Influence of Nozzle Configuration on Spray Deposition and Drift from a Remotely Piloted Aerial Application System

Highlights Three nozzle configurations on a PV35X RPAAS, each replicated 15 times, were evaluated for spray deposition and drift. In-swath deposition was significantly higher for the short boom nozzle configuration. In-swath long boom deposition was bimodal, likely caused by aerodynamics of rotor downwash at the outboard nozzles. Downwind deposition did not differ between nozzle configurations and nozzle position had no effect on drift. ABSTRACT. Increased deployment of remotely piloted aerial application systems (RPAASs) in production agriculture globally has raised uncertainty about spray pattern uniformity and off-target movement of pest control products because no standard exists for optimum RPAAS design, especially related to the configuration of the nozzle locations. Published data on the performance of RPAAS platforms can be misleading because of the wide variations in custom-built features of the aircraft and nozzle configurations. Three treatments, each replicated 15 times, comprised of long boom, short boom, and under-rotor configurations, were investigated for spray pattern uniformity, spray deposition, and drift. The spray nozzle (TT 110-01) used in this study provided a medium droplet spectrum with a volume median diameter equivalent to 241 µm. Flow rate, ground speed, and application height were kept constant for all treatments. Significantly higher in-swath deposition occurred for the short boom compared to the long boom and under-rotor nozzle configurations. In-swath deposition for the long boom was bimodal, likely due to the aerodynamics of the rotor downwash at the outboard nozzles. Wind speed influenced deposition for the long boom, but not for the short boom and under-rotor nozzle configurations. The long boom appeared to be more sensitive to wind speed, resulting in greater spray displacement. Downwind deposition describing spray drift did not differ between nozzle configurations. Test data described here could help aerial applicators better understand how multi-rotor remotely piloted aerial application systems equipped with different nozzle configurations affect spray deposition and drift.