There are plenty of flying objects more energy efficient than quadcopters. Quadcopters are actually very inefficient. They brute force flying using thrust and w

There are plenty of flying objects more energy efficient than quadcopters. Quadcopters are actually very inefficient. They brute force flying using thrust and with enough thrust anything will fly. The big advantage they have is maneuverability and mechanical simplicity. Quadcopters can move in any direction and can hover in place. Quadcopters do not need control surfaces or variable pitch props. All they need is 4 motors with 4 basic props and everything is done electronically in software.