The invention and development of submarines were inspired by fish diving. 1775, after the North American War of Independence broke out, the British colonial rulers relied on their maritime superiority to assemble a large number of warships and bombed the US navy and army in turn, causing heavy casualties to the US military. At that time, there was a general named David bushnell in the American army. He couldn't stand being bullied by the British and was determined to fight back.

He has been thinking hard: how can we sink the enemy ship? From the air, inaccessible; You can't hide from the water. Once, when he walked to the reef by the sea, he suddenly saw a big fish dive under a small fish, jumped up suddenly and bit a small fish.

He was greatly inspired by this "naval battle": Can he build a ship like a big fish and dive into the bottom of a British warship unnoticed and sink it? Fish float and sink freely in the water by the swim bladder. Can a boat imitate a swim bladder?

Starting from this idea, bushnell and military experts jointly developed a motorboat that can dive underwater. The bottom of the boat is a water tank similar to a swim bladder. There are two pumps in the water tank. When the ship sinks into the water, it will fill the cabin with water. When the ship is about to rise, it will press air into the water tank and discharge the water in the ship.

The motorboat skillfully subdued the British warship on its first voyage and was blown upside down. After gradual improvement, it has become a modern submarine.

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The early history of submarines

Submarines can be traced back to 15- 16 th century Leonardo da Vinci. It is said that he once conceived a "ship that can sail underwater", but this ability has always been considered "evil", so he did not draw a design. Until the eve of World War I, submarines were still regarded as "non-gentleman" weapons, and their captured crew members might be regarded as pirates.

/kloc-in the 0 th and 6 th centuries, real submarines appeared. 1578, the British mathematician William Bourne wrote the book Invention and Design to describe submarines. 1620, the first recorded "sub-motor vehicle" was made by Cornelius Jabs de Boer, an Englishman born in the Netherlands. Mainly according to the previous design, the propulsive force is generated by manually operated paddles.

However, some people think that it is just "a bell-shaped thing tied under a surface ship" and is not a submarine at all. From 1620 to 1624, it has two improved models for experiments on the Thames. In 2002, the BBC TV program "Building Impossible" was broadcast. Mark Edwards of Kyle built a Derbord submarine with two people on board according to the design drawings of that year, and successfully snorkelled in Doni Lake of Eton College.