They‘re a staple of childhood play--and a pretty good way to learn about aerodynamics. Paper airplanes are subject to the same physics as any jet you see in the sky.
The forces of thrust, lift, drag, and gravity all work together to send your homemade aircraft flying. To understand how these forces work to create flight, think about movement: something has to push that plane forward.
Force Of The Throw
For jets, this movement comes from engine thrust; for paper planes, it‘s the force of the throw. Now think about air. A wing, whether made of metal or paper, slices through the atmosphere, causing some air to go over top the wing and some to go beneath it. But the air on top is traveling faster than the air on the bottom.
A fast-moving air stream produces lower pressure; a slow-moving air stream produces higher pressure. This means that the air beneath the wing is pushing up more than the air above the wing is pushing down, and so the wing is lifted.
Gravity
Even as thrust and lift move a plane forward and up, opposing forces are at work, too. Drag occurs as air pushes back against a plane, fighting its advancing movement. And gravity is always trying to pull the plane earthwards.
Different plane designs put the four forces to work differently: darts, for instance, use a strong thrust while encountering little drag, but they‘re also susceptible to little lift at low speeds compared to gravity, so be sure to throw them hard. Glider-types, on the other hand, float without much thrust but have a lot of lift.
Thus with a couple minutes and some careful folding, you can watch physics take flight.
Sources And Further Reading:
- "Bernoulli‘s Principle." National Aeronautics and Space Administration. Accessed May 15, 2018.
- Hall, Nancy. "Incorrect Theory #1." NASA: Glen Research Center. April 5, 2018. Accessed May 15, 2018.
- Hall, Nancy. "Paper Airplanes." NASA: Glen Research Center. May 5, 2015. Accessed May 15, 2018.
- Science Buddies. "Soaring Science: Test Paper Planes with Different Drag." Scientific American. February 28, 2013. Accessed May 15, 2018.
- Shaw, Robert J. "Dynamics of Flight." NASA: Kid's Page. June 12, 2014. Accessed May 15, 2018.
- "What Makes Paper Airplanes Fly?" Scholastic. Accessed May 15, 2018.
