The impact of liquid properties on spray drift from fixed-wing aerial application aircraft

Authors: LAWRENCE, MICHAEL - University Of Dayton; Fritz, Bradley; LEE, JONG GUEN - University Of Dayton

Submitted to: Applied Engineering in Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/8/2025
Publication Date: 10/20/2025
Citation: Lawrence, M., Fritz, B.K., Lee, J. 2025. The impact of liquid properties on spray drift from fixed-wing aerial application aircraft. Applied Engineering in Agriculture. https://doi.org/10.13031/aea.16230.
DOI: https://doi.org/10.13031/aea.16230

Interpretive Summary: The physical properties of a liquid pesticide mixture can significantly impact the amount of spray drift that occurs by influencing the droplet size of the applied spray. High speed wind tunnels studies were conducted to measure droplet size that results for multiple spray mixtures. The results were used to model spray drift from a typical aerial application and showed that small changes in surface tension and viscosity can increase or decrease spray drift by up to 50% when compared to a baseline formulation. These findings are being used to improve the accuracy of existing spray atomization models in order to help aerial applicators better optimize their spray systems to increase application accuracy and minimize adverse environmental effects.

Technical Abstract: Two experimental datasets are analyzed to quantify the impact of various spray mixtures and their associated liquid physical properties on spray drift at conditions relevant to aerial application. Droplet size distributions measured in wind tunnels were used as inputs in AgDRIFT, a commercially available software package that simulates drift from various spray vehicles. Near-field drift metrics were extracted from the simulation results and subsequently analyzed, showing that even relatively small changes in liquid physical properties can significantly impact spray drift. For some low-drift cases, these drift metrics increased from 100% to over 250% relative to a baseline formulation, water with a non-ionic surfactant solution typically used as a test surrogate. However, a large majority of the tested cases resulted in between a 13.5% decrease to a 47.6% increase in drift relative to the baseline formulation. These results demonstrate that the typical practice of using a single blank spray solution to represent a broad range of spray materials may result in a significant underprediction of near-field drift.