Secret Life of Kites- Let them Dance (Yaw DOF) by Dave Santos

Apologies to anyone who may not want to know “too much” about passive kite control, but 15yrs of inquiry sorting thru a vast space of possible rigging solutions converges, iteration by iteration, on progressively optimal and simple rigging designs.


One of the last pieces of the puzzle is the relation of passive dynamics to varying wind velocity. Within a narrow wind range, a kite can be rigged and trimmed to self-oscillate at a desired frequency and amplitude. A quiver of kites from small to large cover the velocity spectrum, each kite overlapping somewhat the velocity range of its sequentially adjoining smaller and larger kites. Where once the question was high line drag of a longline proportion of a small fast kite, the optimum is shortline proportions of larger slower kites, where line drag is negligible.

A power kite ideally self-steers its own orbit, but at low or high wind velocity or at min or max work-loading limits, a degree of oversteering or understeering helps match conditions. As usual, there is a tuning of lines and anchor-points that can compensate by the right steering correction factor, the separation distance of two tagline anchors.

At last, the “secret sauce” of passive-dynamic AWE; spring-mass tuned resonance between kite/wind-PTO/load parameters.


There is new progress understanding Kite Dynamic Stall, which serves several functions. Traditionally, for a classic kite, stall angle passively compensates for higher or lower wind. In kitesurfing, the rider can “power-up” in a jump by a sudden stall. For AWE pattern flying, dynamic stall can serve to maximize power resonantly to the tuned PTO (power take off).

Dynamic Stall not only is peak-amplitude but creates a magically unstable Hopf Bifurcation moment in which tiny control inputs suffice but must be fast to stay within Lyapunov Stability envelope.

1 Like