How do Paper Airplanes Fly?

Paper airplanes have long been a source of entertainment for people of all ages.  Taking an ordinary piece of paper, applying a few simple folds to it, and throwing it can suddenly give it the ability to glide across the room elegantly (or nosedive immediately, depending on your skill).
What causes a paper airplane to glide or fall? How does the design affect its flight capability? The answers to these questions are found in studying the physics at work when a paper plane is thrown through the air. There are four aerodynamic forces in particular that I will discuss: Thrust, Gravity, Lift, and Drag. (1)

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There are also interesting features in the design of different paper airplanes, and these can be compared to those of real airplanes. Here is an illustration showing how to build a simple paper airplane.


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