Definition
An airfoil whose upper and lower surfaces have different curvatures, so the mean camber line is not the same as the chord line. The upper surface is typically more curved than the lower surface, producing lift even at a zero angle of attack.
Plain English
A wing or blade shape where the top and bottom are not mirror images of each other. The top is more curved than the bottom, which helps it produce lift naturally as air flows past it.
Context Anchor
Seen in aircraft wing, propeller, rotor blade, and airframe design discussions, especially when comparing how different shapes create lift.
Derivation
From Greek 'a-' meaning 'not' and 'symmetria' meaning 'same measure.' So 'asymmetrical' literally means 'not the same on both sides' — which is exactly what this airfoil is: top and bottom shapes don't match.
Why Pilots Care
Asymmetrical airfoils often deliver better lift at low speeds and are common on light aircraft wings.
Analogy
Think of a spoon held sideways in moving water. Because one side is more curved than the other, the water does not flow around both sides the same way, and the spoon tends to move toward one side.
Intuition Check
Asymmetrical does not mean the part is automatically bent, damaged, or installed wrong. Here it means the airfoil was designed with different upper and lower shapes.
Example Sentence 1
The trainer's wing uses an asymmetrical airfoil, with a more curved upper surface to generate lift in cruise flight.
Example Sentence 2
During preflight the mechanic checked the asymmetrical airfoil for dents that could reduce lift.