Question

The airfoil data in Appendix D were obtained in the NACA two-dimensional Low Turbulence Pressure Tunnel at the NACA Langley Memorial Laboratory. This facility went into operation in Spring 1941. The tunnel was especially designed for airfoil testing, with a test section 3 ft wide and 7.5 ft high. The wing models spanned the entire test section of width 3 ft, so that the flow over the model was essentially two-dimensional. The chord length of the models was 2 ft. When the tunnel became operational, the four- and five-digit airfoil series, originally tested in older tunnels, were retested in the new tunnel. The Low Turbulence Pressure Tunnel is most noted, however, as the testing facility for the NACA Laminar Flow Airfoils. Consider a series of tests where the tunnel is pressurized to 3 atm, the temperature of the airstream in the test section is 60° F, and the flow velocity is 160 mi/h. A wing with an NACA 2412 airfoil is mounted in the tunnel at an angle of attack such that the section lift coefficient is 0.2. a. What is the angle of attack of the model? b. What is the total drag force on the model?

Answer 1

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