How Do Airplanes Fly?

Science Soup

Posted: July 01, 2023

Flight depends on four forces. (Stock)
The air flowing above an airplane wing moves faster, which reduces pressure above the plane. The air flowing under the wing moves slower, which increases pressure below. This creates lift.
When you throw a paper plane, thrust comes from your arm. (Pixabay)
Modern planes usually create thrust with jet engines. (123RF)
Airplane designers got ideas for wing shape by observing birds. (123RF)

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Paper airplanes weigh much less than 200-ton passenger jets. But believe it or not, the same forces make them fly! Flight depends on four forces: thrust, drag, weight (or gravity), and lift. Thrust drives an airplane forward. Drag, caused by air pressure, pulls it backward. Weight (or gravity) draws the plane toward Earth. To overcome weight, the plane needs lift. Lift pushes the airplane upward. But how do airplanes generate enough thrust and lift to soar?

For a paper plane, thrust comes from your arm. You push the plane forward with the “thrust” of your throw.

What about actual airplanes? Modern planes usually create thrust with jet engines. Some planes, such as crop dusters, use propellers.

Lift comes from the aerodynamic shape of an airplane’s wings.

Have you noticed how a plane’s wings curve and tilt up? This shape builds pressure as air passes over and under the wing surface at different speeds. As pressure builds, the force of lift makes the plane rise.

God designed bird wings to work the same way. That gave aerospace engineers the idea for airplane wing shape. When scientists copy nature, it’s called biomimicry.