Which description best defines airfoils?

• A. Surfaces designed to generate lift in flight
• B. Parts that power aircraft propulsion
• C. Devices to store fuel
• D. Structural members of the fuselage

Answer: (A)

Airfoils are shapes that create lift when they move through air. Their curved upper surface and flatter lower surface cause air to split and flow faster over the top than underneath, producing lower pressure above and higher pressure below. This pressure difference generates an upward force that helps wings and blades stay aloft. Lift increases with speed and with the wing’s angle of attack and camber, which is why aircraft wings and propeller blades are designed as airfoils. They’re not meant to power propulsion, store fuel, or form the main structural members of the fuselage; those roles belong to other aircraft components.