Which factor does not directly affect lift?

Which factor does not directly affect lift?

• A. Angle of attack
• B. Wing area
• C. Air density
• D. Engine horsepower

Answer: (D)

Lift comes from the wing acting on air, and it depends on dynamic pressure, wing area, and how the wing’s shape and angle of attack influence the lift coefficient. The basic relation is L ≈ 0.5 ρ V^2 S Cl, so lift increases with air density (ρ), with the square of speed (V^2), with the wing area (S), and with the lift coefficient (Cl). Cl changes as the angle of attack changes and as the wing design dictates. Increasing angle of attack raises Cl up to the stall, thereby increasing lift for a given ρ, V, and S. Increasing wing area directly increases lift for the same flight conditions. Increasing air density increases ρ, boosting lift. Engine horsepower, however, does not appear in this lift equation; it affects thrust and, indirectly, the speed the aircraft can maintain, which in turn can influence lift, but it does not directly change the wing’s lifting force under a given set of air properties. Therefore, engine horsepower is the factor that does not directly affect lift.

Lift comes from the wing acting on air, and it depends on dynamic pressure, wing area, and how the wing’s shape and angle of attack influence the lift coefficient. The basic relation is L ≈ 0.5 ρ V^2 S Cl, so lift increases with air density (ρ), with the square of speed (V^2), with the wing area (S), and with the lift coefficient (Cl). Cl changes as the angle of attack changes and as the wing design dictates.

Increasing angle of attack raises Cl up to the stall, thereby increasing lift for a given ρ, V, and S. Increasing wing area directly increases lift for the same flight conditions. Increasing air density increases ρ, boosting lift. Engine horsepower, however, does not appear in this lift equation; it affects thrust and, indirectly, the speed the aircraft can maintain, which in turn can influence lift, but it does not directly change the wing’s lifting force under a given set of air properties. Therefore, engine horsepower is the factor that does not directly affect lift.