Kite
From Wikipedia, the free encyclopedia
A kite is a flying tethered man-made object. 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 one or more lines held by the operator of the kite.
Today, in addition to kites that are mainly 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.
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[edit] History
Nearly 3,000 years ago the kite was first popularized, if not invented, 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 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.[1]
After its appearance in China, the kite migrated to Korea, Japan, 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.[1]
One ancient design, the fighter kite, became popular throughout Asia. Most variations, including the fighter kites of India 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.[1]
Kite flying began much later in Europe than in Asia. While unambiguous drawings of kites first appeared in print in Holland 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.[1]
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.[1]
Three years later, 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 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.[1]
[edit] Materials
Kites typically consist of one or more spars (sticks) 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, fiberglass or carbon fiber 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, box kites 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.[citation needed]
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 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.
A recent addition to the kite family is the rotorkite. This type of kite consists of a rotor or rotors much like the rotors found on helicopters and autogyros. In a proper wind the rotors spin and create lift. This type of kite requires two control lines, one for each hand.
[edit] 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 (See The MythBuster Season 3 Episode 48 for alternative interpretations of this experiment). 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 sometimes in the past, for example for the reception station of the first transatlantic transmission by Marconi. However captive balloons may be more convenient for such experiments, because kite carried antennas require sometimes running when there is no wind, which may be not always possible with the heavy equipment and a ground conductor. It must be taken into account at such experiments, that a conductor carried up by a kite in the sky can lead due to the earth's electrostatic field a high voltage toward ground, which can endanger people and equipment, if not suitable precautions (grounding through resistors or a parell resonant-circuit tuned to transmission frequency) is done.
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 the kite increases fuel-efficiency by up to 30%. In 2008, this SkySail system will be in commercial production. Kites will be available in sizes from 160 to 5,000 m².[2] Kites are also used as an auxiliary sail or emergency spinnaker for sailing boats. Self-launching Parafoils kites are attached to the mast.
[edit] 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.
Kite flying is very popular in the People's Republic of China, Korea, Japan, Pakistan, India, Bangladesh, Thailand, and many other Asian countries. In all of these countries 'kite fighting', in which kite fighters try to snag each other's kites or cut other kites down, is popular. 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. 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.
The Indian festival of Makar Sankranti is devoted to kite flying in some states where it is a public holiday. 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 Greece, flying kites is a tradition for Clean Monday, the first day of Lent.
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 battle 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 and the festivities are worth seeing.
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.
Weifang (Shandong, China) promotes itself as the Kite Capital of the World. It hosts an annual International Kite Festival on the large salt flats south of the city.
The world kite museum in Weifang is the largest kite museum in the world, the building has a display area of 8100 m². There are several Kite Museums in Japan and others in England, Malaysia, Indonesia, Taiwan, Thailand and the USA.
[edit] 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 kiteflier 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] Types of Kites
- Bow kite
- Bowed kite
- Cellular or box kite
- Centipede kite
- Fighter kites
- Flat kite
- Foil kite
- Indoor kite
- Leading edge inflatable kite
- Power kite
- Rokkaku
- Rogallo wing
- Rotating kites
- Scott sled
- Sport kite
- Tetrahedral kite
- Wau bulan
[edit] See also
- Bali Kite Festival
- Kitesurfing
- Kite buggying
- Kite landboarding
- Windsports
- Kite fishing
- Captive balloon
- Captive helicopter
- Captive plane
- Kite shape (geometry)
[edit] References
- ^ a b c d e f (2007). In Encyclopedia Britannica. Retrieved March 29, 2007, from Encyclopedia Britannica Online
- ^ Skysail ship pulling system