风筝的飞行隐藏着什么科学原理?英文的!

Kite (device),wind-supported flying device consisting of a wooden or similar framework covered with paper,cloth,or synthetic material.A kite is a rudimentary airfoil; it can be flown for pleasure or for purposes of study.Attached to a long string,it can be sent aloft through the action of the wind on its surfaces.Its distance or height is controlled from the ground by playing out the string.Kites are of ancient origin and were flown by various Asian peoples and the ancient Egyptians.Today kite flying is a popular pastime and a competitive sport.In eastern Asia,special competitions are held in which the kites are elaborately designed and decorated in the forms of birds,fish,or dragons and may be equipped with whistles or pipes that emit musical sounds as the wind blows through them.Kite-fighting contests are also held,in which competitors attempt to use their kites to attack and down the kites of opponents.
Kites have been employed for practical purposes as well as for pleasure.American diplomat and scientist Benjamin Franklin experimented with kites to investigate atmospheric electricity,and kite studies were also made by the American physicist and inventor Alexander Graham Bell.Beginning in the 1890s and continuing for about 40 years,box kites,consisting of two or more connected open-ended boxes,were used for sending meteorologic instruments aloft to measure wind velocity,temperature,barometric pressure,and humidity.In the late 19th and early 20th centuries,kites were used for lifting military observers to heights from which they could observe the disposition of enemy forces.During World War II (1939-1945),kites were also used as gunnery targets.Present-day applications include their use as signals in air-sea-rescue operations.