Wing morphology has a profound effect on aerodynamic performance. Gliding birds such as swifts exploit their ability to morph their wings: "Extended wings are superior for slow glides and turns; swept wings are superior for fast glides and turns. This superiority is due to better aerodynamic performance - with the exception of fast turns. Swept wings are less effective at generating lift while turning at high speeds, but can bear the extreme loads."
New research has led to a more refined aerodynamicmodel, enhancing understanding and stimulating ideas for future developments in aircraft design. "Lentink says that these aircraft designs are crude compared with what the swifts can do, thanks to the engineering challenges involved. "The swifts are just better at it," he says, "The amount of feathers and muscle involved is challenging for us [to imitate].""
One might anticipate that research like this might stimulate thoughts about intelligent design. That is certainly the way engineers have to approach their work. The glide speeds at which the birds minimize energy expenditure have been determined. But one of the co-authors is quoted as saying: "They [swifts] have evolved an aerodynamic design for cheap flight". However, there is nothing in this research that suggests that these capabilities are evolved rather than intelligently designed. This comment linking design to an evolutionary origin is theory-laden and is actually a pointer to a socially-constructed 'reality' adopted by the researcher.
How swifts control their glide performance with morphing wings
D. Lentink, U. K. Muller, E. J. Stamhuis, R. de Kat, W. van Gestel, L. L. M. Veldhuis, P. Henningsson, A. Hedenstrom, J. J. Videler and J. L. van Leeuwen.
Nature 446, 1082-1085 (26 April 2007) | doi:10.1038/nature05733
Gliding birds continually change the shape and size of their wings1, 2, 3, 4, 5, 6, presumably to exploit the profound effect of wing morphology on aerodynamic performance7, 8, 9. That birds should adjust wing sweep to suit glide speed has been predicted qualitatively by analytical glide models2, 10, which extrapolated the wing's performance envelope from aerodynamic theory. Here we describe the aerodynamic and structural performance of actual swift wings, as measured in a wind tunnel, and on this basis build a semi-empirical glide model. By measuring inside and outside swifts' behavioural envelope, we show that choosing the most suitable sweep can halve sink speed or triple turning rate. Extended wings are superior for slow glides and turns; swept wings are superior for fast glides and turns. This superiority is due to better aerodynamic performance - with the exception of fast turns. Swept wings are less effective at generating lift while turning at high speeds, but can bear the extreme loads. Finally, our glide model predicts that cost-effective gliding occurs at speeds of 8-10 m s-1, whereas agility-related figures of merit peak at 15-25 m s-1. In fact, swifts spend the night ('roost') in flight at 8-10 m s-1 (ref. 11), thus our model can explain this choice for a resting behaviour11, 12. Morphing not only adjusts birds' wing performance to the task at hand, but could also control the flight of future aircraft7.
Ledford, H. Wings in a wind tunnel show secrets of flight. Study of swifts could improve airplane designs.
firstname.lastname@example.org, 25 April 2007 | doi:10.1038/news070423-7
|<< <||> >>|
Evolution has become a favorite topic of the news media recently, but for some reason, they never seem to get the story straight. The staff at Discovery Institute's Center for Science and Culture started this Blog to set the record straight and make sure you knew "the rest of the story".
A blogger from New England offers his intelligent reasoning.
We are a group of individuals, coming from diverse backgrounds and not speaking for any organization, who have found common ground around teleological concepts, including intelligent design. We think these concepts have real potential to generate insights about our reality that are being drowned out by political advocacy from both sides. We hope this blog will provide a small voice that helps rectify this situation.
Website dedicated to comparing scenes from the "Inherit the Wind" movie with factual information from actual Scopes Trial. View 37 clips from the movie and decide for yourself if this movie is more fact or fiction.
Don Cicchetti blogs on: Culture, Music, Faith, Intelligent Design, Guitar, Audio
Australian biologist Stephen E. Jones maintains one of the best origins "quote" databases around. He is meticulous about accuracy and working from original sources.
Most guys going through midlife crisis buy a convertible. Austrialian Stephen E. Jones went back to college to get a biology degree and is now a proponent of ID and common ancestry.
Complete zipped downloadable pdf copy of David Stove's devastating, and yet hard-to-find, critique of neo-Darwinism entitled "Darwinian Fairytales"
Intelligent Design The Future is a multiple contributor weblog whose participants include the nation's leading design scientists and theorists: biochemist Michael Behe, mathematician William Dembski, astronomer Guillermo Gonzalez, philosophers of science Stephen Meyer, and Jay Richards, philosopher of biology Paul Nelson, molecular biologist Jonathan Wells, and science writer Jonathan Witt. Posts will focus primarily on the intellectual issues at stake in the debate over intelligent design, rather than its implications for education or public policy.
A Philosopher's Journey: Political and cultural reflections of John Mark N. Reynolds. Dr. Reynolds is Director of the Torrey Honors Institute at