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WC Mn/Dakotas | I watched the videos and some rantizo and dji ones also. Here is what I see. I see about 6 rows of corn moving from down draft. At 30" corn that is 15 ft swath for corn fungicide at tassel. That aircraft is 3-5ft off canopy which looks good, but I don't think is going 7-8 m/s like advertised as max spray speed (and used to calculateacres per hour productivity), I think it is going much slower. Flying faster or higher and you would lose that good downdraft pattern because it is getting alot of that downdraft from more of a hover flight than a forward flight. Now if you are spraying basically bare ground, low vegetation (up to v5 corn) you could fly higher/faster and maybe get 20 ft swath. Remember this is a plane not a ground rig, so the swath is wider than the boom as downdraft moves down and out and is going to taper off on the ends unlike a groundrig. The effective swath is something less than the tapered width. The tapered ends need to be overlapped to be considered part of the effective swath. So yes you could fly 8 m/s and 3 m (15ft) high and take a 20ft+ swath, but if you want to do quality work you need to fly lower, slower, and narrower in a canopy situation. You can see on my 1st pic the swath looks like a mountain, then the black dashed box is the effective swath
The second video you linked where the guy checked 60 ft (3 passes) and is in love with his coverage is what I'm referring to as getting a real pattern test done over a string and with those water sensitive cards and having it computer analyzed like we do with full sized planes. I will attach a 2 gpa analysis that I did last year for comparison (I'm not saying it is as good as it should be either, just for reference)
It's hard to tell on just a video, but the droplet spectrum on those cards looked terribly huge droplets that are prone to shearing and creating fines or bouncing and rolling off the leaf and onto the ground. I'm guessing those big spots on his card are way above 800 microns compared to the clothes clip. When you look at my 2nd pic of the dye card my big droplets appear much smaller in comparison. My big droplets measure 550-600 microns and those are bigger than I want to see. I was running old worn tips at time of test and went to new ones because of this test. My spectrum ranged from vd(0.1)= 210 to vd(0.9)=551 with an avg video = 392 and that is bigger than I like to see (we may have had a little higher rate of drift control product than normal that may have been part of larger droplets too). But the amount of too big droplets and the amount of <200 microns tells me there is tip wear.
Now all these pattern tests can be influenced by where boom is placed in the downdraft, the angle of the tip to the direction of flight, the pressure, the airspeed, the viscosity of the product your applying, the number of nozzles, are the wings level or flipping up/down and on and on. This guy indicated he was spraying at less than 5 mph, but how often do you get that? When the wind increases, it will change your pattern. The more you try to stretch the pattern by stretching the boom and swath, the more your pattern gets negatively affected. Those tapered ends will now flip back over on itself on the upwind side and stretch out 2-3x on the downwind side. Or if you go upwind/downwind without flow control or ground speed control your changing rate per acre and psi. A drone may have some advantage here if speed is gps based and pressure is electrically driven. If that is the way they work you would want to spray upwind/downwind and avoid a crosswind. So programming the drone to fly in whatever direction the wind is blowing would be a big deal.
Imho, every spray job is the same it's just a herbicide job is more obvious. If you can do a good job applying herbicide and get confidence in your skills then you can spray anything and do a good job. Fungicide is way more critical than most give it credit for. If you can't do herbicide, I would say you can't do a good job at anything else, difference is you just can't see it as easily.
Good luck with your venture. Keep us posted.
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 20210504_174831 (full).jpg (62KB - 384 downloads)
20210504_170610 (full).jpg (83KB - 419 downloads)
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Photo of Rantizo spray drone
