How does a change in air density affect the required thrust to maintain level flight at a constant airspeed?

Air density significantly impacts the thrust required for level flight at a constant airspeed. Air density is the mass of air per unit volume; lower air density means fewer air molecules are present in a given space. Thrust is the force that propels the UAV forward, counteracting drag. To maintain level flight, the lift generated by the UAV's wings (in fixed-wing aircraft) or rotors (in multirotor aircraft) must equal the weight of the UAV, and the thrust must equal the drag. When air density decreases, the lift generated ....