so we've had the t40 running for about 4 months now and overall its been good but we keep running into problems when theres any kind of crosswind, even moderate stuff like 8-10 mph. the drift off the spray pattern is way more than i expected given that the rotor wash is supposed to help push the droplets down into the canopy. been adjusting flight height and speed but still not happy with the coverage on the downwind edge of each pass.

running it on soybeans mostly, current settings are around 1.5m flight height above canopy and 6m/s forward speed with the default nozzle config that came with it. not sure if its a nozzle selection problem or if i need to tweak the ab line spacing to account for the drift or both. manufacturer reps have been kinda vague about it when i ask so figured id ask here where people actually use the thing in real conditions.

8-10mph is definitely pushing it for any aerial spray application honestly, thats not really a t40 problem thats just physics. most guidelines I've seen put the cutoff around 10-12 kph for ag spraying from drones specifically because of drift regardless of rotor downwash. the downwash helps but it doesnt overcome meaningful crosswind at those speeds.

that said if you want to keep flying in those conditions you'd want to go lower droplet size nozzles which sounds counterintuitive but the smaller droplets actually get pushed down faster by the rotor airflow before they have a chance to drift sideways ? some guys swear by the hollow cone nozzles for that. also tightening your track spacing helps compensate for drift but youre burning more passes obviously. ive also heard of people adjusting the boom angle slightly into the wind on the downwind side but that gets complicated fast.

we had similar headaches with ours early on. ended up dropping flight height to like 1.2m and slowing to 4.5m/s in anything over 7mph wind and that helped quite a bit. also switched to a coarser droplet nozzle because we were getting too much fine mist at higher pressure ? ironically the finer droplets were drifting more even though you'd think they'd penetrate better. might not be your issue but worth checking what your actual droplet spec is coming out of those nozzles under your current pressure settings. the t40 app logs are kinda useless for this so we ended up just doing water sensitive paper tests in different conditions which felt old fashioned but actually showed us exactly what was happening.