Kite equilibrium and bridle length

Kite design has recently seen a revival, with sports such as kite buggying and kite surfing becoming significant businesses in some countries. Since t he aerodynamics of kites has not been explored in much depth this paper set s out to explain a major behaviour of kites, predicting where they will set tle during flight. The analysis is confined to a vertical plane containing the kite string. It examines the basic forces for single-line or two-line k ites and shows how the line azimuth angle(s) and equilibrium settling point (s) can be derived from the aerodynamic properties of the kite, from the ki te mass and from the bridle lengths. It is noted that while several equilib rium points are predicted not all are stable equilibrium points. Wind tunne l tests with a specially built rigid model are described and these are show n to confirm theoretical predictions.