Exam Question

(a) Describe how thrust power is determined. (6)

(b) The following information relates to a model propeller of 400mm pitch:

Rev/min 400 450 500 550 600

Thrust (N) 175 260 365 480 610

Torque (Nm) 16.8 22.4 28.2 34.3 40.5

(i) Plot curves of thrust and torque against rev/ min

(ii) When the speed of advance of the model is 150 m/min and slip 0.20,

Calculate the efficiency. (10)