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Anders Hedenström - One of the best experts on this subject based on the ideXlab platform.
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wake analysis of Drag components in gliding flight of a jackdaw corvus monedula during moult
Interface Focus, 2017Co-Authors: Marco Kleinheerenbrink, Anders HedenströmAbstract:To maintain the quality of the feathers, birds regularly undergo moult. It is widely accepted that moult affects flight performance, but the specific aerodynamic consequences have received relatively little attention. Here we measured the components of aerodynamic Drag from the wake behind a gliding jackdaw (Corvus monedula) at different stages of its natural wing moult. We found that span efficiency was reduced (lift induced Drag increased) and the wing Profile Drag coefficient was increased. Both effects best correlated with the corresponding reduction in spanwise camber. The negative effects are partially mitigated by adjustments of wing posture to minimize gaps in the wing, and by weight loss to reduce wing loading. By studying the aerodynamic consequences of moult, we can refine our understanding of the emergence of various moulting strategies found among birds.
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wake analysis of aerodynamic components for the glide envelope of a jackdaw corvus monedula
The Journal of Experimental Biology, 2016Co-Authors: Marco Kleinheerenbrink, Kajsa Warfvinge, Anders HedenströmAbstract:Gliding flight is a relatively inexpensive mode of flight used by many larger bird species, where potential energy is used to cover the cost of aerodynamic Drag. Birds have great flexibility in their flight configuration, allowing them to control their flight speed and glide angle. However, relatively little is known about how this flexibility affects aerodynamic Drag. We measured the wake of a jackdaw (Corvus monedula) gliding in a wind tunnel, and computed the components of aerodynamic Drag from the wake. We found that induced Drag was mainly affected by wingspan, but also that the use of the tail has a negative influence on span efficiency. Contrary to previous work, we found no support for the separated primaries being used in controlling the induced Drag. Profile Drag was of similar magnitude to that reported in other studies, and our results suggest that Profile Drag is affected by variation in wing shape. For a folded tail, the body Drag coefficient had a value of 0.2, rising to above 0.4 with the tail fully spread, which we conclude is due to tail Profile Drag. (Less)
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Wake analysis of aerodynamic components for the glide envelope of a jackdaw (Corvus monedula).
The Journal of experimental biology, 2016Co-Authors: Marco Kleinheerenbrink, Kajsa Warfvinge, Anders HedenströmAbstract:Gliding flight is a relatively inexpensive mode of flight used by many larger bird species, where potential energy is used to cover the cost of aerodynamic Drag. Birds have great flexibility in their flight configuration, allowing them to control their flight speed and glide angle. However, relatively little is known about how this flexibility affects aerodynamic Drag. We measured the wake of a jackdaw (Corvus monedula) gliding in a wind tunnel, and computed the components of aerodynamic Drag from the wake. We found that induced Drag was mainly affected by wingspan, but also that the use of the tail has a negative influence on span efficiency. Contrary to previous work, we found no support for the separated primaries being used in controlling the induced Drag. Profile Drag was of similar magnitude to that reported in other studies, and our results suggest that Profile Drag is affected by variation in wing shape. For a folded tail, the body Drag coefficient had a value of 0.2, rising to above 0.4 with the tail fully spread, which we conclude is due to tail Profile Drag.
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gliding flight in a jackdaw a wind tunnel study
The Journal of Experimental Biology, 2001Co-Authors: Mikael Rosen, Anders HedenströmAbstract:We examined the gliding flight performance of a jackdaw Corvus monedula in a wind tunnel. The jackdaw was able to glide steadily at speeds between 6 and 11 m s(-1). The bird changed its wingspan and wing area over this speed range, and we measured the so-called glide super-polar, which is the envelope of fixed-wing glide polars over a range of forward speeds and sinking speeds. The glide super-polar was an inverted U-shape with a minimum sinking speed (V(ms)) at 7.4 m s(-1) and a speed for best glide (V(bg)) at 8.3 m s(-)). At the minimum sinking speed, the associated vertical sinking speed was 0.62 m s(-1). The relationship between the ratio of lift to Drag (L:D) and airspeed showed an inverted U-shape with a maximum of 12.6 at 8.5 m s(-1). Wingspan decreased linearly with speed over the whole speed range investigated. The tail was spread extensively at low and moderate speeds; at speeds between 6 and 9 m s(-1), the tail area decreased linearly with speed, and at speeds above 9 m s(-1) the tail was fully furled. Reynolds number calculated with the mean chord as the reference length ranged from 38 000 to 76 000 over the speed range 6-11 m s(-1). Comparisons of the jackdaw flight performance were made with existing theory of gliding flight. We also re-analysed data on span ratios with respect to speed in two other bird species previously studied in wind tunnels. These data indicate that an equation for calculating the span ratio, which minimises the sum of induced and Profile Drag, does not predict the actual span ratios observed in these birds. We derive an alternative equation on the basis of the observed span ratios for calculating wingspan and wing area with respect to forward speed in gliding birds from information about body mass, maximum wingspan, maximum wing area and maximum coefficient of lift. These alternative equations can be used in combination with any model of gliding flight where wing area and wingspan are considered to calculate sinking rate with respect to forward speed.
Marco Kleinheerenbrink - One of the best experts on this subject based on the ideXlab platform.
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wake analysis of Drag components in gliding flight of a jackdaw corvus monedula during moult
Interface Focus, 2017Co-Authors: Marco Kleinheerenbrink, Anders HedenströmAbstract:To maintain the quality of the feathers, birds regularly undergo moult. It is widely accepted that moult affects flight performance, but the specific aerodynamic consequences have received relatively little attention. Here we measured the components of aerodynamic Drag from the wake behind a gliding jackdaw (Corvus monedula) at different stages of its natural wing moult. We found that span efficiency was reduced (lift induced Drag increased) and the wing Profile Drag coefficient was increased. Both effects best correlated with the corresponding reduction in spanwise camber. The negative effects are partially mitigated by adjustments of wing posture to minimize gaps in the wing, and by weight loss to reduce wing loading. By studying the aerodynamic consequences of moult, we can refine our understanding of the emergence of various moulting strategies found among birds.
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wake analysis of aerodynamic components for the glide envelope of a jackdaw corvus monedula
The Journal of Experimental Biology, 2016Co-Authors: Marco Kleinheerenbrink, Kajsa Warfvinge, Anders HedenströmAbstract:Gliding flight is a relatively inexpensive mode of flight used by many larger bird species, where potential energy is used to cover the cost of aerodynamic Drag. Birds have great flexibility in their flight configuration, allowing them to control their flight speed and glide angle. However, relatively little is known about how this flexibility affects aerodynamic Drag. We measured the wake of a jackdaw (Corvus monedula) gliding in a wind tunnel, and computed the components of aerodynamic Drag from the wake. We found that induced Drag was mainly affected by wingspan, but also that the use of the tail has a negative influence on span efficiency. Contrary to previous work, we found no support for the separated primaries being used in controlling the induced Drag. Profile Drag was of similar magnitude to that reported in other studies, and our results suggest that Profile Drag is affected by variation in wing shape. For a folded tail, the body Drag coefficient had a value of 0.2, rising to above 0.4 with the tail fully spread, which we conclude is due to tail Profile Drag. (Less)
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Wake analysis of aerodynamic components for the glide envelope of a jackdaw (Corvus monedula).
The Journal of experimental biology, 2016Co-Authors: Marco Kleinheerenbrink, Kajsa Warfvinge, Anders HedenströmAbstract:Gliding flight is a relatively inexpensive mode of flight used by many larger bird species, where potential energy is used to cover the cost of aerodynamic Drag. Birds have great flexibility in their flight configuration, allowing them to control their flight speed and glide angle. However, relatively little is known about how this flexibility affects aerodynamic Drag. We measured the wake of a jackdaw (Corvus monedula) gliding in a wind tunnel, and computed the components of aerodynamic Drag from the wake. We found that induced Drag was mainly affected by wingspan, but also that the use of the tail has a negative influence on span efficiency. Contrary to previous work, we found no support for the separated primaries being used in controlling the induced Drag. Profile Drag was of similar magnitude to that reported in other studies, and our results suggest that Profile Drag is affected by variation in wing shape. For a folded tail, the body Drag coefficient had a value of 0.2, rising to above 0.4 with the tail fully spread, which we conclude is due to tail Profile Drag.
C P Ellington - One of the best experts on this subject based on the ideXlab platform.
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the aerodynamics of revolving wings i model hawkmoth wings
The Journal of Experimental Biology, 2002Co-Authors: James R Usherwood, C P EllingtonAbstract:SUMMARY Recent work on flapping hawkmoth models has demonstrated the importance of a spiral `leading-edge vortex9 created by dynamic stall, and maintained by some aspect of spanwise flow, for creating the lift required during flight. This study uses propeller models to investigate further the forces acting on model hawkmoth wings in `propeller-like9 rotation (`revolution9). Steadily revolving model hawkmoth wings produce high vertical (≈ lift) and horizontal (≈ Profile Drag) force coefficients because of the presence of a leading-edge vortex. Both horizontal and vertical forces, at relevant angles of attack, are dominated by the pressure difference between the upper and lower surfaces; separation at the leading edge prevents `leading-edge suction9. This allows a simple geometric relationship between vertical and horizontal forces and the geometric angle of attack to be derived for thin, flat wings. Force coefficients are remarkably unaffected by considerable variations in leading-edge detail, twist and camber. Traditional accounts of the adaptive functions of twist and camber are based on conventional attached-flow aerodynamics and are not supported. Attempts to derive conventional Profile Drag and lift coefficients from `steady9 propeller coefficients are relatively successful for angles of incidence up to 50° and, hence, for the angles normally applicable to insect flight.
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the aerodynamics of revolving wings i model hawkmoth wings
The Journal of Experimental Biology, 2002Co-Authors: James R Usherwood, C P EllingtonAbstract:Recent work on flapping hawkmoth models has demonstrated the importance of a spiral 'leading-edge vortex' created by dynamic stall, and maintained by some aspect of spanwise flow, for creating the lift required during flight. This study uses propeller models to investigate further the forces acting on model hawkmoth wings in 'propeller-like' rotation ('revolution'). Steadily revolving model hawkmoth wings produce high vertical ( approximately lift) and horizontal ( approximately Profile Drag) force coefficients because of the presence of a leading-edge vortex. Both horizontal and vertical forces, at relevant angles of attack, are dominated by the pressure difference between the upper and lower surfaces; separation at the leading edge prevents 'leading-edge suction'. This allows a simple geometric relationship between vertical and horizontal forces and the geometric angle of attack to be derived for thin, flat wings. Force coefficients are remarkably unaffected by considerable variations in leading-edge detail, twist and camber. Traditional accounts of the adaptive functions of twist and camber are based on conventional attached-flow aerodynamics and are not supported. Attempts to derive conventional Profile Drag and lift coefficients from 'steady' propeller coefficients are relatively successful for angles of incidence up to 50 degrees and, hence, for the angles normally applicable to insect flight.
James R Usherwood - One of the best experts on this subject based on the ideXlab platform.
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the aerodynamics of revolving wings i model hawkmoth wings
The Journal of Experimental Biology, 2002Co-Authors: James R Usherwood, C P EllingtonAbstract:SUMMARY Recent work on flapping hawkmoth models has demonstrated the importance of a spiral `leading-edge vortex9 created by dynamic stall, and maintained by some aspect of spanwise flow, for creating the lift required during flight. This study uses propeller models to investigate further the forces acting on model hawkmoth wings in `propeller-like9 rotation (`revolution9). Steadily revolving model hawkmoth wings produce high vertical (≈ lift) and horizontal (≈ Profile Drag) force coefficients because of the presence of a leading-edge vortex. Both horizontal and vertical forces, at relevant angles of attack, are dominated by the pressure difference between the upper and lower surfaces; separation at the leading edge prevents `leading-edge suction9. This allows a simple geometric relationship between vertical and horizontal forces and the geometric angle of attack to be derived for thin, flat wings. Force coefficients are remarkably unaffected by considerable variations in leading-edge detail, twist and camber. Traditional accounts of the adaptive functions of twist and camber are based on conventional attached-flow aerodynamics and are not supported. Attempts to derive conventional Profile Drag and lift coefficients from `steady9 propeller coefficients are relatively successful for angles of incidence up to 50° and, hence, for the angles normally applicable to insect flight.
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the aerodynamics of revolving wings i model hawkmoth wings
The Journal of Experimental Biology, 2002Co-Authors: James R Usherwood, C P EllingtonAbstract:Recent work on flapping hawkmoth models has demonstrated the importance of a spiral 'leading-edge vortex' created by dynamic stall, and maintained by some aspect of spanwise flow, for creating the lift required during flight. This study uses propeller models to investigate further the forces acting on model hawkmoth wings in 'propeller-like' rotation ('revolution'). Steadily revolving model hawkmoth wings produce high vertical ( approximately lift) and horizontal ( approximately Profile Drag) force coefficients because of the presence of a leading-edge vortex. Both horizontal and vertical forces, at relevant angles of attack, are dominated by the pressure difference between the upper and lower surfaces; separation at the leading edge prevents 'leading-edge suction'. This allows a simple geometric relationship between vertical and horizontal forces and the geometric angle of attack to be derived for thin, flat wings. Force coefficients are remarkably unaffected by considerable variations in leading-edge detail, twist and camber. Traditional accounts of the adaptive functions of twist and camber are based on conventional attached-flow aerodynamics and are not supported. Attempts to derive conventional Profile Drag and lift coefficients from 'steady' propeller coefficients are relatively successful for angles of incidence up to 50 degrees and, hence, for the angles normally applicable to insect flight.
Kajsa Warfvinge - One of the best experts on this subject based on the ideXlab platform.
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wake analysis of aerodynamic components for the glide envelope of a jackdaw corvus monedula
The Journal of Experimental Biology, 2016Co-Authors: Marco Kleinheerenbrink, Kajsa Warfvinge, Anders HedenströmAbstract:Gliding flight is a relatively inexpensive mode of flight used by many larger bird species, where potential energy is used to cover the cost of aerodynamic Drag. Birds have great flexibility in their flight configuration, allowing them to control their flight speed and glide angle. However, relatively little is known about how this flexibility affects aerodynamic Drag. We measured the wake of a jackdaw (Corvus monedula) gliding in a wind tunnel, and computed the components of aerodynamic Drag from the wake. We found that induced Drag was mainly affected by wingspan, but also that the use of the tail has a negative influence on span efficiency. Contrary to previous work, we found no support for the separated primaries being used in controlling the induced Drag. Profile Drag was of similar magnitude to that reported in other studies, and our results suggest that Profile Drag is affected by variation in wing shape. For a folded tail, the body Drag coefficient had a value of 0.2, rising to above 0.4 with the tail fully spread, which we conclude is due to tail Profile Drag. (Less)
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Wake analysis of aerodynamic components for the glide envelope of a jackdaw (Corvus monedula).
The Journal of experimental biology, 2016Co-Authors: Marco Kleinheerenbrink, Kajsa Warfvinge, Anders HedenströmAbstract:Gliding flight is a relatively inexpensive mode of flight used by many larger bird species, where potential energy is used to cover the cost of aerodynamic Drag. Birds have great flexibility in their flight configuration, allowing them to control their flight speed and glide angle. However, relatively little is known about how this flexibility affects aerodynamic Drag. We measured the wake of a jackdaw (Corvus monedula) gliding in a wind tunnel, and computed the components of aerodynamic Drag from the wake. We found that induced Drag was mainly affected by wingspan, but also that the use of the tail has a negative influence on span efficiency. Contrary to previous work, we found no support for the separated primaries being used in controlling the induced Drag. Profile Drag was of similar magnitude to that reported in other studies, and our results suggest that Profile Drag is affected by variation in wing shape. For a folded tail, the body Drag coefficient had a value of 0.2, rising to above 0.4 with the tail fully spread, which we conclude is due to tail Profile Drag.
