SCIENCE CONCEPT: Naturally adept at flight, the bird has in it's wing many wonderful features that we have adopted in the airplane wing. In a bird's wing we find many of the devices that are found on an airplane wing. STUDENT OBJECTIVE: The student will observe the features in a bird's wing and in an airplane wing and demonstrate these features on a chart. OVERVIEW: The class will be divided into two groups. One group will list the features of a bird's wing and the other group will list the features in an airplane wing. After each group has compiled their list of features, it will be written down on the board so that the other team can have the information. Each student will then make their own chart of the features of the wings of birds and airplanes. In this manner they will come to understand the duo dynamic of flight in nature and with man. Ask students to bring in small model airplanes made out of balsa wood to assemble and fly as a class to visually observe the "flight" of an airplane. For those who cannot bring in an airplane model you can have them make paper airplanes and cut out slats and flaps to see how the paper airplane flies. Also observe the "flight" of birds outside.

PREPARATION TIME: 15 minutes. LESSON TIME: 40 minutes. TEACHER PREP: Gather pictures of airplane wings and bird wings with descriptions of the various parts of the wing. WORDS TO KNOW: slats flaps leading edge angle of attack alula

An airplane has many parts working together to cause it to become airborne. The wings of the airplane cause it to lift and stay in the air. Attached to the wings are the inside flaps that make the plane fly slower and the outside ailerons that make the plane turn. Depending on the particular dimensions and features of an airplane, the wings will essentially have similar features. On some planes their are unique features that have been adopted from bird observation - such as winglets, slats and flaps to stabilize the wings and create features to improve lift. The amount of lift a wing can produce is governed by several factors: the size of the under surface of the wing. The larger the wing the more lift it can produce. The ratio is approximately 1:1. Another way to increase the lift is to change the angle of the wing as it faces the air. Tilt the leading edge up and the distance the upper air stream must flow is even greater. This is called increasing the angle of attack. Therefore, the air speed increases. The bird changes the angle of the whole wing, where a plane lowers the flaps on the trailing edge, but the result is the same. Two times the angle of attack equals two times the lift. This works only to a point. If the angle of attack is to great all lift disappears and the bird or plane begins to fall to the ground. This point is called the stalling point. There is still another way to get maximum lift without reducing the angle of attack. If the air across the wing can be made to move even faster, thus increasing the vacuum which pulls the air stream back down on the wing, then lift will be produced again. This can be accomplished by forcing the air through an even smaller space, or slot, just ahead of the upper surface of the wing. These slots can be formed in a number of ways: In birds there are a few feathers attached to a movable finger bone like our thumb. It is called the alula and it is on the front of each wing. The bird can easily adjust this slot to increase lift. Birds can also manipulate the feathers at their wing tips to produce slots if necessary. Birds can also raise the feathers on the leading edge of the wing to form slots. On an airplane there are slots that can be opened on the top of the wing. All of these ways are used to increase the speed of air moving over the upper surface of the wing. The structure of the bird's wing is such that it can be folded close to the bird's body when it is not in flight. But when the wing is extended, it acts as both wing and propeller. The feathers attached to the "hand" bones are the ones that produce the forward thrust for the bird. The forward motion of flight is the result of pushing backward. The primary flight feathers on a bird are what pushes backward against the air. They can be likened to the blades of a fan, only they only go 1/2 revolution at a time. On the downstroke they push backward against the air. Then the feathers twist in such a way they push air backward on the upstroke too. The feathers twist back and forth as the wing goes up and down.

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