A 1:3 scale model of a torpedo is tested in a wind tunnel to determine the drag force. The prototype operates in water, has 533 mm diameter, and is 6.7 m long. The desired operating speed of the prototype is 28 m=s. To avoid compressibility effects in the wind tunnel, the maximum speed is limited to 110 m=s. However, the pressure in the wind tunnel can be varied while holding the temperature constant at 20C. At what minimum pressure should the wind tunnel be operated to achieve a dynamically similar test? At dynamically similar test conditions, the drag force on the model is measured as 618 N. Evaluate the drag force expected on the full-scale torpedo.