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AA311.Homework4

# AA311.Homework4 - the velocity is 850 ft/s If the test...

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AA311 Homework 4. Due November 7, 2011 Give all your answers in SI units. Problem 1. An aircraft is ﬂying at a true airspeed of 400 ft/s in standard sea-level conditions. Estimate the pitot pressure ( P 0 ) based on the incompressible ﬂow form of the Bernoulli equation. Repeat the calculation at speeds 600 ft/s, 800 ft/s, and 1000 ft/s. Perform the same calculation using the compressible ﬂow form of the Bernoulli equation. Complete Table 1, which includes a comparison of results based on the percent relative error: | P 0 compressible - P 0 incompressible | P 0 compressible V (fps) M P 0 (psf) P 0 (psf) % Relative Error (incompressible) (compressible) 400 600 800 1000 Table 1: Table comparing incompressible and compressible pressure for various speeds. Problem 2. (Problems 5.11 and 5.12 in Anderson) (1) At a point on a wing in a high-speed wind tunnel,
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Unformatted text preview: the velocity is 850 ft/s. If the test section ﬂow velocity is 780 ft/s, with a pressure and temperature of 1 atm and 505 ◦ R, respectively, calculate the pressure coeﬃcient at the point. (2) If the test section ﬂow velocity is reduced to 100 ft/s, what will the pressure coeﬃcient become (at the same point)? Problem 3. (Problem 5.13 in Anderson) Consider a NACA 1412 airfoil at an angle of attack of 4 ◦ . If the free-stream Mach number is 0.8, calculate the lift coeﬃcient. Problem 4. An airfoil is inclined at 5 ◦ degrees angle of attack to the relative ﬂow. The minimum pressure coeﬃcient at low sub-sonic values is C p, = 0 . 5. Calculate the critical Mach number and corresponding critical pressure coeﬃcient for the airfoil. 1...
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