A heavier aircraft changes the work its rotors must do.
Begin with force balance
In a basic model, total hover thrust balances weight; acceleration and disturbance rejection need margin. More battery or liquid also changes required thrust. A single endurance number should not be applied to every loading condition.
Position is not canopy clearance
GNSS/RTK positioning, inertial motion sensing and ranging serve different roles. Terrain elevation is not canopy height. Test loss of corrections, obstacle-detection limits and changing clearance on slopes.
Airflow also carries droplets
A 2026 hexacopter study reports that nozzle placement relative to rotor airflow affects deposition and uniformity. Results from one configuration cannot simply be transferred to another aircraft. Evaluate droplets, airflow and crop structure together. Its scope includes CFD and indoor water tests, not general proof of outdoor pesticide efficacy.
Treat full-load departure and return as different conditions
Evaluate full-load takeoff, mid-mission operation and return on one test sheet instead of comparing maximum payload alone. Liquid mass falls while battery charge also falls, so a lighter aircraft does not automatically retain sufficient margin. A short trip over level ground and a long pass down a slope have different return routes to the support point. Our proposed assessment checks current, voltage, temperature and return charge from aircraft logs within the permitted loading envelope. Separate in-flight readings from values that recover after landing. Do not directly convert a single advertised endurance figure into treatment area or delivery range.
Connect flow, speed and width in consistent units
Consider an illustrative water-only calculation: 0.1 liters per second applied uniformly across a four-meter width at five meters per second. Area coverage is 20 square meters per second, giving 50 liters per hectare. This is unit arithmetic, not a pesticide setting; it excludes overlap, turns and startup. Halving speed without changing flow doubles the amount per area. Even automatic flow control needs evaluation during acceleration, deceleration and spray start/stop. Accurate navigation along a line and uniform delivery on both sides of that line are separate outcomes.
Stronger downwash is not automatically better
A 2024 Korean drift-model study identifies wind speed, atmospheric stability, crop height and spraying height as influential. Its abstract reports spatial behavior different from ground spraying, limiting direct transfer of ground models. These findings do not supply a universal safety-distance formula. Our evaluation separates upper-leaf deposition, penetration into the canopy and off-field movement. The same liquid total can have different agronomic meaning depending on where it lands. Treat downwash together with pest location and canopy structure rather than as a standalone performance score.
Correct positioning does not guarantee correct work
Record positioning, canopy clearance and application delivery independently during acceptance testing. A good RTK status cannot correct an outdated field boundary. Confirm whether ranging represents the ground or foliage under the relevant crop and terrain conditions. Evaluate correction loss or communication delay using manufacturer-approved safe tests or log replay instead of forcing failures during pesticide operations. Record whether the system stops, holds or returns, and verify the restart location. This reveals untreated gaps and duplicated application that successful navigation alone would miss.