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A new approach to airfoil design was pioneered in the 1930s, in which the airfoil shape was mathematically derived from the desired lift characteristics. Prior to this, airfoil shapes were first created and then had their characteristics measured in a wind tunnel. The 1-series airfoils are described by five digits in the following sequence:
The cowling consists of a symmetric, circular airfoil that is wrapped around the engine. In a normal planar airfoil, like a wing, the difference in airspeeds, and their associated changes in pressure, on the top and bottom surfaces, enhances lift. In the case of the NACA cowl, the ring-shaped airfoil is positioned so this lift effect is forward.
Some important parameters to describe an airfoil's shape are its camber and its thickness. For example, an airfoil of the NACA 4-digit series such as the NACA 2415 (to be read as 2 – 4 – 15) describes an airfoil with a camber of 0.02 chord located at 0.40 chord, with 0.15 chord of maximum thickness.
Streamlines around a NACA 0012 airfoil at moderate angle of attack. A foil generates lift primarily because of its shape and angle of attack.When oriented at a suitable angle, the foil deflects the oncoming fluid, resulting in a force on the foil in the direction opposite to the deflection.
NACA experience provided a model for World War II research, the postwar government laboratories, and NACA's successor, the National Aeronautics and Space Administration (NASA). NACA also participated in development of the first aircraft to fly to the "edge of space", North American's X-15. NACA airfoils are still used on modern aircraft.
The Ferrari F40 sports car has "NACA style" side and hood scoops.. It is especially favored in racing car design. [4] [5] Sports cars featuring prominent NACA ducts include the Ferrari F40, the Lamborghini Countach, the 1996–2002 Dodge Viper, the 1971–1973 Ford Mustang, the 1973 Pontiac GTO, the 1979 Porsche 924 Turbo, the Maserati Biturbo, the Nissan S130, and the Porsche 911 GT2.
Supercritical airfoils are characterized by their flattened upper surface, highly cambered ("downward-curved") aft section, and larger leading-edge radius compared with NACA 6-series laminar airfoil shapes. [1] Standard wing shapes are designed to create lower pressure over the top of the wing.
There are two types of ducts; accelerating and decelerating. With accelerating ducts, the duct profile is airfoil-like curved towards the inner side, which increases the inflow velocity and efficiency of the propeller. This effect works at lower speeds and is compensated increasingly at higher speeds by the added drag of the duct, which tends ...