Three steps. Step 1, aerofoil: air flows past an aerofoil section from left to right. This is the relative airflow, opposite to the direction the aerofoil moves. A dashed chord line runs from the leading edge to the trailing edge. The angle of attack (AoA) is the angle between the chord line and the relative airflow, and it opens and closes slightly. Step 2, hover: a multirotor seen from the side. Lift acts up and weight acts down through the centre of gravity, and they are equal (L = W). Step 3, forward flight: the multirotor tilts forward, so the rotor thrust tilts and gets longer. Its upward part is still equal to weight and its forward part is thrust. Drag acts rearward, opposite to the motion, and in steady level flight thrust equals drag (L = W, T = D). The Climb button shows lift greater than weight (L > W). The Descend button shows weight greater than lift (W > L). Arrow lengths are schematic. The still frame shows step 3.
