Combined effects of body posture and three-dimensional wing shape enable efficient gliding in flying lizards

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.

Bridging the gap: Optimising connectivity solutions for an arboreal gliding mammal

“…As the frequency of glider crossings decreases with path length (Soanes et al, 2015), the number of feasible glide paths could be overestimated when using a high single‐value glide ratio. Gliding animals often produce greater forces than required to offset body weight at equilibrium (Bahlman et al, 2013; Byrnes et al, 2008), resulting in shallowing glide angles as glide distance increases (Khandelwal & Hedrick, 2020, 2022). Our glide ratio model (Figure 5) is congruent with this expected pattern of increasing glide ratio with increased glide distance.…”

Numerical investigation on the aerodynamic efficiency of bio-inspired corrugated and cambered airfoils in ground effect

“…Lift coefficient Bio-inspired innovation in engineering design has attracted significant attention in recent years, especially in Micro-Air Vehicles (MAV), for improving flight performance 1,2 . Nature gives us outstanding examples of flight from various points of view, such as optimal energy consumption at high dexterity motions, low noise, stability, and well mobility.…”

Influence of posture during gliding flight in the flying lizard Draco volans

“…The gliding prowess of Draco was recognized early on, but for a long time, our understanding of the aerodynamics of gliding flight in these reptiles remained obscured by their cryptic lifestyle and limitations of experimental setups [9,11,16,17]. New information has come to light recently from direct observations [15,18,19], wind-tunnel experiments [20,21], and computational fluid dynamics (CFD) [21]. These highlight that Draco: (i) usually keeps its wings open using its forelimbs, forming a 'composite wing' [15] that increases lift generation [21]; (ii) negotiates obstacles and plans glide paths using visual cues [18]; (iii) actively changes its body posture, and in turn wing shape, as well as its tail orientation while airborne, allowing for efficient maneuvering [18,20] and control over aerodynamic forces and moments [19]; (iv) takes advantage of wing-tip vortices to keep the flow attached over its wings and delay stall [21].…”