Box kite
From Wikipedia, the free encyclopedia
A box kite is a high-performance kite, noted for developing relatively high lift. It was invented by the Australian Lawrence Hargrave in 1893. Hargrave also linked several box kites together, creating sufficient lift for him to fly some 16 ft (4.9 m) off the ground. A winged variant of this kite is known as the Cody kite following its development by Samuel Cody as a platform for military observation during the Second Boer War. Military uses also involved a kite/radio transmitter combination issued to pilots during World War II for use in liferafts[1].
The typical design has four parallel struts. The ends and box are made rigid with diagonal arrangements of crossed struts. The ends are open. There are two sails, ribbons whose width is about 1/4 of the length of the box. The ribbons wrap around the ends of the box. In flight, one strut is the bottom, and the bridle is tied between the top and bottom of this strut. The dihedrals of the sails help stability.
Large box kites are constructed as cellular kites. Rather than one box, there are many, each with its own set of sails.
Most of the altitude records for kite flying are held by large box kites, with Dacron sails, flown with Spectra cable. Before Dacron, Spectra and Kevlar were available, high performance box kites used oiled silk, linen or hemp sails, and were flown with steel cable. Silk, linen and hemp were used because they could be spun finer than cotton and stretched relatively little when wet. Steel had the highest available strength for its weight.
[edit] Trivia
On Episode 380F of The Simpsons, "Sideshow Bob's Last Gleaming", Martin Prince incorrectly claims the box kite was originally developed as a means of drying wet string.
[edit] See also
[edit] References
- Hudson Shaw, W. and Ruhen, O. (1977) Lawrence Hargrave: Explorer, Inventor and Aviation Experimenter Sydney : Cassell Australia.
- Cellular kites at the Virtual Kite Zoo.
