We wish to do a preliminary design sizing of a propeller that uses the Clark-Y airfoil with properties described in NACA TR-640. design calls for flight at 155 m/s at an altitude 3 where rho = 0.85 kg/m . Assume the engine provides 300 kW of power to the propeller and the rotational speed is 2500 rpm. Compare the required diameters, propulsive efficiency, and blade pitch at 0.75R for 3- and 4-bladed propellers. What is the corresponding thrust in each case? Calculate the Mach number based on air speed relative to the blade tip (VR, tip/a) for the 3- and 4-bladed propellers assuming the air temperature is 265 K.