hover – v. to stay up in the air but without moving anywhere

autonomous – adj. independent and having the power to operate automatically without human involvement

blade – n. an arm of a propeller that spins to lift an aircraft off the ground

joystick – n. a handle used to control movements of a computer game, machine or aircraft

shadow – n. a dark shape that appears on a surface when someone or something moves between the surface and a source of light

achieve – v. to succeed in doing something

indicate – v. to show that something exists or is likely to be true