This document summarizes a project testing the use of unmanned aircraft for spraying specialty crops. Key findings include: - Testing showed unmanned aircraft can spray vineyards and orchards effectively, achieving deposition rates of 12-46 l/ha. However, increasing application rates significantly reduced field productivity. - A Yamaha RMAX aircraft was used, which is suitable for low-volume, small-droplet spraying but its parameters exceeded AGDISP modeling guidelines. - Future work will involve spraying active ingredients to assess efficacy, measuring off-target drift, developing business cases, and pursuing regulatory approval to address permitting and labeling.

1. Unmanned Aircraft
for Agricultural
Spraying of
Specialty Crops
Ken Giles
Ryan Billing
UC-Davis Biological &
Agricultural Engineering
Small Unmanned Systems
Business Expo
July 2013

2. Overview of current project:
- UAV development and deployment in the United States
- Regulatory process
- Commercial availability
- Suitability for specialty crops
- Testing protocol and results
- Future work

3. Overview of current project:
-UAV development and deployment in the United States
Significant interest in the ag sector.
UAV: “Dull, dirty & dangerous”.
(Bob Cabanya, UAS, Inc)
Primarily for inspection, asset tracking.
Hobbyist industry.

4. Overview of current project:
-Regulatory process
No commercial use of UAV’s.
Public agencies can deploy UAV’s via
the COA (Certificate of Authorization)
process.
Current ag spraying R&D project
under UC Davis COA.

5. Overview of current project:
-Regulatory process
Must have pilot and observer with both
passed FAA knowledge test for Private
Pilot and Class 2 Medical Certificates.
Must file NOTAM prior to flight and
notify Air Traffic Control.
Typical line of sight operation, daylight
hours, VFR, > 5 nm from airport.

6. Overview of current project:
-Regulatory process
“Dropping of objects” prohibited.
Conducted a safety analysis of spraying
water and was approved.
Have two operational areas in CA:
Napa grape growing area
Central Valley nut growing area

7. Commercial Product:
RMAX™ –
Yamaha Motor Company.
• 100 kg
• 2-stroke, liquid-cooled,
250 cc, 13.6 kW engine
• 3.1 m rotor diameter
• 16 l liquid capacity
• 3 nozzles (1 or 2 active)
(Fine / Med-Fine cat.)
• 400 m line of sight ops
• 1000 hr life
• Remote control with
visual, not autonomous
operation

8. Specialty Crops:
Small, complex fields
(45° slope)
Limited access during
certain phases of season
Permanent plantings
High value
Season long spraying

9. Specialty Crops:
Napa Valley winegrapes – premium production in Oakville

10. Specialty Crops:

11. Objectives of current project:
- Feasibility of commercial UAV for spraying?
Physical suitability
Spray deposition
Productivity
Key parameters:
l/ha deposit
l/ha applied

12. Spray deposition:
COA allowed only water to be sprayed:
Water sensitive paper for sample medium
13 sample locations
within canopy and
on ground
Analyzed using
Drop Vision AG
(Leading Edge Assoc.)

13. Spray deposition:

14. Application rates & productivity:
Productivity and application rate testing in a Cabernet Sauvignon
block at the Oakville Field Station (UC) in Napa Valley, CA
Forward & downward video
cameras on aircraft
Direct measurement of area
and spray volume discharged
Spray, ferry, refill times
observed.
Local meteorology recorded

15. Test Design:
Due to payload and spray pump constraints on aircraft, only method to
adjust application rate (l/ha) was by swath width and number of passes.

16. Test Results:
Application rates
2.4 m row spacing
13 – 15 km/hr ground speed
2 row swath x 2 passes = 39.03 l/ha
2 row swath x 1 pass = 19.76 l/ha
3 row swath x 2 passes = 29.20 l/ha
3 row swath x 1 pass = 13.99 l/ha

17. Test Results:
Field productivity
0.6 ha test block
61 m length
1 -2 tank loads
2 row swath x 2 passes = 2.02 ha/hr
2 row swath x 1 pass = 3.69 ha/ha
3 row swath x 2 passes = 2.68 ha/hr
3 row swath x 1 pass = 4.50 ha/hr

18. Test Results:
Field deposition

19. Test Results:
Field deposition

20. Test Results:
Field deposition
0.6 ha test block
61 m length
1 -2 tank loads
2 row swath x 2 passes = 46.21 (34.89) l/ha
2 row swath x 1 pass = 12.12 (10.66) l/ha
3 row swath x 2 passes = 15.94 (18.57) l/ha
3 row swath x 1 pass = 2.45 ( 1.77) l/ha

21. Test Results:
Field Deposition
All data means
No trimming

22. Test Results:
Field Deposition
Outliers trimmed

23. Test Results:
Field Deposition
vs. Field Capacity
Outliers trimmed

24. Test Results: Swath Analysis

25. Test Results: Swath Analysis
+ / - 8 m from CL spray cards
Ground speed average 13.3 km/hr
3 m release height
12 replications
Winds 1 – 12 km/hr
+ / - 67°

26. Test Results: Swath Analysis
Winds 23° from left 3.1 m/s

27. Test Results: Model in AGDISP
Many key parameters outside of model limits
Challenges:AGDISP Limit RMAX
Rotor Diameter Min 3.58 m 1.79 m
Boom Vertical Disp. Max -1.80 m -1.00 m
Forward Speed Min 17.88 m/s 3.55 m/s
RPM Max 503 840
Weight 434 kg 100 kg

28. Test Results: Model in AGDISP

29. Test Results: Model in AGDISP

30. Conclusions:
UAV is a feasible spraying alternative to manned aerial application.
The tested platform (Yamaha RMAX™) is a low volume,
small droplet size application.
Increasing application rate volume is challenging and not without
significant decreases in field capacity (work rate).
Flight and vehicle parameters are outside the recommended
ranges for AGDISP inputs.

31. Next Steps:
Will be spraying active ingredients to determine biological
efficacy and performance.
Will develop field measurements of off-target drift.
Will develop business case and grower economics.
Will begin regulatory activities to address permitting and
chemical label constraints.

32. Public acceptance of UAV-based spraying: