Soaring Birds as “Maxwell Demons”
The suggestion implied in the title of this theoretical article was made by Samuel Langley (1893) in his treatise “The Internal Work of the Wind”. He, like a number of other scientists of his time, during which there was great curiosity about bird flight and, as a consequence, about the nature of the wind, was particularly fascinated by the question if birds might in some sense rectify the turbulent fluctuations of the wind as a means to offset their drag, and thereby stay aloft. Until it was discovered by Idrac (1931) that thermal updraughts must in most cases be considered the true source of energy in soaring, there was lively debate over the ways in which turbulence might be exploitable in flight. The work of Klemperer (1926) and Breguet (1925) is typical in this respect.
KeywordsAerodynamic Force Turbulent Fluctuation Inertial Subrange Lively Debate Black Kite
Unable to display preview. Download preview PDF.
- Batchelor, G. K. 1953 The Theory of Homogeneous Turbulence. Cambridge University Press.Google Scholar
- Bréguet, L., 1925 Le Vol à Voile Dynamique des Oiseaux. Gauthiers-Villars, Paris.Google Scholar
- Hendriks, F. 1972 Dynamic Soaring. Ph. D. thesis, UCLA.Google Scholar
- Idrac, P. 1931 Études Éxpérimentales sur le Vol à Voile. Vivien, Paris.Google Scholar
- Klemperer, W. B. 1926 Theorie des Segelfluges. Abh. aus. dem Aerod. Inst. an der Techn. Hochschule Aachen, Heft 5.Google Scholar
- Langley, S. P. 1893 The internal work of the wind. Smithsonian Contributions to Knowledge, No. 884.Google Scholar