This research focuses on the development of two bioinspired micro air vehicle (MAV) prototypes, based on morphing wings and wing grid wingtip devices. The morphing wings MAV tries to adapt the aerodynamics of the vehicle to each phase of flight by modifying the vehicle geometry, while the wing grid MAV aims to minimize the aerodynamic and weight penalty of these vehicles. This work focuses on the design methodology of the flight control system of these MAVs. A preliminary theoretical conceptual design was used to verify the requirements, wind tunnel tests were performed to determine aerodynamic characteristics, and suitable materials were selected. The hardware and software configuration designed for the control system, which fulfills the objective of adaptive and optimal control in the wingtip-based prototype of the wing grid, is described. Finally, the results of the flight control on the prototype MAVs are analyzed.

The article presents a research in the field of morphing wings (adaptive wing geometry) developed over a prototype of micro-unmanned air vehicle based on smart materials technology. This morphing wing will optimize the aircraft performance features. Modifying the curvature of the wing, the micro-unmanned air vehicles will adjust its performance in an optimum mode to cruise flight condition as well as in the phases of takeoff and landing. The installation of mechanical elements for control surfaces in small size aircraft means, on some occasions, an extra complexity. In addition, it takes into account an increase in aircraft weight. In this research, the adaptive wing geometry is based on macro-fiber composites, so that its position on the inner surfaces of the wing allows the appropriate modification of the curvature, adapting them to the flight profile. This research will present the conceptual design of the vehicle, computational calculations, experimental results of the wind tunnel testing, validations using non-intrusive techniques (particle image velocimetry) and a theoretical–experimental analysis of the macro-fiber composite effects over the wing. An Arduino board will perform the control parameters of the macro-fiber composite deformation. With these analytical, computational, and experimental results, the most relevant conclusions are presented.

This article aims to highlight the importance of utilizing flow visualization techniques in the preliminary analysis of streamlined and bluff bodies, especially the potential use of visualization with ink in a water channel as a tool for a preliminary approach during fluid mechanics analysis. According to this, the study compares the results obtained using a classical flow visualization technique, ink injection in water, with those obtained through the employment of a laser-based measurement and visualization technique, called PIV, in a low-speed wind tunnel. The article briefly presents both techniques and highlights the importance of flow visualization in the analysis of aerodynamic bodies. This study focuses on flow over NACA airfoils at extremely low Reynolds numbers, which is of great interest for application in extraterrestrial atmospheres, such as on Mars. After obtaining images of the flow streamlines over the NACA 0018 airfoil, the results of both techniques were compared. The results indicated that there was good agreement between the visualization with the water channel and the PIV results, suggesting that the results obtained in the water channel represented a scientifically valid approximation and an essential complement to computational models that require experimental validation.

A wind tunnel tests campaign has been conducted to investigate the aerodynamic flow around a wing morphing to be used in a micro air vehicle. Non-intrusive whole field measurements were obtained by using PIV, in order to compare the velocity and turbulence intensity maps for the modified and the original version of an adaptive wing designed to be used in a micro air vehicle. Four sections and six angles of attack have been tested. Due to the low aspect ratio of the wing and the low Reynold number tested of 6.4 × 10⁴, the influence of the 3D effects has been proved to be important. At high angles of attack, the modified model prevented the detachment of the stream, increased the lift of the wing and reduced the turbulence intensity level on the upper surface of the airfoil and in the wake.

In this paper, a numerical analysis of a biomimetic unmanned aerial vehicle (UAV) is presented. Its wings feature three grids at the tip similar to the primary feathers of birds in order to modify the lift distribution over the wing and help in reducing the induced drag. Numerical analysis using computational fluid dynamics (CFD) is presented to analyze the aerodynamic effects of the changes in dihedral and angle of attack (with respect of the rest of the wing) of these small grids at the tip. The aerodynamic performances (lift, drag, and efficiency) and rolling capabilities are obtained under different flight conditions. The effects of changing the dihedral are small. However, the change in the grid angle of attack increases aerodynamic efficiency by up to 2.5 times when the UAV is under cruise flight conditions. Changes to the angle of attack of the grids also provide increased capabilities for rolling. Finally, boundary values of the pressure coefficient and non-dimensional velocity contours are presented on the surfaces of the UAV, in order to relate the aerodynamic results to the aerodynamic patterns observed over the wing.

The present work is focused on the investigation of the aerodynamic performances of a novedous bioinspired morphing Micro Air Vehicle (MAV) with an adaptive wing structure geometry. For this purpose, a numerical study of Computational Fluid Dynamics (CFD) implemented by Ansys Fluent 15.0 was performed in order to obtain insight about the aerodynamic effect of wing structure deformation when morphing devices are used, and its influence on the global aerodynamic parameters related with aircraft performances. On the other hand, an experimental study using the Particle Image Velocimetry technique and balance measurements in a Low-Speed Wind Tunnel was conducted to obtain experimental information about performances measured to establish a comparison between both, experimental and numerical results. The Micro Air Vehicle (MAV) presents a Zimmerman wing with an Eppler 61 airfoil. Three different wing configurations according to curvature and thickness variations and for all angles of attack have been studied. A comparative analysis based on aerodynamic features is performed by an assessment of lift coefficient (C_L), total aerodynamic drag coefficient (C_D) and aerodynamic efficiency as lift/drag ratio (C_L/C_D) in order to conclude the best wing configuration in terms of aerodynamic performance.