Definition
Wings whose airfoil cross-section has identical curvature on the upper and lower surfaces, so the shape above the chord line mirrors the shape below it. A symmetrical airfoil produces zero lift at zero angle of attack and generates lift only when the wing is tilted relative to the oncoming air.
Plain English
Wings shaped the same on top as on the bottom. Because both sides match, the wing doesn't lift on its own when flying level into the wind — the pilot has to angle it slightly to make lift.
Context Anchor
Seen in airfoil behavior discussions when comparing symmetrical wings with cambered wings and explaining how wing shape affects lift.
Derivation
Symmetrical comes from the Greek 'symmetria' meaning 'same measure' — both halves have matching shape and size. In this case, the top half of the wing measures the same as the bottom half.
Why Pilots Care
Symmetrical wings create no lift at zero angle of attack, influencing aircraft stability and maneuverability choices.
Intuition Check
Symmetrical does not mean the airplane’s left and right wings are simply the same size. In this airfoil context, it means the top and bottom surfaces of each wing shape match each other.
Example Sentence 1
Aerobatic aircraft often use symmetrical wings so they can produce lift equally well in upright and inverted flight.
Example Sentence 2
At zero angle of attack a symmetrical wing produces no lift, requiring a positive angle to generate upward force.