The flow about a \(150 \mathrm{~mm}\) artillery projectile which travels at \(600 \mathrm{~m} / \mathrm{s}\) through still air at \(30^{\circ} \mathrm{C}\) and absolute pressure \(101.4 \mathrm{kPa}\) is to be modeled in a high-speed wind tunnel with a 1:6 model. If the wind tunnel air has a temperature of \(-18^{\circ} \mathrm{C}\) and absolute pressure of \(68.9 \mathrm{kPa}\), what velocity is required? If the drag force on the model is \(35 \mathrm{~N}\), what is the drag force on the prototype if skin friction may be neglected?