Swifts are among the most aerodynamically refined gliding birds. However, the overlapping vanes and protruding shafts of their primary feathers make swift wings remarkably rough for their size. Wing roughness height is 1-2% of chord length on the upper surface--10,000 times rougher than sailplane wings. Sailplanes depend on extreme wing smoothness to increase the area of laminar flow on the win...

Insect wings do not contain intrinsic musculature to change shape, but rather bend and twist passively during flight. Some insect wings feature flexible joints along their veins that contain patches of resilin, a rubber-like protein. Bumblebee wings exhibit a central resilin joint (1m-cu) that has previously been shown to improve vertical force production during hovering flight. In this study, ...

We use fully-coupled three-dimensional computer simulations to examine aerodynamics of elastic wings oscillating at resonance. Wings are modeled as planar elastic plates plunging sinusoidally at a low Reynolds number. The wings are tilted from horizontal, thereby generating asymmetric flow patterns and non-zero net aerodynamic forces. Our simulations reveal that resonance oscillations of elasti...

Bionic micro-air vehicles (MAV) having the maneuverability of dragonflies would be capable of fast forward flight, hovering and even backward flight. In order to achieve desirable designs for high performing MAVs, it is essential to understand the aerodynamics and structures of the insect wings and more importantly, the interactions between the operating flows and flexible structural wings. Her...

A linear, aeroelastic analysis of a low aspect ratio swept back trapezoidal wing modeled as a cantilever plate is presented. An analytical and numerical formulation for both the aerodynamic forcing and structural response of the wing was developed. The analytical model uses a three dimensional time domain vortex lattice aerodynamic method. A Rayleigh-Ritz approach has been used to transfer equa...

Densely stacked Ag nanoparticles with an average diameter of 199 nm were effectively deposited on TiO2-coated cicada wings (Ag/TiO2-coated wings) from a water-ethanol solution of AgNO3 using ultraviolet light irradiation at room temperature. It was seen that the surfaces of bare cicada wings contained nanopillar array structures. In the optical absorption spectra of the Ag/TiO2-coated wings, th...

Dragonfly wings are highly corrugated, which increases the stiffness and strength of the wing significantly, and results in a lightweight structure with good aerodynamic performance. How insect wings carry aerodynamic and inertial loads, and how the resonant frequency of the flapping wings is tuned for carrying these loads, is however not fully understood. To study this we made a three-dimensio...

Most birds and many insects use periodic wing motion to propel themselves and maneuver. Most conventional flying machines are propelled by rotating machinery, achieve lift through rotating or fixed wings, and are controlled through the production of steady aerodynamic forces produced by rotors or movable wings. Many of the first powered flapping-wing micro air vehicles (MAVs) effectively replac...