quiz-solution3

# quiz-solution3 - Re x = 5 10 5 Solution The wing chord is c...

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650:460 Aerodynamics Quiz No. 3 - Solution Prof. Doyle Knight Tel: 732 445 4464, Email: [email protected] OFce hours: Tues and Thur, 4:30 pm - 6:00 pm and by appointment ±all 2009 1

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Quiz No. 3 A Cessna 172 has a rectangular wing with span b = 10 . 92 m and aspect ratio AR= 7 . 32. Calculate the parasitic drag on the wing for a speed of 180 km/hr at an altitude of 2 km. Note: The density of air at 2 km altitude is 1.01 kg/m 3 and the molecular viscosity is 1 . 728 · 10 - 5 kg/s · m. Assume transition from laminar to turbulent Fow occurs on the wing at
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Unformatted text preview: Re x = 5 10 5 . Solution The wing chord is c = b AR = 10 . 92 7 . 32 = 1 . 49 m The velocity is U = 50 m/s. The Reynolds number based upon chord is Re c = Uc = 1 . 01 50 1 . 49 1 . 728 10-5 = 4 . 354 10 6 2 Quiz No. 3 The skin friction coeFcient is given by Eq (5.37) C f = . 455 (log 10 Re c ) 2 . 58-1700 Re c = 3 . 053 10-3 The drag is D = C f 1 2 U 2 S wet = (3 . 053 10-3 )(0 . 5)(1 . 01)(50) 2 (1 . 49)(10 . 92)(2) = 125 Nt 3...
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quiz-solution3 - Re x = 5 10 5 Solution The wing chord is c...

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