Effect of flight parameters of B-7451 helicopter on distribution pattern of droplet deposition in jujube canopy

Abstract: 【Objective】In order to explore the distribution pattern and application prospect of B-7451 helicopter as a sprayer in jujube orchards, the effects of spraying width of the helicopter and other flight parameters on the distribution of droplet deposition were studied.【Methods】The experiment used a water-soluble fertilizer for spray test at different the heights including 6, 8 and 10 meters. The sampling points were the upper, middle, lower, front and back parts of the jujube canopy. Droplets in the leaves were collected with droplet collection cards. After each flight spray test, the droplet collection cards were taken back to the laboratory for data processing. The effective spraying width was determined based on droplet density. The droplet deposition amount in different parts of jujube canopy was determined using droplet counting cards, and the parameters of droplet deposition distribution pattern (density of droplet deposition, droplet deposition and distribution uniformity) were calculated for different layers of the canopy.【Results】The results showed that the effective spraying width was 35 meters when the working height of the helicopter was 6 meters. The effective spraying width was 40 meters when the working height was 8 meters. It became 50 meters when the working height increased to 10 meters. The total quantity of droplet deposition at the targets was the lowest when the flight altitude was 10 meters but highest when the flight height was 6 meters. The droplet deposition and uniformity were different at the upper, middle and bottom of jujube canopies when the working height was different. The quantity of droplet deposition in upper and middle of jujube canopies was higher than at the bottom of the canopy.The reason may be that the leaves at the upper and middle canopy prevented drops from penetrating into the lower part. When the working height was 6 meters, the wind generated by the helicopter increased the penetrability of the fog droplets. Therefore, droplet deposition was found at each sampling position of the canopy, and the spraying effect was the best. At the same working height, the coefficient of variation of droplet density was smaller in the upper surface of the leaves than in the lower surface, and the deposition uniformity of the droplets in the upper surface was better. When the height was 6 meters, the variation coefficient of droplet density in the leaves was generally small, and the deposition uniformity of the droplets was the best. The variation coefficient of droplet density increased with the increase in working height of the helicopter, and thus the distribution uniformity of droplets became worse.【Conclusion】Flight height and spraying width of the B-7451 helicopter had a significant impact on the sprayed droplet deposition uniformity. Based on our results, we recommend a working height of the helicopter of 6 meters together with a spraying distance of 35 meters for spraying pesticides using B-7451 helicopter.