Physics in the animal world: dragonflies and their flight



    Dragonflies can be called innate flyers. In the air, these insects spend a lot of time, and most species easily show examples of aerobatic techniques. For example, a dragonfly can hover in the air, fly very quickly or very slowly, unexpectedly change the direction of its flight in any direction. Dragonflies have four wings that act independently of each other. One would think that the movements of the front and rear wings are synchronized in such a way that both wings are like a single whole, one plane. But this is not the case.

    Immediately it should be said that the principle of flight of dragonflies is not unique, it is used by many insects, both dipterans and four-winged ones. At the heart of everything is the occurrence of thrust in the event that the flaps of the wings go down faster than those of the flaps up. Compared with the flight apparatus of most insects, this system in dragonflies is much more complicated. For what? The fact is that this complication allows dragonflies to perform in the air tricks that most other insects are not available. In addition, dragonflies can accelerate to a very high speed of 40 kilometers per hour.

    A closer look at the placement of the wings of the dragonfly can be seen that the distance between the joints of the front and rear wings is much smaller than the width of these wings. And even if they are divorced quite widely, all the same, with oncoming movements, such wings should cling to each other. In fact, the dragonfly does not feel any discomfort during the flight. They are trying (although “trying” is a bit of the wrong word) to combine the contours of the front and rear wings. When flying forward, the wings of dragonflies diverge, and when they descend, they flap on each other.

    Moreover, in this case, the planes of the upper and lower wings are not at all parallel. The rear edges of the wings when moving somewhat behind in their movement from the front. So with the sweep of the upper and lower wings forma collapsing wedge, as a result of which a stream of air is thrown back, creating a reactive force pushing the dragonfly forward. Experts say that the layout of the wings of the dragonfly is optimal for flight.



    As a result, in most cases, dragonflies fly faster than their victims. In addition, these insects can perform almost any maneuvers, very quickly turning to the sides, swooping down or rising up. Few insects are able to avoid such a fast hunter.

    Interestingly, before scientists believed that the use of such a complex aircraft requires large physical costs from dragonflies. Scientists from Ulm University in Germany and the Royal Veterinary College in London have recently decided to check this statement. In order to do this, experts have developed a robotic dragonfly. It was placed in mineral oil through which gas was passed. Upward raised bubbles that simulated the movement of air around the wings in flight. The mechanical dragonfly was equipped with sensors by which scientists measured the force required to raise or lower the wing.

    So, the authors of the study obtained data that clearly show: dragonflies use a special flight algorithm, which allows to increase the efficiency of the wings of these insects by 22% compared to flying insects, which have two wings. The fact is, when passing a certain part of the way, the back wing of the dragonfly captures the flow of air from the movement of the wing, which is in front and is repelled from it in a certain way. The important point is also the fact that the wings of dragonflies bend from the base to the tops. This allows you to reject the air without any problems, just as the wings of a bird drop it. The results of the study of the flight of dragonflies by this group of researchers were published in the Journal of the Royal Society Interface.

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    As for the side maneuvers, the dragonflies do this due to the unbalance of the wings. In order to be able to quickly shift to the left, the dragonfly needs to increase the amplitude of the strokes of the right pair of wings. The tilting of the dragonfly becomes unlikely, given the ability of these insects to work with the abdomen. When flying to the left, so that no displacement occurs, the dragonfly bends the abdomen to the right. By the way, in order to turn right, the dragonfly needs to begin to slightly slam the left pair of wings. As a result of this maneuver, the wings will throw a certain amount of air back and the insect will turn to the right.

    By the way, earlier it was believed that the thickenings on the leading edge of the dragonfly wing are intended for leveling the so-called flutter. This term refers to vibrations of rigid wings. Now, some scientists believe that these bulges work as shock absorbers to facilitate the breeding of the upper and lower wings. If it were not for this factor, the upper and lower wings could collapse and the dragonfly could not fly normally anymore.

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    It is interesting that at a set speed dragonfly literally rams its victims. The impact force is very high. But the dragonfly does not suffer from collisions due to its durable and elastic chitinous cover. But the victims of dragonflies are less lucky, they lose the ability to move or even die from such collisions.

    In general, dragonflies - the ideal machine for flight and hunting. The insect organism consists of several unique elements, each of which is complex but effective.

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