The design inspiration for mankind's first helicopter came from the bamboo dragonfly?

Today in Science and Technology History | 1907·11·13 From the "bamboo dragonfly" to the first helicopter in human history

Helicopters are an important tool for people to fly to the blue sky and realize their dreams of flying. In ancient times, our ancestors began to study how to fly, and the earliest helicopter design ideas originated in ancient my country.

In August 1907, French inventor Paul Corny developed a full-size manned helicopter, which was successfully tested on November 13 of the same year. This helicopter is known as "the first helicopter of mankind". This helicopter, called "flying bicycle", not only completed vertical lift by its own power, but also flew continuously for 20 seconds, achieving free flight.

◆The first helicopter in human history

On November 13, 1907, the world's first manned helicopter successfully completed its test flight. As it took off, the name of its designer, Paul Kearney, was remembered by later generations. Kearney's title as a great aviation pioneer was given by later generations. When he tried to fly in 1907, he was still a bicycle repairman and was in the same industry as the Wright brothers, who had not yet made their debut. On that day, November 13, Kearney flew the helicopter for many times. The best flight was to stay in the air for 20 seconds at an altitude of more than 1 meter. This was a remarkable achievement and was also regarded as a glorious milestone in the history of helicopter technology development.

The main structure of Kearney's helicopter is a V-shaped steel tube. The fuselage is composed of a V-shaped steel tube and a star-shaped piece composed of 6 steel tubes, with a pair of rotors at the front and rear. The engine (a 24-horsepower 8-cylinder piston engine) and the pilot are located in the middle of the fuselage. The power of the engine is transmitted to the front and rear rotors through two belts, driving them to rotate in opposite directions, which can offset the counter-torque generated by each other and keep the fuselage stable.

Kearney put a lot of thought into the control problem. He controlled the pitch of the two rotors (that is, the inclination angle of the blades relative to the horizontal plane) through steel cables to control the total lift, which is exactly the same as the modern helicopter later. The helicopter has a control surface at the front and rear that can control the deflection. Kearney hopes that they can guide the downwash airflow of the rotor to achieve the turning of the helicopter.

Through experiments, Kearney found that the control system he designed was not effective and could not achieve effective controllable flight. At that time, he could not find a better solution, so he gave up the design soon. However, Kearney's attempt is still worth remembering. In 2007, the French Air and Space Museum specially made a replica of the Kearney helicopter and displayed it in the museum for people to visit.

◆The Chinese bamboo dragonfly provided inspiration for the invention of the helicopter

China's bamboo dragonfly and Italian Leonardo da Vinci's helicopter sketch provided inspiration for the invention of modern helicopters and pointed out the correct direction of thinking. They are recognized as the starting point of the history of helicopter development.

The bamboo dragonfly is also called the flying spiral and the "Chinese spinning top". It is a unique invention of our ancestors. Some people believe that China had bamboo dragonflies as early as 400 BC, and another more conservative estimate is that it was in the Ming Dynasty (around 1400 AD). This folk toy called the bamboo dragonfly has been passed down to the present day.

Although modern helicopters are thousands of times more complex than bamboo dragonflies, their flight principles are similar to those of bamboo dragonflies. The rotors of modern helicopters are like the blades of bamboo dragonflies, the rotor shaft is like the thin bamboo stick of bamboo dragonflies, and the engine that drives the rotors is like our hands rubbing the bamboo sticks. The blades of bamboo dragonflies are round and blunt in front and sharp in the back. The upper surface is more arched and the lower surface is more straight. When the airflow passes through the arched upper surface, its flow rate is fast and the pressure is small; when the airflow passes through the straight lower surface, its flow rate is slow and the pressure is high. As a result, a pressure difference is formed between the upper and lower surfaces, which generates an upward lift. When the lift is greater than its own weight, the bamboo dragonfly will take off. The principle of helicopter rotors generating lift is the same as that of bamboo dragonflies.

Italian Leonardo da Vinci proposed the idea of ​​a helicopter and drew a sketch in 1483.

At the end of the 19th century, people found an imaginary picture of a helicopter drawn by Leonardo da Vinci in 1475 in the Milan Library in Italy. It was a huge spiral made of starched linen, which looked like a huge screw. It rotated with springs as the power, and when it reached a certain speed, it would lift the body into the air. The pilot stood on the chassis and pulled the wire rope to change the flight direction. Westerners believed that this was the earliest blueprint for the design of a helicopter.

◆The world's first helicopter with normal maneuverability

In 1936, after making many improvements to its early helicopters, the German Fokker company publicly displayed its own FW-61 helicopter, which set several world records one year later. The helicopter industry considers this helicopter to be the world's first truly successful helicopter test flight.

The FW-61 helicopter is a large twin-rotor helicopter with a fuselage similar to that of a fixed-wing aircraft, but without fixed wings. Its two rotors are supported by two sets of thick metal frames to the upper right and upper left, and the two rotors are installed horizontally on the top of the bracket. The blade plane is sharp and connected to the hub with a flap hinge and a swing hinge. The automatic tilt device is used to tilt the rotor rotation plane for longitudinal control, and the yaw control is achieved by tilting the two rotors in different directions.

The FW-61 was powered by a 140-horsepower piston engine. It was the world's first helicopter with normal maneuverability. It had a speed of 100-120 kilometers per hour, a range of 200 kilometers, and a takeoff weight of 953 kilograms.

Comprehensive from "Global Low-Altitude", Institute of Physics, Chinese Academy of Sciences