Bat Flight Generates Complex Aerodynamic Tracks

Hedenström, Anders; Johansson, Lars; Wolf, Marta; Busse, Rhea von; Winter, York; Spedding, Geoffrey

doi:10.1126/science.1142281

Cited by 201 publications

(187 citation statements)

References 19 publications

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“…Although the wake patterns generated by bats are complex (Hedenström et al, 2007;Hubel et al, 2009), simple models such as actuator disk theory can capture some of the relevant connection between kinematics and aerodynamic force production. According to these ideas, a decrease in stroke plane angle should direct the induced velocity of the wing motion more rearward, thereby shifting the contribution of induced velocity towards increased thrust and away from lift generation, to simultaneously overcome increased drag and diminish the lift production of the wings (Pennycuick, 1975).…”

Section: Kinematic Changes With Flight Velocitymentioning

confidence: 99%

“…The mechanics of insect flight differ between fruit flies and hawkmoths, and the way a bird flies also varies from hummingbirds to pigeons to vultures (Combes and Daniel, 2003;Dial and Biewener, 1993;Dickinson and Götz, 1996;Sane, 2003;McGahan, 1973;Warrick et al, 2005). Unlike insects and birds, however, bats have largely been assumed to use similar mechanisms of aerodynamic force production in flight, regardless of size (Bullen and McKenzie, 2002;Hedenström et al, 2007;Norberg and Rayner, 1987), even though bats range in body mass over roughly three orders of magnitude, from the ≤0.002kg bumblebee bat (Craseonycteris thonglongyai) to >1.2kg flying foxes (Pteropus spp.) (Hill and Smith, 1981;Kunz and Jones, 2000;Surlykke et al, 1993).…”

Section: Introductionmentioning

confidence: 99%

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The effect of body size on the wing movements of pteropodid bats, with insights into thrust and lift production

Riskin

Iriarte-Díaz

Middleton

et al. 2010

Journal of Experimental Biology

106

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modes of bats vary widely among families, so we focused on a single family, the Pteropodidae. This family consists of ca. 186 species distributed throughout the paleotropics (Wilson and Reeder, 2005) and is characterized by fruit and nectar-feeding, non-echolocating Accepted 26 None of the bats in our study flew at constant speed, so we used multiple regression to isolate the changes in wing kinematics that correlated with changes in flight speed, horizontal acceleration and vertical acceleration. We uncovered several significant trends that were consistent among species. Our results demonstrate that for medium-to large-sized bats, the ways that bats modulate their wing kinematics to produce thrust and lift over the course of a wingbeat cycle are independent of body size. Supplementary material available online at

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Section: Kinematic Changes With Flight Velocitymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The effect of body size on the wing movements of pteropodid bats, with insights into thrust and lift production

Riskin

Iriarte-Díaz

Middleton

et al. 2010

Journal of Experimental Biology

106

View full text Add to dashboard Cite

show abstract

“…In most cases, the wakes of animals incorporate several distinctly different vortex elements, such as wingtip and wing root vortices (e.g. craneflies [18]; bees [15]; bats [19]; flycatchers [11]; swifts [20] and blackcaps [21]). Using PIV, it is possible to capture these vortex elements as they are shed behind the flying insect.…”

Section: Simplifying the Complexity Of Animal Wakesmentioning

confidence: 99%

Span efficiency in hawkmoths

Henningsson

Bomphrey

2013

J. R. Soc. Interface.

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Flight in animals is the result of aerodynamic forces generated as flight muscles drive the wings through air. Aerial performance is therefore limited by the efficiency with which momentum is imparted to the air, a property that can be measured using modern techniques. We measured the induced flow fields around six hawkmoth species flying tethered in a wind tunnel to assess span efficiency, e i , and from these measurements, determined the morphological and kinematic characters that predict efficient flight. The species were selected to represent a range in wingspan from 40 to 110 mm (2.75 times) and in mass from 0.2 to 1.5 g (7.5 times) but they were similar in their overall shape and their ecology. From high spatio-temporal resolution quantitative wake images, we extracted time-resolved downwash distributions behind the hawkmoths, calculating instantaneous values of e i throughout the wingbeat cycle as well as multi-wingbeat averages. Span efficiency correlated positively with normalized lift and negatively with advance ratio. Average span efficiencies for the moths ranged from 0.31 to 0.60 showing that the standard generic value of 0.83 used in previous studies of animal flight is not a suitable approximation of aerodynamic performance in insects.

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“…Previous work on flying birds [1 -4], bats [5,6], swimming fishes [7 -9] and jellyfish [10,11] using two-dimensional flow visualization techniques has shown how animals generate wake flow patterns, and has allowed calculation of average lift and thrust forces produced by untethered moving animals. Such two-dimensional visualizations, known as particle image velocimetry (PIV), are accomplished by seeding the air or water with small particles, and using a sheet of laser light to illuminate flow patterns that are then imaged at rates varying from 3 to 1000 Hz.…”

Section: Introductionmentioning

confidence: 99%

Volumetric imaging of shark tail hydrodynamics reveals a three-dimensional dual-ring vortex wake structure

et al. 2011

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Understanding how moving organisms generate locomotor forces is fundamental to the analysis of aerodynamic and hydrodynamic flow patterns that are generated during body and appendage oscillation. In the past, this has been accomplished using two-dimensional planar techniques that require reconstruction of three-dimensional flow patterns. We have applied a new, fully three-dimensional, volumetric imaging technique that allows instantaneous capture of wake flow patterns, to a classic problem in functional vertebrate biology: the function of the asymmetrical (heterocercal) tail of swimming sharks to capture the vorticity field within the volume swept by the tail. These data were used to test a previous three-dimensional reconstruction of the shark vortex wake estimated from two-dimensional flow analyses, and show that the volumetric approach reveals a different vortex wake not previously reconstructed from two-dimensional slices. The hydrodynamic wake consists of one set of dual-linked vortex rings produced per half tail beat. In addition, we use a simple passive shark-tail model under robotic control to show that the three-dimensional wake flows of the robotic tail differ from the active tail motion of a live shark, suggesting that active control of kinematics and tail stiffness plays a substantial role in the production of wake vortical patterns.

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Bat Flight Generates Complex Aerodynamic Tracks

Cited by 201 publications

References 19 publications

The effect of body size on the wing movements of pteropodid bats, with insights into thrust and lift production

The effect of body size on the wing movements of pteropodid bats, with insights into thrust and lift production

Span efficiency in hawkmoths

Volumetric imaging of shark tail hydrodynamics reveals a three-dimensional dual-ring vortex wake structure

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