What aerodynamic force counters gravity and enables sustained flight?

• A. Lift
• B. Weight
• C. Drag
• D. Thrust

Answer: (A)

Lift is the aerodynamic force that counters gravity and enables sustained flight. It is generated by the wing as air flows around it, with the wing’s shape and angle of attack causing air to be deflected downward. This downward deflection creates an upward reaction force on the wing, producing lift. The amount of lift depends on air density, speed, wing area, and the wing’s lift coefficient, often summarized by L ≈ ½ ρ V^2 S CL. For level, steady flight, lift must balance weight; if lift exceeds weight, the aircraft climbs, and if lift is less than weight, it descends. Thrust and drag govern forward motion and energy to keep that speed, but they do not counter gravity directly.