MAE305_practice1 - (b) Estimate the (stagnation) pressure...

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Practice Exam 1 Fa 2009 This exam is for your practice only. 1. On a summer day, the temperature in the stratosphere above Edwards Air Force Base in southern California is constant, and equal to T 1 = 236 . 65 K for altitudes in the range 11 , 000 m h 25 , 000 m. A test pilot ±ying there wants to make some performance measurements of her aircraft at a density altitude h d = 20 , 000 m. (a) What must be the local (ambient) density at the altitude of her test? (b) At what pressure altitude h p should she ±y for the test? Note: the distribution of temperature T in the Standard Atmosphere , up to 32,000 meters, is given by 0 h 11 , 000 m: T = 288 . 15 K ( . 0065 K/m) h 11 , 000 m h 20 , 000 m: T = 216 . 65 K 20 , 000 m h 32 , 000 m: T = 216 . 65 K + ( . 0010 K/m) h 2. An open-circuit wind tunnel draws standard sea-level air from the ambient surround- ings and accelerates it into a 1 m × 1 m test section. The static pressure in the test section is measured to be 45 mm of water less than the ambient pressure in the labo- ratory. (a) Estimate the test section velocity.
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Unformatted text preview: (b) Estimate the (stagnation) pressure at the nose of a model mounted in the test section. Note: the density of water is given below, in Exercise 5. 3. We wish to know the drag of a prototype blimp (airship) that will move through Standard Sea-level air at V p = 10 m/s. We will perform a model experiment in which a 1/30 scale model (based on linear dimension) of the prototype will be tested in a water tunnel. (a) What should the velocity in the water tunnel be in order to ensure dynamical similarity? (b) If the measured drag on the model in the water tunnel for a properly scaled experiment is D m = 3 , 000 N, what will be the corresponding drag force D p on the prototype blimp? Note: the viscosity of air at standard sea level conditions is SL = 1 . 789 10-5 kg/(m s) , and the density and viscosity of the water in the tunnel can be taken to be Water = 998 . 2 kg/m 3 and Water = 0 . 001 kg/(m s) , respectively....
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MAE305_practice1 - (b) Estimate the (stagnation) pressure...

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