Aerial Application Using Unmanned Aircraft – A flight

plan for success!! Brad Fritz USDA-ARS

Aerial Application Technology Research Unit

College Station, TX

Damon Reabe National Agricultural Aviation Association

What is an Aerial Application?

•  The FAA defines it has – …the operation of an aircraft for the purpose of (1)

dispensing any [pesticide, plant regulator, defoliant or desicant], (2) dispensing any other substance intended for plant nourishment, soil treatment, propagation of plant life, or pest control, or (3) engaging in dispensing activities directly affecting agriculture, horticulture, or forest preservation, but not including the dispensing of live insects.

Are UAS making aerial applications?

•  Operators conducting aerial applications are governed by FAR Part 137 and require a Part 137 operating certificate

•  So when an unmanned Aircraft performs a pesticide application is it an aerial application?

•  It is a type of aerial application but in many cases different and untested compared to manned aerial applications

•  FAA requires all UAS spraying operations to obtain a Part 137 operating certificate

Agricultural Aircraft •  Fixed wing and Helicopters (single rotor) •  1,560 Operators nationwide applying in all 50 states •  Treat roughly 25% of cropland nationwide •  Guidance – GPS - 20 Hz – used by 99% of industry

– Application mapping – Job/report files push/pull via cellular data – Variable and constant rate applications with flow control

•  Droplet size - adjusted via nozzle orifice, type, and deflection – Very Fine to Extremely coarse

•  Additional drift mitigation – Boom configuration – ½ boom shutoff and length reductions – Onboard weather measurement – AIMMS and smokers – Capstan Pulse Width Modulation system

Fungicide Label Example

•  Aerial application label requirements – Apply as a medium or coarser spray (ASAE Standard

572). • Medium droplet size: 250 – 350 microns

– Boom length must not exceed 75% of wingspan or 90% of the rotor blade diameter

– For field crops apply in a minimum spray volume of 2 gallons per acre

UAS Applications •  Example based on one UAV manufacturer’s operating

characteristics – 5.9 gallon capacity – They advertise 37 acres per load – This equates to 0.16 GPA – label violation – To meet Fungicide label, 3 acres per load

•  Droplet size of 20-100 microns – Not able to meet Fungicide label requirement – 100 microns or less is considered driftable fines

Requirements for Aerial Product Registration •  Drift modeled in AgDRIFT includes these variables

– Droplet size – Gallons per acre – Vortice models for existing fixed wing aircraft and helicopters

•  Droplet size data in AgDRIFT based on wind tunnel testing at USDA-ARS Aerial Application Technology Unit

•  AgDRIFT output data used to access risk of aerial applications

•  Used to decide whether aerial label is issued and what label restrictions are required

Data Collection needs for UAS •  UAV specific – all existing data based on manned single rotor •  Many UAV are multi-rotor and much lighter •  Spray Drift Task Force level study to collect data •  Droplet size

– Efficacy – field trials needed to verify efficacy – Drift

• Spray droplet spectrums measured in aerial wind tunnel • Field trials to physically measure drift • Model in AgDRIFT • Field trials and AgDRIFT models must be specific to UAV

Data Collection needs for UAS •  GPA – need efficacy and drift data similar to droplet size •  Weight – UAS are considerably lighter than manned

agricultural aircraft; weight effects downwash which effects efficacy and drift

•  Need full integration of UAS aircraft into the AgDRIFT models

•  Determination of appropriate AEZ •  Visual assessment of drift – swath width of UAS ¼ of

manned aircraft – need 4 passes and drift plumes required to match 1 pass manned aircraft

Mixing and Loading Impacts

•  More refills due to small tank size – 100 acre field @ 2 GPA – 500 gallon manned ag aircraft – 1 load – UAV with 5.9 gallon payload – 34 loads

•  Mixing and loading done in field, not contained load site •  More people on site – observer and pilot •  Increased concentration of spray and greater exposure risk

American National Standards Institute •  American National Standards Institute’s (ANSI) Unmanned

Aircraft Systems Standardization Collaborative (UASSC) - created to facilitate integration of UAS into NAS

•  Recently released standardization roadmap for UAS identified gaps in existing standards and specifications

•  4 identified for UAS conducing aerial applications – Communications – Treatment Efficacy – Operational Safety and Environmental Protection – Airspace Integration

Moving Forward

•  Complete studies to gather required data •  Model UAV drift and incorporate into AgDRIFT •  Verify efficacy •  Decide how to classify UAV used for aerial applications:

– Aerial application as currently understood and thus follow existing label aerial instructions?

– New type of aerial application method with its own label section?