When will the blade pitch angle of a constant-speed propeller be the greatest?

When will the blade pitch angle of a constant-speed propeller be the greatest?

• A. during high-speed, high-altitude cruising flight
• B. during takeoff
• C. during landing
• D. during taxi

Answer: (A)

Constant-speed propellers are governed to keep the engine RPM steady by automatically varying the blade pitch. As speed increases, the prop encounters more aerodynamic load, so the governor raises the pitch angle (coarser) to maintain the set RPM. This higher pitch during high-speed cruise reduces the load on the engine while still delivering the required thrust, and it also helps prevent overspeed at fast airspeeds. In takeoff, you want maximum thrust and the engine RPM near its limit, so the pitch remains relatively fine. At lower speeds during taxi or approach/landing, the load conditions are different and the pitch isn’t driven to the maximum. So the blade pitch angle is greatest during high-speed, high-altitude cruising flight.

Constant-speed propellers are governed to keep the engine RPM steady by automatically varying the blade pitch. As speed increases, the prop encounters more aerodynamic load, so the governor raises the pitch angle (coarser) to maintain the set RPM. This higher pitch during high-speed cruise reduces the load on the engine while still delivering the required thrust, and it also helps prevent overspeed at fast airspeeds. In takeoff, you want maximum thrust and the engine RPM near its limit, so the pitch remains relatively fine. At lower speeds during taxi or approach/landing, the load conditions are different and the pitch isn’t driven to the maximum. So the blade pitch angle is greatest during high-speed, high-altitude cruising flight.