Perpetual Dynamic Soaring in Linear Wind Shear

Abstract

A study was conducted to analyze dynamic soaring in linear wind shear and discuss the necessary and sufficient conditions to enable sustainable flight with dynamic soaring. The system under analysis was defined by a wind shear model with constant vertical velocity gradient and the aircraft equations of motion, which model the aircraft behavior when subject to a wind gradient. The study defined the inequalities that characterized the sufficient and necessary conditions for dynamic soaring. The conditions were applicable to a wide variety of unmanned aerial vehicles (UAVs), allowing the determination of the suitability of an aircraft for dynamic soaring under different environmental conditions. The equations of flight dynamics based on the flight-path and the lift were also derived in the study. The investigations derived the necessary and sufficient conditions for sustainable dynamic soaring as an explicit function of several aircraft and environment parameters. The characterization of the minimum vertical wind gradient dependence on environmental and aircraft parameters was obtained by running multiple trajectory optimizations, evaluating a range of values for several parameters.