The technology has improved rapidly. We got a DJI Argus T30. It has almost an 8-gallon tank and claims to cover up to 40 acres per hour. We hope to get 25 ac/hour but time will tell. We did inter seed a little clover into a small pasture a month ago and it seems to work well. We don't intend it to replace a sprayer. It's main purpose will be fungicides and cover crops. The dry tank holds around 70 pounds of seed so should be able to cover a few acres with just switching battries each 7 minutes or so. Flight time is 8 minutes per battery and they recharge in about the same amount of time. It came with 3 batteries.