Which factor is primarily responsible for producing lift on aircraft?

• A. Changes in air speed and pressure caused by wings or rotors
• B. Gravity
• C. Drag
• D. Thrust

Answer: (A)

Lift is produced by changes in air speed and pressure caused by wings or rotors. As the aircraft moves, the wing’s shape and angle of attack make air flow faster over the top surface and slower underneath, creating lower pressure on top and higher pressure below. This pressure difference pushes the wing upward. Rotor blades work the same way by pushing air downward, and Newton’s third law gives the aircraft an upward reaction force.

Gravity is the weight pulling downward, so it doesn’t generate lift. Drag is the resistance from air as the aircraft moves, not a lifting force. Thrust moves air to create that flow, enabling lift to form, but the lifting force itself comes from the pressure differences created by the wing or rotor through the moving air.