FAA Powerplant Written Practice Test

What is the term for the actual distance a propeller moves forward through the air during one revolution?

1. Effective pitch

2. Relative speed

3. Propeller angle

4. Blade angle

The correct answer is: Effective pitch

The term for the actual distance a propeller moves forward through the air during one revolution is known as effective pitch. This concept is crucial in understanding a propeller's performance because effective pitch takes into account the slip that occurs as the propeller rotates through the air. In an ideal scenario, if there were no slippage, the distance moved forward would equal the theoretical pitch, which is determined by the angle of the propeller blades and their width. However, in reality, factors such as air resistance and the nature of the medium in which the propeller operates (air, in this case) often lead to a situation where the propeller does not move forward as much as theoretically expected. The effective pitch provides a more realistic measure of the propeller's performance by incorporating these factors. This makes effective pitch a key parameter for evaluating how efficiently a propeller converts engine power into forward motion, influencing both performance and operational capabilities of the aircraft.