| Winglets have been shown to improve the efficiency of large aircraft at high subsonic speeds, but winglet designs for smaller aircraft like UAVs are unproven. Winglets improve efficiency by diffusing the shed wingtip vortex, which in turn reduces the drag due to lift and improves the wings lift over drag ratio. This research investigates methods for designing and optimizing winglet geometry for UAVs that operate at Reynolds numbers near 10 6. The design methodology is based on the vortex lattice method. Optimized designs are tested and compared with base designs for validation and include both Whitcomb and blended winglets. Designs are validated using wind tunnel tests. The resulting methodology is then applied to existing UAV platforms for specific performance improvements. For example, winglets were designed for the Shadow UAV where endurance was increased by 35% and 83% and range was in- creased by 21% and 31%, for the Whitcomb and blended wing designs, respectively. |
