Graduation date: 2007Extending the flight time of an autonomous unmanned air vehicle by soaring is considered. A suboptimal controller is developed and successful static soaring is demonstrated with a 6 degree of freedom glider model. Altitude gain rates of between ¼ and ½ m/s are achieved with this simple implementation. A hybrid optimal trajectory generation algorithm is developed and used to find optimal closed cycles in typical wind conditions using a point mass model. The algorithm is shown to be robust to a poor initial guess, with computational performance comparable to a common direct shooting algorithm. A receding horizon optimal controller strategy is investigated for the problem of autonomous soaring. An efficient Riccatti recursion algorithm is used to determine the next step in the Newton Iteration of the Non-Linear optimization problem. A real time strategy for optimal soaring is developed and shown to perform very well for a point mass model, resulting in repeatable trajectories with significant altitude gain. Sensitivity to errors including wind model errors is investigated. The real time algorithm was found to be insensitive to reasonable errors.