title: On the Estimation of Time Dependent Lift of a European Starling (Sturnus vulgaris) during Flapping Flight.
abstract: We study the role of unsteady lift in the context of flapping wing bird flight. Both aerodynamicists and biologists have attempted to address this subject, yet it seems that the contribution of unsteady lift still holds many open questions. The current study deals with the estimation of unsteady aerodynamic forces on a freely flying bird through analysis of wingbeat kinematics and near wake flow measurements using time resolved particle image velocimetry. The aerodynamic forces are obtained through two approaches, the unsteady thin airfoil theory and using the momentum equation for viscous flows. The unsteady lift is comprised of circulatory and non-circulatory components. Both approaches are presented over the duration of wingbeat cycles. Using long-time sampling data, several wingbeat cycles have been analyzed in order to cover both the downstroke and upstroke phases. It appears that the unsteady lift varies over the wingbeat cycle emphasizing its contribution to the total lift and its role in power estimations. It is suggested that the circulatory lift component cannot assumed to be negligible and should be considered when estimating lift or power of birds in flapping motion.
authors.affiliation: Faculty of Engineering and the Environment, University of Southampton, Southampton, Hampshire, SO17 1BJ, United Kingdom.
authors.forename: Oksana
authors.initials: O
authors.lastname: Stalnov
authors.affiliation: Faculty of Aerospace Engineering, Technion, Israel Institute of Technology, Haifa, 32000, Israel.
authors.forename: Hadar
authors.initials: H
authors.lastname: Ben-Gida
authors.affiliation: Boundary Layer Wind Tunnel Laboratory, London, ON N6A3K7, Canada.
authors.forename: Adam J
authors.initials: AJ
authors.lastname: Kirchhefer
authors.affiliation: Department of Biology, Advanced Facility for Avian Research, University of Western Ontario, London, ON, N6A5B7 Canada.
authors.forename: Christopher G
authors.initials: CG
authors.lastname: Guglielmo
authors.affiliation: Boundary Layer Wind Tunnel Laboratory, London, ON N6A3K7, Canada.
authors.forename: Gregory A
authors.initials: GA
authors.lastname: Kopp
authors.affiliation: School of Mechanical Engineering, Tel Aviv University, Tel Aviv, 69978, Israel.
authors.forename: Alexander
authors.initials: A
authors.lastname: Liberzon
authors.affiliation: School of Coastal and Marine Systems Science, Coastal Carolina University, Conway, SC 29528, United States of America.
authors.forename: Roi
authors.initials: R
authors.lastname: Gurka
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D005060:Europe; D005426:Flight, Animal / Q000502:physiology*; D008954:Models, Biological; D012212:Rheology; D046749:Starlings / Q000502:physiology*