Reducing Drag of Small UAVs with Passively Adaptive, Bio-Inspired Wingtips

Abstract

Small unmanned aerial vehicles (UAVs) have demonstrated a need for improved aero- dynamic efficiency and handling characteristics. Research on the slotted wingtips of birds, highlighting their ability to improve both aerodynamic efficiency and ma- neuverability, has demonstrated these wingtips as a possible solution. Research has also shown that multiple wingtip configurations are needed, which requires a pas- sive method of actuation given the limited capacity of small UAVs. This thesis aims to demonstrate and characterize a passive method of bio-inspired wingtip actuation, applying prior studies of composites with bend-twist coupling to achieve planar and nonplanar wingtip configurations without the need for moving parts. An aeroelastic tailoring of these composite wingtips is conducted, utilizing vortex lattice method simulations and thin airfoil theory, as well as cantilever static testing, to iterate to- wards a composite layup sequence that will be capable of deflecting to the required nonplanar configuration at higher angles of attack. The performance of these com- posite wingtips - both in terms of elastic deflection and aerodynamic efficiency - is later demonstrated and analyzed in the wind tunnel.