Abstract
Gliding animals change their body shape and posture while producing and modulating aerodynamic forces during flight. However, the combined effect of these different factors on aerodynamic force production, and ultimately the animal’s gliding ability, remains uncertain. Here, we quantified the time-varying morphology and aerodynamics of complete, voluntary glides performed by a population of wild gliding lizards (Draco dussumieri) in a seven-camera motion capture arena constructed in their natural environment. Our findings, in conjunction with previous airfoil models, highlight how three-dimensional (3D) wing shape including camber, planform, and aspect ratio enables gliding flight and effective aerodynamic performance by the lizard up to and over an angle of attack (AoA) of 55° without catastrophic loss of lift. Furthermore, the lizards maintained a near maximal lift-to-drag ratio throughout their mid-glide by changing body pitch to control AoA, while simultaneously modulating airfoil camber to alter the magnitude of aerodynamic forces. This strategy allows an optimal aerodynamic configuration for horizontal transport while ensuring adaptability to real-world flight conditions and behavioral requirements. Overall, we empirically show that the aerodynamics of biological airfoils coupled with the animal’s ability to control posture and their 3D wing shape enable efficient gliding and adaptive flight control in the natural habitat.
Highlights
Gliding animals change their body shape and posture while producing and modulating aerodynamic forces during flight
Dimensionless number used to categorize the inertial versus viscous properties of the fluid The outline of the airfoil when projected on a horizontal plane Distance between the leading and trailing edge of the wing Ratio of the wingspan to the wing chord length Angle made by the airfoil relative to the wind The curvature of the wing in the chordwise direction Upward angle made by the wing with respect to the horizontal plane body posture and airfoil properties on the animal’s aerodynamic performance and flight control, and the animal’s gliding ability, remains unclear
We address these challenges by performing detailed aerodynamic measurements in a population of wildcaught gliding lizards (Draco dussumieri) executing complete, voluntary glides in a seven-camera motion capture arena constructed in their natural environment (Fig. 1b, see Supplementary Information)
Summary
Gliding animals change their body shape and posture while producing and modulating aerodynamic forces during flight. Dimensionless number used to categorize the inertial versus viscous properties of the fluid The outline of the airfoil (shape) when projected on a horizontal plane Distance between the leading and trailing edge of the wing Ratio of the wingspan to the wing chord length Angle made by the airfoil relative to the wind The curvature of the wing in the chordwise direction Upward angle made by the wing with respect to the horizontal plane body posture and airfoil properties on the animal’s aerodynamic performance and flight control, and the animal’s gliding ability, remains unclear We address these challenges by performing detailed aerodynamic measurements in a population of wildcaught gliding lizards (Draco dussumieri) executing complete, voluntary glides in a seven-camera motion capture arena constructed in their natural environment (Fig. 1b, see Supplementary Information). We hypothesized that the aerodynamic forces in Draco gliding lizards are primarily controlled by varying the body orientation ( body pitch) and the AoA to enable a high lift-to-drag ratio during the mid-glide to cover horizontal distance, and high lift and drag forces at landing to minimize elevation loss while reducing kinetic energy before touchdown
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