It seems that multirotors have to be powered by the expensive battery. And the helicopter can use engine and could have much larger load. I’m wondering what’s the advantage of multirotor compared with helicopter in the agricultural UAVs pesticide spraying field? What’s the drawback of helicopter?
I find online that engine vibration is a serious problem to autopilot when the helicopter has a large load and the engine becomes big. But as a newbie to this area, I would think there's a lot of way to reduce the engine vibration so it doesn't look like a problem that can't be solved.