Impact of sprayer drone flight height on droplet spectrum in mountainous coffee plantation/Impacto da altura de voo de drone pulverizador no espectro de gotas em cafe de montanha

Weather conditions and sprayer operating parameters influence spray quality. Unmanned aerial vehicles are considered a modern, useful, and very efficient technological tool in the application of pesticides, as they carry out punctual spraying, and reduce environmental and public health problems. The objective of this study was to characterize the spraying quality carried out with an unmanned aerial vehicle as a function of flight height and target position in a coffee plantation in a mountainous region. Three flight heights (2.5, 3.0, and 4.0 m) were used, and the targets were placed at the top and bottom of the plant. For each plant, six water sensitive papers were placed on top of the plant and six were placed at the bottom. CIR 1.5 software was applied to determine the coverage percentage, drop density, volume median diameter, volumetric diameter corresponding to 10 and 90%, numerical median diameter, and relative amplitude. The results showed that the flight height only influenced the parameters of the volumetric diameter corresponding to 10% of the volume, numerical median diameter, and coverage percentage. The target position on the canopy influenced all the evaluated spraying parameters. In mountainous coffee plantations, the spraying system using unmanned aerial vehicle spraying is more efficient for the lower part of the plant. Key words: coverage percentage, drop density, droplet size Condicoes climaticas e parametros operacionais dos pulverizadores influenciam a qualidade da pulverizacao. Os veiculos aereos nao tripulados sao considerados uma ferramenta tecnologica moderna, util e bastante eficiente na aplicacao de defensivos agricolas, uma vez que realizam pulverizacoes pontuais, reduzindo problemas ambientais e de saude publica. O objetivo deste estudo foi caracterizar a qualidade da pulverizacao realizada com um veiculo aereo nao tripulado em funcao da altura de voo e a posicao do alvo em lavoura de cafe de regiao montanhosa. Utilizou-se tres alturas de voo (2,5; 3,0; e 4,0 m) e os alvos foram colocados na parte inferior e superior da planta. Em cada planta utilizou-se 12 etiquetas de papel hidrossensivel no total, seis para a parte inferior e seis para a parte superior. O software CIR 1.5 foi aplicado para determinar a porcentagem de cobertura, densidade de gotas, diametro da mediana volumetrica, diametro correspondente a 10 e 90% do volume, diametro mediano numerico e amplitude relativa. Os resultados mostraram que a altura de voo apenas in