FAA Powerplant Written Practice Test

What is geometric pitch of a propeller defined as?

1. Pitch minus slippage

2. Effective pitch plus slippage

3. Effective pitch minus slippage

4. Pitch at maximum thrust

The correct answer is: Effective pitch plus slippage

The geometric pitch of a propeller is defined as the effective pitch plus slippage. Geometric pitch is a theoretical measure that indicates how far a propeller would move forward in one revolution if there were no slippage. In practice, because of slippage caused by factors such as drag and the efficiency of the propeller, the actual distance traveled (effective pitch) is less than the geometric pitch. Therefore, to arrive at the value of geometric pitch, you must account for the slippage by adding it to the effective pitch. This relationship helps in understanding the performance characteristics of the propeller, which is crucial for optimizing aircraft efficiency and performance during operation.