7.29 A 150 mm artillery projectile that travels at 600 m/s through still air at 30 C and air pressure of 101.4 kPa is to be modeled in a high-speed wind tunnel with a 1:6 scale model. The wind tunnel air has a temperature of −18 C and a pressure of 68.9 kPa. Determine the velocity required for dynamic similarity. Determine the drag force on the prototype for a drag force on the model of 35 N.