Extended-range agri-drone wouldn't be limited by batteries
While crop-spraying drones do have some advantages over full-size piloted aircraft, they're limited by their battery range. Dutch startup Drone4Agro is developing a solution to that problem, though, in the form of a range-extended electric multicopter.
Typically, pure-electric crop-spraying drones have a battery life of no more than about 30 minutes per charge. This means that they have to periodically stop spraying and return to their base for a battery-change. Additionally, in order not to use up their batteries too quickly, they don't carry particularly heavy loads of pesticide or fertilizer – this means that frequent refills are required.
As an alternative, Drone4Agro has built a prototype multicopter that's 6 meters wide (19.7 ft), has 16 propellers/motors, can carry up to 50 liters of liquid, and incorporates a Loweheiser 2-stroke electronic fuel injection engine coupled to an electric generator. That generator in turn provides power to the props' electric motors.
According to the company, the aircraft should require refuelling approximately once every five flights. There's currently no word on when it may be commercially available.
You can see the prototype in action, in the following video.