Kite

[left]A kite is a tethered aircraft.[1] The necessary lift that makes the kite wing fly is generated when air (or in some cases water)[2][3][4] flows over and under the kite's wing, producing low pressure above the wing and high pressure below it. This deflection also generates horizontal drag along the direction of the wind. The resultant force vector from the lift and drag force components is opposed by the tension of the one or more lines or tethers.[5] The anchor point of the kite line may be static or moving (e.g., the towing of a kite by a running person, boat,[6] or vehicle).[7][8]
Kites are usually heavier-than-air, but there is a second category of lighter-than-air kite called a kytoon which may be filled with hydrogen, hot air, methane, or helium; these stay aloft with or without wind; at calm they float; at wind they receive lift from buoyancy and aerodynamic lift. Kytoons have been made in toy-scale as well as military large scale.[9]
Kites may be flown for recreation, art or other practical uses. Sport kites can be flown in aerial ballet, sometimes as part of a competition. Power kites are multi-line steerable kites designed to generate large forces which can be used to power activities such as kite surfing, kite landboarding, kite buggying and a new trend snow kiting. Kites towed behind boats can lift passengers[10] which has had useful military applications in the past.[11]

History



Woodcut print of a kite from John Bate's 1635 book, The Mysteryes of Nature and Art in which the kite is titled How to make fire Drakes. The caption The Fiery Drake or Kite is from the reprint in Joseph Strutt's 1801 book, The sports and pastimes of the people of England from the earliest period.
Kites were used approximately 2,800 years ago 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. Alternatively, the kite authors Clive Hart and Tal Streeter hold that leaf kites existed far before that time in what is now Indonesia, based on their interpretation of cave paintings on Muna Island off Sulawesi.[12] 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.[13] Ancient and medieval Chinese sources list other uses of kites for measuring distances, testing the wind, lifting men, signaling, and communication for military operations.[13] 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.[14][15][16]
After its introduction into India, the kite further evolved into the Fighter kite known as the patang in India. In India annual kite running competitions are held every year on the day of Makar Sankaranti.

Stories of kites were brought to Europe by Marco Polo towards the end of the 13th century, and kites were brought back by sailors from Japan and Malaysia in the 16th and 17th centuries.[17] Although they were initially regarded as mere curiosities, but by the 18th and 19th centuries kites were being used as vehicles for scientific research.[17]
In 1750, Benjamin Franklin published a proposal for an experiment to prove that lightning is electricity by flying a kite in a storm that appeared capable of becoming a lightning storm. It is not known whether Franklin ever performed his experiment,[18][19] but on May 10, 1752, Thomas-François Dalibard of France conducted a similar experiment (using a 40-foot (12 m) iron rod instead of a kite) and extracted electrical sparks from a cloud.[18]
The period from 1860 to about 1910 became the "golden age of kiting". Kites started to be used for scientific purposes, especially in meteorology, aeronautics, wireless communications and photography; reliable manned kites were developed as well as power kites. Invention of powered airplane diminished interest in kites.World War II saw a limited use of kites for military purposes (see Focke Achgelis Fa 330 for example). Since then they are used mainly for recreation due to a vast improvement in technology.
[edit]Materials



Art kites at a German kite festival


Sparless Styrofoam kites


Octopus kite at Clovis, New Mexico kite festival
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.
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.
[edit]Practical uses

Main article: Kite applications


Chinese dragon kite more than one hundred feet long which flew in the annual Berkeley, California, kite festival in 2000.


A quad-line traction kite, commonly used as a power source for kite surfing
[edit]Human flight
Humans are sometimes bound to a large kite to fly, such as Yuan Huangtou in 559AD.
[edit]Military applications
Kites have been used for military uses in the past for signaling, for delivery of munitions, and for observation, by lifting an observer above the field of battle, and by using kite aerial photography.
According to Samguk Sagi, in 637, Kim Yu-sin, a Korean general of Silla rallied his troops to defeat rebels by lofting a kite with a straw man which looked like a burning ball flying to the sky.[20]
Russian chronicles mention prince Oleg of Novgorod use kites during the siege of Constantinople in 906 A.D.: "and he crafted horses and men of paper, armed and gilded, and lifted them into the air over the city; the Greeks saw them and feared".
Kites were also used by Admiral Yi of the Joseon Dynasty (1392-1910) 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.[21] The war eventually resulted in a Korean victory; the kites played a minor role in the war's conclusion.
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, for example with the kite developed by Samuel Franklin Cody.[22] Barrage kites were used to protect London as well as the Pacific coast of the United States during the last century.[23][24] Kites were used for anti-aircraft target practice.[25] Kites and kytoons were used for lofting communications antenna.[26] Submarines lofted observers in rotary kites.[27] The Rogallo parawing kite[28] and the Jalbert parafoil kite were used for governable parachutes (free-flying kites) to deliver troops and supplies.[29]
[edit]Science and meteorology
Kites have been used for scientific purposes, such as Benjamin Franklin's famous experiment proving that lightning is electricity. Kites were the precursors to the traditional 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 a historical role in lifting scientific instruments to measure atmospheric conditions for weather forecasting.
[edit]Radio aerials and light beacons
Kites can be used for radio purposes, by kites carrying antennas for MF, LF or VLF-transmitters. This method was used 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 by a kite can lead 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 be used to carry light effects such as lightsticks or battery powered lights.
[edit]Kite traction
Kites can be used to pull people and vehicles downwind. Efficient foil-type kites such as power kites can also be used to sail upwind under the same principles as used by other sailing craft, provided that lateral forces on the ground or in the water are redirected as with the keels, center boards, wheels and ice blades of traditional sailing craft. In the last two decades several kite sailing sports have become popular, such as kite buggying, kite landboarding and kite surfing. Snow kiting has also become popular in recent years.
Kite sailing opens several possibilities not available in traditional sailing:
Wind speeds are greater at higher altitudes
Kites may be manoeuvered dynamically which increases the force available dramatically
There is no need for mechanical structures to withstand bending forces; vehicles or hulls can be very light or dispensed with all together
The German company SkySails has developed ship-pulling kites as a supplemental power source for cargo ships, first tested in January 2008 on the ship MS Beluga Skysails.[30] Trials on this 55 m ship have shown that, in favorable winds, the kite reduces fuel consumption by up to 30%. This system is planned to be in full commercial production late 2008.[31] Kites are available as an auxiliary sail or emergency spinnaker for sailing boats. Self-launching Parafoil kites are attached to the mast.[citation needed]
MS Beluga Skysails is the world's first commercial container cargo ship partially powered by a giant computer-controlled kite (160 m² or 1,722 sq ft). The kite could reduce fuel consumption by 20%. It was launched on 17 December 2007 and was set to leave the northern German port of Bremerhaven to Guanta, Venezuela on 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".[32]
[edit]Power generation
A conceptual research and development projects by over 100 entities are investigating the use of kites in harnessing high altitude wind currents to generate electricity. A separate Delft University of Technology project has used a 10 m² kite to generate 10 kilowatts of power.[33]
See also laddermill and High altitude wind power.
At the KULeuven, there also is a research group investigating the use of kites for power generation. But rather than flexible kites, they use a rigid wing structure, like a plane, because of the higher gliding number, easier control and better understanding of plane dynamics. A small prototype is being built.

[edit]Cultural uses



Launch of ram-air inflated Peter Lynn single-line kite, shaped like an octopus and 90 feet (27 m) long.
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.
[edit]Asia


Making a traditional Wau jala budi kite in Malaysia. The bamboo frame is covered with plain paper and then decorated with multiple layers of shaped paper and foil.
Kite flying is popular in many Asian countries, where it often takes the form of 'kite fighting', in which participants try to snag each other's kites or cut other kites down.[34] Fighter kites are usually small, flat, flattened diamond-shaped kites made of paper and bamboo. Tails are not used on fighter kites so that agility and maneuverability are not compromised.
In Afghanistan, kite flying is a popular game, and is known in Dari 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 more easily. The abrasive strings can also injure people. During the Taliban rule in Afghanistan, kite flying was banned, among various other recreations.
In Pakistan, kite flying is often known as Gudi-Bazi or Patang-bazi. Although kite flying is a popular ritual for the celebration of spring festival known as Jashn-e-Baharaan (lit. Spring Festibval) or Basant, kites are flown throughout the year. Kite fighting is a very popular all around Pakistan, but centered in urban centers across the country especially Lahore. The kite fights are at their maximum during the spring celebrations and the fighters enjoy competing with rivals in which one have to cut-loose the string of the kite of other, this is popularly called as "Paecha". During the spring festival, kite flying competitions are held across the country and the skies are colored with kites. As people cut-loose an opponents kites, shouts of 'wo kata' ring through the air. Reclaiming the kites after they have been cut-loose by running after them, is a popular ritual especially among the youth (similar to scenes depicted in the Kite Runner which is based in neighboring Afghanistan). Kites and strings are a big business in the country and many types of strings are used: glass-coated strings, metal strings and tandi. However, kite flying was recently banned in Punjab due to recent motorcyclist deaths caused by glass-coated or metal kite-strings. Kup, Patang, Guda, and Nakhlaoo are some of the kites used. They vary in balance, weight and speed through the air.
In Vietnam, kites are flown without tails. 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 used to create a whistle as the kite flies.[citation needed]


A kite shop in Lucknow, India
Kites are popular during the Indian festival of Makar Sankranti. This spring festival is celebrated generally during mid of January, in accordance with the Indian calender, with millions of people flying kites all over northern India. The states of Bihar, Jharkhand, Gujarat, West Bengal, Rajasthan, Punjab etc are notable for their kite fighting festivals. Kite flying in Hyderabad starts a month before the official kite flying festival (Sankranthi). The thread used to fly kites is known as 'Manjaa'. 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. Kite flying/fighting is an important part of other celebrations, including Republic Day, Independence Day, Raksha Bandhan, and Janmashtami. An international kite festival is held every year before Uttarayan for three days in Vadodara, Surat and Ahmedabad. People start flying kites early in the morning and continue until the evening. The kite is known as 'Patang' in India. People fly kites in Indian Punjab on occasion of Lohri (Punjabi name for Makar Sankranti) and Basant Punchami.


Bermuda kite.
Weifang, Shandong, China is the kite capital of the world. China is the oldest place , probably with India where kites have been flown since antiquities. It is home to the largest kite museum in the world, the thousands of kites here have 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, UK, Malaysia, Indonesia, Taiwan, Thailand and the USA.
[edit]Europe
In Greece and Cyprus, flying kites is a tradition for Clean Monday, the first day of Lent. In the British Overseas Territory of Bermuda, traditional Bermuda kites are made and flown at Easter, to symbolise Christ's ascent. Bermuda kites hold the world records for altitude and duration.
[edit]South America
In Chile, it is very popular, especially during Independence Day festivities (September 18).
In Colombia kites can be seen flown in parks and recreation areas during August which is known to be windy. It is during this month that most people, especially the young ones would fly kites.
In Guyana, kites are flown at Easter and is an activity participated in by all ethnic and religious groups. Kites are generally not flown at any other time of year. Kites start appearing in the sky in the weeks leading up to Easter and school children are taken to parks for the activity. It all culminates in a massive airborne celebration on Easter Monday especially in Georgetown, the capital, and other coastal areas. The history of the practice is not entirely clear but given that Easter is a Christian festival, it is said that the flying kite is symbolic of the Risen Lord. Moore[35] describes the phenomenon in the 19th century as follows:
A very popular Creole pastime was the flying of kites. Easter Monday, a public holiday, was the great kite-flying day on the sea wall in Georgetown and on open lands in villages. Young and old alike, male and female, appeared to be seized by kite-flying mania. Easter 1885 serves as a good example. “The appearance of the sky all over Georgetown, but especially towards the Sea Wall, was very striking, the air being thick with kites of all shapes and sizes, covered with gaily coloured paper, all riding bravely on the strong wind"
(His quotation is from a letter to The Creole newspaper of December 29, 1858). The exact origins of the practice of kite flying (exclusively) at Easter are unclear. Brereton and Yelvington[36] speculate that kite flying was introduced by Chinese indentured immigrants to the then colony of British Guyana in the mid 19th century. The author of an article in the Guyana Chronicle newspaper of May 6, 2007 is more certain:
Kite flying originated as a Chinese tradition to mark the beginning of spring. However, because the plantation owners were ever so suspicious of the planter class [read, plantation workers], the Chinese claimed that it represented the resurrection of Jesus Christ. It was a clever argument, as at that time, Christians celebrated Easter to the glory of the risen Christ.
[37]
[edit]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.
[edit]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 kite fliers 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.
[edit]Kite designs



Delta (triangular) kite


Train of connected kites
Bermuda kite
Bowed kite, e.g. Rokkaku
Cellular or box kite
Chapi-chapi
Delta kite
Foil, parafoil or bow kite
Malay kite see also wau bulan
Tetrahedral kite
[edit]Kite types

Main article: Kite types
Expanded polystyrene kite
Fighter kite
Indoor kite
Inflatable single-line kite
Kytoon
Man-lifting kite
Rogallo parawing kite
Stunt (sport) kite
Water kite
[edit]Types of kite line materials

Cotton
Dacron
Dyneema
Hemp
Kevlar
Linen
Manja or Manjha, Hindi word for the glass powder coated kite flying & fighting string from Indian subcontinent and surrounding regions
Nylon
Polyester
Rayon
Silk
Ultra-high-molecular-weight polyethylene
[edit]