There is some debate about where kites originated. Some say China and some say, no, it originated in the South Pacific with the islanders there. The Balinese have their own story which explains the origin of kites. Nevertheless we are left with a heritage of wonderful stories, designs and techniques for flying kites. Some cultures used kites to communicate with spirits. In other cultures kites were used for practical purposes. They are used as a fishing aid in the Solomon Islands. Kites are used by the Koreans to announce the birth of a child. Kites were used by the Chinese during battles. They were made of bamboo and had the tendency to hum and shriek in the wind which frightened the enemy. Kites in the Chinese and Japanese cultures were capable of holding or "flying" a person in the air where the person could spy or act as a sniper using bows and arrows. In India and Japan some of the best "fighter" kites were developed. Fighter kites are a specialty that can be enjoyed at some kite festivals.
There is good luck associated with kites . In some cultures, when the line of the kite is cut, the kite takes away the bad luck or the evil spirits. In Thailand the kites are used to communicate with the gods so that monsoons will not be so bad and the crops will be saved from the floods.
How did the idea of kites get to Europe? There are many theories. Some believe that European travelers brought the idea back from China. Certainly the cultures in the Middle East had been using kites for centuries. In Rome windsock banners that looked like dragons were used for military and religious purposes. For a short time, kites were used by the Europeans during hunting to flush out birds from the bushes. The kites would get stuck in the bushes so he hunters gave up on the kites and found other ways to find the birds.
Later kites were used for scientific purposes and maybe just for fun too! Benjamin Franklin flew kites for the fun of it. Later, in 1752 he used a kite for his now famous experiment to find out if there was an electrical charge in clouds. Kites are used by meteorologists to lift measuring instruments. In 1750 Dr. Alexander Wilson of Edinburgh put a thermometer on a kite and sent the kite up to test air temperatures at different altitudes. In the 1880's E.D. Archibald a British scientist use anemometers on kites to measure wind speeds at different altitudes. Dr. Alexander Bell who invented the telephone used kites to learn more about weather. He also contributed to aviation by experimenting with kites to learn more about the possibility of enabling people to fly. Like the Chinese and the Japanese he developed a kite that could raise a person up in the air. He developed what is called the tetrahedral cell. It had great strength and a light structure. The Wright Brothers used kites to learn more about flying as did Otto Lilienthal and Octave Chanute.
Samuel Cody, Texas inventor and showman was known to most as "Buffalo Bill" In his later years he moved to England and became well known for his "Wild West Shows." For one event, he used kites to tow a boat across the English Channel with what he called "Cody Kites." Cody and his son, Leon, developed larger and larger kites and often competed against each other. Cody developed observation kite systems for the Russians and the French. Many kite designs that were developed for the military or for scientific purposes can be seen at kite festivals and competitions today.
Windsocks are a Japanese tradition that has caught on elsewhere. In the Japanese culture the windsocks are made in the shape of a fish called a carp and they are the symbol of strength and strong will, overcoming great obstacles to achieve their goal. Like the Chinese, the Japanese have a special day for flying kites or windsocks. In Japan it is May 5th, "Children's Day." In China, Kite Day was on the ninth day of the ninth moon and was celebrated with kite-flying festivals. Today, we don't need a special day to fly kites and there are many kite-flying festivals throughout the year. We can enjoy the magic of kites any time!
How do kites fly? Let's explore the aerodynamics of kites. Kites are heavier-than-air devices. They weigh more than the volume of the air they displace. They are flown at the end of a string, line or rope. Kites are aerodynes. In other words, they overcome the force of gravity and are kept in the air by the force of the wind or the forces of wind pressure on the kite. The aerodynamic force involved is called lift. Lift on a kite is perpendicular to the relative wind direction. What is relative wind? It is the actual wind, the actual direction of wind and speed of the wind. The kite reacts to the wind pushing on it. Lift is exerted in an upward direction thereby opposing the pull of gravity on the kite.
Air is made of particles that are in constant motion and air is actually quite heavy. A cubic yard of air will weigh 2 pounds at sea level. Air will resist motion of any object through it. You can test this by trying to move forward while holding a flat surface in front of you. The speed at which you move is resisted by the air on the flat surface. A kite is sort of an air deflector. The drag of a kite is the resistance of the air to the forward and backward motion of the kite. Drag occurs in the direction that the kite moves, not the direction of the wind.
There are two principles involved in the aerodynamics of kite flight. One is Newton's law of action and reaction. Think of the kite as flying on an inclined plane and flying in one spot. The kite exerts a downward force upon the air. The air passes over the top edge of the kite and goes down the upper surface of the kite. Remember that air is relatively heavy. As the kite pushes downward, it gets an equal push upward by the air. As this happens, the kite gets an upward counter force and it flies! Newton's law states that for every action there is an equal and opposite reaction.
The second of the two principles is Bernoulli's Theorem. Bernoulli was a Swiss mathematician who discovered this principle in 1738. Bernoulli stated that as air passes below a wing, air also passes above it. The air on the top of the wing moves a longer distance over the curved surface of the wing. It moves faster and reduces the pressure above the wing. The air below the wing moves more slowly and the air pressure below the wing is increased. It is the change in relative pressures above and below the kite that allows the kite to lift.
For a kite to fly, the air lift potential must be greater than the weight of the kite. For example, if the downward and upward force of the air is equal to the weight of the kite, the sum of all the forces will be zero and the kite will be in a state of equilibrium. It will not fly up or down. If the downward force upon the air is greater than the weight of the kite the upward force will also be greater and the kite will move upward and climb higher. If the downward force is less than the weight of the kite, the upward force will be less and the kite will sink sometimes very quickly, crashing to the ground. Knowing these basic principles can help us learn how to fly a kite and how to design a kite. Also, knowing the strength of the wind and wind direction are useful in developing a knowledge of the basic moves and tricks in kite flying.
When designing kites several things must be considered. The first is angle of attack. What is angle of attack? It is the angle by which the kite is inclined in relation to the direction the air is moving toward it. The air meets the kite as its inclined angle and the air is forced downward and as was discussed before the kite achieves lift. Different kite designs use different angles of attack. Different kites are used for different wind conditions depending on their angle of attack. The flying angle is also important.
An angle has two sides with a focal point at the point where the two sides come together. In the case of flying a kite, the ground is one side, the string with the kite at the end of it is another. Assume for this discussion that the kite in anchored to a point on the ground. If the kite moves to greater heights, the angle of attack becomes less
The flying angle of a kite can also be changed by making adjustments to things attached to the kite such as the "bridle" or the tail. All these adjustments will add or subtract to the ability of the kite to maintain angle of attack, balance and stability. Because, in reality, kites do not have perfect balance and stability we need to consider some of the ways to add those qualities. A kite does pitch forward, backward and side to side. It does stall and dive. All these qualities make kites fun and thrilling to fly but it is also a challenge to design the kite so it will fly the way it is intended.
The tail of a kite adds to its stability and balance. It also acts as a drag and for some kites will put a limit on the maximum altitude that can be reached by a particular kite. In designing kites one must consider the pros and cons to each element of design . For example, one can eleminate the tail, but bow out the design for stability and thus achieve greater altitude. Other ways to achieve stability may be in the cover material, the sticks or frames, addition of wings or keels or using shaped wing surfaces. Rudders, airfoil-shaped surfaces and tapering are some other design possibilities.
How do you construct a kite?
When you get ready to launch your kite, make sure you are in an area that is open and free from trees, electrical and telephone lines buildings and automobile traffic. Stand with you back to the wind. Hold the kite with one hand and the reel of string with the other. Let the wind lift the kite and as it does, feed out the line to the height you wish. Walk in the direction of the wind as you feed out the line. If the kite won't climb you can reduce the bridle angle. To land the kite, walk toward it winding the line on the reel as you walk.
More expertise with kites can lead to investigations of stunt or novelty kites. Another challenge is sending climbers up the kite string or dropping small parachutes, balloons, confetti or messages from kites. Kites can also carry balloons, banners, and other decorations. Attach a camera to a kite and with a time shutter release, take a picture. Fly kites in tandem or like the people of the Solomon Islands, try fishing with a kite. The possibilities are endless.
Visit kite festivals in your local area, join a kite club or start one in your school or community. There are a wide variety of kite societies and associations and some of them are on the internet. You can learn everything from kite safety , the basics, and first aid for your kite to some of the more technical skills for flying fighter and stunt kites.
Kites provide a "hook" to learning through art, craft skills, engineering, mathematics, science, physics, aeronautics, history, language arts, poetry, writing, drama,and history. Kites provide an excellent vehicle for a multi-cultural community or school event. They are a fun activity that can be enjoyed by people of all ages. Because there is no one right way to design or fly a kite, success in kite flying is attainable for everyone. Even Charlie Brown can fly a kite. Maybe he just needs a little help from the rest of us who are also working on the trial and error of flight. After all, isn't that what the great inventors did? They kept working and experimenting until they learned what worked. They learned from failure. That is the essence of invention and progress. What a great lesson for children to learn. For the poetic inventor spirit in all of us we can make our kite and watch it soar. In doing so, our final success and triumphant feeling also soars.
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