cruise ships have a more important mission: to conduct engineering tests for the new torpedo protection system of Germany's future large warships.

Since its invention at the end of the 19th century, the torpedo, a ghost that can be launched from the air, surface and underwater, has undoubtedly become a lingering nightmare for all ships.In World War II on the previous plane, the number of large and medium-sized warships killed by torpedoes was far more than the number of large and medium-sized warships killed by naval guns (if the loss of merchant ships is counted, the record of torpedoes will be even more amazing)!

The reason why torpedoes frighten warships is that the killing mechanism of torpedoes is completely different from that of naval gun shells and aerial bombs.Although naval gun shells and aerial bombs are also extremely destructive, as long as the armor box of the battleship is strong enough, they can prevent these guys from breaking into the core compartment.As long as the core cabin is fine, and the damage control of the battleship is not too bad, the battleship is generally not in danger of life.

The torpedo is different. It doesn't need to directly compete with the solid armor box of the battleship like naval artillery shells and armor-piercing bombs. It only needs to detonate the moment it touches the hull, and a large amount of high-pressure gas will engulf the seawater and rush away. Everything that dares to stand in its way!The next step is a series of serious consequences such as hull tearing, structural damage, and cabin flooding.

In order to fight against the torpedo, the big devil, from before World War I, warships began to try to install an underwater defense system called "Torpedo Defense System" (TDS for short) to reduce the damage of torpedoes to warships. The specific structure of the "torpedo defense system" is different, but its basic principles are similar. They are all installed multi-layered compartments on the sides and bottom of the hull, and through the compression and conduction of the medium in the compartments and the multi-layered compartments To disperse, absorb, and resist the energy of the torpedo explosion through structural deformation, so as to protect the core compartment located deep in the hull as much as possible.

When Germany designed the "Emden class", "Konigsberg class" and [-]-ton armored ships, they also installed "torpedo defense systems" on these warships. However, the depth of the mine protection system cannot be made very large, and the defense effect against torpedoes is actually very limited.

In fact, even the [-]-ton armored ship with the most complete mine protection system under construction cannot guarantee that it can resist a light aviation torpedo.So much so that some good people in the German Navy joked: "The only function that the torpedo defense system of these cruisers does not have is mine protection!" Although this may be a bit too absolute, after all, once hit by a medium or heavy torpedo, Although the existing mine protection system on German cruisers cannot completely prevent torpedo damage to the core compartment, it can at least reduce the damage area of ​​some torpedoes and protect a little reserve buoyancy.

However, the above sentence does express the embarrassment of the mine protection design of the battleship of the cruiser class: after the cruiser is hit by a mine, it is life or death, and the element of luck is even higher than the element of design.If you are lucky, the battleship can be moved back after being blown up; if you are unlucky, it is also possible for the battleship to be sent directly to the bottom of the sea by a torpedo.

Due to the limited tonnage and relatively simple mine protection system of cruisers, it is understandable that they cannot completely withstand powerful torpedoes.But if large warships of the level of battleships and aircraft carriers also entrust the outcome of being hit by mines to illusory luck, then it is unreasonable (although luck is still very important).Therefore, strengthening torpedo protection and striving to keep the enemy out of the core cabin became an inevitable requirement at the beginning of the design of the "Bremen-class" high-speed cruise ship.

In order to design a "torpedo defense system" with outstanding protection capabilities, German technicians have done a lot of underwater blasting experiments. The scaled-down models of the test products have always been decommissioned merchant ships with part of the lightning protection structure installed, and finally designed a shocking Satisfactory underwater protection system.Of course, Helena's handwriting was also indispensable. Helena incorporated many successful design experiences from the previous plane into the design of this "torpedo defense system".In fact, the underwater lightning protection design of the "Bremen class" is very close to the large US aircraft carrier during the Cold War on the previous plane.

Although the new "torpedo defense system" performed well in underwater blasting tests, it has not experienced engineering applications after all.In order to prevent problems that may arise in practical applications from being brought to future large-scale warships.The high-speed cruise ships "Bremen" and "Europa" became the crab eaters.

The lightning protection systems of "Bremen" and "Europa" are divided into four lines of defense:

The first line of defense is the outer void, which is filled with foam rubber and is called an expansion chamber.Its function is that when the torpedo explodes outside the hull, enough deformation space is left for the outer hull that is blown through, and the high-pressure air wave generated by the explosion expands, so that the energy of the shock wave is reduced.

The second line of defense is the liquid tank, which is called the absorption tank for loading the heavy oil used by the ship for navigation.The middle of this tank is divided by a partition made of hollow corrugated sandwich panels.Among them, the outer liquid tank is called the front liquid tank, which has two functions: one is to allow the fragments of the torpedo explosion and the secondary fragments produced by the rupture of the hull to attenuate the energy after penetrating into the liquid tank, so as to prevent damage to the inner bulkhead; The explosion shock wave is transmitted inward, and the corrugated sandwich panel in the middle of the liquid tank is deformed to absorb part of the energy again.The inner tank is called the rear tank, and its main function is to transfer the residual energy absorbed by the corrugated sandwich panel evenly inward.

The third line of defense is also a layer of empty cabins. This layer of empty cabins is located between the defensive partition at the rear of the tank and the underwater main armor. The middle is connected by an elastic support structure, which is called an energy-absorbing cabin.Its main function is that when the rear bulkhead of the tank cannot resist the residual energy of the shock wave, the support structure between the rear wall of the tank and the main armor will deform or even collapse, which reduces the transmission of shock wave energy to the main armor plate. Chance.In addition to resisting residual energy, the main armor plate also has the function of preventing water bombs from invading the core compartment.

The fourth line of defense is still an empty cabin, which is composed of a layer of waterproof longitudinal wall behind the main armor, which is called the filter cabin.Due to the high rigidity of the main armor belt, water leakage may occur due to deformation due to violent impact. At this time, this longitudinal wall can isolate the water leakage from the core cabin.

The total depth of the above four lines of defense can reach about 7 meters, and it is conservatively estimated that they can withstand torpedoes equivalent to 500 kg of TNT warheads.In other words, the vast majority of aviation torpedoes are in front of this protection system.It is difficult to pose a fatal threat to the core compartments of the "Bremen" and "Europa".In addition, the bottoms of the "Bremen" and "Europa" also adopted a strong three-layer bottom, which further improved their survivability.

The unprecedented success of the maiden voyage of the "Bremen" gave the German Navy great confidence.However, what is more puzzling is that when many people in the Navy proposed to build more "Bremen-class" high-speed cruise ships, Helena, who single-handedly contributed to the construction of the "Bremen-class" class, opposed it. Opinion.

Chapter 56 Structural limitations

Seeing the anxious expression on the face of the lieutenant commander in front of her eyes, Helena already roughly guessed his intention.But Helena still pretended to be ignorant and greeted him: "Congratulations on being promoted! Major Goring."

That's right, it took only less than a year for Hermann Göring to complete the leap from a navy captain to a lieutenant commander. This speed was called astronomical speed in the German navy at this time!You must know that since the military strength is limited to 15000 by the treaty, in order to accumulate strength for future revival in the German Navy, even the cooking soldiers on board have been trained according to the standards of officers. easy thing.

There are two main reasons for Goering to be promoted by the Rockets:

The first is because of Goering's contribution to the construction of "naval aviation". The word "naval aviation" is in quotation marks because Germany now has neither aircraft carriers nor aircraft.However, Goering still used his brains, and soon built a flat-roofed building more than 200 meters long and 30 meters wide on land.The downstairs of the building is a large-area warehouse, and the upper floor is a flat roof. There are many elevators connecting the upstairs and downstairs.This building was "abandoned" as soon as it was built, and soon this "abandoned warehouse" became a paradise for German folk "flying enthusiasts". "Folk aviation enthusiasts" drove their planes to take off and land on the roof.

The second is because of political reasons.Due to the gradual spread of the economic crisis in the United States, the German economy has also been hit hard.The economic downturn naturally changed people's minds. In the parliamentary elections in October 1930, the Nazi Party gained momentum and won 10 congressional seats.We must know that in the parliamentary elections two years ago, the Nazi Party won only 107 seats.At this time, the Navy promoted Goering, an old friend of the Nazi Party leader, and also intended to form a good relationship with the Nazi Party, an emerging political force.

But Goering, who had just been promoted, was not in a happy mood at this time.The Navy has decided not to build high-speed cruise ships that can be converted into aircraft carriers, which makes the newly promoted "carrier school" lieutenant commander feel uncomfortable and restless.After a lot of running around in the navy was fruitless, Goering finally decided to visit Helena who was most likely to influence the navy's equipment policy, so there was the scene at the beginning.After a simple exchange of pleasantries, Goering couldn't wait to explain his intention for coming.

"Actually, I also think that we should not continue to build more "Bremen-class" high-speed cruise ships that can be converted into aircraft carriers." Helena said.

"What? Miss Sektor, you also object? But, at the beginning you..." Goring felt as if a basin of cold water had been poured into his head, and his tired expression became even more gloomy.

Seeing Goring who was as thin as a monkey in front of her, and comparing the image of the fat man with big ears in her previous life memory, Helena almost felt a little sympathy for Goring.It is not difficult to see that these days, for the preparations for the naval aviation, the ace pilot of the First World War is indeed exhausted and worried.

"Come with me." Helena led Goering to her study, took a volume of hand-drawn drawings from the bookshelf, and spread them out on the desk. "This is a cross-sectional sketch of the high-speed cruise ship 'Bremen'. Do you see anything?" Helena pointed to the drawing and asked Goering.Göring stared at the blueprint for a while, then shook his head. The construction of ships was not an area he was familiar with.

Helena had no choice but to point to the drawings with a pen and patiently explained: "In order to improve the survivability after being converted into an aircraft carrier, the 'Bremen-class' high-speed cruise ship has a solid built-in armor box. The top of the box is 80mm horizontal armor, and the sides It is a 12mm side armor inclined at 105 degrees. In order to protect the core area, the 'Bremen' has a dome covering the power compartment and the future ammunition depot and aviation fuel tank near the waterline. This The thickness of the dome above the power cabin is: 40mm in the horizontal part and 60mm in the inclined part, and the thickness above the ammunition depot is: 80mm in the horizontal part and 120mm in the inclined part."

Seeing Goering nodding, Helena went on to say, "The above armors are not only part of the protective structure of the whole ship, but also part of the load-bearing structure of the whole ship. Especially the main horizontal armor and the dome armor, besides being In addition to resisting vertical artillery shells and aerial bombs, it is also a structural component that maintains the overall longitudinal strength of the hull. Therefore, the main load-bearing structure of this ship has actually been built, and no matter how it is modified in the future, it will generally not Major changes will be made to the main load-bearing structure of the ship. If the main load-bearing structure is to be changed, the amount of work will be very large, and it is better to rebuild a ship."

"This is the limitation of a cruise ship refitting an aircraft carrier. Since the hangar and flight deck of a cruise ship refitting an aircraft carrier can only be built in the later stage of transformation, it is impossible to participate in the bearing of the hull!" Helena put down the pen in her hand and said: "So we can only design the uppermost load-bearing deck of the 'Bremen', which is the deck where the 80mm main horizontal armor is located, on the floor of the hangar. When it is necessary to install the 'Bremen' When the ship is transformed into an aircraft carrier, we will level all the buildings above the main bearing deck of the cruise ship, and then build five box-shaped "hangar-flight deck" modules on the uppermost bearing deck in sequence like building blocks on. Add an island to it and lead the funnel over the side and you're done."

Seeing that Goering was thinking, Helena sighed and said: "This is the problem. These modules cannot share the overall longitudinal strength of the hull. In order not to affect the initial stability of the ship too much, These 'hangar-flight deck modules' cannot be made too heavy, at least not significantly exceeding the weight of the buildings above the original cruise ship's main load-bearing deck."

"So even if the 'Bremen' is converted into an aircraft carrier, it is impossible for the flight deck to be heavily armored?" Goering was not stupid, and he immediately understood the key.

"That's right." Helena replied: "If it is forced to lay heavy armor on its flight deck, the refitted aircraft carrier will become top-heavy, and then it will be difficult to take off and land aircraft, even in high sea conditions. Guaranteed. Therefore, the flight deck of the remodeled 'Bremen' will only have light armor protection at most."

Helena knows that in the case of tight displacement, it is actually wise to give up or partially give up the protection of the flight deck, and set the armored deck on the hangar deck below to prevent aerial bombs from penetrating the flight deck and pouring into the core compartment. practice.For example, in the previous plane, Japan's "Shokaku-class" aircraft carrier and the American "Essex-class" aircraft carrier both did this.

However, in Helena's view, if it is an aircraft carrier with a displacement of less than 4 tons, since the protection cannot be comprehensive, will it cause an "armored aircraft carrier" with heavy flight deck protection like the "Taho-class" or an "Essex aircraft carrier"? The "protective aircraft carrier" such as the Stalin class, which is heavily defended by the core cabin, may still be controversial.But the "Bremen" is a ship of more than [-] tons!With the same tonnage level as the "Midway Island-class" aircraft carrier, you finally transformed into a semi-naked thing on the flight deck, which is a bit embarrassing.

To be honest, the reason why Helena was willing to promote the construction of the "Bremen-class" high-speed cruise ship was largely because the "Bremen-class" could conduct engineering tests for the new torpedo protection system of Germany's future large warships .In Helena's view, the "Bremen-class" high-speed cruise ship converted into an aircraft carrier is roughly stronger than the "Xianghe-class" and "Essex-class" in the previous plane, but the price is lower. It is much more expensive (high-speed cruise ship itself is very expensive, and a modification fee will be added later), so it is almost enough to build two to accumulate engineering experience.The military expenditure of the German Navy did not come from strong winds, and more should be invested in more cost-effective places.

Major Goering obviously also figured this out, but looking at his painfully tangled expression, Helena knew that he was still attached to his "German Naval Air Force" that only existed on paper.Helena had no choice but to comfort him: "In the future, there will be aircraft carriers and planes, and everything will be fine." Only then did Goering be dismissed.

Chapter 57 Eight Questions

After sending away the thoughtful Goering, Helena went back to the desk and sat down. She turned her gaze back to the sketch of the "Bremen-class" high-speed cruise ship on the table, and fell into long-term thinking.Don't look at what Helena said to Goering just now, but in fact Helena herself didn't fully consider the future development route of the German aircraft carrier. After all, the development route of the aircraft carrier involves too many fields.

Designing an aircraft carrier is different from designing a battleship or cruiser. To design a battleship or cruiser, you only need to ensure that the core cabin is safe enough, the firepower is strong enough, and the speed is fast enough. However, the design of an aircraft carrier must consider the coupling relationship between battleships and aircraft.Although Helena has a reserve of knowledge from later generations, it can help the future development of the German Navy to avoid some technical traps recognized by later generations.But on many technical route issues, the experience of later generations cannot directly give Helena the answer. In fact, it is difficult for Helena to make a decision just on the structure of the hangar.

In the major military forums in Helena's previous life, whenever aircraft carriers during World War II were discussed, military fans often debated the topic of "closed hangar" and "open hangar".However, because the two parties in the debate have not clearly defined the two concepts of "open hangar" and "closed hangar", there is often an embarrassment that the two sides say that they are not on the same channel, so here we need to explain this issue in advance.

In fact, the United States and Japan in the last plane have quite different standards for defining whether aircraft carrier hangars are "closed hangars" or "open hangars".This is also the historical root cause of military fans' perception of the same noun.

Let me talk about the more common American definition first (British people have the same definition as Americans).In the American discourse system, the so-called "open hangar" and "closed hangar" do not mean "open" or "closed" in the sense of air circulation, but "open" in the load-bearing structure of the hull And "closed", whether it is a "closed hangar" depends on whether the hangar structure participates in the general longitudinal bending of the hull.More generally speaking, in the definition of the Americans, any hangar that is part of the load-bearing structure of the ship is a "closed hangar"; any hangar that is not part of the load-bearing structure of the ship is an "open hangar".

Now let's talk about the definition of Japanese.The Japanese's definition of "open hangar" and "closed hangar" is relatively straightforward, which is "open" and "closed" in the very common sense of air circulation.Therefore, in the Japanese discourse system, any hangar that is not sealed by wall panels is an "open hangar"; any hangar that is surrounded by wall panels is a "closed hangar".For example, the hangars of the U.S. "Essex-class" aircraft carrier are surrounded by large ventilation shutter doors, which are naturally "open hangars" in the eyes of the Japanese, but if these ventilation shutter doors are sealed with wall panels (Just like Japan's "Taiho" class aircraft carrier), that is "closed hangar".

In order to prevent the embarrassing situation of the previous plane, Helena is going to adopt a new naming standard in Germany for the different types of hangars, so as to describe the characteristics of different types of hangars more straightforwardly:

Helena plans to call the "open hangar" of the American standard in the previous plane a "non-load bearing hangar".

Helena plans to call the "closed hangar" of the American standard in the previous plane a "load bearing hangar".

The Japanese standard "open hangar" of the last plane, Helena is going to call it an "open hangar".

The Japanese standard "closed hangar" of the last plane, Helena is going to call it a "closed hangar".

According to this classification standard, the hangar structure of the "Bremen-class" high-speed cruise ship to be transformed in the future is a typical single-layer open hangar with a non-load-bearing structure.If it is placed on the previous plane, the hangar structure most similar to this one is the "Essex-class" fleet aircraft carrier built in large quantities by the United States during World War II, except that the "Essex" The open bow was replaced by a closed one.

Helena gradually recovered from deep thinking, she took out a notebook, and began to list the technical route selection problems that Germany would face in the development of aircraft carriers in the future.

In Helena's view, after all, there are many constraints in refitting an aircraft carrier, and the degree of freedom in choosing a technical route is not very high.But if history still develops like the previous plane, it won’t be long before the German Navy will build an aircraft carrier openly. At that time, the following eight questions must be answered:

Question [-]: In the future, will Germany need a smaller number of heavy-duty aircraft carriers or a larger number of medium-sized aircraft carriers?

Question [-]: Does Germany need an armored aircraft carrier that focuses on deck protection or a protected aircraft carrier that focuses on core cabin protection?

Question [-]: Should the hangar be made into a non-load-bearing type that is easier to maintain, or a load-bearing type that is conducive to reducing the weight of the overall structure?

Question [-]: Is the hangar an open type with good ventilation or a closed type with high structural strength?

Question [-]: Is the lift an inboard lift or a side lift?

Question [-]: Should the carrier-based aircraft be liquid-cooled or air-cooled?

Question [-]: Is the wing of the carrier-based aircraft a space-saving folding type or a lighter non-folding type?

Question [-]: Should one develop a multi-purpose carrier-based aircraft, or develop a variety of specialized carrier-based aircraft?

After Helena finished writing these eight questions, she closed her notebook.Answering these questions is not in a hurry right now. Instead of making a decision based on a little knowledge of the time traveler, it is better to wait for practice to give the answer.

Chapter 58 New housing

In early 1931, Hiroshima, Japan.After nearly ten years of development, the Shipbuilding Engineering Bureau, which was established in Japan led by major German shipyards and enterprises after the Washington Conference, is no longer an empty shell company, but has gradually developed into a company with A medium-sized ship design and manufacturing enterprise.

On this day, the Ship Construction Engineering Bureau ushered in a special guest.

"Hahahaha, I'm dying of laughter!" Listening to the staff of the Shipbuilding Engineering Bureau telling the interesting things the company encountered in Japan, Helena held her stomach hurting from laughing, and almost lost her image of a smiling lady. The exhaustion brought about by the sea journey was thrown away by this laughter.

It turned out that after the Japanese Navy obtained superhard aluminum alloy technology from the Ship Construction Engineering Bureau, the Japanese Navy not only used this superhard aluminum alloy on some warships designed by Kikuo Fujimoto, but also used this aluminum alloy to improve The Type [-] carrier-based fighter has achieved a good weight reduction effect.

When the Japanese army saw that the navy was using it well, it also wanted to obtain the production and processing technology of this superhard aluminum alloy.However, the Japanese navy was willing to take advantage of the army's Malu for nothing. Not only did it resolutely refuse to provide technology, but it also defended the army like it was against thieves.Afterwards, the navy quoted a frightening transfer price, which was directly double the price that the navy had imported from the Germans!So the Japanese Army found the Ship Construction Engineering Bureau in a fit of rage, and introduced the same technology at the price originally introduced by the Navy.In this way, the Ship Construction Engineering Bureau collected the money again in a daze.

Helena smiled and thought: The super-hard aluminum alloy should have been developed by Igarashi in Japan in the last plane. How dare I cheat the Japanese twice with something that should have been developed by the Japanese themselves?Just because the Japanese are stupid and have a lot of money, I'm sorry for my conscience if I don't make more mistakes in the future!

After finally laughing enough, Helena didn't forget the purpose of spending more than a month and traveling half the world to the Ship Construction and Engineering Bureau. The personnel of the Ship Construction and Engineering Bureau naturally knew the purpose of Helena's trip.So, accompanied by a group of company personnel, Helena walked towards the dock of the shipyard.

The Ship Construction and Engineering Bureau was established after the Washington Conference under the impetus of Behnke and Kato Yusaburo. Its establishment was actually the result of Germany and Japan taking what they needed: Japan needed German technology, especially submarine technology, to expand its naval strength; Germany, on the other hand, relied on Japanese cover to develop technologies prohibited by the Treaty of Versailles, including submarines.

In the past few years, Germany has been deeply involved in the development of various types of Japanese submarines, and even directly built and repaired several for Japan.Therefore, although the restrictions of the "Treaty of Versailles" are very strict, Germany's submarine research and development capabilities have not experienced serious interruptions. Not only have there been no interruptions, but they have continued to improve under the guidance of Helena.

Helena and her party walked to the dock of the shipyard, where a very inconspicuous-looking experimental submarine was quietly moored.According to the information provided by the shipyard to Helena, this small submarine built in the name of "sightseeing submarine" is not armed, and its surface displacement is only 240 tons, and its underwater displacement is only 270 tons.But Helena will not dislike this submarine because of its loli figure. On the contrary, Helena attaches great importance to the construction of this small submarine.He even traveled thousands of miles from Europe to Japan to learn about the technical progress of the Ship Construction Engineering Bureau.

Compared with other submarines of this era, the most distinctive feature of this small submarine is first of all its "monocoque" structure.

In the last plane, until the end of World War II, almost all submarines used a so-called "half-shell" structure.The shape of a submarine with this structure is just like what we see in historical video materials: a ship-shaped body in the middle, with long cylindrical protrusions on both sides.In fact, the body in the middle is the pressure hull of the submarine, which is used to arrange the important mechanical equipment of the submarine and to accommodate the crew; the long cylindrical structures on both sides are the ballast water tanks of the submarine, which are used to control the submarine's Dive and surface.

Although this "half-shell" structure is relatively easy to construct when used on submarines, it also has serious problems:

On the one hand, submarines with a "half-shell" structure generally have ballast water tanks installed on both sides of the midship of the hull.And the ballast water tank that bulges hull greatly can bring greater sailing resistance, and this is very unfavorable to improving the maneuverability of submarine.

On the other hand, the midship ballast tanks are more vulnerable to damage.For submarines, once there is a problem with the main ballast water tank, it is easy to cause the submarine to be unable to dive.In World War II in the last plane, there were many examples of submarines being hit by machine guns or machine guns on the anti-submarine aircraft when they encountered anti-submarine aircraft, making it impossible to dive.

In order to overcome the inherent defects of the "half-shell" structure, Germany began to explore a new shell structure during World War II on the last plane.The result was the Type 21 submarine with a "double hull structure" and the Type 23 submarine with a "monohull structure". Type 21 submarines and Type 23 submarines are also the world's first double-hull submarine and the first single-hull submarine.

So where is the difference between "single shell structure" and "double shell structure"? A submarine with a "single-hull structure" has only one layer of shell, that is, the pressure-resistant shell, and the ballast water tank and other equipment of the submarine are wrapped in the middle of this layer of shell. The submarine with "double hull mechanism" has two shells, the inner layer is a pressure-resistant shell that bears force, and the outer layer is wrapped with a non-pressure-resistant shell that does not bear force, and the ballast water tank is arranged in the two-layer shell between.

Helena's plan for the future structure of German submarines is to assume that small submarines adopt a single-hull structure, and large and medium-sized submarines adopt a double-hull structure.

In fact, this plan is basically the same as the submarine development route of Germany in the late war of the last plane.Germany on the last plane also used double hulls on large submarines like Type 21, and single hulls on small submarines like Type 23 submarines.This choice itself is still very reasonable. The only problem is that the Type 21 and Type 23 submarines are too late to serve, and basically they have not played much role.

Chapter 59 Closed Loops

In Helena's eyes, this small submarine with an underwater displacement of only 270 tons built by the Ship Construction Engineering Bureau is bound to be recorded in the history of submarine development on this plane.In addition to abandoning the backward half-shell structure and adopting a novel single-shell structure, the submarine is also equipped with an "air-independent" power plant-a closed-cycle diesel engine for the first time in the world.

"Air-independent" power plant, referred to as AIP, is a general term for power plants that can provide driving force for submarines for a long time without gas exchange with the outside air.In the absence of an AIP system, the submarine's surface navigation relies on diesel engines to provide power, and its underwater navigation relies on the battery's electric drive motor to provide power. Due to the limited battery capacity, the underwater self-sustainability of ordinary conventional submarines is no more than a few days at most, and This can only be achieved at low speeds.If you want to sail at high speed underwater, it only takes a few hours before the power in the battery will dry up.At this time, the submarine has to take the risk of floating to recharge before regaining its underwater mobility.In order to solve this embarrassment and improve the concealment of submarines, humans have invented various power devices that can support long-term underwater navigation of submarines. This is the AIP power device, and the closed-cycle diesel engine is also a kind of AIP device.

For submarines equipped with a closed-cycle diesel engine AIP system, the diesel engine has two circulation modes when it works: open cycle and closed cycle.When the submarine is sailing on the water surface, the engine adopts an open cycle, that is, like an ordinary diesel engine, it first inhales air from the atmosphere, burns and does work, and then discharges the exhaust gas into the atmosphere.The engine cycle mode is switched to a closed cycle when the submarine is navigating underwater. This cycle mode is also the essence of this AIP device. Its specific working principle is as follows:

In the first step, the oxygen carried by the submarine through the liquid oxygen storage tank will first enter an oxygen mixing chamber. In the mixing chamber, the oxygen is mixed with the oxygen-depleted exhaust gas from which water vapor and carbon dioxide have been removed to form a mixture with an oxygen content close to that of air.

In the second step, the oxygen-containing mixture is sucked into the diesel engine, so that the diesel engine can work normally as if it is on the water.While the diesel engine is working, it emits exhaust gas rich in water vapor and carbon dioxide.

In the third step, the exhaust gas enters a condenser, and the water vapor in the exhaust gas is condensed by condensation to achieve the purpose of removing water vapor in the exhaust gas.