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| The crain is one of the most graceful migratory birds. |
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| This is why Lufthansa chose the crane for their logo. |
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How do birds and insects fly?
Interesting facts from the world of natural fliers
People have always dreamed of being able to fly like the birds. For centuries, they watched birds fly and tried to imitate them until finally building the first flying machines. What makes birds so interesting is that they fly under their own power. Just like in an airplane, two mechanisms come into play here: lift and propulsion.
The bird's own power plays a role in lift. Birds cannot weigh more than 15 kg, otherwise they would be much too heavy to even get off the ground. Swans and pelicans are therefore some of the heaviest birds capable of flight. Lift is created by the wing's movement, or rather by its downward movement. This is made possible by two powerful chest muscles. In fact, these muscles account for over 15% of a bird's total weight! The wings press the air downward, forcing it to flow in this direction. This downward flow of air produces a higher pressure above the wing than below it. The bird thus gains lift and can now rise from the ground.
Propulsion, or forward thrust, is equally important, for it enables the bird to fly long distances. Propulsion involves a number of different factors. First of all, it is produced by the wing's curved shape, which is also used by aircraft. The wings are rounded at the front and taper toward the back. Propulsion is also generated to a large extent when the bird turns its wings and swivels them back and forth. On the upbeat, the bird swivels its wings forward and turns them slightly upward; on the downbeat, it swivels them to the back and turns them slightly downward. Even when a bird holds its outspread wings motionless, as it does when gliding, there is enough lift to keep the bird in the air. It must only have reached a certain flying speed.
Air resistance works against propulsion - just as it does in aircraft. The less aerodynamic the shape of the body and the higher the speed, the greater the resistance. Because a plane flies much faster than a bird, it must contend with greater air resistance. As a result, it flies much higher than does a bird, since the air resistance is a lot lower at greater altitudes.
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