The design used laminar airfoil sections throughout. Pitching moment coefficient is fundamental to the definition of aerodynamic center of an airfoil. An airfoil that is not cambered is called a "symmetric airfoil". One such design is called the supercritical airfoil. The construction of the wing starts with the rib which defines the airfoil shape. This minimizes the stalling speed of aircraft using the airfoil. Construction of solid airfoil designs requires inflexible materials such as metals or composites. It can be imagined as addressing an airfoil of zero thickness and infinite wingspan. The theory idealizes the flow around an airfoil as two-dimensional flow around a thin airfoil. The wing was the Boeing "117" airfoil, regarded as the "fastest wing of its time". Modern wingsuits use a combination of materials in order to create an airfoil shape. The aspect ratio is the width of the airfoil divided by its chord. The terminal's roof is shaped like an airfoil. The upper streamtubes constrict as they flow up and around the airfoil. This is because the body of the tube acts as an airfoil and creates lift.