been having a recurring problem with the T40 on flat terrain, getting visible overlap stripes in some fields that are just dead obvious once the crop gets a bit bigger. im running the standard flat fan nozzles, wind was pretty calm both times this happened, and i had the AB lines set up correctly as far as i can tell. route planning was done in DJI Agras app and the boom width was set to match. its not every field, maybe 3 out of the last 15 or so jobs but thats enough to be annoying and the farmer on one of them was not happy at all.

my first thought was that the boom width setting was slightly off because even a few centimeters off across the whole field adds up, but ive double checked it multiple times now. wondering if its a GPS drift thing or if maybe the flow rate calibration is contributing somehow. anyone run into this on the T40 specifically or even the T30 since the systems are pretty similar

had somthing similar on the T30 last spring. turned out my RTK base station wasnt getting a solid fix before i started the mission, i was being impatient and launching like 3 minutes after setting up the base. once i started waiting for a proper fix the overlap issue basically went away on its own. might not be your problem but worth ruling out if youre not already super careful about that warmup time

flow rate calibration is usually the last thing people think to check but it can absolutely create that stripe effect if youre slightly under-applying on the edges of each pass. the visual overlap you see in crop damage isnt always about GPS positioning, sometimes its chemistry concentration variation and it just looks like mechanical overlap. i'd recalibrate the flow sensors and run a clean spray test on pavement or tarps before blaming the route planning.

also what nozzle angle are you running and at what height above canopy? if height varies even a little with terrain following on flat ground ? and flat ground sometimes isnt as flat as it looks ? your effective swath width changes. T40 terrain following works well but ive seen it get twitchy near irrigation berms and stuff like that