How advanced is dragonfly’s flying technique?
Dragonflies can fly at a speed of up to 50 kilometers per hour, which is much faster than most insects. They can rest quickly in high-speed motion and hover steadily in the air, or switch from hover to high-speed flight in a very short period of time. During the flight, dragonflies can also make “sharp turns” without warning. When hunting for hunters, the instantaneous acceleration of dragonflies can reach more than 9g, this undoubtedly greatly improved their hunting success rate.
The direction of dragonfly flight can be any direction in the air, you are not wrong, it is any direction, whether it is down or up, left or right, even they can fly upside down directly.
In addition, dragonflies can also fly a very long distance at a time. People have already observed that some dragonflies can migrate to Africa through the Indian Ocean. In 2016, a study by a biologist from Rutgers University showed that, there is a thin-winged dragonfly that can actually cross the Pacific Ocean, and its flight distance can be as high as 6440 kilometers.
If we have never seen dragonflies before, we may not imagine that there are insects with such superb flying skills in nature. So how do they do it? Although scientists have studied for many years and have not fully understood the secrets of dragonflies, there are still many gains. Let’s take a look at them.
As the King of the flying world, dragonflies have four huge wings. Their wings are very light and thin, and the thickness of the thinnest part can be less than 2 micrometers. After enlarging them, you can see, the wings of dragonfly have a special reticular wing structure. Its “main pulse” is a quadrilateral network, while the “secondary pulse” is mostly Pentagram and hexagon. Scientists believe that, this structure gives dragonfly wings strong toughness.
The above figure shows the microstructure of dragonfly wings observed by scientists by scanning electron microscope. It can be seen that the surface of dragonfly wings is covered with nanoscale columnar structure, they can not only directly affect the fluid dynamics when air flows through the surface of the wings, but also make the wings of dragonflies have good hydrophobic properties and are difficult to be stained with water and dust.
It is worth mentioning that in the past days, “flutter” has always been a big problem for human beings in the field of aircraft. The so-called “flutter” refers to that during flight, the wing of the aircraft is a harmful vibration under the combined action of aerodynamic force, elastic force and inertial force. The faster the aircraft is, the stronger the “flutter” will be. In severe cases, it may even cause the wing to break directly.
Theoretically, huge wings like dragonflies will also “flutter”, but in fact, dragonflies are not threatened by “flutter” at all. Why is this?
After research, scientists found that the reason was that there was a thickened area called “wing eye” at the front of dragonfly wings (as shown in the above figure), it can effectively eliminate the “flutter” generated by dragonfly flying at high speed “. In the following days, people imitated dragonflies and added similar structures to the wings of aircraft, thus overcoming the problem of “flutter” at one stroke.
Research shows that each wing of dragonfly is controlled by independent muscles, and they can also rotate, this means that Dragonfly can control the inclination angle of front wing and back wing and the amplitude and frequency of wing vibration individually when flying. Through different phase differences, various flight requirements can be realized.
For example, when the rear wing of the dragonfly leads the front wing by one fourth of the cycle, the dragonfly can obtain a large lift, thus hovering in the air steadily, when the rear wing is 90 degrees earlier than the front wing, a large thrust can be obtained, thus flying at a high speed. When all wings are synchronized, the maximum thrust in a certain direction can be obtained, therefore, the “sharp turn” is realized. When all wings stop vibrating, dragonflies can enter the gliding mode. Scientists believe that gliding mode is the secret that dragonflies can fly ultra distance.
Dragonfly’s superb flying skills are worthy of the title of “The King of the flying world”, and they are also the best teachers of our human beings. At present, although we have not fully understood Dragonfly’s secrets, however, scientists have never stopped studying dragonflies. We hope that in the near future, our human aircrafts can also fly in the sky like dragonflies.