Camber and Thickness

Camber Explained

Camber is the curvature of an airfoil's mean line, which is the line drawn midway between the upper and lower surfaces from leading to trailing edge. If the mean camber line sits above the straight chord line, the airfoil is positively cambered (common in most aircraft wings). Symmetrical airfoils have a straight camber line coinciding with the chord, resulting in zero camber.

The amount and position of maximum camber influence how much lift an airfoil generates at a given angle of attack. Increasing camber generally increases the lift coefficient (CL) for a given angle, shifting the CL-alpha curve upwards and allowing the wing to generate more lift at lower angles of attack. Negative camber (mean line below the chord) is rare but used in specific applications, such as some aerobatic aircraft.

Thickness and Thickness-to-Chord Ratio

Thickness is the maximum vertical distance between the upper and lower surfaces of the airfoil. The thickness-to-chord ratio (T/C) expresses this as a percentage of the chord length (e.g., a 1 m thick airfoil with a 10 m chord has a 10% T/C ratio). Thicker airfoils typically have a larger nose radius, promoting higher maximum lift and gentler stall characteristics. Thinner airfoils, often used for high-speed or transonic flight, reduce drag but may have sharper stall and lower maximum lift.

Camber vs Thickness: Effects on Performance

• Camber effect on lift: More camber increases lift at a given angle of attack but can also increase drag.
• Thickness effect: Thicker airfoils provide structural strength and better low-speed handling but may increase drag at high speeds. Thin airfoils are preferred for high-speed efficiency.
• Control surface movement: Deploying flaps or other control surfaces temporarily increases camber, boosting lift for takeoff and landing.

Camber and Thickness in Aviation

Aircraft designers select camber and thickness based on the intended flight regime. For example, gliders use highly cambered, thick airfoils for maximum lift at low speeds, while jet fighters use thin, low-camber sections for speed and reduced drag. Pilots must understand these parameters to anticipate aircraft handling, especially during configuration changes.