The pitch number equals the number of inches the prop will move through a solid material in one revolution. This is theory, since the prop slips in the air. GIVEN THE SAME RPM, more pitch, less diameter equals more speed and less pull. Conversely, more diameter, less pitch equals more pull, less top speed.

A small diameter, high pitch prop is like high gear on a car. A large diameter, low pitch prop is like low gear.

Airplanes with a lot of drag seem to fly better with large diamater, low pitch props than with smaller, high pitch props.

Dr.1