Flight height and speed — two numbers that decide whether spray reaches the crop or drifts away

New drone users often think that flying higher gives a wider spray swath and finishes the job faster, which is only half true.

What flying higher gains and loses

The swath does get wider, but the downwash from the propellers spreads out before it reaches the crop, so droplets stay in the air longer. The result is more drift out of the field, more evaporation in hot weather, and less penetration into the canopy.

Flying too low has problems too

The swath gets narrower, more passes are needed, and downwash that is too strong may flatten plants or bruise leaves, especially young plants or plants with soft stems. There is also a risk of hitting obstacles you cannot see.

Flight speed is tied directly to rate per rai

If the nozzle flow rate is constant, flying faster means proportionally less product per area. Flying twice as fast without adjusting anything gives you only half the dose.

Most newer drones adjust the flow rate to the speed automatically, but this system only works within a certain range. If you fly faster than the pump can supply, the system cannot deliver the set amount, and there is often no clear warning.

What to do before starting real work

Set the volume per rai you planned, then make a short test flight to see whether the tank level drops as calculated. If it does not match, something is wrong, such as worn nozzles, a weak pump, or settings that are not what you think they are.

Record the settings used in each field

Record the height, speed, volume per rai, nozzle type and wind conditions that day. Over many jobs you will see a pattern of which settings work best for which kind of field, which is worth more than just remembering the standard values from the manual.
Important note
This article explains general principles. It is not a recommendation for any specific chemical. Suitable mixing rates and timing differ by substance, crop, growth stage and field conditions. Always treat the product label as the authority, and ask our staff or an agricultural specialist before deciding.