Question 1 [Total 30 marks] Calculate the drag coefficient (based on the frontal area) of the 2-dimensional wedge- shaped projectile shown in the figure below, moving at a Mach number of 1.8. The projectile's length (in the flow direction) is 1 m. State all assumptions. M = 1.8 p = 1 atm Supersonic projectile 10 110 Notes: Some useful information is provided on the following pages. If using tables, use the nearest tabulated value - do not interpolate. For air, R = 287 J/kg.K and k = 1.4. Shock-wave angle, 8, degrees 90 60 30 M, 1.1 1.2 1.3 1.4 1.5 1.6 10 1.7 1.8 2.0 2.2 2.4 2.6 2.8. 3.03.4 4.05.0 6.0 20.0 10.0 Weak shock wave Strong shock wave --Sonic limit (M1) Shock wave M. Streamline 20 30 Deflection angle, 8, degrees fo Shock wave parameters for wedge flow 40 Variation of shock-wave parameters with wedge flow-deflection angle for various upstream Mach numbers, y = 1.4. Image source: Aerodynamics for Engineers, 3rd Ed., by Bertin & Smith, Prentice-Hall, 1998. 50 110 100 90 80 70 50 40 30 20 10 3 6 7 M Prandtl-Meyer function for k= 1.4 10 10 11 12 13