2026-10-13T06:56:13Z https://api.figshare.com/v2/oai

oai:figshare.com:article/34036041 2026-09-30T17:43:04Z category_1 category_915 category_21 category_272 category_39 category_734 category_106 portal_5 item_type_1 month_year_09_2026

Flight efficiency increases with flight speed, but lift production becomes less efficient. L. Christoffer Johansson (8029388) Gabriel Norevik (589846) Sonja Friman (25145400) Anders Hedenström (150704) Biophysics Physical Sciences not elsewhere classified Biotechnology Environmental Sciences not elsewhere classified Ecology Biological Sciences not elsewhere classified Science Policy using wake visualization reduced span efficiency phenomenon may stem multiple costly behaviors may apply generally kinematic analysis suggests characteristic previously attributed caprimulgus europaeus </ cruising speed efficiency reflects complex tradeoffs european nightjar (< also uses slow div >< p cruising flight — cruising speeds tradeoffs seen slow flight nightjar ’ hummingbirds — wing shape wing folding wind tunnel results highlight particularly interesting makes studies generating lift flight speeds flight performance flapping flight feeding ecology faster speeds existing paradigm ecological demands distance migrant animals engaged aerodynamic mechanisms aerodynamic measurements (a) The lift-specific power across flight speed. Each dot represents the mean value for a sequence, and the fitted curve (blue) shows a U-shaped pattern with a minimum close to 9.3 m/s. The black curve is the expected weight-specific power curve, estimated using the Animal Flight Performance Tool (afpt, in R) [<a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.3004023#pbio.3004023.ref003" target="_blank">3</a>]. Data used to produce this figure (i.e., Power and Mean lift) can be found in <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.3004023#pbio.3004023.s029" target="_blank">S1 Data</a>. (b) The cost of transport (COT) decreases systematically with flight speed, indicating more efficient flight at higher speeds. Data used to produce this figure can be found in <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.3004023#pbio.3004023.s029" target="_blank">S1 Data</a>. (c) The power factor (PF) increases with increasing flight speed with a shallow peak around 9 m/s, indicating that the overall force production is more efficient at higher than at lower speeds. Data used to produce this figure can be found in <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.3004023#pbio.3004023.s029" target="_blank">S1 Data</a>. (d) Span efficiency (black) and vertical force efficiency (blue), during the downstroke, decrease with flight speed. This indicates that the efficiency of lift generation is lower at higher speeds than at lower speeds. The lower vertical force efficiency compared to span efficiency indicates efficiency loss due to generation of side forces that cancel between left and right wing and do not contribute to weight support. Circles represent median values during the downstroke. Data used to produce this figure can be found in <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.3004023#pbio.3004023.s029" target="_blank">S1 Data</a>. (e) Span efficiency (black) and vertical force efficiency (blue) varies over a downstroke. Span efficiency varies relatively little during the downstroke (circles and dots), while vertical force efficiency shows a peak during mid-downstroke. The graph shows a sample of two wingbeats of a European nightjar flying at 7 m/s. 2026-09-30T18:03:55Z Image Figure 10.1371/journal.pbio.3004023.g003 https://figshare.com/articles/figure/_p_Flight_efficiency_increases_with_flight_speed_but_lift_production_becomes_less_efficient_p_/34036041 CC BY 4.0