Kite
2008/9 Schools Wikipedia Selection. Related subjects: Recreation
A kite is a flying tethered object, not necessarily, but usually made by humans A spider web holding a leaf just right would form a kite; humans are not essential.. The necessary lift that makes the kite fly is generated when airflow over and under the kite creates low pressure above the kite and high pressure below it. In addition to the lift, this deflection generates horizontal drag along the direction of the wind. This drag is opposed with the tension of the one or more lines held by the operator of the kite.
In addition to kites that are flown for recreation, art or practical use, there are sport kites and power kites. Sport kites are flown in aerial ballet. Power kites are multi-line steerable kites designed to generate excess force which can be applied in related activities such as kite surfing, kite landboarding or kite buggying.
The medium of a kite need not be air; the stream may be water, plasma, soil, gases that are not air, etc. A kite is an object tethered in a stream of matter so that interaction of that stream with the specific shape of the object results in a net positioning of the object off the ambient direction of the streaming matter. There are kites in plasma, water, gases, soils, and even solids. Air kites are simply the most popular. Tethering kites from satellites, asteroids, spacecraft dragging kites in the space plasma, tractors (pulling soil kites), ships trolling hydro kites (large industry for fishing[2], sounding, research of water characteristics, surveillence, delivery of munitions, site-seeing, etc.), etc.
History
Approximately 2800 years ago the kite was first invented and popularized in China, where materials ideal for kite building were readily available: silk fabric for sail material, fine, high-tensile-strength silk for flying line, and resilient bamboo for a strong, lightweight framework. The kite was said to be the invention of the famous 5th century BC Chinese philosophers Mozi and Lu Ban. By at least 549 AD paper kites were being flown, as it was recorded in that year a paper kite was used as a message for a rescue mission. Ancient and medieval Chinese sources list other uses of kites for measuring distances, testing the wind, lifting men, signaling, and communication for military operations. The earliest known Chinese kites were flat (not bowed) and often rectangular. Later, tailless kites incorporated a stabilizing bowline. Kites were decorated with mythological motifs and legendary figures; some were fitted with strings and whistles to make musical sounds while flying.
After its appearance in China, the kite migrated to Japan, Korea, Thailand, Myanmar (Burma), India, Arabia, and North Africa, then farther south into the Malay Peninsula, Indonesia, and the islands of Oceania as far east as Easter Island. Since kites made of leaves have been flown in Malaya and the South Seas from time immemorial, the kite could also have been invented independently in that region.
One ancient design, the fighter kite, became popular throughout Asia. Most variations, including the fighter kites of India, Thailand and Japan, are small, flat, roughly diamond-shaped kites made of paper, with a tapered bamboo spine and a balanced bow. Flown without tails that would hinder their agility, these highly maneuverable flat kites have a length of cutting line coated with an abrasive attached to the bridle, which is then tied to a light cotton flying line. Although the rules of kite fighting varied from country to country, the basic combat was to maneuver the swift kite in such a way as to cut the opponent's flying line.
Kite flying began much later in Europe than in Asia. While unambiguous drawings of kites first appeared in print in the Netherlands and England in the 17th century, pennon-type kites that evolved from military banners dating back to Roman times and earlier were flown during the Middle Ages.
During the 18th century tailless bowed kites were still unknown in Europe. Flying flat arch- or pear-shaped kites with tails had become a popular pastime, mostly among children. The first recorded scientific application of a kite took place in 1749 when Alexander Wilson of Scotland used a kite train (two or more kites flown from a common line) as a meteorologic device for measuring temperature variations at different altitudes.
Three years after, in June 1752, in what is the most famous of kite experiments, the American inventor and statesman Benjamin Franklin, with the aid of his son, lofted a flat kite fitted with a pointed wire and silk sail on a hemp line during a thunderstorm. Somehow both father and son avoided electrocution as a metal key attached to the flying line became electrified. Franklin proved that lightning was the natural phenomenon called electricity, not the wrath of the gods. One immediate and practical outcome of the experiment was Franklin's invention of the lightning rod.
Materials
Kites typically consist of one or more spars to which a paper or fabric sail is attached, although some, such as foil kites, have no spars at all. Classic kites use bamboo, rattan or some other strong but flexible wood for the spars, paper or light fabrics such as silk for the sails, and are flown on string or twine. Modern kites use synthetic materials, such as ripstop nylon or more exotic fabrics for the sails, fibreglass or carbon fibre for the spars and dacron or dyneema for the kite lines.
Kites can be designed with many different shapes, forms, and sizes. They can take the form of flat geometric designs, boxes and other three-dimensional forms, or modern sparless inflatable designs. Kites flown by children are often simple geometric forms (for example, the diamond). In Asia, children fly dried symmetrical leaves on sewing thread and sled-style kites made from sheets of folded writing paper.
Chinese kite designs often emulate flying insects, birds, and other beasts, both real and mythical. The finest Chinese kites are made from split bamboo (usually golden bamboo), covered with silk, and hand painted. On larger kites, clever hinges and latches allow the kite to be disassembled and compactly folded for storage or transport. Cheaper mass-produced kites are often made from printed polyester rather than silk.
Tails are used for some single-line kite designs to keep the kite's nose pointing into the wind. Spinners and spinsocks can be attached to the flying line for visual effect. There are rotating wind socks which spin like a turbine. On large display kites these tails, spinners and spinsocks can be 50 feet (15 m) long or more.
Modern acrobatic kites use two or four lines to allow fine control of the kite's angle to the wind. Traction kites may have an additional line to de-power the kite and quick-release mechanisms to disengage flyer and kite in an emergency.
Practical uses
Kites have been used for military uses in the past, both for delivery of messages and munitions, and for observation, by lifting an observer above the field of battle, and by using kite aerial photography.
Kites have also been used for scientific purposes, such as Benjamin Franklin's famous (but dangerous) experiment proving that lightning is electricity. Kites were the precursors to aircraft, and were instrumental in the development of early flying craft. Alexander Graham Bell experimented with very large man-lifting kites, as did the Wright brothers and Lawrence Hargrave. Kites had an historical role in lifting scientific instruments to measure atmospheric conditions for weather forecasting.
Kites can also be used for radio technical purposes, either by kites carrying antennas or by using a kite, which carries up an antenna wire ( for MF, LF or VLF-transmitters). This was done in the past, for the reception station of the first transatlantic transmission by Marconi. Captive balloons may be more convenient for such experiments, because kite carried antennas require a lot of wind, which may be not always possible with heavy equipment and a ground conductor. It must be taken into account during experiments, that a conductor carried up by a kite in the sky can lead due to a high voltage toward ground, which can endanger people and equipment, if suitable precautions (grounding through resistors or a parallel resonant-circuit tuned to transmission frequency) are not taken.
Kites can also be used as light effect carrier, for example by carrying lightsticks or battery powered light effects.
A German company has developed ship-pulling kites as an additional power source for cargo ships. Trials on a 55m ship have shown that, in favorable winds, the kite increases fuel-efficiency by up to 30%. This SkySails system is planned to be in commercial production by 2008. Kites are also available as an auxiliary sail or emergency spinnaker for sailing boats. Self-launching Parafoil kites are attached to the mast.
MS Beluga Skysails is the world's first commercial container cargo ship which is partially powered by a giant computer-controlled kite (160sq. m. or 1,722 sq ft.). The kite could reduce fuel consumption by 20%. It was launched 17 December 2007 and is set to leave the northern German port of Bremerhaven to Guanta, Venezuela at 1700 local time (1600 GMT), January 22, 2008. Stephan Wrage, managing director of SkySails GmbH announced: "During the next few months we will finally be able to prove that our technology works in practice and significantly reduces fuel consumption and emissions." Verena Frank, project manager at Beluga Shipping GmbH, SkySails GmbH's partner further stated that "the project's core concept was using wind energy as auxiliary propulsion power and using wind as a free of charge energy".
A research and development project called Makani Power, based in California, is investigating the use of kites to harness high altitude wind currents to generate electricity.
Ancient military use of kites
Kites were often used in the military of China as signal equipment. Military adoption of this was more common in East Asia than in Europe. Much like modern flares, kites were flown engulfed in fire to provide a way to deliver messages to nearby or distant allies or soldiers.
Kites were also used by Admiral Yi of the Joseon (1392-1910) Dynasty of Korea. During the Japanese invasions of Korea (1592-1598), Admiral Yi commanded his navy with kites. His kites had specific markings directing his fleet to perform his order. Admiral Yi was said to have over 300 such kites. The war eventually resulted in a Chinese and Korean victory, and although kites played a minor role in the war's conclusion, they were by no means a predecessor to modern day radio and/or flares.
In more modern times the British navy also used kites to haul human lookouts high into the air to see over the horizon and possibly the enemy ships. The famed Cody Kite (named after the creator Samuel Franklin Cody) (see, for example, this webpage) is known for its classic beauty as well as its lifting abilities.
Cultural uses
Kite festivals are a popular form of entertainment throughout the world. They include small local events, traditional festivals which have been held for hundreds of years and major International Festivals which bring in kite flyers from overseas to display their unique art kites and demonstrate the latest technical kites.
Asia
Kite flying is very popular in many Asian countries, where it often takes the form of ' kite fighting', in which kite fighters try to snag each other's kites or cut other kites down. Fighter kites are usually small, flat, flattened diamond-shaped kites made of paper and bamboo. Tails were left off of the fighter kites so that agility and maneuverability were not compromised. The usual goal of a 'kite fighter' is to maneuver his/her kite to cut the opponent's string. In Afghanistan this is known as Gudiparan Bazi. Some kite fighters pass their strings through a mixture of ground glass powder and glue. The resulting strings are very abrasive and can sever the competitor's strings. The modernization of the sport of 'kite fighting' comes with newer technology, as canny arms dealers begin importing a flexible razor sharp wire from China, rather than the old, nylon fishing line used for kite string. However, this practice is dangerous since the abrasive strings can also injure people. During the Taliban rule in Afghanistan, kite flying was banned, among various other recreations.
In Korea kites were usually flown to make a wish or wish the person flying the kite good luck. The kites were usually flown on festive days and national holidays. In countrysides children used to take part in a fun battle where a person tried to disconnect the main bit of a kite of their opponent when the opponent tried to disconnect theirs. To disconnect an opponent's kite one would have to have a strong, steel-like thread to attach the main bit of a kite to the traditional Korean wooden reel, called Earl Leil
In Vietnam, kite flown by adults are "tail-less". Instead small flutes are attached allowing the wind to "hum" a musical tune. There are other forms of sound-making kites. In Bali, large bows are attached to the front of the kites to make a deep throbbing vibration, and in Malaysia row of gourds with sound-slots are use to create a whistle as the kite flies.
The Indian festival of Makar Sankranti is devoted to kite fighting in some states. This spring festival is celebrated every January 14 (or January 15 on leap years), with millions of people flying kites all over northern India. The cities of Ahmedabad and Jaipur are particularly notable for their kite fighting festivals. Highly maneuverable single-string paper and bamboo kites are flown from the rooftops while using line friction in an attempt to cut each other's kite lines, either by letting the line loose at high speed or by pulling the line in a fast and repeated manner. The activity is not without risk as the line is treated to be abrasive and flyers can, and occasionally do, fall from the rooftops. In some Indian cities kite flying/fighting is an important part of other celebrations, including Republic Day, Independence Day, Raksha Bandhan, and Janmashtami.
In Pakistan, kite flying is a ritual for the spring festival known as Basant. However, kite flying is currently banned as some kite fliers engage in kite battles by coating their strings with glass or shards of metal, leading to injuries and death. Kite fighting is a very popular sport in Pakistan, mainly centered in Lahore people spend thousands of dollars in preparing different types of kites and threads best suited to battle. The kites that are manufactured for battling are very different from the conventional kites as they are especially designed and made for this purpose. Kup, Patang, Guda, Nakhlaoo, etc are some of the kites used in the battle and they vary in balance, weight and speed through the air. Threads for kite battling are manufactured using especial glues, chemicals and crushed glass and are numbered based on their ability to cut other threads and to handle kite's weight. Kite Battle is an art and the more experienced a person is in this art the more likely he is to win the battle. It is a very popular social event in Pakistan that happens once a year.
Weifang (Shandong, China) promotes itself as the Kite Capital of the World. It is home to the largest kite museum in the world, which has a display area of 8100 m². Weifang hosts an annual International Kite Festival on the large salt flats south of the city. There are several kite museums in Japan and others in England, Malaysia, Indonesia, Taiwan, Thailand and the USA.
Europe
In Greece, flying kites is a tradition for Clean Monday, the first day of Lent.
South America
In Guyana, on Easter Weekend thousands turn out for mass kite flying. In the capital city of Georgetown the massive sea wall protecting the city from the Atlantic ocean is filled with throngs of families picnicking and flying kites of all shapes and colors. Many participate in kite flying competitions. In certain South American countries the verb Kitar is used to describe the art of kite-flying.
Popular culture
- The Kite Runner, a 2005 novel by Khaled Hosseini dramatizes the role of kite fighting in pre-war Kabul.
- The Peanuts cartoon character Charlie Brown was often depicted having flown his kite into a tree as a metaphor for life's adversities.
General safety issues
There are safety issues involved in kite-flying, more so with power kites. Kite lines can strike and tangle on electrical power lines, causing power blackouts and running the risk of electrocuting the kite flier. Wet kite lines or wire can act as a conductor for static electricity and lightning when the weather is stormy. Kites with large surface areas or powerful lift can lift the kite flier off the ground or drag them into stationary objects. In urban areas there is usually a ceiling on how high a kite can be flown, to prevent the kite and line infringing on the airspace of helicopters and light aircraft. In Asia, specially in the Indian subcontinent the twine is coated with powdered glass to cut opponent's lines and these deadly strings known as Manja are reported to kill number of pedestrians or motorcyclists each year all over the region.
Mediums where kites operate
Air, plasma, soil, non-air gases, solids, ice, water, and non-water liquids. There are air kites, plasma kites, soil kites, water kites, ice kites, etc. There are references for kites in each medium. The most popular medium is air; but that popularity does not make the other kiting environments any less actual. Hobby and commercial fishing use hydro kites. The military use hydro and space plasma kites. Farmers use soil plowing kites. Anchor the kite tow line to a mountain and set an ice kite in a glacier that flows and the ice kite will move off the direction of the stream of ice. There is plenty of air, but air is not essential for a kite to be a kite; the flow of a non-air gas would suffice.
Types of kites
- Arch kite (rotary two-anchor rainbow arch) and (static two-anchor rainbow arch)
- Bow kite
- Bowed kite
- Cellular or box kite
- Fighter kites
- Foil kite
- Indoor kite
- Inflatable single-line kite
- Parafoil
- Kytoon
- Miniature kite
- Rogallo Parawing kite
- Stunt kite
- Styrofoam kites
- Tetrahedral kite
Types of kite line
- Cotton
- Dacron
- Dyneema
- Hemp
- Kevlar
- Linen
- Nylon
- Polyester
- Rayon
- Silk
- Manja, the glass powder coated kite flying & fighting string from Indian subcontinent and surrounding regions