Introduction to Flight 7th Edition by John Anderson

Exercise 5

Consider hypersonic flow over an infinitely thin, flat plate. The zero-lift drag coefficient is denoted by C D ,0. (Note that the zero-lift drag for a flat plate is entirely due to skin friction.) Consider that the wave drag coefficient is given by the Newtonian result for drag coefficient-that is, by Eq. (10.12). Also assume that the lift coefficient is given by the Newtonian result in Eq. (10.11). We wish to examine some results associated with ( L / D ) max for this flat plate. Because ( L / D ) max occurs at a small angle of attack, make the assumption of small ? in Eqs. (10.11) and (10.12). Under these conditions, show that at maximum L/D , ( a )
and occurs at
and ( b ) the wave drag coefficient = 2 C D ,0.