d) A three-blade propeller design has uniform chord c = 0.15m along the blade span, and will run at advance ratio J=1.5 with blade diameter D =2.62m and rotational speed n = 25rev s respectively. The blade aerofoil section has C = 2a, where a is the angle of attack in radians, and drag coefficient Ca =0.01, and the in-flow factor is estimated to be a = 0.022. Table shows a suggested pitch angle distribution. Non-dimensional thrust and torque coefficient gradients at all the radial locations except x = 0.7 are shown along the entire blade. Evaluate the non-dimensional thrust gradient dat x = 0.7, and calculate the propeller thrust and torque coefficients. Hence calculate the propeller efficiency n. Confirm that the in-flow factor a corresponds to the value used for the blade element theory calculation