How did the bamboo dragonfly take off?

The lift-off principle of bamboo dragonfly is as follows: when the rotor rotates, the rotating blades push the air downward to form strong wind, and the air also gives the bamboo dragonfly an upward reaction lift, which varies with the inclination angle of the blades. When the inclination angle is large, the lift is large, and when the inclination angle is small, the lift is small. The larger the resistance area, the greater the required rotating force, which is not practical in the actual operation of bamboo dragonfly. It may be necessary to find a balance between force and angular area in order to make the bamboo dragonfly easy to operate and fly high.

Bamboo dragonfly is one of the traditional folk children's toys in China, which is widely spread. Bamboo dragonfly consists of two parts. One is a bamboo handle. The second is "wings". When playing, rub your hands together, then let go, and the bamboo dragonfly will fly to the sky.

After a while, it will fall. It is a very subtle little invention in ancient China. This simple and magical toy once amazed western missionaries and called it "China spiral". In 1930s, Germans invented the helicopter propeller according to the shape and principle of "bamboo dragonfly".

Extended data:

The origin of bamboo dragonfly:

Bamboo dragonfly is an ancient children's toy in China. Its shape is T-shaped, with a horizontal bar like a propeller and a small hole on it. When a straight bamboo stick is inserted into it, the bamboo dragonfly will fly into the sky and then fall to the ground when the lift is weakened. In the process of making and playing bamboo dragonflies, we can appreciate the fun of ancient children's toys in China and the mystery of science and technology.

Inspired by observing the flying of dragonflies in nature, people in China made bamboo dragonflies in 500 BC. Bamboo dragonflies have been in the hands of children in China for more than 2,000 years.

/kloc-spread to Europe in the 0/8th century, which inspired people's thinking. George Kelly?? The Englishman, known as the "father of aviation", has been fascinated by bamboo dragonflies all his life. His first aviation research was to imitate the "bamboo dragonfly" in 1796, and thus realized some working principles of the propeller. His research promoted the development of aircraft. And it has inspired western designers to develop helicopters.

Baidu encyclopedia-bamboo dragonfly