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Four Forces of Flight

In this quick activity, students think, pair, and share their thoughts on the forces that affect an airplane.

An airplane in flight is acted on by four forces: lift, the upward acting force; gravity, the downward acting force; thrust, the forward acting force; and drag, the backward acting force (also called wind resistance).

Lift opposes gravity and thrust opposes drag .

Drag and gravity are forces that act on anything lifted from the earth and moved through the air. Thrust and lift are artificially created forces used to overcome the forces of nature and enable an airplane to fly.

Airplane engine and propeller combination is designed to produce thrust to overcome drag. Their wings are designed to produce lift to overcome gravity.

Objectives

  • Describe the four forces involved in flight.

Materials

  • a sheet of paper

  • marker or pencil

  • scissors (optional)

Key Questions

  • In which directions would forces act on a plane while it is in flight? What causes the forces?
  • How is thrust created in an aircraft? In a paper plane?
  • To speed up a plane, which force would you increase?
  • To get the plane to climb, which force would you increase?
  • Which of the force(s) are due to natural phenomena? Which are artificially created?

What To Do

  1. Hand out a piece of paper to each student and have them make a basic paper airplane, and then fly their airplane.
  2. Have students draw arrows on their planes to label the forces that act on an airplane when it is in flight. Each arrow should identify the direction of the force and what’s causing it.
  3. Have students compare their arrows with a partner.
  4. Introduce the terms thrust, drag, lift and gravity.
  5. Ask students to discuss with their partner the forces they identified, and whether those forces are thrust, drag, lift or gravity. (For example, a student might identify friction, or air resistance, or the force of the propeller…)

Teacher Tip: Connecting the “Four Forces” diagram to having the class make their own paper airplanes really aids in helping students understand and visualize the concept. Paper airplane patterns and folding instructions can be found here.

Extensions

  • Use a paper airplane to determine how the angle of your plane will affect the thrust andthe drag.
  • Expand the discussion to include how animals create the forces required for flight. Examples include minimising drag by having a streamlined shape, increasing lift by having a small body, increasing thrust with large wing muscles. Soaring, gliding and parachuting also feature in animal flight techniques.

Other Resources

10 Paper Airplanes | Paper Airplane models and folding instructions