Change increases aerodynamic performance: common swift

1 of 2 Flock of Common Swift / Keta / License

Wings of gliding birds increase aerodynamic performance by continuously changing shape and size.

Biomimicry Taxonomy

	Move or stay put >
	Move >
	In gases

Biomimetic Application Ideas

Developing maneuverable wings to increase efficiency and decrease fuel consumption.

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[Collapse all sections] Summary

"Gliding birds continually change the shape and size of their wings, presumably to exploit the profound effect of wing morphology on aerodynamic performance. That birds should adjust wing sweep to suit glide speed has been predicted qualitatively by analytical glide models, 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 behaviour. Morphing not only adjusts birds' wing performance to the task at hand, but could also control the flight of future aircraft." (Lentink et al. 2007: 1082)

About the inspiring organism

Common Swift
Apus apus (Linnaeus, 1758)
[Common swift]

IUCN Red List Status: Least Concern
Habitat(s): Artificial - Terrestrial, Desert, Forest, Grassland, Rocky Areas, Savanna, Shrubland, Wetlands

Some organism data provided by: ITIS: The Integrated Taxonomic Information System
Organism/taxonomy data provided by:
Species 2000 & ITIS Catalogue of Life: 2008 Annual Checklist

Bioinspired products and application ideas

Application Ideas: Developing maneuverable wings to increase efficiency and decrease fuel consumption.

Industrial Sector(s) interested in this strategy: Airline industry

Experts

Experimental Zoology Group
David Lentink Johan van Leeuwen
Department of Animal Sciences of Wageningen University

Animal Flight Lab
Anders Hedenström
Animal Ecology, Lund University

References

Lentink, D.; Muller, U. K.; Stamhuis, E. J.; de Kat, R.; van Gestel, W.; Veldhuis, L. L. M.; Henningsson, P.; Hedenstrom, A.; Videler, J. J.; van Leeuwen, J. L. 2007. How swifts control their glide performance with morphing wings. Nature. 446(7139): 1082-1085.

Henningsson, P.; Spedding, G.R.; Hedenström, A. 2008. Vortex wake and flight kinematics of a swift in cruising flight in a wind tunnel. J. Exp. Biol. 211: 717-730.

Change increases aerodynamic performance: common swift

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