Farm Machinery Training & Testing Institutes Agricultural Drones, Robotics & Automation: practice questions

1 · UAV types and payload · medium

A spray drone battery is a 12S lithium polymer pack (12 cells in series, 3.7 V nominal per cell) of 22 Ah capacity. What is its nominal stored energy?

1. 264 Wh
2. 977 Wh
3. 81 Wh
4. 1,109 Wh

2 · Spray drones: swath, flow rate and application rate · easy

For a spray drone, what is the 'effective swath width'?

1. The widest lane spacing that still gives an acceptably uniform deposit when passes overlap
2. The distance between the two outermost nozzles or atomisers on the spray boom
3. The total width of the visible spray cloud measured from the ground beneath the drone
4. The tip-to-tip span of the rotors, since downwash carries all of the spray straight down inside that width

3 · Spray drones: swath, flow rate and application rate · easy

A spray drone uses rotary (centrifugal) atomisers. What happens to droplet size when the atomiser speed is increased?

1. Only the flow rate changes
2. Droplets become coarser
3. Droplet size does not change
4. Droplets become finer

4 · Spray drones: swath, flow rate and application rate · easy

Why does a spray drone's controller adjust pump flow in step with ground speed?

1. To keep the battery current constant so the flight time can be predicted accurately
2. To keep the droplet size constant whatever the wind speed and direction at the time
3. To keep the tank level constant by drawing liquid only when the drone is cruising
4. To keep the litres applied per hectare constant as the drone speeds up and slows down

5 · Spray drones: swath, flow rate and application rate · medium

A drone spreads granular fertiliser at a metered 6 kg/min over an effective spread width of 7 m at 6 m/s. What rate is applied?

1. 23.8 kg/ha
2. 238 kg/ha
3. 0.04 kg/ha
4. 85.7 kg/ha

6 · Droplet drift from drones · medium

Early on a clear, calm morning the air is still and the crop is wet with dew. Why is this often a poor time for drone spraying despite the calm?

1. GNSS signals are weakest at dawn, so the drone cannot hold its flight line accurately
2. Dew dilutes the spray so much that the label rate is no longer reached on the leaf surface
3. A temperature inversion is likely, trapping fine droplets in a stable layer that can carry them far
4. Still air prevents the rotor downwash from forming, so no spray reaches the crop canopy at all until the wind rises

7 · Droplet drift from drones · medium

Which combination of changes reduces drift from a spray drone most reliably?

1. Raising the rotary atomiser speed so droplets break up and settle before the wind acts
2. Flying higher so the swath widens and fewer passes are needed over the same area
3. A coarser droplet setting with adequate coverage and a lower, still-safe flight height
4. Flying faster so the job is finished before the wind has time to pick up later

8 · Droplet drift from drones · hard

An agronomist wants better coverage for a contact fungicide and asks the drone operator for a much finer spray. The field borders a sensitive vegetable crop downwind. What is the best engineering response?

1. Fly at twice the normal height so the finer droplets spread evenly and land on the fungicide target more slowly
2. Keep the droplet category the label requires, raise volume within the label to improve coverage, and keep a downwind buffer
3. Switch to the finest droplet setting, because the vegetable crop is downwind and drift will move away from the target
4. Spray only when the wind blows towards the vegetables, since that wind direction makes the fine droplets fall faster onto the target crop

9 · Drone regulations (country-specific) · medium

India's Drone Rules, 2021 divide airspace on an interactive map into three types of zone. Which are they?

1. Open, specific and certified zones
2. Class A, Class B and Class C zones
3. Green, yellow and red zones
4. Rural, peri-urban and urban zones

10 · Mechatronic actuators · easy

Why are brushless DC motors almost universal on multirotor drones?

1. Electronic commutation without brushes gives high efficiency, low wear and fine speed control
2. They produce constant torque at all speeds, so propellers need no speed control at all
3. They run on alternating current from the battery, so no electronics are needed onboard
4. They need no controller, because the battery voltage alone sets their speed and direction of rotation