The rotary-wing analogue of fixed-wing soaring is illustrated in this work. Periodic energy-neutral trajectories for a rotorcraft where energy is harvested from a spatially varying (de-terministic) wind field is computed as solution to an optimal control problem. The extracted energy aids in countering the losses due to drag on the rotor and fuselage. We illustrate that an updraft component in the wind field is necessary for enabling periodic motion. For this reason, thermal columns provide an ideal setting for such manoeuvres, while the wind field typically considered for fixed-wing dynamic soaring is inadequate. A non-spinning frame formulation, inspired by a six-degrees-of-freedom (6DoF) boomerang model is adopted for developing the equations of motion of the rotorcraft. Optimal periodic trajectories within a Gaussian thermal model are obtained by considering collective, cyclic and linear twist inputs for the rotor blades. © 2019 by Xin Ning. Published by the American Institute of Aeronautics and Astronautics, Inc.