What does geometric pitch describe?

Geometric pitch refers to the theoretical distance a propeller should ideally advance in a single revolution if there were no slippage. This concept is critical for understanding how propellers convert rotational motion into forward thrust, as it represents the distance that the propeller's blades would travel through a solid medium, such as a screw moving through wood. The geometric pitch is determined by the shape and angle of the blades, which together define how effectively the propeller can pull the aircraft through the air.

Understanding that geometric pitch is an ideal measurement helps clarify the operation of a propeller, as real-world conditions can cause variances due to aerodynamic effects such as slippage or drag, which are not accounted for in the theoretical model. Therefore, this concept is foundational in aviation propulsion, as it informs pilots and engineers about the expected performance of the aircraft.