In order to develop an precision aerial pesticide application system to be attached to an unmanned helicopter which can
be applied to small lots of land, this study analyzed the flowing and spraying characteristics of the spray droplets by the
main rotor downwash by setting the application conditions at the flight altitude of 3 m, the diameter of main rotor of 3.1
m, the boom length of around 2.8 m, and the spraying rate of 8 L/ha. The results of this study are summarized below.
Through analysis of the covering area ratio of the spray droplets by main rotor downwash by nozzle type, boom with
tilt angle and height, it found that the covering area ratio of the twin flat-fan nozzle of around 25% was more uniform
than other types of nozzle, also boom with 10?tilt angle and spraying height of 3m was shown to be the appropriate
conditions for aerial application of pesticides. It was found that the nozzle position to minimize the scattering loss of spray
droplets due to vortex phenomenon at both ends of the main rotor is around 10cm from the end of the main rotor. A
application test for the aerial pesticide application system attached to the HUA-ACEI unmanned helicopter developed by
the Rural Development Administration showed that the range of covering area ratio of the spray droplets was 10-25%, and
the spraying width was approximately 7 m when over 10% of covering area ratio is considered for valid spraying.