An asymmetric double-wedge aerofoil, as shown in Fig Q3, is tested in a wind tunnel. The aerofoil is aligned at an angle such that its upper leading surface (1) is at 2 degrees inclination with an oncoming flow. The angle of attack is defined relative to the aerofoil's chord which is effectively given by the bottom surface (3). The aerofoil is tested at a speed of Mach 2.7. This line parallel with (1).. (ii) 2 y= Mo = 2.7 (1) Fig. Q3 177 dec (3) (a) (i) Ackeret's theory may be used to analyse the supersonic flow around this aerofoil. Outline the main assumptions in Ackeret's theory. (2) Use Ackeret's theory to estimate the lift coefficient. (iii) Calculate the pressure coefficient on the bottom surface (3) using: 1. Ackeret's theory for supersonic flow. 2. Newtonian theory for hypersonic flow. Compare your answers and comment on the appropriateness of both methods for the flow conditions, stating which result is more likely to be correct.