Propeller Wash Effects on Spray Drift

For aerial spray application, there is some question if off-target drift (both near and far) is influenced by which boom is spraying and the direction of propeller wash rotation. This information may be useful when switching off one boom close to a field boundary. The effect of alternate boom switching and propeller wash direction on aerial spray drift from a turbine-powered aircraft was investigated. Both high volume and alpha cellulose spray sampling sheets were placed at three sample lines to collect drift fallout 104, 134, 195, and 3 1 7 meters downwind, perpendicular to the flight path. An aqueous mixture of malathion was applied from the aircraft through fifty D6-46 hollow cone tips. Five total replications were conducted over two days. Each replication had four treatment combinations of boom switch (left or right, on or off) and airplane direction. Propeller wash effects were surmised from boom selection and aircraft direction. Data from a preliminary study served as a basis for refinement of analysis procedures. The present analysis introduced weather variables besides wind and adjusted downwind distances to account for wind direction. Results showed that The authors are solely responsible for the content of Ws technical presentation. The technical presentation does not necessarily reflect the official position of the American Society of Agricultural Engineers (ASAE), and its printing and distribution does not constitute an endorsement of views which may be expressed. Technical presentations are not subject to the formal peer review process by ASAE editorial committees; therefore, they are not to be presented as refereed publications. Citation of this work should state that it is from an ASAE meeting paper EXAMPLE: Author's Last Name, Initiils. 2003. Tile of Presentation. ASAE Paper NO. AA03-00x. St. Joseph, Mich.: ASAE. For information about securing permission to reprint or reproduce a technical presentation, please contact ASAE at [email protected] or 269-429-0300 (2950 Niles Road, St. Joseph, MI 49085-9659 USA). neither active boom nor boom location (upwind or downwind) was statistically significant for either sampling method at the 0.05 level. There was significant influence of horizontal sampler location for the HiVol samplers (p=O. 0343, and solar radiation was significant at the 0.0 1 level for both sampling methods (p=O. 0043; p=0.0021, respectivelyl. When analysis was limited to the second day of testing, propeller wash direction was significant at the 0.10 level for the fallout sheets (P=0.0773), and at the 0.05 level for HiVol samplers (P =O. 0200). Graphical representation hdicated that higher concentrations occuned when propeller wash spiraled downwind. Differences between PW= downwind and PW= upwind increased with downwind distance and sample variability was higher when propeller wash spiraled downwind.