A box kite is a high-performance

kite A kite is a tethered heavier than air flight, heavier-than-air craft with wing surfaces that react against the air to create Lift (force), lift and Drag (physics), drag forces. A kite consists of wings, tethers and anchors. Kites often have ...

, noted for developing relatively high lift; it is a type within the family of cellular kites. The typical design has four parallel struts. The box is made rigid with diagonal crossed struts. There are two sails, or ''ribbons'', whose width is about a quarter of the length of the box. The ribbons wrap around the ends of the box, leaving the ends and middle of the kite open. 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. The box kite was invented in 1893 by Lawrence Hargrave, an English-born Australian, as part of his attempt to develop a manned flying machine. Hargrave linked several of his box kites (Hargrave cells) together, creating sufficient lift for him to fly some 16 ft (4.9 m) off the ground. A winged development of this kite is known as the Cody kite following its development by Samuel Franklin Cody. Military uses also involved a kite/radio transmitter combination issued to pilots during

World War II World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...

for use in liferafts. 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. However in 2014 Robert Moore and a team of kite experts flew a 12 sq metre DT delta to 16,009 ft above their launch point. The location of the flights was near Cobar in Western NSW, Australia. While this was primarily a triangular winged delta kite, it has a triangular box centre cell for additional stability. Future attempts on either the single kite record or multiple kite record (trained), may use Hargrave box kites or a variant. Before Dacron, Spectra, and

Kevlar Kevlar (para-aramid) is a strong, heat-resistant synthetic fiber, related to other aramids such as Nomex and Technora. Developed by Stephanie Kwolek at DuPont in 1965, the high-strength material was first used commercially in the early 1970s as ...

were available, high performance box kites used oiled

silk Silk is a natural fiber, natural protein fiber, some forms of which can be weaving, woven into textiles. The protein fiber of silk is composed mainly of fibroin and is most commonly produced by certain insect larvae to form cocoon (silk), c ...

linen Linen () is a textile made from the fibers of the flax plant. Linen is very strong and absorbent, and it dries faster than cotton. Because of these properties, linen is comfortable to wear in hot weather and is valued for use in garments. Lin ...

hemp Hemp, or industrial hemp, is a plant in the botanical class of ''Cannabis sativa'' cultivars grown specifically for industrial and consumable use. It can be used to make a wide range of products. Along with bamboo, hemp is among the fastest ...

sails, and were flown with

steel Steel is an alloy of iron and carbon that demonstrates improved mechanical properties compared to the pure form of iron. Due to steel's high Young's modulus, elastic modulus, Yield (engineering), yield strength, Fracture, fracture strength a ...

cable. Silk, linen and hemp were used because they could be spun finer than

cotton Cotton (), first recorded in ancient India, is a soft, fluffy staple fiber that grows in a boll, or protective case, around the seeds of the cotton plants of the genus '' Gossypium'' in the mallow family Malvaceae. The fiber is almost pure ...

and stretched relatively little when wet. Steel had the highest available strength for its weight. After Hargrave invented the box kite, weather stations from around the world saw the potential for his design. Blue hill observatory and the German weather station at Lindenberg used kites routinely until weather balloons took over in the 1920s and 1930s.

References

External links

Cellular kites
at the Virtual Kite Zoo Australian inventions Kites {{kite-stub

See also

References

External links