Bird-like Wing Research Articles

Tip-vortex flow characteristics investigation of a novel bird-like morphing discrete wing structure

A bird-like morphing discrete wing, inspired by primary feathers of birds’ wings, was designed to control the wing-tip vortex strength. The influence of both the morphing process and discrete (non-continuous) surface feature for the bird-like wing structure on the tip-vortex flow characteristics was investigated in detail at Re = 87 000. The results reveal that the morphing process of the bird-like discrete wing structure can achieve the effective control of the core vortex strength by changing the flow structures around the tip-vortex core center(s). The induced drag yielded by the bird-like morphing wing structure is tightly related to its vorticity distribution in the near-wake region. Moreover, compared with the fully extended fixed-wing model with a continuous surface structure, the bird-like discrete wing model with the fully extended morphing state can suppress the core vortex strength by destroying the tip-vortex merging process. Meanwhile, the core vortex strength of the fully extended discrete wing model decays more sharply with the increase in x/c. The maximum proportions of the induced drag relative to the total drag for both the discrete and continuous wing models with the fully extended shape are 14.33% and 19.97%, respectively. However, the fully folding process of the bird-like wing structure significantly weakens the induced-drag reduction effect of the discrete surface structure. The maximum proportions of the induced drag relative to the total drag for both the discrete and continuous wing models with the fully folded shape are 17.59% and 18.41%, respectively.

A polar dinosaur feather assemblage from Australia

Exceptionally preserved Mesozoic feathered dinosaur fossils (including birds) are famous, but recognized from only very few localities worldwide, and are especially rare in the Southern Hemisphere. Here we report an assemblage of non-avian and avian dinosaur feathers from an Early Cretaceous polar (around 70°S) environment in what is now southeastern Australia. The recovered remains incorporate small (10–30 mm long) basal paravian-like tufted body feathers, open-vaned contour feathers, and asymmetrical bird-like wing feathers that possess high-angled barbs with possible remnants of barbicels — amongst the geologically oldest observed to date. Such morphological diversity augments scant skeletal evidence for a range of insulated non-avian theropods and birds inhabiting extreme southern high-latitude settings during the Mesozoic. Although some of these fossil feathers exhibit what may be residual patterning, most are uniformly toned and preserve rod-shaped microbodies, as well as densely-packed microbody imprints on the barbules that are structurally consistent with eumelanosomes. Geochemical analysis detected no identifiable residual biomolecules, which we suspect were lost via hydrolysis and oxidization during diagenesis and weathering. Nevertheless, an originally dark pigmentation can be reasonably inferred from these melanic traces, which like the coloured feathers of modern birds, might have facilitated crypsis, visual communication and/or thermoregulation in a cold polar habitat.

Numerical analysis of geometrical and aerodynamic enhancements of a birdlike wing

Purpose – Biomimetic study existing natural biological elements to produce engineering products with similar performance and abilities. The purpose of this paper is to highlight biomimetic studies to produce a new type of airplanes: adding remiges, bending ability and flapping mechanisms. Design/methodology/approach – The used methodology was to thoroughly investigate the literature, to define the proper endurance and fatigue parameters, to perform a series of numerical studies and report improvement percentages relevant to defined parameters. Findings – By adding remiges and the bending mechanism, the authors managed to reach – numerically – the preset desired structure goal. Efficiency increased using remiges with less drag force. In addition, with the help of the bending wing technique, the drag force was improved. The flapping mechanism showed high vibration rates. Last but not least, applying multiple winglets gave a better optimization of the endurance parameter. Research limitations/implications – Research is conducted at a university without any research facilities. No laboratories exist, and acquiring research papers is mostly difficult and costly. Originality/value – The research study is original in the sense of its numerical investigation. Proposing biomimetic was at the heart of the airplane invention and cannot be stated as an original contribution. Rather the field has been recently abandoned, and performing this major literature review can be considered as original in a sense it summarizes recent to somewhat old advancement.

Unsteady aerodynamics on a flapping bird-like wing. Comparison of two wing types during flapping flight on a bird-like model

Unsteady aerodynamics on a flapping bird-like wing. Comparison of two wing types during flapping flight on a bird-like model