Experimental investigation of a flapping wing model

Hubel, Tatjana Y.; Tropea, Cameron

doi:10.1007/978-3-642-11633-9_30

Cited by 5 publications

(7 citation statements)

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“…A benefit of adding thrust via a non-flapping mode, if completely decoupled from the flapping, is that the flight velocity can be increased aiding the aerodynamic lift term without altering the flapping mechanics. Based on equation (20), the implications are an increase in payload by the net increase of the lift or a trade-off scenario where an increase in the aerodynamic lift would decrease the demand for continuous flapping, allowing greater utilization of independent wing control to rapidly change the flight path vector and vehicle orientation.…”

Section: Enhancing Thrust Production In Fwavs Using Propellersmentioning

confidence: 99%

“…10,16 Similar feats of aerodynamic force control through actuation can been seen in mammalian flight. 9 Duplicating these feats in engineered systems proves to be difficult because direct force measurements on flying animals is difficult to perform and analyze 3,17,20 ; current aerodynamic models do not yet provide accurate predictions of behavior at low Reynolds numbers (<10 5 ), 13,21,22,23 and current actuator technologies impose limitations due to design challenges and system integration. 24 The energy requirements for bird-inspired flapping wing fling are higher than for other forms of location such as swimming, walking or running.…”

Section: Introductionmentioning

confidence: 99%

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Characterizing and modeling the enhancement of lift and payload capacity resulting from thrust augmentation in a propeller-assisted flapping wing air vehicle

Holness

Bruck

Gupta

2017

International Journal of Micro Air Vehicles

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Biologically-inspired flapping wing flight is attractive at low Reynolds numbers and at high angles of attack, where fixed wing flight performance declines precipitously. While the merits of flapping propulsion have been intensely investigated, enhancing flapping propulsion has proven challenging because of hardware constraints and the complexity of the design space. For example, increasing the size of wings generates aerodynamic forces that exceed the limits of actuators used to drive the wings, reducing flapping amplitude at higher frequencies and causing thrust to taper off. Therefore, augmentation of aerodynamic force production from alternative propulsion modes can potentially enhance biologicallyinspired flight. In this paper, we explore the use of auxiliary propellers on Robo Raven, an existing flapping wing air vehicle (FWAV), to augment thrust without altering wing design or flapping mechanics. Designing such a platform poses two major challenges. First, potential for negative interaction between the flapping and propeller airflow reducing thrust generation. Second, adding propellers to an existing platform increases platform weight and requires additional power from heavier energy sources for comparable flight time. In this paper, three major findings are reported addressing these challenges. First, locating the propellers behind the flapping wings (i.e. in the wake) exhibits minimal coupling without positional sensitivity for the propeller placement at or below the platform centerline. Second, the additional thrust generated by the platform does increase aerodynamic lift. Third, the increase in aerodynamic lift offsets the higher weight of the platform, significantly improving payload capacity. The effect of varying operational payload and flight time for different mixed mode operating conditions was predicted, and the trade-off between the operational payload and operating conditions for mixed mode propulsion was characterized. Flight tests revealed the improved agility of the platform when used with static placement of the wings for various aerobatic maneuvers, such as gliding, diving, or loops.

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Section: Enhancing Thrust Production In Fwavs Using Propellersmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Characterizing and modeling the enhancement of lift and payload capacity resulting from thrust augmentation in a propeller-assisted flapping wing air vehicle

Holness

Bruck

Gupta

2017

International Journal of Micro Air Vehicles

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“…. (14) where k is the induced drag factor and S b is the body frontal area, which can be approximated by S b = 0 . 00813m b 2/3 .…”

Section: Simulation Parameters and Objectivesmentioning

confidence: 99%

“…The experiments were carried out in 2007. Footage of the geese flying at three different wind speeds (14,16 and 18ms -1 ) was collected at 100 frames per second (fps) using a Sony HDR-SR8E camera. The wind tunnel's ceiling was solid steel so it was not possible to film from above; all filming was carried out through the side window.…”

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confidence: 99%

Experimental and numerical study of the flight of geese

et al. 2015

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The flight of barnacle geese at airspeeds representing high-speed migrating flight is investigated using experiments and simulations. The experimental part of the work involved the filming of three barnacle geese (Branta Leucopsis) flying at different airspeeds in a wind tunnel. The video footage was analysed in order to extract the wing kinematics. Additional information, such as wing geometry and camber was obtained from a 3D scan of a dried wing. An unsteady vortex lattice method was used to simulate the aerodynamics of the measured flapping motion. The simulations were used in order to successfully reproduce the measured body motion and thus obtain estimates of the aerodynamic forces acting on the wings. It was found that the mean of the wing pitch angle variation with time has the most significant effect on lift while the difference in the durations of the upstroke and downstroke has the major effect on thrust. The power consumed by the aerodynamic forces was also estimated; it was found that increases in aerodynamic power correspond very closely to climbing motion and vice versa. Root-mean-square values of the power range from 100W to 240W. Finally, it was observed that tandem flying can be very expensive for the trailing bird.

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“…Slow motion cameras have also been used to capture the kinematics and geometric twist of the wings. Force and PIV measurements are conducted on a flapping model goose with a wingspan of 1.13 m by Hubel and Tropea (2009). Experiments on flapping wing models of different shapes and size are carried out by Banerjee et al (2011) robots and insect flight by Ellington (1984) and Ellington et al (1996).…”

Section: Introductionmentioning

confidence: 99%

Aerodynamic modelling of flapping flight using lifting line theory

Bhowmik

Das

Ghosh

2013

International Journal of Intelligent Unmanned Systems

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PurposeThe purpose of the work is to design a flapping wing that generates net positive propulsive force and vertical force over a flapping cycle operating at a given freestream velocity. In addition, an optimal wing is designed based on the comparison of the force estimated from the quasi‐steady theory, with the wind‐tunnel experiments. Based on the designed wing configuration, a flapping wing ornithopter is fabricated.Design/methodology/approachThis paper presents a theoretical aerodynamic model of the design of an ornithopter with specific twist distribution that results generation of substantial net positive vertical force and thrust over a cycle at non‐zero advance ratio. The wing has a specific but different twist distribution during the downstroke and the upstroke that maintains the designed angle of attack during the strokes. The wing is divided into spanwise strips and Prandtl's lifting line theory is applied to estimate aerodynamic forces with the assumptions of quasi‐steady flow and the wings are without any dihedral or anhedral. Spanwise circulation distribution is obtained and hence lift is calculated. The lift is resolved along the freestream velocity and perpendicular to the freestream velocity to obtain vertical force and propulsive thrust force. Experiments are performed in a wind tunnel to find the forces generated in a flapping cycle which compares well with the theoretical estimation at low flying speeds.FindingsThe estimated aerodynamic force indicates whether the wing geometry and operating conditions are sufficient to carry the weight of the vehicle for a sustainable flight. The variation of the aerodynamic forces with varying flapping frequencies and freestream velocities has been illustrated and compared with experimental data that shows a reasonable match with the theoretical estimations. Based on the calculations a prototype has been fabricated and successfully flown.Research limitations/implicationsThe theory does not take into account the unsteady effects and estimates the aerodynamic forces at wing level condition. It doesn’t predict stall and ignores structural deformations due to aerodynamic loads. The airfoil section is only specified by the chord, zero lift angle of attack, lift slope, profile drag coefficient and angle of attack as given inputs. To fabricate a light weight wing that maintains a very accurate geometric twist and camber distribution as per the theoretical requirement is challenging.Practical implicationsUseful for designing ornithopter wing (preferably bigger) involving an unswept rigid spar with flapping and twisting.Originality/valueThe novelty of the present wing design is the appropriate spanwise geometric twisting about the leading edge spar.

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Experimental investigation of a flapping wing model

Cited by 5 publications

References 0 publications

Characterizing and modeling the enhancement of lift and payload capacity resulting from thrust augmentation in a propeller-assisted flapping wing air vehicle

Characterizing and modeling the enhancement of lift and payload capacity resulting from thrust augmentation in a propeller-assisted flapping wing air vehicle

Experimental and numerical study of the flight of geese

Aerodynamic modelling of flapping flight using lifting line theory

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