The Lift Of Various Wings

SCIENCE CONCEPT:

You have noticed that fast airplanes usually have rather small wings. With such small wings lift is less and the airplane must move faster before it can take off. It must also land at a higher speed. With such disadvantages, why are wings of fast airplanes made small? The greater the drag the harder the motor must pull to make the airplane move through the air. Thus, to increase the speed of an airplane designers try to cut down on drag. One way to reduce drag is to cut down on the size of the part that faces the air. Therefore, the wing is made smaller for fast airplanes.

STUDENT OBJECTIVE:

The student will explore how different shaped wings will produce different types of lift for an airplane.

OVERVIEW:

In this activity, the student will examine how different shaped wings of an airplane responds to lift. The materials that will be used are a fan, a large bundle of tubes, platform balance, large container box, models of airplane wings, and weights.

PREPARATION TIME:

20 minutes.

LESSON TIME:

30 minutes.

TEACHER PREP:

Gather the materials that are needed for the experiment. You will need a fan, a large bundle of tubes made of straws, protector for the fan, models of wings, platform balance, and weights.

WORDS TO KNOW:

lift

drag

flat wing

curved wing

trailing edge

air resistance

TEACHER TEXT:

How much lift do wings of different shape produce? Which shapes are best for airplanes? Designers of airplanes use large wind tunnels to experiment with different shapes for parts of airplanes. They seek shapes for parts of airplanes. They seek shapes that reduce drag, and therefore increase the speeds of airplanes.

Planes and other flying objects use the wind indirectly through Bernoulli's principle. Daniel Bernoulli was a Swiss scientist who discovered that when any fluid, such as air, flows, its pressure decreases as its speed increases. This decrease in air pressure can lift objects from a Frisbee to a jet airplane. His discovery explains why the wings of birds and planes are sucked upward, creating the lift necessary for flight.

The curved upper surface of the wing forces the air to increase its speed as it flows over the top in order to reach the trailing edge of the wing at the same time as the air flowing in the path below the wing. With the increase in speed on top, the pressure exerted decreases. This change makes the pressure pushing up from under the wing greater than the pressure pushing down on the top of the wing, so the wing moves up naturally.

There is another force acting on a wing from the flow of air. This is the force of drag. Drag acts to slow the speed of the wing through the air. If there were no drag, an aircraft could just keep going faster and faster. A flat wing, such as you might make for a paper airplane, can create lift if given some angle of attack, but it will have greater drag for the same amount of lift than a properly curved wing.

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Last modified: Sat Dec 20 12:49:47 PST 1997