hw4_soln

hw4_soln - Problem 1. 25 points Part a) NACA 2412: 2%...

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Problem 1. 25 points Part a) NACA 2412: 2% camber +1 point 12% thickness +1 point Angle of Attack (°) cl (from FoilSim) cl (from charts) % Error cd (from FoilSim) cd (from charts) % Error 4 0.735 0.65 13.077 0.02 0.006 233.333 8 1.218 1.08 12.778 0.03 0.009 233.333 Summary of results +4 points The coefficient of lift values generated by FoilSim are reasonably close to the accepted values. The coefficient of drag values, however, are off by a factor of 10. Discussion: +4 points Part b) Max Thickness (%) 8 9 10 11 12 13 Max Camber (%) 2 35.786 39.244 43.382 41.372 39.556 37.905 15 15 15 15 15 15 0.087556 0.088333 0.089111 0.089889 0.090667 0.091444 3 35.372 38.378 41.9 40.6 39.387 38.249 15 14.8 14.8 14.8 14.8 14.8 0.085556 0.088295 0.089091 0.089773 0.090568 0.091364 4 35.051 37.718 40.79 40.006 39.253 38.529 14.6 14.6 14.6 14.6 14.6 14.6 0.087558 0.088372 0.089186 0.090116 0.090814 0.091628 Summary of results +6 points Key L/D (at AoA = 6 deg) Stall AoA Lift-Curve Slope Choose max thickness = 10% and max camber = 2% to maximize L/D and stall angle of attack. Correct decision based on information: +5 points Part c) The results from part b will need to be independently verified, perhaps in a wind tunnel test, since the validation of the program in part a cast doubt on the reliability of the program. Discussion of trustworthiness of program: +4 points
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Problem 2. Given: NACA 2415 Airfoil Section: Chord c = 0.6 m , Span b = 2 m , Span efficiency factor e=0.9 Standard Sea Level Conditions: Density = 1.225 kg/m 3 , Viscosity = 0.00001789 kg/m s , Speed of sound a = 340.3 m/s
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hw4_soln - Problem 1. 25 points Part a) NACA 2412: 2%...

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