DJI Agras Tutorial: Agricultural Drone Basics & Operation Guide (FAA Part 137)

Updated September 9, 2026

Agricultural drones look complex because flight control, positioning, propulsion, obstacle sensing, spraying, spreading, networking, and mission planning all operate at the same time. The fastest way to understand a DJI Agras aircraft is to stop thinking of it as one machine and start thinking of it as a group of coordinated systems.

This Ares Acres guide uses the DJI training video below as its procedural spine, then expands the lesson with operator context, current DJI specification references, U.S. regulatory considerations, troubleshooting logic, and practical preflight checks. It is written for pilots, fleet managers, technicians, applicators, and new agricultural-drone operators who want to understand what the aircraft is doing rather than simply memorize button presses.

For additional training, browse the Ares Acres DJI Agriculture Tutorials, shop DJI Agras OEM parts, review DJI Agras accessories, or explore the complete Ares Acres product catalog.

Watch the DJI Agras Agricultural Drone Basics Tutorial

If you prefer to learn visually first, watch the original training video and then use this article as the detailed reference.

Open the original video on YouTube.

What You Will Learn

• The three major functional groups of an agricultural drone.
• How DJI Agras Mode 2 control-stick inputs translate into aircraft movement.
• Why smooth stick inputs and correct antenna orientation matter.
• How the remote controller connects to the internet and how controller-to-aircraft linking works.
• How the battery, ESCs, motors, and CW/CCW propellers work together to create controlled flight.
• How GNSS, RTK, compass heading, radar, obstacle sensing, and terrain following support automated operations.
• How the T40/T20P centrifugal or dual-atomized spraying architecture moves liquid from tank to crop.
• Why flow measurement and weight sensing affect application accuracy and refill planning.
• How droplet size changes coverage, evaporation, and drift risk.
• Where FAA Part 137 fits into U.S. agricultural-drone spraying operations.

1. The Three Main Systems of a DJI Agras Agricultural Drone

The training video divides the aircraft into three broad parts: the remote controller, the aircraft or flying platform, and the spraying or spreading system. That is a useful mental model because nearly every operation can be traced back to one of those groups.

The key point is that the controller does not physically make the drone fly or spray. It sends commands. The aircraft flight-control system interprets those commands and coordinates propulsion, positioning, sensing, and payload output.

2. DJI Agras Remote Controller Basics

Most manual flight commands are entered through the two control sticks. The video demonstrates both one-finger and two-finger techniques and uses one-finger operation as the simpler training example. With a conventional thumb grip, the pilot places the thumb pad on each stick while the remaining fingers support the controller.

Mode 2 Stick Mapping

The video explains the controls using Mode 2, the most common configuration. If your controller uses another stick mode, the mapping will differ, so verify the selected mode before takeoff.

The training video also demonstrates a combined-stick command to unlock or start the motors. Do not assume a gesture shown for one Agras generation is universal. Before operating a different model or a different controller configuration, confirm the motor-start/stop procedure in that aircraft's current manual and in-app prompts.

Why Smooth Stick Control Matters

An agricultural drone is often heavier than a camera drone, especially with a full liquid or granular payload. Abrupt manual inputs can create unnecessary pitch and roll changes, increase workload, disturb spray deposition, and reduce the pilot's margin near obstacles. Smooth inputs also make it easier to distinguish a real aircraft response problem from pilot-induced oscillation.

For broader preflight training, see the DJI T100 Drone Safety Tutorial.

3. Remote Controller Antenna Orientation

The controller-to-aircraft command link depends on the antennas. The video emphasizes a common RF principle: do not point the antenna tips directly at the aircraft. The strongest transmission region is generally broadside to the antenna rather than directly off the tip.

In practical terms, orient the antennas so their broad transmitting surfaces face the operating area and maintain clear line of sight whenever possible. Avoid shielding the antennas with your body, a vehicle, metal structure, or other equipment. If signal quality begins to fall, do not simply continue farther away; correct your position, orientation, and operating geometry.

4. Internet Connectivity: SIM Dongle vs Wi-Fi

The training controller can connect to the internet through a cellular dongle with a SIM card or through Wi-Fi. Internet service supports cloud-connected functions such as field synchronization, downloading or uploading operational data, task management, map resources, and firmware workflows.

The aircraft's direct command-and-control radio link is a separate concept from internet access. Losing cellular service does not automatically mean the controller has lost its radio link to the aircraft, but cloud-dependent or network-dependent features may become unavailable.

The video recommends Wi-Fi for data-heavy jobs such as firmware downloads or transferring batches of fields and tasks when cellular data is limited. That remains sensible fleet practice: perform major updates on a stable connection before arriving at a field whenever possible.

5. How to Link a DJI Agras Remote Controller to the Aircraft

New aircraft are generally delivered already linked to the supplied controller. Linking becomes necessary when a controller is replaced, changed, or otherwise no longer paired with the aircraft.

The training video demonstrates the following sequence:

1. Power on the equipment and enter Settings on the remote controller.
2. Open the Remote Controller interface.
3. Select Link. The controller begins emitting an audible linking tone.
4. With the aircraft powered on, press and hold the aircraft battery power button for approximately five seconds as demonstrated in the video.
5. The battery indicators flash alternately while linking is active.
6. When the controller emits the completion beeps and the aircraft/controller interface confirms connection, linking is complete.

If Linking Fails

• Confirm both controller and aircraft have adequate battery power.
• Move the controller closer to the aircraft and away from strong RF interference.
• Confirm the controller is actually in linking mode before starting the aircraft-side sequence.
• Check whether the controller or aircraft is already linked to another device.
• Restart both units and repeat the sequence once, deliberately, rather than repeatedly pressing buttons.
• Check for firmware compatibility if the controller or aircraft was recently replaced or repaired.

6. Propulsion System: Battery, ESC, Motor, and Propeller

A multirotor agricultural drone generates lift through a coordinated propulsion chain:

Battery → ESC → Motor → Propeller → Thrust

The intelligent flight battery supplies electrical energy. Each electronic speed controller, or ESC, meters power to its motor. The motors rotate the propellers. The flight controller continuously changes individual motor speeds so the aircraft can climb, descend, yaw, pitch, roll, hover, and track a route.

How a Multirotor Changes Direction

The aircraft does not need airplane-style control surfaces. Instead, it creates a thrust imbalance. As the video explains, if the motors on one side generate more thrust while the opposite side generates less, the aircraft tilts and accelerates laterally. The flight controller performs these adjustments continuously.

This is why a problem that appears to be a motor problem may actually originate elsewhere in the propulsion chain: an ESC, connector, battery, damaged propeller, installation error, motor bearing, control signal, or physical obstruction can all change thrust.

7. Intelligent Battery Behavior: Self-Discharge and Cold Weather

The video highlights two characteristics of lithium-based intelligent flight batteries that every fleet operator should understand.

Smart Self-Discharge

Leaving a lithium battery at a full state of charge for extended periods is undesirable. DJI intelligent batteries therefore use managed storage behavior that can reduce charge after the battery has remained unused for a period. During that process, the battery enclosure may feel warm because stored electrical energy is being dissipated.

Do not confuse expected managed self-discharge with every case of unexpected heating. Abnormal odor, swelling, physical damage, extreme heat, liquid contamination, connector damage, or error messages require the battery to be removed from service and evaluated according to the current battery manual.

Cold-Temperature Performance

Low temperatures reduce electrochemical performance. The training video notes that both charging and discharging capability decrease in cold conditions and charging can take longer. A cold battery may also be less able to support sudden high-current demand during takeoff or heavy-payload flight.

For fleet-level battery care and troubleshooting, read the DJI Agras Battery Fleet Management Guide and browse DJI Agras OEM replacement parts.

8. CW vs CCW Propellers: Why Rotation Direction Matters

Multirotor aircraft use opposing propeller rotation directions to balance torque. The training video explains that a portion of the propellers rotate clockwise (CW) and the others counterclockwise (CCW). The propeller type must match the intended motor position.

Before installing or replacing a propeller:

• Verify the correct CW or CCW propeller for the motor position.
• Match the propeller markings to the aircraft/motor markings.
• Inspect the blades, hub, fasteners, folding joints, and mounting surfaces.
• Remove contamination that could prevent the propeller from seating correctly.
• Never install a cracked, bent, delaminated, chipped, or otherwise damaged propeller.
• After service, rotate the assembly by hand only when the aircraft is safely powered down and the manual permits the inspection.

9. GNSS: The Foundation of Hovering and Autonomous Routes

Satellite positioning allows the aircraft to determine its position and support stable hovering and automated route execution. In the video, the operator is told to verify a healthy green flight-status indication before flight. The exact status colors, icons, and wording can differ by Agras generation, so the operational principle is more important than memorizing one display state: do not launch until the controller indicates the positioning and flight-control state required for the planned operation.

GNSS by itself provides useful positioning, but agricultural operations often demand more repeatability than ordinary standalone satellite positioning can provide. That is where RTK becomes important.

10. RTK: Centimeter-Level Agricultural Positioning

RTK, or Real-Time Kinematic positioning, uses correction data to greatly improve GNSS accuracy. With a valid RTK fix and appropriate correction source, agricultural drones can achieve positioning precision suitable for repeatable swaths, field boundaries, row work, mapping, and other precision-agriculture tasks.

DJI's published T20P specifications list hovering accuracy with RTK enabled at approximately ±10 cm horizontally and ±10 cm vertically under strong GNSS conditions. That number is a model-specific published specification, not a promise that every field environment will produce the same result.

The two mushroom-shaped RTK antennas visible on many T-series aircraft do more than receive correction-capable satellite signals. Dual-antenna geometry can also support heading determination. The training video explains that this directional function helps flight accuracy and increases resilience where magnetic-compass information is less dependable.

RTK Orientation vs Compass

The video instructs operators that if RTK orientation is disabled, the aircraft may rely more heavily on the compass for heading and the compass should be calibrated as required. In practice, do not calibrate a compass routinely without reason; follow the aircraft's prompts and current manual. Calibration should be performed in an appropriate environment away from large metal structures, vehicles, power infrastructure, magnets, and other sources of magnetic interference.

For a deeper positioning workflow, see the DJI T100 D-RTK 3 Calibration Tutorial.

11. Radar, Obstacle Sensing, and Terrain Following

The agricultural-drone radar system emits and receives radio-frequency energy to estimate the location of terrain and obstacles around the aircraft. Depending on model and configuration, radar and vision systems can support obstacle sensing, obstacle bypassing, altitude control, and terrain following.

The downward sensing system is particularly important in crop operations because the objective is often to maintain a relatively consistent height over the crop or terrain even when the ground elevation changes.

As a current model reference, DJI publishes for the T20P active phased-array omnnidirectional radar a horizontal sensing distance of approximately 1.5–50 m, a 360° horizontal field of view, and terrain-follow capability with a maximum slope specification of 30° in Mountain mode. These are T20P reference specifications and should not be copied to another Agras model without checking that model's manual.

12. The DJI Agras T40 / T20P Spraying System

The training video uses the DJI Agras T40 and T20P to explain a centrifugal, dual-atomized spraying architecture. At a high level, the liquid path is:

Tank → Filter → Flow measurement → Pump → Atomizing sprinkler → Crop

Each component has a distinct job. The tank stores the spray mixture. The filter helps prevent contaminants from reaching the pump and atomizer. The impeller pumps move liquid through the system. The centrifugal sprinklers break the liquid into droplets for application.

Current T20P Published Reference

DJI's current T20P specification page lists a 20 L spray tank, two LX8060SZ atomized sprinklers, a maximum pump flow of 6 L/min × 2, and a published droplet-size range of 50–500 μm. DJI's T20P FAQ currently lists a sprinkler-speed range of 8,000–16,000 rpm and a droplet range of 50–300 μm. Because those two official DJI pages are not perfectly aligned, operators should use the current aircraft interface, current manual, installed sprinkler hardware, firmware, and chemical label rather than treating any single historical RPM-to-droplet table as universal.

Official reference: DJI Agras T20P specifications.

13. Flow Meter: Measuring What the Aircraft Actually Applies

The training video identifies the flow meter between the tank and the pump system. Its purpose is to measure actual liquid movement so the aircraft can regulate application more accurately.

This matters because a spray mission is not simply pump on or pump off. The system is trying to match target application rate while flight speed, route geometry, pump output, sprinkler behavior, and remaining liquid change.

If measured flow no longer matches expected output, possible causes include:

• Clogged filters or restricted plumbing.
• Air in the liquid path.
• Pump wear or pump malfunction.
• Incorrect calibration.
• Flow-meter contamination or sensor error.
• Leaks or loose fittings.
• Incorrect liquid properties or mixture behavior.

Do not compensate for a suspected flow problem simply by increasing application settings. Diagnose the cause before returning the aircraft to treatment work.

14. Weight Sensors: More Than an Empty-Tank Alarm

Weight sensors help the aircraft estimate remaining liquid or spreading material. The training video highlights three operational benefits:

• Recognizing when the tank or hopper is approaching empty.
• Providing the signal used for empty-tank/material alerts.
• Predicting when a refill will be required so route execution and battery use can be planned more efficiently.

That predictive function is important in commercial operations. A good refill plan reduces unnecessary deadhead flight, avoids beginning a pass that cannot be completed, and helps the crew coordinate batteries, mix/load activity, and aircraft turnaround.

15. Centrifugal Sprinkler RPM and Droplet Size

In a centrifugal atomizer, rotational speed is one of the variables affecting droplet formation. The training video teaches the simple relationship that higher sprinkler speed generally produces finer droplets, while lower speed produces coarser droplets.

The video gives historical training examples of approximately 6,500 rpm producing an average droplet size around 140 μm and 14,000 rpm producing an average around 60 μm for the configuration shown. Do not treat those two values as universal T40/T20P calibration points. Current DJI-published ranges differ, and real droplet spectra depend on the installed hardware, liquid properties, flow rate, firmware/control logic, and operating setup.

Why Finer Droplets Can Increase Coverage

At the same application volume, dividing liquid into smaller droplets creates a larger number of droplets. That can improve surface coverage and may be desirable for certain insecticide or fungicide applications when the chemical label, crop, canopy, and environmental conditions support that droplet category.

Why Finer Droplets Increase Drift and Evaporation Risk

Small droplets have lower mass and a higher surface-area-to-volume ratio. They decelerate more quickly, remain airborne longer, and are more easily carried away by wind. They are also more vulnerable to evaporation before reaching the intended target. That means a setting that improves coverage can simultaneously increase off-target movement.

The training video suggests medium droplets for ordinary field work in summer, coarser droplets for herbicide/weeding work, and finer droplets for some fruit-tree operations. Treat those as general training concepts, not a replacement for the pesticide label.

16. Droplet Size Is Only One Part of Drift Management

Operators should not reduce drift management to a single coarse-vs-fine setting. Off-target movement is affected by the interaction of:

• Droplet spectrum.
• Wind speed and wind direction.
• Temperature and relative humidity.
• Temperature inversions.
• Aircraft height above the target.
• Flight speed.
• Application rate and pump flow.
• Sprinkler/nozzle configuration and rotational speed.
• Crop canopy and target geometry.
• Chemical formulation and adjuvants.
• Nearby sensitive crops, waterways, people, animals, roads, and property.

A technically functioning drone can still make a poor application if the environmental and label conditions are wrong.

17. FAA Part 137: Where Agricultural Drone Spraying Fits in the U.S.

In the United States, FAA rules for agricultural aircraft operations matter because dispensing chemicals or agricultural products from an aircraft is not merely a normal camera-drone mission. The FAA states that 14 CFR Part 137 governs aircraft, including drones, used to dispense or spray substances.

FAA operating authority is only one layer. Depending on the aircraft and operation, a commercial agricultural drone operator may also need the applicable remote-pilot credentials, aircraft registration, Part 137 agricultural-aircraft operator certification, an FAA exemption or other authority for aircraft/operations outside standard small-UAS rules, and the applicable Certificate of Waiver or Authorization. Larger Agras aircraft commonly require authority beyond ordinary Part 107 operating limits.

Current FAA reference: Dispensing Chemicals and Agricultural Products (Part 137) with UAS.

18. Practical DJI Agras Preflight System Check

Use the aircraft's model-specific checklist and manual first. The following is a system-oriented training checklist that helps connect the concepts in this guide.

19. Common Operator Mistakes

Mistake 1: Learning stick directions but not checking the selected stick mode

A pilot can memorize Mode 2 perfectly and still make the wrong input if the controller has been configured differently. Verify stick mode before flight.

Mistake 2: Pointing antenna tips at the aircraft

The video explicitly warns against using the antennas like pointers. Maintain appropriate broadside orientation and line of sight.

Mistake 3: Treating internet connectivity as the aircraft control link

Cellular/Wi-Fi connectivity and the aircraft's radio command link serve different functions. Understand which feature is actually failing before troubleshooting.

Mistake 4: Assuming a warm stored battery is automatically defective

Managed self-discharge can generate warmth. But do not normalize swelling, extreme heat, odor, damaged connectors, or battery errors.

Mistake 5: Installing a propeller by appearance alone

CW and CCW positions matter. Confirm markings and motor position every time.

Mistake 6: Assuming RTK means positioning can never fail

RTK requires valid correction data, sufficient satellite geometry, healthy antennas, and a proper fix. Monitor status rather than assuming accuracy.

Mistake 7: Depending on obstacle sensing to see every wire or branch

Sensing systems reduce risk but do not eliminate the pilot's responsibility for site survey and separation.

Mistake 8: Using a historical sprinkler RPM value as a universal droplet calibration

DJI specifications, firmware, sprinkler hardware, liquid properties, and settings vary. Use the current system and chemical label.

Mistake 9: Selecting the finest droplet because coverage looks better

Coverage is only one objective. Drift, evaporation, target crop, chemical label, weather, and nearby sensitive areas may require a coarser spectrum.

20. Troubleshooting by System Instead of by Symptom

Agricultural-drone troubleshooting becomes much faster when you identify which subsystem could produce the symptom.

21. Frequently Asked Questions

What are the main parts of a DJI Agras agricultural drone?

At the training level, think of three groups: the remote controller, the flying platform, and the spraying/spreading payload system. Each group contains several subsystems.

What does the left stick do in Mode 2?

Left-stick up/down controls vertical movement; left/right controls yaw or aircraft heading rotation.

What does the right stick do in Mode 2?

Right-stick up/down commands forward/backward movement, and left/right commands lateral movement.

Should I point the controller antennas directly at the drone?

No. The training video warns that pointing the antenna tips directly at the aircraft can create weak signal geometry. Keep the transmitting surfaces properly oriented toward the operating area and maintain line of sight.

Do DJI Agras controllers need cellular service to fly?

The controller-to-aircraft command link is distinct from internet service. Cellular or Wi-Fi is used for network-dependent functions such as field/task synchronization, firmware, and cloud data. Check the exact model and workflow for offline limitations.

Why does a fully charged DJI Agras battery lose charge while stored?

Intelligent batteries may deliberately self-discharge toward a safer storage state after a period of inactivity. The timing is model/firmware specific.

Why are there CW and CCW propellers?

Opposing rotation directions balance reaction torque and are part of how a multirotor maintains stable yaw control. Each propeller must be installed on its correct motor position.

What is the difference between GNSS and RTK?

GNSS provides satellite positioning. RTK adds correction data to improve positioning accuracy dramatically, commonly into the centimeter class under good conditions.

Does radar guarantee obstacle avoidance?

No. Radar and vision are assistance systems with environmental and geometric limitations. Site survey, visual awareness, speed management, and separation remain essential.

What droplet size should I use for herbicide?

Use the droplet category and operating limitations required by the pesticide label. The source training video strongly cautions against fine and extra-fine herbicide droplets because they increase drift and phytotoxicity risk.

Does FAA Part 137 apply to drone spraying?

Yes. The FAA states that Part 137 governs agricultural aircraft operations involving dispensing or spraying substances, including drone operations. Additional FAA authority can be required depending on aircraft weight and operating profile.

22. Build the System Knowledge Before You Build Speed

The most important lesson from this training video is not a particular button sequence. It is the relationship between systems. The controller tells the aircraft what to do. The flight controller combines pilot input with positioning and sensor data. The battery and propulsion system create the force required to move. Radar and RTK improve awareness and precision. The spray system meters and atomizes the product. All of those systems must work together for a safe, accurate agricultural application.

For operators trying to become faster, the best path is to become more systematic first: know what each component does, know what status confirms it is healthy, and know which subsystem to investigate when the aircraft behaves unexpectedly.

Related Ares Acres DJI Agras Resources

• DJI Agriculture Tutorials
• DJI T100 Drone Safety Tutorial
• DJI T100 D-RTK 3 Calibration Tutorial
• DJI T100 Flight Tutorial: Plot Multiple Fields and Program Autonomous Flights
• DJI Agras Battery Fleet Management Guide
• Agricultural Drone Spraying Efficiency Guide
• Shop DJI Agras OEM Parts
• Shop DJI Agras Accessories
• Browse the Ares Acres Product Catalog
• Contact Ares Acres

Ares Acres is an independent agricultural-drone parts and technical-resource provider. DJI product names and specifications are used for identification and operator education. Always verify current DJI documentation and regulatory requirements before flight or chemical application.