Inspired by dragonflies, the composition of helicopters was invented (400 words).

Helicopters come from the principle of bamboo dragonflies, that is, the toys we played when we were young, which are sculls that fly when we put them with our hands. The development of helicopters has experienced several twists and turns in the history of human scientific development, which is much more difficult than fixed-wing aircraft. The reason is that its unique rotor flight mode has brought too many technical obstacles, and it needs a lot of technical progress to bring about a breakthrough in helicopters. But the future development trend of helicopters is to combine the functions of helicopters and fixed-wing aircraft.

The concept of helicopter can be traced back to the ancient bamboo dragonfly in China. According to well-documented historical records, in the book "Holding the Robot" written by Ge Hong in the Jin Dynasty, the scene of the spinning bamboo dragonfly taking off vertically and the spinning propeller pulling vertically upward is described, which is considered to be the description of the basic principle of the earliest vertical take-off and landing helicopter in the world. Although these records lack reliable basis, the contribution of bamboo dragonfly to the development of world aviation is universally recognized. Long before the invention of hot air balloon, bamboo dragonfly was introduced to Europe as a toy, and its wonderful vertical lift-off principle was studied by Europeans as an aircraft. Many western aviation pioneers have realized some important aviation principles from bamboo dragonflies.