Steering response to roll control of a two-line disk kite

Kites are utilized in both professional sporting activities and potential new energy generation applications. Most of these use two or four-line steerable kites, but the steering response is not well understood. Previous work on kite behaviour has focused on single-line kites, and the dynamics of two-line kites has been limited to quasi static analysis. The mathematical formulation of the few models that consider the dynamics have been based only on energy methods. Furthermore, existing work relies on not-validated generalised aerodynamic models unsuitable for design optimisation tasks. Understanding the dynamics of two-line steerable kites allows for innovative improvements for such applications. In this work we introduce a two-disk kite as a simplified generic model for analysis of steering response. We derive the fully non-linear governing dynamic equations of motion for a two-line four-attachment point disk kite using 4DOF with a Newton-Euler formulation. The aerodynamic model of the kite is taken from previous work of our group (CFD/wind-tunnel tested and validated). The analysis considers the stability regions for flight behaviour and the manoeuvrability of the kite. Kite design parameters are investigated to guide future designs.