MAE 3241: Aerodynamics and Flight Mechanics Assigned: March 4, 2011 Homework #4 Due: March 18, 2011 Question 1: Consider an infinite wing with an NACA 1412 airfoil section and a chord length of 3 ft. The wing is at an angle of attack of 5º in an airflow with velocity 100 ft/s at standard sea-level conditions. Calculate the lift, drag, and moment about the quarter chord per unit span. Question 2: The ratio of lift-to-drag, L/D, for a wing or airfoil is an important aerodynamic parameter, and may be considered as a direct measure of the aerodynamic efficiency of the wing . If a wing is pitched through a range of angle of attack, L/D first increases, then goes through a maximum, and then decreases. Consider an infinite wing with an NACA 2412 airfoil. Estimate the maximum value of L/D and indicate at which angle of attack the maximum L/D occurs. Assume that the Reynolds number is 9 million. Question 3:
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