Wake analysis of aerodynamic components for the glide envelope of a jackdaw (<i>Corvus</i> <i>monedula</i>)

KleinHeerenbrink, Marco; Warfvinge, Kajsa; Hedenström, Anders

doi:10.1242/jeb.132480

Cited by 24 publications

(36 citation statements)

References 39 publications

(22 reference statements)

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“…close to the one obtained by the subtraction method. By using PIV, Klein Heerenbrink et al () obtained values of C D,pro for a jackdaw of the same magnitude as the previous studies, with a minimum of 0.019. Hence, a value around 0.02 seems motivated on the basis of relatively large birds in gliding flight.…”

Section: Aerodynamic Equations Of Bird Flightsupporting

confidence: 61%

“…From time‐lapse images the vortex wake can be imaged and quantitative details derived, such as vorticity, circulation and body drag from the retardation of the airflow caused by the body. By using PIV, C D,par has been estimated for a common swift Apus apus at 0.25 (Henningsson and Hedenström ) and a jackdaw Corvus monedula in gliding flight at 0.20 (Klein Heerenbrink et al ), which are both higher than the 0.1 obtained from the in‐direct wing beat frequency method (Pennycuick et al ).…”

Section: Aerodynamic Equations Of Bird Flightmentioning

confidence: 95%

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Wind tunnel as a tool in bird migration research

Hedenström

Lindström

2017

Journal of Avian Biology

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Wind tunnels, in which birds fly against an artificially generated air flow, have since long been used to evaluate aerodynamic properties of steady bird flight. A new generation of wind tunnels has also allowed the many processes associated with migratory flights to be studied in captivity. We review how wind tunnel studies of aerodynamics and migratory performance together have helped advancing our understanding of bird migration. Current migration theory is based on the power‐speed relationship of flight as well as flight range equations, both of which can be evaluated using birds flying in wind tunnels. In addition, and depending on wind tunnel properties, performance during gliding and climbing flight, and effects of air pressure, humidity and turbulence on bird flight has been measured. Long‐distance migrant species have been flown repeatedly for up to 16 h non‐stop, allowing detailed studies of the energy expenditure, fuel composition, protein turnover, water balance, immunocompetence and stress associated with sustained migratory flights. In addition, wind tunnels allow the fuelling periods between migratory flights to be studied from new angles. We end our review by suggesting several important topics for future wind tunnel studies, ranging from on of the key questions remaining, the efficiency at which chemical power in converted to mechanical power, to new useful avenues, such as improving and calibrating the techniques used for tracking of individual birds in the wild.

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Section: Aerodynamic Equations Of Bird Flightsupporting

confidence: 61%

Section: Aerodynamic Equations Of Bird Flightmentioning

confidence: 95%

Wind tunnel as a tool in bird migration research

Hedenström

Lindström

2017

Journal of Avian Biology

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“…1; Movie 1). Application of automated Lagrangian particle tracking velocimetry (see Movie 2) to the study of bird flight is novel, though seeding the air with helium bubbles builds upon the early studies of animal flight (Spedding et al, 1984;Spedding, 1987); and wakes have been measured using smoke and particle image velocimetry for a range of considerably smaller flapping (Spedding et al, 2003;Warrick et al, 2005;Van Griethuijsen et al, 2006;Tobalske et al, 2009;Altshuler et al, 2009;Johansson et al, 2018) and gliding (Henningsson and Hedenström, 2011;Henningsson et al, 2014;KleinHeerenbrink et al, 2016) birds.…”

Section: Introductionmentioning

confidence: 99%

High aerodynamic lift from the tail reduces drag in gliding raptors

Usherwood

Cheney

Song

et al. 2020

Journal of Experimental Biology

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Many functions have been postulated for the aerodynamic role of the avian tail during steady-state flight. By analogy with conventional aircraft, the tail might provide passive pitch stability if it produced very low or negative lift. Alternatively, aeronautical principles might suggest strategies that allow the tail to reduce inviscid, induced drag: if the wings and tail act in different horizontal planes, they might benefit from biplane-like aerodynamics; if they act in the same plane, lift from the tail might compensate for lift lost over the fuselage (body), reducing induced drag with a more even downwash profile. However, textbook aeronautical principles should be applied with caution because birds have highly capable sensing and active control, presumably reducing the demand for passive aerodynamic stability, and, because of their small size and low flight speeds, operate at Reynolds numbers two orders of magnitude below those of light aircraft. Here, by tracking up to 20,000, 0.3 mm neutrally buoyant soap bubbles behind a gliding barn owl, tawny owl and goshawk, we found that downwash velocity due to the body/tail consistently exceeds that due to the wings. The downwash measured behind the centreline is quantitatively consistent with an alternative hypothesis: that of constant lift production per planform area, a requirement for minimizing viscous, profile drag. Gliding raptors use lift distributions that compromise both inviscid induced drag minimization and static pitch stability, instead adopting a strategy that reduces the viscous drag, which is of proportionately greater importance to lower Reynolds number fliers.

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“…It may be that the selective pressures acting on wing tip morphology are more nuanced, complex, and species‐specific than what aerodynamic theory alone suggests. Previous research by Tucker () showed that emarginate primary feathers reduced drag in a gliding Harris's hawk, but more recent work contradicts these findings: A study exploring the wake behind a gliding jackdaw ( Corvus monedula ) showed that vertically separated primary feathers did not significantly affect efficiency (KleinHeerenbrink, Warfvinge, & Hedenström, ). A recent study of swept and extended wings with emarginate feathers showed that lift and drag coefficients (aerodynamic force per unit wing area) were virtually the same during emulated gliding flight, but varied significantly in emulated flapping flight and were predominantly mediated by changes in lift (Klaassen van Oorschot et al, ).…”

Section: Introductionmentioning

confidence: 98%

“…It may be that the selective pressures acting on wing tip morphology are more nuanced, complex, and species-specific than what aerodynamic theory alone suggests. Previous research by Tucker (1993Tucker ( , 1995 showed that emarginate primary feathers reduced drag in a gliding Harris's hawk, but more recent work contradicts these findings: A study exploring the wake behind a gliding jackdaw (Corvus monedula) showed that vertically separated primary feathers did not significantly affect efficiency (KleinHeerenbrink, Warfvinge, & Hedenstr€ om, 2016).…”

mentioning

confidence: 97%

Phylogenetics and ecomorphology of emarginate primary feathers

Oorschot

Tang

Tobalske

2017

Journal of Morphology

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Wing tip slots are a distinct morphological trait broadly expressed across the avian clade, but are generally perceived to be unique to soaring raptors. These slots are the result of emarginations on the distal leading and trailing edges of primary feathers, and allow the feathers to behave as individual airfoils. Research suggests these emarginate feathers are an adaptation to increase glide efficiency by mitigating induced drag in a manner similar to aircraft winglets. If so, we might expect birds known for gliding and soaring to exhibit emarginate feather morphology; however, that is not always the case. Here, we explore emargination across the avian clade, and examine associations between emargination and ecological and morphological variables. Pelagic birds exhibit pointed, high-aspect ratio wings without slots, whereas soaring terrestrial birds exhibit prominent wing-tip slots. Thus, we formed four hypotheses: (1) Emargination is segregated according to habitat (terrestrial, coastal/freshwater, pelagic). (2) Emargination is positively correlated with mass. (3) Emargination varies inversely with aspect ratio and directly with wing loading and disc loading. (4) Emargination varies according to flight style, foraging style, and diet. We found that emargination falls along a continuum that varies with habitat: Pelagic species tend to have zero emargination, coastal/freshwater birds have some emargination, and terrestrial species have a high degree of emargination. Among terrestrial and coastal/freshwater species, the degree of emargination is positively correlated with mass. We infer this may be the result of selection to mitigate induced power requirements during slow flight that otherwise scale adversely with increasing body size. Since induced power output is greatest during slow flight, we hypothesize that emargination may be an adaptation to assist vertical take-off and landing rather than glide efficiency as previously hypothesized.

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Wake analysis of aerodynamic components for the glide envelope of a jackdaw (Corvus monedula)

Cited by 24 publications

References 39 publications

Wind tunnel as a tool in bird migration research

Wind tunnel as a tool in bird migration research

High aerodynamic lift from the tail reduces drag in gliding raptors

Phylogenetics and ecomorphology of emarginate primary feathers

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