A simulation of release height and wind speed effects for drift minimization

The near-wake portion of the USDA Forest Service aerial application predict ion model FSCBG is applied to a sensitivity study of release height and win d speed, the most important factors, along with droplet size distribution, in assessing deposition and drift from aerial application. Building on exte nsive previous work, this study examines the predictions by the near-wake L agrangian trajectory model of drift fraction downwind of the edge of the fi eld. Ten aircraft and four BCPC droplet size distributions are used to simu late a typical agricultural spraying scenario. Findings from this study dem onstrate the effects of varying release height and wind speed on downwind d rift, the reduction of downwind drift with larger droplets, and the inheren t ability of certain aircraft type to reduce downwind drift more easily tha n others. Model results indicate that fixed-wing aircraft generate lower dr ift at lower release heights, that helicopters generate lower drift at high er release heights, and that biplanes exhibit greater drift potential than the other two aircraft types.