Kite Flying Day
A kite is a tethered aircraft. The necessary lift that makes the kite wing fly is generated when air 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. The anchor point of the kite line may be static or moving (e.g., the towing of a kite by a running person, boat, free-falling anchors as in paragliders and fugitive parakites or vehicle).
The same principles can be used in water and experiments have also been made with lighter-than-air kites (kytoons)
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 fishing, kite buggying and a new trend snow kiting. Kites towed behind boats can lift passengers which has had useful military applications in the past.
It is generally accepted that kites were first developed 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.
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 introduction into India, the kite further evolved into the fighter kite known as the patang in India where thousands are flown every year on festivals such as Makar Sankranti.
Kites were known throughout Polynesia, as far as New Zealand, with the assumption being that the knowledge diffused from China along with the people. Anthropomorphic kites made from cloth and wood were used in religious ceremonies to send prayers to the gods. Polynesian kite traditions are used by anthropologists get an idea of early 'primitive' Asian traditions that are believed to have at one time existed in Asia.
Boys flying a kite in 1828 Germany, by Johann Michael Voltz.
Kites were late to arrive in Europe, although windsock-like banners were known and used by the Romans. Stories of kites were first 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. Although they were initially regarded as mere curiosities, by the 18th and 19th centuries kites were being used as vehicles for scientific research.
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, 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.
Kites were also instrumental in the research and development of the Wright brothers when building the first airplane in the late 1800s. Over the next 70 years, many new kite designs were developed, and often patented. These included Eddy's tail-less diamond kite, the tetrahedral kite, the flexible kite, the sled kite, and the parafoil kite, which helped to develop the modern hang-gliders. In fact, 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; many different designs of man-lifting kite were developed as well as power kites.
The development 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) but since then they are used mainly for recreation.