According to the plan of the exercise, at the summary stage of the exercise, the warships of the participating formations docked at the port of Vladivostok, and the participants of the two sides visited the exercise.

Among them, there are destroyers, frigates, battleships, conventional (nuclear) powered submarines.

For Yang Wenbin, he is already familiar with destroyers and frigates, and he is most interested in submarines.

From the books, he knew that among the weapons that went through the baptism of two world wars, the submarine turned out to be a deadly, and yet very economical weapon.

It is not only the nemesis of all kinds of surface ships, but also has excellent concealment performance, and is not easy to be discovered by warships, aircraft and satellites, therefore, after World War II, all military powers have invested a lot of financial and technical resources to give priority to the development and construction of submarines.

In China, Journey to the West is a well-known book. The protagonist of the story, Sun Wukong, used the water avoidance method to sneak into the Dragon Palace of the East China Sea and took the golden hoop stick from the Dragon King of the East China Sea. This wonderful and strange myth reflects the fantasy of people to conquer the natural world and engage in underwater activities.

There are also legends of underwater activities in foreign countries. More than 2,000 years ago, there was a king named Alexander the Great, who wanted to have a good time under the water, and ordered craftsmen to make a glass vessel for him. He lay in this container and sank to the bottom of the sea, where he stayed for some time to see the bizarre aquatic life. This kind of glass container is not a submarine, of course, but a diving container.

Although these early people made these utensils, although they could dive into the water and float out of the water, they had no power and could not move forward. Some scientists and explorers have carried out many studies and explorations to build a ship that can both float and move underwater.

At the beginning of the sixteenth century, there was a Dutch physicist named Cornelius Drebel. In order to make the diving boat able to move forward in the water, he did a long period of research and experimentation.

In the twenties of the sixteenth century, he rowed forward with an oar, one of the largest diving boats, carrying twelve sailors.

The dive boat is made of wood, covered with an oiled cowhide, and dives to a depth of four to five meters, with a sheepskin bag as a tank.

The sheepskin pouch was filled with water, and the boat dived; The water in the sheepskin pouch was squeezed out, and the boat floated to the surface.

This is the world's earliest prototype of a submarine.

During the American Revolutionary War in the 18th century, British warships ran rampant in the seas and ports of the United States, arousing the righteous indignation of Americans.

There was an American named Davit Busnell, who was at the mercy of patriotic fervor and soon created a submarine called "Turtle". The boat is about two meters high, and the shell is made of oak wood and can accommodate one person.

He tried to use it to blow up and sink British ships. Although unsuccessful, this was the first time in the history of world naval warfare that a submarine entered real combat.

Subsequently, Robert Fulton of the United States sprung up in the field of submarine development. Originally a landscape and portrait painter, he came to England in 1794 and invented the linen loom. Three years later, he moved to France to begin the development of submarines, although the design of the model was so successful that the French Minister of the Navy dismissed it as dismissive.

It was not until 1800 that Napoleon, the French chief consul, finally gave him a sum of money to build a submarine, which was completed in 1801 and named the "Nautilus".

The Nautilus's shell plate is copper, the frame is iron, and the length of the boat is 6.98 meters, and it is shaped like a cigar.

When the submarine is driving on the surface, it relies on a foldable mast to pull up the sails to move forward, and when diving, it is powered by hand-operated propellers, and when diving, seawater is injected into the ballast water tank, and a horizontal rudder is used to keep the submarine at the desired depth.

The Nautilus's method of operation was to place explosives and mines under the hulls of enemy ships. This is exactly the same approach to the attack of the "Turtle". In one test, the Nautilus successfully attacked an old sail warship moored in Brest, and the target was blown to pieces.

So Fulton began to use it to attack the British warships blockading the French coast, and the British warships did not let the "Nautilus" get close, so that although several warships were chased, none of them were sunk.

In the sixties of the nineteenth century, during the American Civil War, a colonel of the Southern Army, Hen Ray, funded engineers McLean and Watson to develop another submarine, which was named "Hen Lei".

It was converted from an iron boiler and was about 18.3 meters long, like an elongated cigar. It has a speed of four knots per hour and is armed with a torpedo.

On the night of 17 February 1864, the "Henley" attacked the Northern warship in Chariton Harbor and sank the Northern battleship Tonic.

Nevertheless, the submarine that was the first to sink a warship went down in the annals of world naval warfare.

In 1889, a naval captain named Isaac Burr in Hebanga designed the world's first submarine propelled by an electric motor, but the submarine plan was rejected due to a feud between him and his superiors.

Seeing that Spain was preparing to build submarines, the United States decided to allocate $2 million for the Navy to hold an open submarine design competition.

Of course, Holland's design is outstanding. In 1893 the Admiralty held another competition for the design of submarines, and Holland once again came out on top. So the U.S. Navy gave him $150,000 in research and development funds, and he began the design and construction of a fifth submarine.

The submarine, called the Diver, was 26 meters long and was equipped with a steam engine that could propel a surface boat and an electric motor that could propel a boat underwater.

The Diver can be said to be the ancestor of the submarine with a dual propulsion system. Since then, the development of submarines has entered a new period.

In 1897, when he was fifty-six years old, he built his sixth and last submarine, the Horan-16, about 15 meters, with a 33-kilowatt gasoline engine on it, capable of traveling 1,000 nautical miles per hour at a speed of seven knots per hour on the surface. It is also equipped with an electric motor powered by a battery, which can travel 50 nautical miles at a speed of 5 knots per hour, and its successful development is an important milestone in the history of submarine development.

When the good news of the success reached the U.S. Department of the Navy, some officers were still prejudiced against Holland, an inventor from a mediocre background without a degree, and were slow to recognize and accept it. Although Holland claimed in the Sun newspaper in New York at the time that if the Navy paid for the submarine, he would personally pilot it and guarantee to sink all the ships of the Spanish fleet, he was still ridiculed and resigned.

From the first submarine of Dreber to the advent of Holland's dual-propulsion submarine, it took more than 280 years, and the reason for its slow development was mainly that the navies of various countries did not pay enough attention to it, but submarines shined in the two world wars. After World War II, the development of submarines gradually entered the fast lane.

After the submarine was put into naval warfare, it played a huge role in the First and Second World Wars, dealing a heavy blow to the enemy's surface ships.

However, due to the fact that conventional submarines use battery-powered electric propulsion when navigating underwater, when the battery is exhausted, it must be born out of the water and recharged by diesel generator sets.

This makes conventional submarines must have two sets of propulsion devices, one diesel engine power propulsion device suitable for surface navigation, and the other set of battery-powered electric motor power propulsion device suitable for submarine.

These two sets of power units have their own insurmountable drawbacks, especially electric propulsion, the submarine underwater speed is very low, the endurance is limited, and the underwater combat performance of the submarine is seriously weakened.

In addition, when it surfaces to charge, it is also very dangerous.