Final answer:
A symmetrical airfoil always has zero camber because its upper and lower surfaces are identical, causing the chord line to align with the mean camber line along the entire span of the airfoil.
Step-by-step explanation:
The question "Do symmetrical airfoils have zero camber?" pertains to the design and characteristics of airfoils in the field of aerodynamics, which is a branch of engineering. The answer to this question is A. Yes, always. A symmetrical airfoil by definition has identical upper and lower surfaces such that the chord line, which is a straight line connecting the leading and trailing edges of the airfoil, aligns exactly with the mean camber line, which is the line midway between the upper and lower surfaces.
Since the upper and lower surfaces are identical, there is no deviation between the chord line and the mean camber line, resulting in zero camber. This property is consistent across the entire span of the airfoil, not just at the leading or trailing edges.
Symmetrical airfoils have zero camber, meaning that the curve of the upper and lower surfaces are the same. The most common example of a symmetrical airfoil is the NACA 0012 airfoil, which has a flat upper and lower surface.
However, symmetrical airfoils can still have differing thicknesses, known as the thickness ratio. This means that the airfoil can have the same shape but with different thicknesses at different points.
Therefore, the answer to the question is B. No, never. Symmetrical airfoils can have zero camber, but they do not always have to.