July 28, 2009                           For public-domain AWE:  

Passive Dutch-roll power cycle

Attached is a mpg showing how a naturally dancing/unsteady kite (tailless Eddy-Malay) under a stable lifter (tailed delta) can be made to provide passive Dutch-roll power cycle. (note crosswind sweep & large horizontal motion of the lower line).

Unhappy with the spiral waves that develop with centrally run Eddy-kite-train line, Eddy put each kite on a sub tether for his trains so that unsteadiness canceled. The Eddy kite's "defect" is that its tail spar is a regular pendulum giving it a characteristic dance. Here the defect is effectively harnessed to regulate a crosswind sweep cycle. Better demo video soon. In the second experiment a driven string A-frame reciprocated vigorously.

Many kites can be made to do passive eights with a lifter holding them up. So far no crashes or other mishaps. A rare single loop caused no perceptible difference in the power cycle; swivels are possibly unneeded.     See first video.

This is the fifth major KiteLab "passive control" scheme to work well & the simplest yet.
~~~~ Dave Santos