FAA Powerplant Written Practice Test

What is the distance a propeller actually moves forward through the air during one revolution called?

1. Effective pitch

2. Geometric pitch

3. Pitch angle

4. Blade pitch

The correct answer is: Effective pitch

The distance a propeller actually moves forward through the air during one revolution is referred to as effective pitch. This term describes the real-world performance of the propeller, which takes into account factors such as air density, rotational speed, and the propeller's design. Effective pitch essentially reflects the actual advancement of the aircraft through the air for each full revolution of the propeller. In contrast to effective pitch, geometric pitch represents the theoretical distance a propeller would advance in a single rotation if it were moving through a solid medium, calculated based solely on the dimensions and angle of the blades. While geometric pitch provides a useful baseline, it does not account for the effects of slip, which occurs due to the difference between the theoretical and actual movement through the air. Pitch angle refers to the angle at which the blades are set relative to the plane of rotation and affects both the thrust produced and the efficiency of the propeller but does not represent distance traveled. Blade pitch can refer to the angle of the blades or the adjustment setting to control the advancement of the propeller through the air, but it is not directly related to the actual forward distance achieved in one revolution. Therefore, effective pitch is the best term to describe the actual movement of a propeller through the