In the very simplest terms, the wing foil itself has to be pitched up to the approaching air to generate lift. Separate the angle of flow into the horizontal and vertical components. The horizontal component is the wing's speed and makes drag, and vertical could be said to be the amount of air needed to deliver the lift. Now take the two wings of a turning aircraft. The same amount of air must be coming up vertically to each wing, but one is travelling faster. Recombine the two sets of vectors for each wing.
Last edited by boguing; 29th Oct 2021 at 18:48.