Meeting Abstract
Free takeoff flight recordings of thrips (body length under 1 mm) show that they can intermittently cease flapping and float passively downwards by spreading their bristled wings. This type of drag-based parachuting can be advantageous in lowering the falling speed, and could potentially aid in long-distance dispersal by minimizing energetic demands needed for active flight. It is unclear whether bristled wings such as those observed in thrips can reduce drag generated in parachuting. In this study, we comparatively examine parachuting using bristled wings and solid (non-bristled) wings. Forewing angles in parachuting and settling velocities were obtained from free takeoff flight videos. A solid wing model and bristled wing model with bristle spacing to diameter ratio of 5 performing translational motion were comparatively examined using a dynamically scaled robotic model. We measured force generated under varying wing angle from 45-75 degrees across a Reynolds number (Re) range of 1 to 15. Drag experienced by the wings decreased in both wing models when varying Re from 1 to 15. Leakiness of flow through bristles, visualized using spanwise particle image velocimetry measurements, and implications for force generation will be presented.
