How do camber and airfoil thickness affect lift and stall behavior?

• A. Camber increases Cl and lift at a given AoA and raises Clmax; thicker airfoils can delay stall moderately but may increase parasite drag
• B. Camber decreases Cl and lowers Clmax; thicker airfoils always delay stall with no drawbacks
• C. Camber has no effect on Cl or stall characteristics
• D. Camber only affects drag, not lift

Answer: (A)

Camber and thickness shape how the airfoil creates lift and when it stalls. Increasing camber makes the upper surface suction stronger and the pressure difference between the top and bottom surfaces larger at the same angle of attack, so the lift coefficient (Cl) goes up and the airfoil can reach a higher maximum lift before flow separation occurs (Clmax) than a non-cambered shape. That means more lift at a given AoA and a higher stall lift limit.

Thickness changes the pressure distribution and the boundary layer as the flow moves over the airfoil. A thicker airfoil tends to offer more lift at moderate angles because of the larger curvature and camber-like effect from its shape, but it also adds more parasite drag due to the bigger frontal area and surface roughness. In many practical cases, this modestly helps keep the flow attached to higher angles, delaying stall somewhat, but the trade-off is greater drag and potentially earlier separation at very high AoA in some configurations.

So, camber clearly increases lift at a given AoA and raises Clmax, while thicker airfoils give a modest delay to stall with the cost of increased drag.