Have you ever wondered what makes a kite fly, or what a kite and an airplane have in common? The truth is that they both rely on the same science - the science of flight.↵
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Story 1 : Basic of Flight↵
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There are four main forces involved in flight: lift, weight, thrust, and drag. Lift is created by the difference in air pressure between the air flowing over an airplane's wings and the air flowing under them. Lift is opposed by weight, which is the force of gravity that is constantly pulling the airplane down. If the amount of lift is greater than the amount of weight, the airplane will rise. At the same time, thrust is created by the airplane's engines and propellers pushing the airplane forward. Opposed to that force is drag, which is the air pushing the airplane back. If thrust is greater than drag, the airplane will move forward. The interaction between these four forces makes airplanes fly.

Airplanes are designed with these forces in mind. The engines and propellers provide thrust to move airplanes forward. The wings are shaped so that air has to travel faster over them than under them. According to Bernoulli's principle, an increase in the speed of air results in a decrease in pressure. Thus, air traveling faster creates lower pressure above the wings, and the higher pressure under the wings pushes the airplane up, creating lift.

You can see for yourself how the force of lift works. Cut a strip of paper about 4 cm wide. Hold one end of the strip near your lips, and blow slowly and evenly over the paper. The other end of the strip will rise. This is because the air blown out over the top of the↵
paper moves quickly, so its pressure is lower than the still air under the paper. The still air, with a higher pressure, pushes the paper upward into the lower↵
pressure air.

A kite flies in the same way as an airplane does. To make a kite fly, it is sometimes necessary to run with it behind you. This creates lift and pushes the kite up. Once the kite gets up in the sky where the wind is strong enough, you can stop running, and the kite will fly. Instead of engines and propellers, the tension from someone pulling on the kite's string provides thrust for a kite. For a kite to remain flying, the amount of lift needs to be equal to the amount of weight so that those forces balance each other. Likewise, thrust and drag must also be equivalent.

Bangpaeyeon, the most popular Korean kite, looks simple, but is the toughest of all kites flown in Korea. This rectangular kite is traditionally 10 made from five bamboo sticks and is covered with traditional Korean paper. It is always made so that the width and length are in a 2-by-3 proportion. Unlike kites in other countries, it has a circular hole in the center, with a diameter half the width of the kite. What this hole does is control the air. The push of air on the front of the kite is greatly reduced because some of the wind passes through the hole to the back. This allows you to turn the kite quickly. Without the hole, it would not be easy to control. In addition, the kite is not easily damaged by a strong wind.

As you can see from the example of the kite, things we use every day often act in accordance with interesting principles of science. Make sure you think about these principles at work in 90 your daily life.↵
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Story 5 : A Way to Increase Stability: A Tail↵
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A tail is sometimes added to a kite. It can help make a kite fly more stably by adding not just some weight but also drag to its lower end. The tail should have the right length, though. Adding a short tail, for example, a 10 cm tail, will make the kite spin and roll around a lot. Adding a longer tail, such as a 100 cm tail, can help the kite fly well, allowing it to go high without rolling very much. Our ancestors knew all this and made the tail the right length.