Conceptual Wing Design for UAV inspired by the Magnificent Frigate Bird

Abstract

Bioinspired wing designs are becoming more commonplace as engineers constantly seek to enhance the performance of aerial vehicles. This paper presents the experimental study done to analyse how a wing design inspired by the Magnificent Frigatebird (Frigata magnificens), a large sea bird known to be able to fly long ranges. Being one of the only two bird species that are capable of spending days and night on the wing, its wing geometry is expected to result high gliding efficiency. A conceptual wing was developed to closely resemble the bird’s wing geometry. It was then compared with the wing of a UAV currently used in Sri Lanka for reconnaissance. The aerodynamic comparison of the wings was done by conducting Computational Fluid Dynamic (CFD) simulations using OpenFOAM with K-Omega Shear Stress Transport (SST) as the turbulence model. Having simulated flight conditions resembling the practical flying envelop of the UAV, it was found that aerodynamic efficiency of the conceptual wing is improved for cruise conditions, in comparison with the existing UAV wing. A validation of a computational results for drag was done using a wake survey in a low-speed wind tunnel by employing a wake rake. Since it was impossible to have direct correlation between the Reynold’s number of the computational and experimental results, results for drag coefficient were matched through extrapolation. The results show that the bioinspired wing design proves to be suitable candidate to enhance the cruising capability, and thereby range and endurance of the said UAV as it does not engage in extreme manoeuvring flight in its role.