How Kites Have Changed History
European explorers returning from Asia introduced kites to that continent. Marco Polo gave a very detailed account of kites and their construction in his writings. In 1405 the first known reference to kite flying appeared in a text about European military technology. In 1430 another text described how to make a kite from parchment. The text explained in detail how to connect the flying line to various points on the kite for flying in different wind conditions.
In Europe kites were generally regarded as toys. However, the eighteenth century saw the first use of kites as a tool for scientific experiment. In Scotland in 1749 a meteorologist by the name of Alexander Wilson used kites to lift thermometers to measure temperature variations at different altitudes.
The man most famous for using a kite for scientific experimentation was Benjamin Franklin. In 1752 Franklin flew a kite in an electrical storm with a key suspended from the flying line. Franklin observed sparks coming from the key and thus proved lightning’s similarity in nature to static electricity. The scientists of the day generally regarded lightning as an electrical current that only traveled from storms clouds to the ground. Franklin’s experiment with the kite gave direct evidence that the electrical current also traveled from the ground to the clouds. His kite and key experiment eventually led to the invention of the lightning conductor.
The nineteenth century saw the further development of kites in scientific experiment. In 1853 Sir George Cayley of England developed a full sized glider with two kite-shaped wings from his experiments with kites. The glider carried a man aloft for a 40 second flight. From these experiments, Cayley discovered the properties of lift, thrust, and drag.
E.D. Archibold, an English meteorologist, began experimenting with kites in 1833. He used the kites to lift anemometers to various altitudes to measure wind speeds. This led to the wider use of kites in meteorology during the nineteenth century and resulted in an improvement in weather forecasting. Archibold followed his experiments in use of kites in meteorology to experiments in using kites for aerial photography in 1887. The principles of aerial photography he developed are still in use today.
A natural extension of kite use became the quest to build a powered, heavier-than-air aircraft in the late nineteenth century. Following the principles of lift, thrust, and drag established by Sir George Cayley in his experiment with kites, inventors began the systematic process of developing a flying machine.
In the 1890’s a Sydney, Australia man by the name of Lawrence Hargrave experimented with a number of kite designs. He finally settled on a box kite design that he called a gliding kite. In his quest to find a stable airfoil that would hold an engine, he developed the cambered, or curved, airfoil. Today’s aircraft designers still use Hargrave’s curved airfoil. Hargrave’s inability to overcome the weight problem in attaching an engine to his kites kept him from building a successful flying machine. Of course, as the world knows, the Wright brothers overcame all obstacles to powered flight in 1903 when they flew the world’s first heavier-than-air machine.
Kites were also the basis for the development of hang gliders and ultralight aircraft. During the 1960s Francis Rogallo, a NASA scientist, invented a flexible kite with no supporting spars. This kite used the wind to keep it open and maintain its shape. Rogallo was searching for a way to develop a controllable recovery system for spacecraft. “The Rogallo Wing” is still being used by the military for various uses.
Another recent kite design is the “parafoil.” This kite also has no spars and uses the wind to maintain its shape. This kite design also supplies the greatest amount of lift of any design. It has been developed into steerable parachutes and non-rigid hang gliders. With this develop in kite design kites have come full circle. Kites were the origin for the evolution of the airplane. Today kites are now beginning to emulate the form and function of the airplane. The next time you see the sky filled with kites of various colors, shapes, and sizes, you’ll realize that kites are more than just toys.
