FAA Powerplant Written Practice Test

What is the geometric pitch of a propeller defined as?

1. Effective pitch plus slippage

2. Effective pitch minus slippage

3. Total pitch minus drag

4. Effective pitch times slippage

The correct answer is: Effective pitch plus slippage

The geometric pitch of a propeller is defined as the theoretical distance a propeller would move in one complete revolution if there were no slippage. In other words, it is the pitch calculated based on the physical design of the blades and the angle at which they are set relative to the plane of rotation. The correct definition includes the concept of effective pitch, which takes into account the actual distance the aircraft moves forward during one revolution of the propeller, including the effect of slippage. Slippage refers to the difference caused by various factors such as the efficiency of the propeller design and the aerodynamic drag. The geometric pitch can therefore be understood as the effective pitch plus slippage, as this addition gives a more comprehensive measure of the true performance characteristics of the propeller in motion. This understanding is fundamental in determining the operational efficiency of a propeller and optimizing its performance in specific flight conditions.