Ornithopter Aerodynamic Experiments

Bennett, A. G.; Obye, R.; Jeglum, Paul M.

doi:10.1007/978-1-4757-1326-8_33

Cited by 8 publications

(4 citation statements)

References 1 publication

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“…of 125 are depicted in Figure 10 for two cycles of flapping at V ¼ 3m=s and f ¼ 4:5Hz. As Liu and Kawachi 55 and Bennett et al 56 showed, the maximum normal force happens near the mid-downstroke zone, where the maximum value of separation vortex is achieved. Next, shedding the vortex causes the normal force to be reduced at the beginning of the upstroke.…”

Section: Resultsmentioning

confidence: 90%

Experimental investigation of flapping mechanism of the black-headed gull in forward flight

Feshalami

Djavareshkian

Yousefi

et al. 2018

Proceedings of the Institution of Mechanical Engineers, Part G:

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Many developments in aerospace science have originated from nature. One of these developments has been obtained through inspirations from flying locomotion. The aim of this study is to simulate the flapping mechanism of the black-headed gull in forward flight. The wing of the black-headed gull is characterized entirely by complex dihedral, dividing the wing into two distinct parts. Hence, a flapping mechanism with different bending deflection angles is constructed and compared with a primitive flapping mechanism. Firstly, parametric studies are conducted to assess the role of flapping frequency, velocity and bending deflection angle on the lift, thrust and power loading of the membrane flexible wing at 10 ° angle of attack. Secondly, dimensional analysis is used to establish the similarity between the real gull and the constructed mechanism. Superiority of the bending deflection mechanism is concluded in forward flight against simple flapping wing in terms of aerodynamic forces as well as power loading parameter. It is found that although the aerodynamic coefficients decrease with increase in advance ratio, the best power loading of the black-headed gull is obtained between advance ratio of 2 and 3, in the gull's aerodynamically quasi-steady regime.

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Section: Resultsmentioning

confidence: 90%

Experimental investigation of flapping mechanism of the black-headed gull in forward flight

Feshalami

Djavareshkian

Yousefi

et al. 2018

Proceedings of the Institution of Mechanical Engineers, Part G:

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“…The instantaneous normal forces for the rigid wing at V ¼ 0 m=s and f ¼ 4:5Hz, the flapping angle of the mechanism and also the bending deflection angle are depicted in Figure 6 for two cycles of flapping. As Liu and Kawachi 42 and Bennett et al 43 manifested, the maximum normal force occurs near the mid-downstroke zone, where the separation vortex achieves its maximum value. Subsequently, shedding the vortex causes the normal force to decrease at the beginning of the upstroke.…”

Section: Methodsmentioning

confidence: 90%

The role of wing bending deflection in the aerodynamics of flapping micro aerial vehicles in hovering flight

Feshalami

Djavareshkian

Zaree

et al. 2018

Proceedings of the Institution of Mechanical Engineers, Part G:

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Scientists have been improving the aerodynamic performance of flapping micro aerial vehicles by drawing inspiration from birds and insect flight. In this research study, first, the flapping mechanism of the black-headed gull is designed and then it is constructed in order to investigate the effects of wing bending deflection on the aerodynamic performance. Thrust generation, power consumption and power loading are considered as performance parameters. Three wings representing different underlying structures, namely flexible membrane, rigid membrane and airfoil, are fabricated with the same planform to investigate the roles of flexibility, thickness and camber. Experiments are performed for flapping frequencies ranging from 1.5 Hz to 6 Hz, 10 degrees angle of attack and no wind tunnel velocity (hovering flight). The results indicate that the aerodynamic performance is improved by using the bending deflection mechanism in comparison with the simple flapping mechanism. Moreover, we can conclude that the performance of the airfoil wing is superior to flexible and rigid wings.

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“…In 1943, Holst (3) measured the lift and thrust forces generated by a small elliptical wing (32 mm semi-span) in an attempt to show how small Reynolds numbers (below 1000) affected the forces obtained. In 1974, Bennet, Obye and Jeglum (1) measured the instantaneous lift and thrust forces on a symmetrical aerofoil section undergoing sinusoidal oscillation.…”

Section: Introductionmentioning

confidence: 99%

Technical Note

Fejtek¹,

Nehera²

1980

Aeronaut. j.

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An experimental study was undertaken to measure the instantaneous lift and propulsive forces generated by a rigid, sinusoidally flapping wing at Reynolds numbers ranging from 72 000 to 120 000. The wing was flapped about a fulcrum at the root at frequencies of 2.55 Hz and 3.30 Hz. Instrumentation and a data reduction system were developed to provide quick and reliable assessment of the effects of changes in flapping amplitude, flapping frequency, flapping plane angle, wing incidence, and windspeed. In this way it was attempted to model, however crudely, the forward flapping flight of birds.The instantaneous values of lift coefficient and thrust coefficient were plotted against position in the cycle while the average CL and CT were plotted against advance ratio (ratio of the windspeed to the maximum tip speed velocity). The experimental results were compared to the theories of Walker(e) and Hoist ' Kuchemann(4) both modified to correspond more closely to the experimental conditions.

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Ornithopter Aerodynamic Experiments

Cited by 8 publications

References 1 publication

Experimental investigation of flapping mechanism of the black-headed gull in forward flight

Experimental investigation of flapping mechanism of the black-headed gull in forward flight

The role of wing bending deflection in the aerodynamics of flapping micro aerial vehicles in hovering flight

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