PS: The second more asks for votes

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South-east, Australia, the submarine Mako Shark.

"The report found the Australian warship, in the direction of 11 o'clock, at a distance of 89 km, with a course of 145 and a speed of 18 knots...... Judging by the voiceprint and appearance, it should be a Lin Xian-class light cruiser, which belongs to the Australian Navy's Sydney ......"

"Okay, don't worry about this scum, keep on course. Yu Taiming pursed his mouth disdainfully, and ordered: "By the way, let those who watch TV be quiet, although the mute effect of our big shark is good, but it is also necessary to prevent accidents." ”

After receiving the captain's order, everyone immediately lowered the volume, and the TV in the dining room also turned the volume to very low. In fact, Taiming has a lot of confidence in the great white shark, and this order is completely just in case.

Because all the current Chinese submarines are pasted with "artificial shark skin", all the internal bulkheads are compartmentalized design, and one to three layers of submarine sound insulation panels are installed below the surface.

The history of human ship development is a history of speed racing, and since the advent of ships as a tool, human beings have been trying to improve their speed all the time. From oars, sails, paddle wheels to propellers, in the 20th century, hydrofoils, catamarans, hovercraft, and so on, all kinds of strange methods have been thought of.

In addition to the improvements made to these tools, humans have also turned the idea to animals in an attempt to improve the ship's subsystems in an attempt to mimic marine life. Sharks are arguably one of the most successful species on Earth, they have been breeding on Earth for hundreds of millions of years, watching countless species go extinct on the sidelines, but they are still alive and well. One of the main reasons for this is that they swim fast and can easily catch prey and escape predators. Then there's the dolphin, which is also an extremely fast swimming animal.

After research, scientists have found that both animals swim fast because of their special epidermis.

On a microscopic level, the surface of the shark's skin is not smooth, and its surface is covered with numerous overlapping small tooth-like scale spines, which are quite rough. Therefore, in ancient times, shark skin was used as sandpaper to polish wood. However, these fine teeth can disrupt the flow trajectory of water on the surface of the shark's body, thus reducing the resistance of the water. As the shark moves forward at high speed, the seawater attached to the skin forms a laminar flow along these small spines, which greatly reduces the resistance of the water.

Dolphin skin is a different story, it is smooth, but it has the same drag-reducing effect. The skin of dolphins is divided into three layers: the black epidermis is extremely smooth and soft, the second layer is the white dermis with numerous milk# head-like hollow protrusions, which are filled with fluid, and the third layer is a thick fat layer that is elastic. This biological structure allows the skin to fluctuate in response to the pressure of the water when swimming, with very little resistance, allowing the dolphin to swim very quickly.

Chinese biomimics have imitated these two animals in the past few years to create "artificial shark skin" and "artificial dolphin skin", after actual experiments, the effect on the drag reduction and speed of the ship is very obvious.

Of course, people of this era do not know that in later generations of the original time and space, someone invented a high-tech swimsuit modeled after the structure of shark skin, and athletes broke dozens of world records in this new style of swimsuit. Because this kind of thing is so powerful, it finally led to FINA announcing a complete ban on this kind of thing and other high-tech swimsuits starting in 2010. The glorious history of the sharkskin swimsuit for nearly a decade has come to an end, and I can only play at home in the future.

When the two products appeared, some people opened their minds, since the dolphin skin and shark skin are so powerful, so if the two kinds of skin are combined together, will it be more powerful?

So a new generation of "artificial shark skin" was born, well, in fact, this kind of thing is more accurate to call it "shark skin". However, although this kind of thing was invented 20 years ago, it was not really put into practical use until a few years ago due to technical problems. Because whether it is artificial dolphin skin or shark skin, the structure is complex and soft. How to accurately embed these small toothed scales on a piece of soft material becomes a big problem, and it is not a big problem to make a piece of clothing, just stick it slowly by hand. But if it is to be used on ships, this method is obviously impossible, and it will have to be glued to the year of the monkey.

Therefore, it was not until a few years ago that various technologies had new developments that this process problem could be solved. However, even so, the cost of this artificial shark skin is still very expensive, and it is only used in submarines, high-speed warships and torpedoes, as well as racing speedboats, and it will have to wait for it to be popularized in ships.

Moreover, this bunker is not only used for this purpose.

Originally, the "artificial shark skin" was used to reduce drag and speed up, but after model testing, it was found that it also has an excellent noise reduction effect.

Hydroacoustics have confirmed from software simulations that most of the vibration and noise from inside the submarine is absorbed as it passes through this honeycomb heterogeneous interface, due to the wide variation in the speed of sound propagation in metals, polymers, and liquids. Another part of the noise disappears in the water flow near the hull in a diffuse form due to the action of small spines. The noise reduction effect is far superior to that of traditional sound-dampening tiles.

And the inspired engineers have used this principle to design a new type of sound insulation board, the effect of this sound insulation board is far more than the previous similar products, many years ago has been widely used in various fields, such as all kinds of buildings that need sound insulation, have a large number of this kind of sound insulation board. Just install a 10 cm thick soundproof panel in the room, even if you jump inside, you can't hear it outside. Of course, this kind of civilian use cannot be compared with that used in submarines, but the principle is the same, only the difference in refinement and coarseness.

Under the multiple absorption of sound insulation panels and shark skin, the noise inside the submarine can hardly be transmitted to the outside, and even if there is a singing and dancing party inside, the sound transmitted to the outside is difficult to detect.

Then coupled with the seven-blade large-dip propeller, shock-absorbing floating raft and other means, the Great White Shark-class submarine has been reduced to less than 90 decibels when diving at a speed of less than 25 knots, which is almost the same as the background noise of the ocean, and the passive sonar is almost completely ineffective. The most important thing is that artificial shark skin also has a strong ability to absorb and diffuse the sound waves of active sonar, making it a real "ocean black hole". Whether it is active or passive sonar, it is difficult to detect its existence, and it is not much more than the Kilo-level of the original space-time.

Not to mention that foreign sonar technology is not good, even China's own sonar is difficult to detect the current Chinese submarines. If you want to find them, you can only use other means such as magnetic field detection.

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USS Sydney light cruiser.

HMS Sydney was a British Lynsen-class light cruiser, a treaty-type cruiser built in the early thirties. Originally, the limit of treaty-type light patrol was 10,000 tons of standard displacement and 400,000 tons of total tonnage. But in the case of the British, the British Navy naturally wanted to build a larger number of cruisers with limited tonnage. The British considered that their territory was too large and that they needed too many warships, and if they were to build a large light patrol of 10,000 tons, they would not be able to build much with the British share, and 40 light cruisers would not be enough at all.

So they specially allocated some light cruiser tonnage and designed the Lin Xian class, a small light cruiser with a class of only 5,000 tons, so that one share could build two, and the price was still cheap, how good is it? The opium cow felt that he was really too witty. Of course, the British are also playing with scales, and the actual standard row of the Lin Xian class is 5,600 tons, but everyone is playing scales, and other countries pretend not to know. The Sydney was ordered by Australia in the UK.

Because the British were frightened by German submarines in World War I, they paid special attention to anti-submarine, and the Lin Xian class was also a kind of cruiser that attached importance to anti-submarine. Not only is the most advanced anti-submarine sonar installed in the UK, but on its wide aft deck, it also carries an anti-submarine aircraft equipped with radar.

Originally, the Sydney was sent to monitor East African submarines in the Indian Ocean, but because the relationship with China was a little stiff some time ago, in order to prevent accidents, the kangaroos transferred this cutting-edge warship back to watch the family and courage, and they also had a quarrel with Britain for this.

"Hmph, I haven't found anything abnormal, I don't think the top is too sensitive......" Lieutenant Commander Tex said very unpleasantly, "Chinese shouldn't come......"

"I also think that China's navy is so powerful, even if it wants to fight, it will be the main force coming, why send submarines over?" the first mate echoed beside him.

At this time, the deep voice of the fat man Qiu sounded on the radio: "...... Let's remember the bloody day of "April 1st". Tonight, we are all Americans! May God bless America! May God bless mankind! May the victims rest in peace!"

"It's disgusting!, shameless fat man!" said Tex slammed the radio off. "You have to be the son of an American, and don't pull everyone else along!"

The first mate smiled and said: "Hahaha, Prime Minister Churchill is also trying to win over the Yankees, and it is understandable to say a few good words." ”

Tex picked up the phone and said, "Sonar, have you found anything ......?"

"No, nothing but fish...... "Chief Thunder reported.

"Alright then, we're ready to sail back, we've been out long enough. ”

At that moment, five Chinese submarines were at a depth of 300 meters below them, staggering their course, including the Mako Shark, which passed directly below the Sydney......

"It's a pity, if only there was a war now, a torpedo would be able to reimburse it!" said to the cursor on the screen indicating the Sydney, and grunted unwillingly.