Spreader Setup for Aerial Application

Spreaders are attached to agricultural aircraft and used to distribute seeds, fertilizers and dry chemical products. The first time an airplane was used to treat crops was in 1921 when a U.S. Army pilot applied insecticide to Ohio’s catalpa trees infested with moth. Since then, agricultural aviation has proven to be a fast and efficient form of product application to our crops.

The most common spreader used in agricultural aviation in the United States is the venturi or RAM spreader. Venturi spreaders clamp to the gate box at the base of the aircraft’s hopper. The gate boxes are 25, 38 or 41 inches wide depending on the size of the aircraft. As the adjustable door (gate) on the gate box opens, material from the hopper falls into the venturi spreader, and it is distributed by the airflow through the spreader. The opening of the door determines the flow rate. Some of the limitations on venturi spreaders include high aerodynamic drag, high power requirements and low quality pattern of distribution for high application rates (greater than 250 pounds per acre).

 

The venturi spreader is composed of ducts, also called vanes that can vary in number from five to 13. Each vane has adjustable sections at the front or rear. Adjustments on the front portion of the vane modifies the amount of material and air that moves through it. Adjustments of the rear section of the vanes may change the initial path of the material leaving the spreader.

 As an aerial applicator your job is to deliver product (fertilizer, seeds, etc.) on time, with great quality and precision. Major concerns to applicators are swath width, uniformity and operation efficiency. How the spreader is mounted (attitude), the rate of application and variations in the material’s physical properties have major effects on swath width and uniformity of application. Larger swath widths will increase operation efficiency (acres per hour), a “must-do” today with the increasing operational costs.

Variable-rate application (VRA) is a technique often used by progressive farmers in which different product rates are applied in the field in an attempt to match varying field requirements according to features such as soil type or field topography. Farmers and agricultural consultants work together to develop variable-rate maps. Computerized systems for variable-rate application of dry material are available for agricultural airplanes.

These systems automatically adjust gate opening during flight, releasing more or less material according to a prescription map, ground coordinates and aircraft speed. The system also can be used to adjust material release based on aircraft ground speed, offering a precise single-rate application. VRA may be a great option for farmers wishing to apply precision-farming technology to their fields, and it may offer aerial applicators the opportunity to add value to their services, therefore enhancing their level of customer service.

With credit to https://aerialspray.co.za/ewExternalFiles/pub3078SpreaderSetupforAerialLOWRES.pdf  and Farmland Aviation Kenya.