Dynamics of Flight

Many people wonder just how birds and planes fly, to understand how, start with the basics. Air is a physical substance which has weight. It has molecules which are constantly moving. Air pressure is created by the molecules moving around. Moving air has a force that will lift kites and balloons up and down. Hot air expands and spreads out and it becomes lighter than cool air. When a balloon is full of hot air it rises up because the hot air expands inside the balloon. When the hot air cools and is let out of the balloon it comes back down. In the case of airplanes, the wings are curved on the top which make air move faster over the top of the wing. It moves slower underneath the wing. The slow air pushes up from below while the faster air pushes down from the top. This forces the wing to lift up into the air. Birds' wings are the same way, their feathers are also hollow which make the bird lighter. By moving its wings up and down, a bird can turn while in the air. For example, if a bird moves it's left wing up, and right wing down, it will turn right because all of its weight falls onto that wing, this is called the aileron. A bird or plane can move up and down by controling its head of body. If a plane's nose or a bird's head is moved down, the body will follow.