Unmanned Aerial Spraying Systems (UASS) are undergoing rapid development and uptake around the world. To date, pesticide applications from UASS have mainly been focused within agriculture, public health, and industrial vegetative management.  The majority of commercial UASS are small drones, limited in terms of both payload and endurance, although larger payload drones in development are approaching manned aircraft capabilities. Both small and large payload drones benefit from operating at Low or Ultra-Low Volumes (LV or ULV) to remain cost-effective tools.  There is general enthusiasm for the new technology but there is also a pressing need for research. This research is required to generate data to evaluate this developing technology as well as informing regulation, including understanding atomization methods suited to LV and ULV application. It is essential that existing data and research on LV and ULV aerial and ground application is consulted to minimize the need for new data generation (which is expensive).  Traditional hydraulic nozzles struggle in LV and ULV applications due to the inherent inefficiencies of sheet breakup atomization – resulting in a wide range of droplet sizes. Rotary/ centrifugal atomizers, however, can produce droplets either by direct drop or ligament atomization. This results in much tighter control of droplet size, allowing lower application volumes due to their increased atomization efficiency. LV and ULV applications have a long history of use in, and are essential for, manned aerial application, public health operations and migrant pest control. Concerns over drift from UASS have also been raised, with the biggest unknowns being the complex flow fields and wake patterns created by multi-rotor UASS. Single-rotor and fixed-wing UASS can be expected to be similar to their larger, manned counterparts (and could thus possibly be evaluated using existing regulatory models) but the multi-rotors of most small UASS introduce additional complexity. The creation and validation of new spray atomization and transport models capable of incorporating multi-rotors must be a key step in evaluating UASS application within regulatory frameworks.  Despite the many challenges, UASS appear well suited to a variety of applications and both current and future research should answer some of the outstanding questions and refine this technology into an effective pesticide application platform.

Spray application from UASS: A sprayer manufacturer’s perspective

ACS Fall 2021

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.