Evaluation of Cube-type Collectors for Assessing Liquid Spraying Performance

We evaluated five-surface (excluding the base) cube-type collectors to assess liquid spraying by drone at various nozzle settings. Across 50 flights, the droplet area and relative span differed markedly among the cube surfaces, indicating that droplet deposition was not uniform in three dimensions and could not be inferred from single-surface collectors. Furthermore, these trends remained consistent even when we accounted for wind conditions and nozzle type. However, the ranking tendencies were not uniform, and because droplet particle size is expected to influence behavior under downwash conditions, we consider it necessary to refine experimental methods and analytical approaches. These findings suggest that the aerodynamic interactions between droplet size and drone downwash strongly affect the three-dimensional deposition behavior. Therefore, three-dimensional observation using cube-type collectors is useful for drone applications using helical downwash to spray crops with complex three-dimensional structures.