Effect of Camber on the Aerodynamics of Adaptive-Wing Micro Air Vehicles

Null, William; Shkarayev, Sergey

doi:10.2514/1.12401

Cited by 43 publications

(33 citation statements)

References 7 publications

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“…As shown in Fig. 1, the airfoil cross-sectional shape design is similar to that used by Null and Shkarayev [20]. One unique feature of the airfoil is that there exists a small inverse camber section at the rear portion of the airfoils to compensate for the high positive pitching moment for MAV applications.…”

Section: Studied Airfoils and Experimental Setupmentioning

confidence: 68%

Flexible-Membrane Airfoils at Low Reynolds Numbers

Tamai

Murphy

2008

Journal of Aircraft

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An experimental study was conducted to assess the benefits of using flexible-membrane airfoils/wings at low Reynolds numbers for micro air vehicle applications compared with using a conventional rigid airfoil/wing. In addition to measuring aerodynamic forces acting on flexible-membrane airfoils/wings, a high-resolution particle image velocimetry system was used to conduct flowfield measurements to quantify the transient behavior of vortex and turbulent flow structures around the flexible-membrane airfoils/wings to elucidate the associated underlying fundamental physics. The aerodynamic force measurements revealed that flexible-membrane airfoils could provide better aerodynamic performance compared with their rigid counterpart at low Reynolds numbers. The flexibility (or rigidity) of the membrane skins of the airfoils was found to greatly affect their aerodynamic performance. Particle image velocimetry measurements elucidated that flexible-membrane airfoils could change their camber (i.e., crosssectional shape) automatically to adapt incoming flows to balance the pressure differences on the upper and lower surfaces of the airfoils, therefore suppressing flow separation on the airfoil upper surfaces. Meanwhile, deformation of the flexible-membrane skins was found to cause significant airfoil trailing-edge deflection (i.e., lift the airfoil trailing edge up from its original designed position), which resulted in a reduction of the effective angles of attack of the flexible-membrane airfoils, thereby delaying airfoil stall at high angles of attack. The nonuniform spanwise deformation of the flexible-membrane skins of the flexible-membrane airfoils was found to significantly affect the characteristics of vortex and turbulent flow structures around the flexible-membrane airfoils.

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Section: Studied Airfoils and Experimental Setupmentioning

confidence: 68%

Flexible-Membrane Airfoils at Low Reynolds Numbers

Tamai

Murphy

2008

Journal of Aircraft

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“…Rigid wings show aerodynamic benefits within a camber range of 3 to 4% [10,11]. For larger camber values, flexible membrane wings offer larger benefits than similar shaped rigid cambered wings due to their inherent shape adaptability [12,13].…”

Section: Armentioning

confidence: 99%

Aspect-Ratio Effects on Aeromechanics of Membrane Wings at Moderate Reynolds Numbers

2015

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The aspect ratio of a membrane wing at moderate Reynolds number Re 67;500 affects aerodynamic performance as well as membrane deformations. Wind-tunnel experiments are conducted using three different lowaspect-ratio wings (aspect ratios of 1, 1.5, and 2). Aerodynamic performance is determined from force and moment measurements, which are performed using a six-component force transducer. Membrane deformations are obtained using photogrammetry. Mean values and unsteady effects are examined for both aerodynamic performance and membrane deformations. Mean deflection results indicate that lower-aspect-ratio membrane wings show defined Ushape deflections along the span, whereas higher aspect ratios display a progressive rise in deformation to the wing tip. Dominant chordwise vibration modes of the membrane and their spectral content show that lower aspect ratios exhibit higher mode shapes and frequencies, likely caused by increased downwash, which delays the influence of vortex shedding into higher incidences. The frequencies of the dominant modes in membrane motions are found to correlate with the frequencies of lift and drag fluctuations.Reynolds number S = half-wing area St = fc∕U ∞ , Strouhal number x = streamwise coordinate y = spanwise coordinate z = camberwise coordinate α = global angle of attack, deg Π = Et∕qc 1∕3 , aeroelastic parameter σ = standard deviation

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“…The S5010-TOP24C-REF airfoil [16] was used in designing the wing, with a maximum camber of 3% located at 0:24c and an inverse camber of 1% at 0:85c. The wing area is 335 cm 2 .…”

Section: B Wing Designmentioning

confidence: 99%

Aerodynamic Design of Micro Air Vehicles for Vertical Flight

Shkarayev

Moschetta

Bataille

2008

Journal of Aircraft

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The research and development efforts outlined in this paper address the aerodynamic design of micro air vehicles with hovering and vertical takeoff and landing capabilities. The tilt-body configuration of the vertical takeoff and landing micro air vehicle is proposed based on a propulsion system consisting of two coaxial contrarotating motors and propellers. Values of thrust, torque, power, and efficiency of this propulsion system were measured in pusher and tractor arrangements of propellers and compared against single motor-propeller propulsion. With comparable efficiency, the developed propulsion system has very little propeller torque. Hot-wire measurements have been conducted to investigate the velocity profile in slipstream. The lower average velocity and significant decrease in velocity in the core of the slipstream found in the tractor arrangement are mostly due to the parasite drag caused by the motors. It causes the decrease of the thrust force observed for the tractor arrangement in comparison with the pusher arrangement. Wind-tunnel testing was conducted for a motor, a wing, and an arrangement of a wing with a motor. The drag force on the wing is produced by two mixing airflows: freestream and propeller-induced pulsating slipstream. The zero-lift drag coefficient increases by about 4 times with propeller-induced speed increased from 0 to 7:5 m=s. The results of this study were realized in the design of a vertical takeoff and landing micro air vehicle prototype that was successfully flight tested. Nomenclature a = distance from propeller disk to the leading edge of the wing C D = drag coefficient C D 0 = zero-lift drag coefficient C D P = zero-lift drag coefficient on the part of the wing submerged into a propeller slipstream C L = lift coefficient c = chord F total = total force measured by a wind-tunnel balance P = electric power input P ind = induced power Q = torque R = propeller radius R m = maximum distance of velocity measurements from the z axis R s = radius of stream tube at distance s r = motor radius Re = mean aerodynamic chord Reynolds number S p = area of a part of the wing covered by propeller slipstream S S = area of the side wall S 0 = wing area T = thrust force T s = thrust force determined from air-velocity data V 0 = freestream velocity W = takeoff weight of an aircraft ws = induced velocity based on propeller momentum theory w e = measured propeller-induced velocity = air density

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Effect of Camber on the Aerodynamics of Adaptive-Wing Micro Air Vehicles

Cited by 43 publications

References 7 publications

Flexible-Membrane Airfoils at Low Reynolds Numbers

Flexible-Membrane Airfoils at Low Reynolds Numbers

Aspect-Ratio Effects on Aeromechanics of Membrane Wings at Moderate Reynolds Numbers

Aerodynamic Design of Micro Air Vehicles for Vertical Flight

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