Pauli Rautakorpi

Stable lying-eight orbits for kites.

A kite simulator to study kite flight when kite is controlled by a given passive periodic control for control angle has been made. It was noticed that simple sine function for control angle with suitable amplitude and period gives a stable orbit for kite and thus infinite flight time with fixed tether length and constant wind. The kite stabilizes itself to a unique lying-eight orbit in the middle of wind window with completely passive sinusoidal control when initial conditions are not too far outside the stable orbit.

With small tether length change within one orbit it is possible to get many lying-eight orbits with shape close to each other and generate significant amount of energy with passive control before kite gets out of control due to longer tether. Thus controls and orbits close to the stable orbits with fixed tether might be useful also for kite wind generators with variable tether length when modified with small
corrections.