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Aerospace
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Bioinspired Flying Systems
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Bioinspired Flying Systems

A special issue of Aerospace (ISSN 2226-4310). This special issue belongs to the section "Aeronautics".

Deadline for manuscript submissions: closed (15 March 2023) | Viewed by 16506

Special Issue Editor

Dr. Mostafa Nabawy

E-Mail Website
Guest Editor
Department of Mechanical, Aerospace and Civil Engineering, The University of Manchester, Manchester, UK
Interests: microsystems; micro-robots; piezoelectric actuators; piezoelectric harvesters; bioinspiration; biomimetics; biomechanics, fluid dynamics, aerodynamics

Special Issue Information

Dear Colleagues,

Nature offers diverse, successful examples of flying concepts that have always been a source of inspiration when building human-made flying vehicles. To realize bioinspired flying systems, the challenge is both one of understanding—how do natural flying systems work?—and one of technology—how can we make engineering solutions that can efficiently realize these systems at appropriate scales? Recent progress in the fields of biomechanics and bioinspired robotics has offered exciting opportunities for scientific discovery and allowed the development of new classes of robotic systems that were probably unthinkable until very recently. This Special Issue invites researchers from different communities to present research outcomes that (1) enable improved understanding of the biomechanics and evolution of flight systems in nature and/or (2) develop the underlying models and engineering design tools for bioinspired flying systems. We invite all types of contributions, including original theoretical, modeling, and experimental research outcomes covering areas relevant to bioinspired flight including, but not limited to, aerodynamics, biomechanics, flight stability, control, actuation, smart materials, structures, and flying vehicle design.

Dr. Mostafa Nabawy
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Aerospace is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Published Papers (5 papers)

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Research

32 pages, 21525 KiB  
Article
Sectional Leading Edge Vortex Lift and Drag Coefficients of Autorotating Samaras
by Byung Kwon Jung and Djamel Rezgui
Aerospace 2023, 10(5), 414; https://doi.org/10.3390/aerospace10050414 - 28 Apr 2023
Cited by 1 | Viewed by 1982
Abstract
Autorotating samaras such as Sycamore seeds are capable of descending at exceptionally slow speeds and the secret behind this characteristic is attributed to a flow mechanism known as the leading edge vortex (LEV). A stable LEV is known to increase the maximum lift [...] Read more.
Autorotating samaras such as Sycamore seeds are capable of descending at exceptionally slow speeds and the secret behind this characteristic is attributed to a flow mechanism known as the leading edge vortex (LEV). A stable LEV is known to increase the maximum lift coefficient attainable at high angles of attack and recent studies of revolving and flapping wings have proposed suitable lift and drag coefficient models to characterise the aerodynamic forces of the LEV. For the samara, however, little has been explored to properly test the suitability of these low-order lift and drag coefficient models in describing the aerodynamic forces produced by the samara. Thus, in this paper, we aim to analyse the use of two proposed aerodynamic models, namely, the normal force and Polhamus models, in describing the sectional aerodynamic lift of a samara that is producing a LEV. Additionally, we aim to quantify the aerodynamic parameters that can describe the lift and drag of the samara for a range of wind speed conditions. To achieve this, the study first examined the samara flight data available in the literature, and from it, the profiles of the lift coefficient curves were investigated. Subsequently, a numerical Blade Element-Momentum model (BEM) of the autorotating samara encompassing different lift profiles was developed and validated against a comprehensive set of samara flight data, which were measured from wind tunnel experiments conducted at the University of Bristol for three different Sycamores. The results indicated that both the normal force and Polhamus lift models combined with the normal force drag can be used to describe the two-dimensional lift characteristics of a samara exhibiting an LEV. However, the normal force model appeared to be more suitable, since the Polhamus relied on many assumptions. The results also revealed that the aerodynamic force parameters can vary with windspeed and with the samara wing characteristics, as well as along the span of the samara wing. Values of the lift curve slope, zero-lift drag coefficient, and maximum lift coefficient are predicted and presented for different samaras. The study also showed that the low-order BEM model was able to generate a good agreement with the experimental measurements in the prediction of both rotational speed and thrust. Such a validated BEM model can be used for the initial design of bio-inspired rotors for micro-air vehicles. Full article
(This article belongs to the Special Issue Bioinspired Flying Systems)
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23 pages, 7696 KiB  
Article
Effects of Stroke Amplitude and Wing Planform on the Aerodynamic Performance of Hovering Flapping Wings
by Hao Li and Mostafa R. A. Nabawy
Aerospace 2022, 9(9), 479; https://doi.org/10.3390/aerospace9090479 - 29 Aug 2022
Cited by 9 | Viewed by 2117
Abstract
In this paper, the effects of stroke amplitude and wing planform on the aerodynamics of hovering flapping wings are considered by numerically solving the incompressible Navier–Stokes equations. The wing planform geometry is represented using a beta-function distribution for an aspect ratio range of [...] Read more.
In this paper, the effects of stroke amplitude and wing planform on the aerodynamics of hovering flapping wings are considered by numerically solving the incompressible Navier–Stokes equations. The wing planform geometry is represented using a beta-function distribution for an aspect ratio range of 3–6 and a dimensionless radial centroid location range of 0.4–0.6. Typical normal hovering kinematics has been employed while allowing both translational and rotational durations to be equally represented. The combined effects of stroke amplitude with wing aspect ratio and radial centroid location on the aerodynamic force coefficients and flow structures are studied at a Reynolds number of 100. It is shown that increasing the stroke amplitude increases the translational lift for either small aspect ratio or large radial centroid location wings. However, for high aspect ratio or low radial centroid location wings, increasing the stroke amplitude leads to higher lift coefficients during the translational phase only up to a stroke amplitude of 160°. Further increase in stroke amplitude results in reduced translational lift due to the increased wingtip stall effect. For all the cases considered, the lift and drag coefficients of the rotational phase decrease with the increase of stroke amplitude leading to decreased cycle-averaged force coefficients. Furthermore, it is found that the significant reduction in the rotational drag as the stroke amplitude increases leads to a consistently increasing aerodynamic efficiency against stroke amplitude for all aspect ratio and radial centroid location cases. Full article
(This article belongs to the Special Issue Bioinspired Flying Systems)
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31 pages, 135826 KiB  
Article
Clap-and-Fling Mechanism in Non-Zero Inflow of a Tailless Two-Winged Flapping-Wing Micro Air Vehicle
by Loan Thi Kim Au, Hoon Cheol Park, Seok Tae Lee and Sung Kyung Hong
Aerospace 2022, 9(2), 108; https://doi.org/10.3390/aerospace9020108 - 16 Feb 2022
Cited by 3 | Viewed by 3154
Abstract
The aerodynamic performance of clap-and-fling mechanism in a KU-Beetle—a tailless two-winged flapping-wing micro air vehicle—was investigated for various horizontal free-stream inflows. Three inflow speeds of 0 (hovering), 2.52 m/s and 5.04 m/s corresponding to advance ratios of 0, 0.5 and 1 were considered. [...] Read more.
The aerodynamic performance of clap-and-fling mechanism in a KU-Beetle—a tailless two-winged flapping-wing micro air vehicle—was investigated for various horizontal free-stream inflows. Three inflow speeds of 0 (hovering), 2.52 m/s and 5.04 m/s corresponding to advance ratios of 0, 0.5 and 1 were considered. The forces and moments for two wing distances of 16 mm (in which the clap-and-fling effect was strong) and 40 mm (in which the clap-and-fling effect was diminished) were computed using commercial software of ANSYS-Fluent 16.2. When the advance ratio increased from 0 to 0.5 and 1, the lift enhancement due to clap in the down-stroke reversal increased from 1.1% to 1.7% and 1.9%, while that in the up-stroke reversal decreased from 2.1% to −0.5% and 1.1%. Thus, in terms of lift enhancement due to clap, the free-stream inflow was more favorable in the down stroke than the up stroke. For all investigated inflow speeds, the clap-and-fling effect augmented the lift and power consumption but reduced the lift-to-power ratio. The total contributions of the fling phases to the enhancements in lift, torque, and power consumption were more than twice those of the clap phases. For the advance ratio from 0 to 0.5 and 1, the enhancement in average lift slightly decreased from 9.9% to 9.4% and 9.1%, respectively, and the augmentation in average power consumption decreased from 12.3% to 10.5% and 9.7%. Meanwhile, the reduction in the average lift-to-power ratio decreased from 2.1% to 1.1% and 0.6%, implying that in terms of aerodynamic efficiency, the free-stream inflow benefits the clap-and-fling effect in the KU-Beetle. Full article
(This article belongs to the Special Issue Bioinspired Flying Systems)
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32 pages, 10540 KiB  
Article
Dynamic Stability and Flight Control of Biomimetic Flapping-Wing Micro Air Vehicle
by Muhammad Yousaf Bhatti, Sang-Gil Lee and Jae-Hung Han
Aerospace 2021, 8(12), 362; https://doi.org/10.3390/aerospace8120362 - 24 Nov 2021
Cited by 8 | Viewed by 3019
Abstract
This paper proposes an approach to analyze the dynamic stability and develop trajectory-tracking controllers for flapping-wing micro air vehicle (FWMAV). A multibody dynamics simulation framework coupled with a modified quasi-steady aerodynamic model was implemented for stability analysis, which was appended with flight control [...] Read more.
This paper proposes an approach to analyze the dynamic stability and develop trajectory-tracking controllers for flapping-wing micro air vehicle (FWMAV). A multibody dynamics simulation framework coupled with a modified quasi-steady aerodynamic model was implemented for stability analysis, which was appended with flight control block for accomplishing various flight objectives. A gradient-based trim search algorithm was employed to obtain the trim conditions by solving the fully coupled nonlinear equations of motion at various flight speeds. Eigenmode analysis showed instability that grew with the flight speed in longitudinal dynamics. Using the trim conditions, we linearized dynamic equations of FWMAV to obtain the optimal gain matrices for various flight speeds using the linear-quadratic regulator (LQR) technique. The gain matrices from each of the linearized equations were used for gain scheduling with respect to forward flight speed. The reference tracking augmented LQR control was implemented to achieve transition flight tracking that involves hovering, acceleration, and deceleration phases. The control parameters were updated once in a wingbeat cycle and were changed smoothly to avoid any discontinuities during simulations. Moreover, trajectories tracking control was achieved successfully using a dual loop control approach. Control simulations showed that the proposed controllers worked effectively for this fairly nonlinear multibody system. Full article
(This article belongs to the Special Issue Bioinspired Flying Systems)
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9 pages, 1924 KiB  
Article
Aerodynamic Performance of a Nanostructure-Induced Multistable Shell
by Shenghui Yi, Lu Shen, Chih-Yung Wen, Xiaoqiao He and Jian Lu
Aerospace 2021, 8(11), 350; https://doi.org/10.3390/aerospace8110350 - 18 Nov 2021
Cited by 1 | Viewed by 1806
Abstract
Multistable shells that have the ability to hold more than one stable configuration are promising for adaptive structures, especially for airfoil. In contrast to existing studies on bistable shells, which are well demonstrated by the Venus flytrap plant with the ability to feed [...] Read more.
Multistable shells that have the ability to hold more than one stable configuration are promising for adaptive structures, especially for airfoil. In contrast to existing studies on bistable shells, which are well demonstrated by the Venus flytrap plant with the ability to feed itself, this work experimentally studies the aerodynamic response of various stable configurations of a nanostructure-induced multistable shell. This multistable shell is manufactured by using nanotechnology and surface mechanical attrition treatment (SMAT) to locally process nine circular zones in an original flat plate. The aerodynamic responses of eight stable configurations of the developed multistable shell, including four twisted configurations and four untwisted configurations with different cambers, are visually captured and quantitively measured in a wind tunnel. The results clearly demonstrate the feasibility of utilizing different controllable configurations to adjust the aerodynamic performance of the multistable shell. Full article
(This article belongs to the Special Issue Bioinspired Flying Systems)
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