What is effective pitch?

• A. the actual distance a propeller moves forward through the air during one revolution
• B. the distance traveled by the airplane per propeller revolution
• C. the geometric shape of the blade
• D. the pitch angle at zero airspeed

Answer: (A)

Effective pitch is the actual forward distance the aircraft travels through the air in one revolution of the propeller, taking into account slip between the blade and the air. The pitch of a propeller is the theoretical distance it would advance with each turn if there were no slip, but in real flight there is slip, so the airplane doesn’t move as far as the theoretical pitch. The description that best matches the real, in-flight forward movement per revolution is the propeller’s actual progress through the air in one turn. The other ideas refer to blade shape or to pitch at zero airspeed, which don’t describe the real forward distance achieved per revolution.