12.72 Propellers

12.72.2 With respect to propeller terminology, define the meaning of the following:

(a) blade section;

(b) blade angle;

(c) helix (or pitch) angle;

(d) angle of attack.

12.72.4 Explain the reason for blade (or helical) twist.

12.72.6 With the aid of a diagram, identify and define the following for a rotating blade section:

(a) direction of rotation;

(b) relative airflow;

(c) total reaction, with its components;

(d) thrust and propeller torque.

12.72.8 For a fixed-pitch propeller at a constant throttle setting, explain the relationship between airspeed, angle of attack and rpm.