Power, Energy, and Communication

The Weight Budget

You are designing a delivery drone. The total takeoff weight your motors can handle is 25 kg. The airframe, motors, and propellers weigh 8 kg. The payload (a package) weighs up to 5 kg. The cameras, LIDAR, flight computer, and electronics weigh 3 kg. That leaves 9 kg for batteries.

At current lithium-ion energy densities (roughly 250 to 270 Wh/kg for the best commercially available cells), those 9 kg of batteries store about 2,300 Wh of energy. Your drone’s motors consume approximately 800 W in cruise. Simple division: you get about 2.8 hours of flight time. If you need to fly into a headwind or carry a heavier package, that number drops.