Collapsible wings may be a bird’s answer to turbulence according to an Oxford University study in which an eagle carried its own ‘black box’ flight recorder on its back.
Researchers set out to examine how soaring birds such as eagles, vultures, and kites, are able to fly in ‘gusty’ turbulent flight conditions that would keep a light aircraft grounded. They gave a captive steppe eagle (Aquila nipalensis), called ‘Cossack’, its own flight recorder backpack – a 75g black box incorporating GPS that also measured acceleration, rotation rate, and airspeed – and recorded it soaring over the Brecon Beacons in Wales.
An analysis of data from 45 flights revealed that in windy conditions the eagle would collapse its wings in response to particularly strong gusts rather than hold them out stiffly as an aircraft would. During these ‘wing tucks’, the bird’s wings were briefly (for around 0.35 seconds) folded beneath its body so that it was effectively ‘falling’. The results suggest that these ‘wing tucks’ may occur up to three times a minute in some conditions.
A report of the research is published in the Journal of the Royal Society Interface.
‘Soaring flight may appear effortless but it isn’t a free ride,’ said report author Professor Graham Taylor of Oxford University’s Department of Zoology. ‘Soaring may enable a bird to travel long distances but it also puts an enormous strain on its flight muscles. The nature of rising air masses, such as thermals, is that they create lots of turbulence and buffeting that jolts a bird’s wings and could knock it out of the sky.’
A number of theories have been suggested to explain why birds perform wing tucks but up until now no one had tested these conclusively.
‘Our evidence suggests that wing-tucking (collapsing the wings) is a direct response to a substantial loss of lift that occurs when a bird flies through a pocket of atmospheric turbulence,’ said Professor Taylor. ‘We think that, rather like the suspension on a car, birds use this technique to damp the potentially damaging jolting caused by turbulence. Whilst we won’t see large aircraft adopting collapsible wings this kind of technique could potentially be used to keep micro air vehicles aloft even in very windy conditions.’
For more information contact Professor Graham Taylor on +44 (0)1865 271219 or email email@example.com OR co-author Professor Adrian Thomas of Oxford University on +44(0)1865 271208 or email firstname.lastname@example.org
The steppe eagle ‘Cossack’ wearing his ‘black box’ flight recorder backpack. Credit: Graham Taylor [Creative Commons CC-BY license]:https://dl.dropboxusercontent.com/u/44078414/Collapsible%20wings/Cossack_Taylor.jpg
VIDEO: footage of a typical wing tuck performed by the captive steppe eagle ‘Cossack’: https://www.youtube.com/watch?v=Al9300qgFOs&feature=youtu.be
Alternatively contact the Oxford University News Office on +44 (0)1865 283877 or email email@example.com
Notes to editors
*A report of the research, entitled ‘Wing tucks are a response to atmospheric turbulence in the soaring flight of the steppe eagle Aquila nipalensis, is published in theJournal of the Royal Society Interface. The report is embargoed until 00:01 BST 15 October 2014/19:00 US ET 14 October 2014.
*The research team consisted of Kate Reynolds, Adrian Thomas and Graham Taylor of Oxford University’s Department of Zoology, and grew out of an earlier study in the saem Department with James Gillies. Go to: http://flight.zoo.ox.ac.uk
We are seeking a full-time Postdoctoral Research Assistant to join the Oxford Animal Flight Group (http://flight.zoo.ox.ac.uk). The post is funded by the Engineering and Physical Sciences Research Council and is fixed-term for 2.5 years, starting as soon as possible. This project aims to develop computational and mechanical models of the insect wing hinge. This research builds on the recent advances in time-resolved high-speed synchrotron tomographic imaging, which makes it now possible to visualize the inner workings of an insect during flight (Walker et al., 2014; see below for examples of media coverage).
The insect wing hinge forms the most complex joint found in nature. Such is the difficulty in understanding its mechanics that there is currently no consensus on how the wing even moves back and forth. The postdoctoral researcher will analyse microtomography data of flying insects and develop computational and mechanical models that replicate the movement of the insect wing hinge mechanism.
You should possess, or be very close to possessing, a PhD/DPhil in a relevant subject, and should have a background in modelling mechanical systems. You should also have an interest in biomechanics, be able to work well in a team, and have strong evidence of research achievement to date.
Informal enquiries may be made to Simon Walker (firstname.lastname@example.org)
Further details can be found here: http://www.jobs.ac.uk/job search: “114007”
Scientists have used a particle accelerator to obtain high-speed 3D X-ray visualizations of the flight muscles of flies. The team from Oxford University, Imperial College, and the Paul Scherrer Institute (PSI) developed a groundbreaking new CT scanning technique at the PSI’s Swiss Light Source to allow them to film inside live flying insects. Their article, including 3D movies of the blowfly flight motor, is published March 25 in the open access journal PLOS Biology. The movies offer a glimpse into the inner workings of one of nature’s most complex mechanisms, showing that structural deformations are the key to understanding how a fly controls its wingbeat.
In the time that it takes a human to blink, a blowfly can beat its wings 50 times, controlling each wingbeat using numerous tiny steering muscles – some as thin as a human hair. The membranous wings contain no muscles, so all of the flight muscles are hidden out of sight within the thorax. “The thoracic tissues block visible light, but can be penetrated by X-rays”, says Dr. Rajmund Mokso from PSI. “By spinning the flies around in the dedicated fast-imaging experimental setup at the Swiss Light Source, we recorded radiographs at such a high speed that the flight muscles could be viewed from multiple angles at all phases of the wingbeat. We combined these images into 3D visualizations of the flight muscles as they oscillated back and forth 150 times per second.”
The flies responded to being spun around by trying to turn in the opposite direction, allowing the scientists to record the asymmetric muscle movements associated with turning flight. “The steering muscles make up less than 3% of a fly’s total flight muscle mass”, says Prof. Graham Taylor who led the study in Oxford, “so a key question has been how the steering muscles can modulate the output of the much larger power muscles. The power muscles operate symmetrically, but by shifting each wing’s mechanism between different modes of oscillation, the fly can divert power into a steering muscle specialized to absorb mechanical energy – rather like using the gears of a car for braking.”
The scientists hope to use their results to inform the design of new micromechanical devices. “Flies have solved a problem faced by engineers working on the same scale” says Prof. Taylor: “How to produce large, complex, three-dimensional motions, using actuators that only generate small, simple, one-dimensional ones?” The clever design of the blowfly flight motor solves that problem admirably, as the results of this study show. Dr. Simon Walker from Oxford, who was joint first author of the study with Daniel Schwyn, adds: “The fly’s wing hinge is probably the most complex joint in nature, and is the product of more than 300 million years of evolutionary refinement. The result is a mechanism that differs dramatically from conventional manmade designs; built to bend and flex rather than to run like clockwork.”
The full article can be read here: