1. Fig. 1 A new aerodynamic force platform accurately measures the complete transfer of vertical impulse generated during foraging flights.
A new aerodynamic force platform accurately measures the complete transfer of vertical impulse generated during foraging flights. (A) Two plates, each connected to three force sensors (black discs), integrate the pressure field along the top and bottom surfaces of the “control volume” in which the bird flies. Instrumented perches measure leg forces during takeoff (red) and landing (blue). Five kinematic high-speed cameras are synchronized with force measurements at 1000 Hz. Mirrors on the bottom plate provide a ventral view of the projected area swept out by the wings (see Materials and Methods). (B) To test how distance and inclination (γ) between perches modify bimodal locomotion, five variations were used: 20-cm (dark green), 40-cm (green), and 75-cm (light green) level (γ = 0°) versus 75-cm ascending (γ = +20°; light blue) and descending (γ = −20°; purple) flights. (C) A typical 75-cm, level flight force recording shows parrotlets support bodyweight primarily with their legs (red and blue) and wing downstrokes (black line and gray shaded regions). (D) Legs are the dominant weight support contributors. Bars show mean ± SD for N = 4 birds and n = 5 flights each, except that 20- and 40-cm wing contributions are n = 10 (see Materials and Methods). The platform and perches recover ~100% of vertical impulse needed to support bodyweight.
Diana D. Chin, and David Lentink Sci Adv 2017;3:e
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