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MEM425F09.Ex2.soln

# MEM425F09.Ex2.soln - a 0.075 deg-1 Aerodynamic center...

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MEM 425: Aircraft Performance and Design MidTerm Exam II November 12, 2009 (Relevance to Program Outcomes a-k : a, c, d, e, g, k) open-book, open-notes. No computers

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Problem 1: A propeller-driven aircraft with the characteristics given below has been designed so that its level cruise flight (i.e., max_range flight) can be maintained with zero elevator deflection. Determine the elevator deflection required to maintain a level loiter (i.e., max_endurance) flight . Characteristics : Zero-lift moment coefficient about c.g., = 0.06 Lift-curve slope, a = 0.08 deg -1 Parasite drag coefficient, = 0.025 Drag polar parameter, K = 0.05373 Tail volume ratio, V H = 0.3 Elevator effectiveness, = 0.04 deg -1 Problem 2: A few wind tunnel experiments conducted on a wing-body shape (with a wing area S of 0.25 m 2 , and a chord c of 0.2 m), have resulted in the following data: Lift curve slope,

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Unformatted text preview: a : 0.075 deg-1 Aerodynamic center location, : 0.25 Coefficient of moment about the aero-center :-0.03 Zero-lift downwash angle, ε : 0 deg Downwash angle slope, : 0.25 deg-1 A horizontal stabilizer/tail (with no elevator) with a plan area S t of 0.025 m 2 and a lift curve slope a t of 0.1 /deg, is given to you. For a c.g. location, h = 0.2 determine the horizontal location of the tail and the tail setting angle , to ensure a static margin SM of 0.15, and that the a/c can be trimmed at an angle of attack of 5 deg. solution: Problem 1: Use the subscripts “E” for endurance and “R” for range. Since it is given that , from above we get . So that Now, since , we have: for range and for endurance. From these, . This yields Problem 2: Now use to get To determine , use the trim condition :...
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MEM425F09.Ex2.soln - a 0.075 deg-1 Aerodynamic center...

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