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MEM425F11_HW6 - moment about the center of gravity when the...

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MEM 425: Aircraft Performance & Design Home work #6 (due 11/03/11) Problem 1: Consider a wing-body model mounted in a wind tunnel. The flow conditions in the test section are sea level properties with a velocity of 100 m/sec. The wing area and chord are 1.5 m 2 and 0.45 m, respectively. The moment about the center of gravity (located at 0.285c ) when the lift is zero is measured to be -12.4 Nm. When the model is pitched to another angle of attack, the lift and the moment about the center of gravity are measured to be 3675 N and 20.67 Nm, respectively. Calculate the moment coefficient about the aerodynamic center and the location of the aerodynamic center. Problem 2: Consider the model in Problem 1. If a mass of lead is added to the model so that the center of gravity is shifted rearward by a length equal to 20% of the chord, calculate the
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Unformatted text preview: moment about the center of gravity when the lift is 4000 N. Problem 3: (if ‘tail’ is not covered by 11/01/11, you may ignore this problem) Consider the model in Problem 1. Assume that a horizontal tail with no elevator is added to this model with the incidence angle i t = 0). The distance from the model’s center of gravity to the tail’s aerodynamic center is 1.0m. The tail area is 0.4 m 2 . The lift-curve slope of the tail is 0.12 per degree. From experimental measurements ε = 0 , and . If the absolute angle of attack of the model is 5 o , and the lift is 4134 N, calculate the moment about the center of gravity. Does this model have longitudinal static stability and balance?...
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