A hover-capable flying machine such as a drone includes a robotic arm extending from the body, and an instrumentality for balancing the machine in response to disturbances such as those caused by picking up and dropping of the payload by the extended robotic arm. In embodiments, the end of the arm is equipped with a balancing rotor assembly that may provide lift sufficient to counteract the weight of the payload and/or of the arm. In embodiments, the machine's power pack is shifted in response to the disturbances. The power pack may be moved, for example, on a rail within and/or extending beyond the machine in a direction generally opposite to the extended arm. The power pack may also be built into a bandolier-like device that can be rolled-in and rolled out, thus changing the center of gravity of the machine.