Effect of spray parameters of small unmanned helicopter on distribution regularity of droplet deposition in hybrid rice canopy

Abstract: In order to find out the distribution regularity of droplet deposition of small unmanned helicopter in rice canopy, spray test with different flight parameters was carried out to study the effect of different operation parameters on the distribution of droplet deposition. The distribution regularity of droplet deposition was obtained by drawing the operation trajectory with BeiDou Navigation Satellite System carried by one-rotor small unmanned helicopter HY-B-10L. The spraying and deposition of the growth regulator (Ponceau 2R solution with the mass fraction of 5‰) were simulated, and the parameters results of droplet deposition in the target areas and non-target areas were analyzed by Image processing software Deposit-Scan. The analysis results showed that: The trends of droplet deposition were similar in the 3 trials, the parameters of flight height and flight speed both had a great influence on the mean droplet deposition amount in the collection point of target areas but had not significant influence on the uniformity of droplet deposition. In the target area, the droplet deposition decreased with the increase of the flight height in the 3 trials. The total droplet deposition was respectively 2.380, 1.905 and 1.156 μL/cm2, and the average droplet deposition of collection point was respectively 0.198, 0.159 and 0.064 μL/cm2. The uniformity of droplets deposition was the best in the flight height of 1.92 m, the best value of uniformity could reach 29%, and the amount of droplets drift was 0.174 μL/cm2, which was the least in the drift area in this case, while the amount of droplets drift in the flight height of 3.15 m was 0.270 μL/cm2, which was the largest value. The larger value of droplet drift was 0.205 μL/cm2 in the flight height of 1.33 m, and it had the worst uniformity in the 3 trials. In addition, the amounts of the droplet deposition in the first and second collection zone were clearly more than the amount of the third collection zone which had a faster flight speed in the target area. In the 3 trials, the average amount of droplet deposition in the first and second collection zone was higher than the amount in the third collection zone by 184.27%, 53.51% and 72.31% respectively. Due to the effect of environmental wind field, the amount of droplets deposition and the drift distance of droplets on the left side of flight route were more than that on the right side of flight route, and with the effect of flight speed, the amount of droplet deposition in the third collection zone on the left side of flight route was more than the droplet deposition in the first and second collection zone on the right side in the drift area. The results have fully revealed the effect of operation parameters on the distribution regularity of droplet deposition and drift, and surmised the impact on the droplet deposition from the perspective of wind field factor. It also has an important guiding significance for the reasonable spraying and increasing the spraying efficiency.