Well, I can only speak to the drone I have, as it’s the only one I’m familiar with. It holds 13.5 gallons. It sprays at 31mph at a width of 28 feet at a height of 10 feet. Droplet size is up to your discretion and is easily set from the app. Larger droplets equals less drift. As with any method of spraying you’ll want to have an idea as to the recommended droplet size for what you are doing. Based on the height, droplet size and speed of application I can’t see how drift would be as much as an airplane or helicopter.
My drone (all drones as far as I know) use an app. The app will use satellite imagery. Setting field boundary can be as easy as setting points and connecting dots on the screen. Or you can take your controller around the field and push a button to make the dots that the app will connect for you to form the boundary. Spraying the field is a matter of sliding a button on the screen to send the drone to work. It figures out the best pattern and the most efficient way to go about it. When it is low on product it automatically returns to where it came from at which point you reload product and switch batteries.
This fall was my first go at it, and it was surprisingly easy to get the hang of. Took me less time to figure out than my little old self propelled Spra-Coup