Soaring energetics and glide performance in a moving atmosphere
Here, we analyse the energetics, performance and optimization of flight in a moving atmosphere. We begin by deriving a succinct expression describing all of the mechanical energy flows associated with gliding, dynamic soaring and thermal soaring, which we use to explore the optimization of gliding i...
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Published in | Philosophical transactions of the Royal Society of London. Series B. Biological sciences Vol. 371; no. 1704; p. 20150398 |
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Main Authors | , , |
Format | Journal Article |
Language | English |
Published |
England
The Royal Society
26.09.2016
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Subjects | |
Online Access | Get full text |
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Summary: | Here, we analyse the energetics, performance and optimization of flight in a moving atmosphere. We begin by deriving a succinct expression describing all of the mechanical energy flows associated with gliding, dynamic soaring and thermal soaring, which we use to explore the optimization of gliding in an arbitrary wind. We use this optimization to revisit the classical theory of the glide polar, which we expand upon in two significant ways. First, we compare the predictions of the glide polar for different species under the various published models. Second, we derive a glide optimization chart that maps every combination of headwind and updraft speed to the unique combination of airspeed and inertial sink rate at which the aerodynamic cost of transport is expected to be minimized. With these theoretical tools in hand, we test their predictions using empirical data collected from a captive steppe eagle (Aquila nipalensis) carrying an inertial measurement unit, global positioning system, barometer and pitot tube. We show that the bird adjusts airspeed in relation to headwind speed as expected if it were seeking to minimize its aerodynamic cost of transport, but find only weak evidence to suggest that it adjusts airspeed similarly in response to updrafts during straight and interthermal glides.
This article is part of the themed issue ‘Moving in a moving medium: new perspectives on flight’. |
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Bibliography: | Theme issue ‘Moving in a moving medium: new perspectives on flight’ compiled and edited by Steven J. Portugal and Emily L. C. Shepard ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 One contribution of 17 to a theme issue ‘Moving in a moving medium: new perspectives on flight’. |
ISSN: | 0962-8436 1471-2970 |
DOI: | 10.1098/rstb.2015.0398 |