Experimental Characterization of Additively Manufactured Multi-Feather Wingtip Devices

Soaring birds have evolved to fly for long periods of time without flapping their wings. Inspired by the flight of these birds, the proposed thesis presents an experimental investigation focused on wingtip devices designed based on biomimicry. The overarching engineering objective was to reduce the induced drag as a means to improve the fuel efficiency via these experimental wingtips. An associated secondary objective was to establish a method for manufacturing complex structures suitable for wing tunnel testing. A manufacturing technique that involved using composite weaves to reinforce additively manufactured structures was developed. This technique has the potential to reduce manufacturing times by as much as three weeks, when compared to traditional manufacturing methods. Three “featherlet” wing tip attachments were designed and manufactured. Surface flow visualization and force balance campaigns were then conducted at the ERAU Micaplex low speed wind tunnel. The surface streamlines from the oil surface flow visualization campaign showed that the basic winglet had flow over the wing that was closest to two-dimensional flow. This was reinforced by the analysis of the lift to drag ratio where the basic winglet had an increased aerodynamic efficiency of up to 25% over the wing with no attachment. Two of the three featherlets tested showed an improved aerodynamic efficiency as well as a significant reduction in induced drag when compared to the no attachment case. Data suggests that with further development, a featherlet attachment could one day perform better than the basic winglet attachment