We measure wind speed in knots, or miles per hour (or kilometers per hour). When the different temperatures of air interact, wind is created! Wind is measured by its speed and its direction. Warm air has a different pressure than cool air. This means that there are constantly different temperatures of air moving around in the atmosphere. When Earth is heated by the sun, it does not heat up evenly all over because of the differences caused by land and water. Wind is air moving through the atmosphere (layers of air surrounding the whole earth). Likewise, thrust and drag must be equal to each other. 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. Instead of an engine, the tension from someone pulling on a kite’s string and some help from wind is what provides thrust for a kite. The still air with the higher pressure pushed the paper upwards into the lower pressure air from your breath.Ī kite flies in the same way as an airplane, but it needs wind to help it move more than a plane does. This is because the air you blew out over the top of the paper was moving quickly, so its pressure was lower than the still air around the paper. Holding a short end of the paper strip near your lips and blow slowly and evenly over the paper. You can demonstrate Bernoulli’s Principle with this simple exercise. This is provided by the engine and propellers. Once an aircraft has lift, it needs thrust to move forward. The higher pressure under the wing pushes the airplane up through the air above the wing, which has a lower pressure. The air traveling a shorter distance under the wings creates a higher pressure. When air has to travel farther over the wings, it will automatically go faster, which results in a lower pressure above the airplane’s wings. This is explained by what is known as Bernoulli’s Principle, which states that an increase in the velocity (speed) of air (or any fluid) results in a decrease in pressure. Wings need to use lift to their advantage – by being shaped so that air has to travel farther over the top of them than under them. The interaction between those four forces is how an airplane can move up and forward.Īirplanes are designed with these forces in mind. If thrust is greater than drag, the plane will accelerate (speed up). If lift is greater than weight, the plane will rise. Opposed to thrust is drag, which comes from air resistance. Thrust is caused by the action of the plane’s propellers moving the plane forward. Lift is opposed by weight, or the force of gravity that is constantly pulling downward on the airplane. Lift is caused by differences in pressure when air flows over and under an airplane’s wings. Picture an airplane as you read about how these forces work together during flight. There are four main forces involved in flight: lift, weight, thrust, and drag. Try building a different style of kite and compare how it flies with how the sled kite flies. Build a similar kite but make it larger.Ħ. Build a new kite using the pattern described above but with a different material: For example, use newspaper and plastic straws instead of a paper bag and wooden skewers.ĥ. Make tails from different materials such as strips of plastic, paper, or fabric.Ĥ. Fly the same kite with one, two, three, or even more tails, and compare the difference each time.ģ. Once you master flying your kite, experiment with different tails and materials and their effects on the kite. Just enjoy watching it and be prepared for it to make its way down if the wind changes or stops. Once your kite is up and flying, there isn’t much you need to do.Staying away from trees is a good idea, too. As soon as the string becomes tight, slowly let out more and watch your kite rise higher in the air! When you feel the wind pushing against your kite, let it go, pushing it up into the air. Hold your kite in one hand and the spool of string in the other, then begin to run into the wind.You don’t need strong wind, but you do need constant wind. The best way to get a kite flying is to have a steady wind. Once the glue has dried, your kite is ready to fly! Up, Up & Away: Tips & Tricks Reinforce with a strip of tape so the tails won’t fly off in a gust of wind. Cut two tails each at least 2′ long and glue them to the kite – one next to each folded flap.
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