Effects of flight pattern and spray particle size on the adhesion of droplets in citrus canopy sprayed by multirotor unmanned aerial vehicle

Abstract

We evaluated the effects of flight pattern and spray particle size on the adhesion of droplets sprayed by a multirotor unmanned aerial vehicle (UAV) by placing water-sensitive test papers into citrus canopies at different orientations and heights. The coverage area ratio was higher when the UAV flew in a circle over each tree than when it flew linearly over the row. Within the size range of 100 to 195 μm, a smaller spray particle size achieved a higher coverage area ratio. The coverage area ratio and the effect of the flight pattern and spray particle size on it depended on the orientation and height of the test papers. These results suggest that the UAV downwash and the airflow deflected upward from the ground contributed to the adhesion of the droplets.