The influence of Unmanned Agricultural Aircraft System design on spray drift

Field experiments were conducted to determine the influence of the Unmanned Agricultural Aircraft Systems (UAAS) design on spray drift during a common arable field application and a simulated vineyard treatment. In both cases, edge of field airborne drift collectors were used in addition to determine the drift potential as a possible alternative for characterising the downwind sedimentation drift. Four models of UAAS representing three different designs, one single rotor, one 6-rotor and two 8-rotor designs, were involved in the study. All UAASs where equipped with individual spraying systems but the same nozzles were used: Lechler TR 80-0067 and Lechler IDK 120-015, providing nominal application rates of 40 L ha-1 and 75 L ha-1, respectively. The results of the study show that the effect of the UAAS design on spray drift was relatively low compared to the influence of the type of nozzles used. The conventional hollow cone nozzle TR 80-0067 produced much more spray drift compared to the air induction flat fan nozzle IDK 120-015. A good correlation was found between drift sediment and airborne drift potential. Therefore, the latter seems to be a suitable alternative for spray drift evaluations, at least for comparing different spraying systems where a downwind fetch may not be available.