# Problems

14.1 Problem 1

14.1.1 Thin Airfoil Theory (2-D Inviscid Flow)

14.1.1.1 Quiz—Answer by Yes/no

• in subsonic flow, does the aerodynamic coefficient given below depend upon the small parameters:

Aerodynamic coefficient e/c d/c a

Ci

Cm, o

Cm, ac

Cd

• in supersonic flow, does the aerodynamic coefficient given below depend upon the small parameters:

Aerodynamic coefficient e/c d/c a

Ci

Cm, o

Cm, ac

Cd

14.1.1.2 Lift Coefficient

A thin profile with parabolic camber d = 0.02 is set at angle of attack a = 5°. Find the lift coefficient Ci in incompressible flow. Find the lift coefficient in compressible flow at M0 = 0.7. Hint: use linear correction method.

© Springer Science+Business Media Dordrecht 2015

J. J. Chattot and M. M. Hafez, Theoretical and Applied Aerodynamics,

DOI 10.1007/978-94-017-9825-9_14

14.1.1.3 Drag Coefficient

If the drag coefficient of the same profile at a = 0 and M0 = 1.4 is (Cd)м0=1.4 = 0.02, find the drag at M0 = 2. (hint: look at the definition of (Cd)a=0). What will the drag be at M0 = 2. if a = 5°? What is the drag coefficient at M0 = 0.7?

14.1.1.4 Equilibrium About an Axis

Give the definition of the aerodynamic moment coefficient Cm, o in terms of the dimensional quantities.

If the profile is attached to a vertical axis located at x = 0 (nose of profile), write the equation of equilibrium that will give the equilibrium angle of attack aeq. Find aeq, and sketch the profile at equilibrium. Is the equilibrium stable?

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