The obvious answer to why paper airplanes fly is because someone threw it in the air. Whether you throw a paper airplane or a ball, it’ll fly for a short distance. In physics, the technical term for this is thrust. Thrust is the force that propels a thing forward. For real airplanes, the engine(s) provide the thrust required for it to continue flying.
The opposite force to thrust is drag. Drag is all the factors that prevent a thing from propelling forward. For example, stick your hand slightly out the window when the car is moving. You can feel your hand being pushed backwards. Try rotating your hand at different angles, what do you notice? When you hand is held horizontal to the ground, there’s less drag. I like to imagine my hand cutting through the air. You get the most push from the wind when your hand is held perpendicular to the ground. You are feeling the effects of drag.
We now know about the two forces that move a paper airplane forward and backwards. What about upwards and downwards? Good question!
Let’s talk about the obvious, the downward force. It’s gravity. Everything on earth is pulled downwards by gravity. When you throw a paper airplane into the sky, gravity will eventually pull it to the ground.
The last force acting on a paper airplane when it is in flight is lift. When a paper airplane is thrown in the air, the wind passing above is slightly slower then the wind passing below the wings. This provides enough lift to allow the paper airplane to glide. As there’s no additional thrust after the initial throw, drag will slow the paper airplane down where gravity pulls it to the ground.
The study of how an object flows through the air is called, aerodynamics. Now that you know the 4 aerodynamic forces (thrust, drag, lift, and gravity) acting on the paper airplane when it is in motion, think about ways to improve the paper airplanes you know how to fold. How can you design a paper airplane with less drag? You cannot control gravity so what can you do to overcome gravity with more lift?
Let’s take a closer look at some things we can do to make a paper airplane fly faster and farther!