2010 Annual Report 1a.Objectives (from AD-416) Evaluate and present improvements to a hydraulically operated variable-rate aerial application system used to apply liquid crop production materials. 1b.Approach (from AD-416) The Autocal II aerial flow controller allows target flow to be maintained regardless of ground speed. An expanded use of this controller is to provide variable flow to meet the needs of site-specific application. To accomplish this, the SATLOC M3 guidance system with global positioning communicates with the flow controller to signal when an application boundary has been reached via a programmed prescription map. System tests are required to determine accuracy of application at specified field boundaries and to investigate response time to changing flow requirements. Field testing will indicate needed changes to control algorithms, and the manufacturer will modify the control programs to improve controller response and accuracy of application. 3.Progress Report Flow control algorithms for the aerial variable-rate system were further refined and verified for proper operation by site visit from our cooperator at Houma Avionics. Data have been processed from several evaluations of the refined flow controller and published. The project was monitored through emails, telephone calls, and site visits.