Kinematic Strategies of Dragonfly Free-Fall Recovery from an Asymmetric Body Roll

Insect aerial righting is a critical locomotor response to flight perturbations. However, the kinematic strategy of dragonfly (Pantala flavescens) free-fall recovery under asymmetric perturbations remains unclear. In this study, free-fall experiments were conducted using single-wing release to induce an initial asymmetric body roll, and three-dimensional kinematics were reconstructed using high-speed videography. The results show that the free-fall recovery process was divided into two phases based on body velocity: a free-fall phase with increasing downward velocity and a recovery phase marked by the cessation of this trend and a rise in horizontal velocity. During the free-fall phase, thorax roll developed and then attenuated, accompanied by relative abdominal and wing posture variations, without sustained wing flapping. Near the onset of recovery, hindwings initiated the downstroke earlier than forewings, forming a hindwing-leading flapping pattern. These findings indicate that dragonflies employ a phased kinematic strategy during asymmetric free-fall recovery, involving early body and wing posture adjustments followed by asymmetric wing flapping during the transition from gravity-dominated descent to maneuvering flight.