How Can Birds Fly?

A bird's wing is so shaped that the air must travel farther over the top of the wing than underneath it. Hence, the air above the wing travels faster to 'catch up,' as it were.

Due to increased speed, the air above the wing is "thinner" than the air below. The compressed "thicker" air under the wing exerts greater pressure and pushes the bird up, providing the needed lift. Something similar occurs when you drink with a straw. As you suck on the straw, you are thinning out the air inside the straw. The normal air outside is then "thicker" and pushes the liquid up the straw.

The air striking the underside of the bird's wing also tends to lift it. At the same time, however, the creature has to use some of its strength to overcome the air's dragging effect.

To get airborne, a bird usually jumps into the air, flapping its wings. At first it may seem that the bird just flaps them up and down. But closer investigation reveals that this flapping flight is far more complex. The bird pulls its wings down and back with the feathers tightly closed and wings outstretched, thereby pushing as much air as possible. Then it pulls the wings forward and up with the feathers separated to allow the air to pass through. The wings are also pulled in close to the body so that there is minimum air resistance.

Wing movement provides lift as well as the propulsion needed to overcome "drag" and to gain speed. The bird's wing movement might be compared to a swimmer's doing the "butterfly stroke." His arms rotate around his shoulder joint, as he throws them forward through the air and then pulls them back through the water.

When man decided he wanted to fly, he had to create a flying machine. When you examine a bird, you can see that Nature has done everything possible to make the bird a perfect flying machine, attached to the bone of the outer arm by a tough cord of tissue called a "sinew". The supporting flight feathers are attached to the upper arm bone in the same way.

Each feather has its own set of muscles, so the bird can control each feather in flight. On the up-beat of the wing, the main and some of the supporting flight feathers are turned so the edges are turned up. The air can pass easily between the feathers. On the down-beat, ail the flight feathers have flat sides down and air cannot pass through the wings. In this way the bird pushes himself into the air and takes off in flight!

But a flying body must have the greatest possible lightness, compactness, and strength. So the large bones of u bird are hollow. Many of them have air sacs. The ribs of a bird are fused to make a firm support for the down-beat of the wings.The head, tail, wings, and legs of a bird are extremely light, The bones of the skulls are very thin.

A bird does not have teeth and jaws with heavy bones and muscles it has instead a hollow beak,The strong muscles that move the wings are attached to the breastbone, bringing them closer to the centre of gravity. Even the fact that birds arc warm-blooded is a help, because cold-blooded creatures become sluggish in winter. So you see everything about the bird is "designed" to help it to fly!