ok so we finally pulled the trigger on an Agras T40 setup and the first two weeks have been kind of a disaster not gonna lie. not the aircraft itself thats actually solid but getting the flow rate calibration dialed in for different chemical viscosities has been a headache

we were spraying a contact herbicide last week and the application rate was coming out about 15-20% higher than the target according to our post-spray checks and i cannot figure out if its a nozzle thing, a pump calibration thing, or if the onboard RTK is causing the speed variations that are throwing off the rate controller

the dealer just keeps telling us to redo the calibration wizard which we've done like four times now. were running the standard flat fan nozzles it came with, havent swapped to anything else yet. field conditions were pretty calm, wind maybe 3-4 mph so thats not it

anyone with T40 experience have thoughts? like at what point do you just start swapping nozzle types and testing

had almost the exact same issue with our setup, turned out the flow sensor needed recalibration separately from the wizard ? theres a manual flow sensor check buried in the DJI Agras app that the wizard doesnt automatically run and our sensor was reading low which meant the pump was compensating by running higher. took us way too long to find that

also worth checking if the nozzle orifice size matches what the system profile expects, the T40 can be weirdly picky about that

15-20% over is a lot, that kind of variance would make me nervous for anything with a tight application window like a systemic. i'd honestly be tempted to do a straight water calibration pass over a tarp and actually measure what comes out before flying another chem run. dealers are useless for this stuff half the time, they know the aircraft but not actual spray application