scholarly journals Role of Active Morphing in the Aerodynamic Performance of Flapping Wings in Formation Flight

Drones ◽  
2021 ◽  
Vol 5 (3) ◽  
pp. 90
Author(s):  
Ethan Billingsley ◽  
Mehdi Ghommem ◽  
Rui Vasconcellos ◽  
Abdessattar Abdelkefi

Migratory birds have the ability to save energy during flight by arranging themselves in a V-formation. This arrangement enables an increase in the overall efficiency of the group because the wake vortices shed by each of the birds provide additional lift and thrust to every member. Therefore, the aerodynamic advantages of such a flight arrangement can be exploited in the design process of micro air vehicles. One significant difference when comparing the anatomy of birds to the design of most micro air vehicles is that bird wings are not completely rigid. Birds have the ability to actively morph their wings during the flapping cycle. Given these aspects of avian flight, the objective of this work is to incorporate active bending and torsion into multiple pairs of flapping wings arranged in a V-formation and to investigate their aerodynamic behavior using the unsteady vortex lattice method. To do so, the first two bending and torsional mode shapes of a cantilever beam are considered and the aerodynamic characteristics of morphed wings for a range of V-formation angles, while changing the group size in order to determine the optimal configuration that results in maximum propulsive efficiency, are examined. The aerodynamic simulator incorporating the prescribed morphing is qualitatively verified using experimental data taken from trained kestrel flights. The simulation results demonstrate that coupled bending and twisting of the first mode shape yields the highest propulsive efficiency over a range of formation angles. Furthermore, the optimal configuration in terms of propulsive efficiency is found to be a five-body V-formation incorporating coupled bending and twisting of the first mode at a formation angle of 140 degrees. These results indicate the potential improvement in the aerodynamic performance of the formation flight when introducing active morphing and bioinspiration.

2012 ◽  
Vol 39 (1) ◽  
pp. 11-20 ◽  
Author(s):  
H. Yusoff ◽  
M.Z. Abdullah ◽  
M. Abdul Mujeebu ◽  
K.A. Ahmad

Drones ◽  
2021 ◽  
Vol 5 (3) ◽  
pp. 64
Author(s):  
Ethan Billingsley ◽  
Mehdi Ghommem ◽  
Rui Vasconcellos ◽  
Abdessattar Abdelkefi

Many research studies have investigated the characteristics of bird flights as a source of bioinspiration for the design of flapping-wing micro air vehicles. However, to the best of the authors’ knowledge, no drone design targeted the exploitation of the aerodynamic benefits associated with avian group formation flight. Therefore, in this work, a conceptual design of a novel multi-flapping-wing drone that incorporates multiple pairs of wings arranged in a V-shape is proposed in order to simultaneously increase the propulsive efficiency and achieve superior performance. First, a mission plan is established, and a weight estimation is conducted for both 3-member and 5-member configurations of the proposed air vehicle. Several wing shapes and airfoils are considered, and aerodynamic simulations are conducted, to determine the optimal planform, airfoil, formation angle, and angle of attack. The simulation results reveal that the proposed bioinspired design can achieve a propulsive efficiency of 73.8%. A stability analysis and tail sizing procedure are performed for both 3-member and 5-member configurations. In addition, multiple flapping mechanisms are inspected for implementation in the proposed designs. Finally, the completed prototypes’ models of the proposed multi-flapping-wing air vehicles are presented, and their features are discussed. The aim of this research is to provide a framework for the conceptual design of bioinspired multi-flapping-wing drones and to demonstrate the sizing, weight estimation, and design procedures for this new type of air vehicles. This work establishes the first multi-flapping-wing drone design which exploits the aerodynamic features of the V-formation flight observed in birds to achieve superior performance in terms of payload and endurance.


Author(s):  
Jose E. Rubio ◽  
Uttam K. Chakravarty

Biologically-inspired micro air vehicles (MAVs) are miniature-scaled autonomous aircrafts which attempt to biomimic the exceptional maneuver control during low-speed flight mastered by insects. Flexible wing structures are critical elements of a nature-inspired MAV as evidence supports that the wings of aerial insects experience highly-elastic deformations that enable insects to proficiently hover and maneuver in different airflow conditions. For this study, a crane fly (family Tipulidae) forewing is selected as the target specimen to replicate both its structural integrity and aerodynamic performance. The artificial insect-sized wing is manufactured using photolithography with negative photoresist SU-8 to fabricate the vein geometry. A Kapton film is attached to the vein pattern for the assembling of the wing. The natural frequencies and mode shapes of the artificial wing are determined to characterize its vibrations. A numerical simulation of the fluid-structure interaction is conducted by coupling a finite element model of the artificial wing with a computational fluid dynamics model of the surrounding airflow. From these simulations, the deformation response and the coefficients of drag and lift of the artificial wing are predicted for different freestream velocities and angles of attack. The deformation along the span of the wing increases nonlinearly with Reynolds number from the root to the tip of the wing. The coefficient of lift increases with angle of attack and Reynolds number. The coefficient of drag decreases with Reynolds number and angle of attack. The aerodynamic efficiency, defined as the ratio of the coefficient of lift to the coefficient of drag, of the artificial wing increases with angle of attack and Reynolds number.


2009 ◽  
Author(s):  
Christopher Kroninger ◽  
Jeffrey Pulskamp ◽  
Jessica Bronson ◽  
Ronald G. Polcawich ◽  
Eric Wetzel

2005 ◽  
Vol 127 (4) ◽  
pp. 817-824 ◽  
Author(s):  
Rafał Z˙bikowski ◽  
Cezary Galin´ski ◽  
Christopher B. Pedersen

This paper describes the concept of a four-bar linkage mechanism for flapping wing micro air vehicles and outlines its design, implementation, and testing. Micro air vehicles (MAVs) are defined as flying vehicles ca. 150 mm in size (handheld), weighing 50–100 g, and are developed to reconnoiter in confined spaces (inside buildings, tunnels, etc.). For this application, insectlike flapping wings are an attractive solution and, hence, the need to realize the functionality of insect flight by engineering means. Insects fly by oscillating (plunging) and rotating (pitching) their wings through large angles, while sweeping them forward and backward. During this motion, the wing tip approximately traces a figure eight and the wing changes the angle of attack (pitching) significantly. The aim of the work described here was to design and build an insectlike flapping mechanism on a 150 mm scale. The main purpose was not only to construct a test bed for aeromechanical research on hover in this mode of flight, but also to provide a precursor design for a future flapping-wing MAV. The mechanical realization was to be based on a four-bar linkage combined with a spatial articulation. Two instances of idealized figure eights were considered: (i) Bernoulli’s lemniscate and (ii) Watt’s sextic. The former was found theoretically attractive, but impractical, while the latter was both theoretically and practically feasible. This led to a combination of Watt’s straight-line mechanism with a drive train utilizing a Geneva wheel and a spatial articulation. The actual design, implementation, and testing of this concept are briefly described at the end of the paper.


Author(s):  
Miguel R. Visbal

Unsteady low-Reynolds-number flows are of importance in understanding the flight performance of natural flyers, as well as in the design of small unmanned air vehicles and micro air vehicles [1,2]. The imposed motion of flapping wings or the large excursions in effective angle of attack during gust encounters may induce the formation of dynamic-stall-like vortices [3–10] whose evolution and interaction with the aerodynamic surfaces impact both flight stability and performance.


2019 ◽  
Vol 868 ◽  
pp. 369-384 ◽  
Author(s):  
Shantanu S. Bhat ◽  
Jisheng Zhao ◽  
John Sheridan ◽  
Kerry Hourigan ◽  
Mark C. Thompson

Wing shape is an important factor affecting the aerodynamic performance of wings of monocopters and flapping-wing micro air vehicles. Here, an evolutionary structural optimisation method is adapted to optimise wing shape to enhance the lift force due to aerodynamic pressure on the wing surfaces. The pressure distribution is observed to vary with the span-based Reynolds number over a range covering most insects and samaras. Accordingly, the optimised wing shapes derived using this evolutionary approach are shown to adjust with Reynolds number. Moreover, these optimised shapes exhibit significantly higher lift coefficients (${\sim}50\,\%$) than the initial rectangular wing forebear. Interestingly, the optimised shapes are found to have a large area outboard, broadly in line with the features of high-lift forewings of multi-winged insects. According to specific aerodynamic performance requirements, this novel method could be employed in the optimisation of improved wing shapes for micro air vehicles.


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