When you need to get somewhere quickly, what do you usually do? Most likely, you would either skateboard or ride a bicycle. In urgent situations, you might ask a friend or family member to drive you in their car.
Wouldn’t it be great if you could just leap into the air and fly? Life would be so much easier if you could effortlessly soar through the sky and reach your destination. Unfortunately, humans cannot overcome gravity without wings.
Isn’t it odd that a human weighing less than a couple hundred pounds cannot fly, but a massive metal airplane weighing thousands of pounds can race down a runway and take off into the sky? What is the science behind flight?
Although technology has advanced significantly since the time of Orville and Wilbur Wright, the principles of flight remain the same. For an airplane to fly, it requires two vital forces: thrust and lift.
Thrust is the forward motion of an airplane, which is generated by either a propeller or a jet engine. Sufficient thrust must be produced to overcome the opposing force of drag, which is caused by the friction between the airplane and the air it moves through.
To understand drag better, you can conduct a simple experiment the next time you are in a car. Stick your hand out of the window and feel the air rushing past. When you hold your hand up, as if giving someone a high five, you will feel a significant amount of force from the air pushing against your hand. This is drag.
However, if you turn your hand palm down, the force of drag is greatly reduced. This is why airplanes are designed with an aerodynamic shape, to minimize drag and maximize thrust from the propellers or jet engines. For an airplane to fly, the thrust must be equal to or greater than the drag.
The other crucial force for flight is lift. Lift is created by the unique shape of an airplane’s wing, also known as an airfoil. The wings of an airplane are shaped and tilted in a way that, when air flows over them, an upward force is generated on the wings. When the force of lift becomes greater than the force of gravity pulling the airplane downwards, the airplane can take off into the sky.
Experts still debate the exact mechanism behind lift. Some believe that lift is explained by Bernoulli’s principle, which states that the faster-moving air above the wing has lower pressure than the slower-moving air beneath the wing. As a result, the higher pressure below the wing pushes the airplane upwards, creating lift.
Others argue that lift can be explained by Newton’s laws. According to this explanation, the air flowing over the wing gets deflected downwards due to the wing’s angle. As per Newton’s laws, this deflection must be met with an equal and opposite reaction, thus creating lift on the underside of the wing.
Regardless of which theory provides the best explanation for lift, it is evident that an airplane must generate more lift than gravity in order to take off. Therefore, the heavier an airplane is, the more lift it needs to generate. Conversely, a lighter airplane requires less lift.
Give It a Try
Are you ready to experience flight? Make sure to explore the following activities with a friend or family member:
- Do you live close to an airport? Even if you don’t reside in a major city, there is likely a small regional or local airport nearby. Ask an adult friend or family member to take you on a field trip to the local airport and observe the takeoffs and landings of airplanes. If the only airport nearby is a small regional or local one, it may be a good idea to contact the airport in advance to determine the best time to visit. Enjoy watching airplanes soar!
- Would you like to experiment with the fundamental scientific principles of flight within the comfort of your own home? All you need are some pieces of paper. How can you conduct flight experiments using just paper? The answer is simple: make a paper airplane! Try out different designs and see how far you can make a paper airplane fly.
- Have you ever flown on an airplane? If you have, write a brief story describing your experience. How did you feel the first time you took off in an airplane and felt it leave the ground? If you have never flown on an airplane, write a short story imagining what it would be like to fly on one. Do you think you would feel scared, excited, or a mix of both? Explain why or why not. Share your story with a friend or family member. Have they ever flown on an airplane? How does their experience compare to yours?
Sources of Wonder
- http://www.avjobs.com/history/how-aircraft-fly.asp
- http://science.howstuffworks.com/transport/flight/modern/airplanes.htm
- http://www.livescience.com/7109-planes-fly.html
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