FAA Powerplant Written Practice Test

During takeoff, what are the typical rotational speed and blade pitch angle requirements of a constant-speed propeller?

1. High speed and high pitch angle.

2. Low speed and low pitch angle.

3. High speed and low pitch angle.

4. Low speed and high pitch angle.

The correct answer is: High speed and low pitch angle.

In the context of constant-speed propellers during takeoff, the correct choice highlights the requirement for high rotational speed and low blade pitch angle. During takeoff, the propeller must generate significant thrust to lift the aircraft off the ground while minimizing drag. A low blade pitch angle allows the blades to bite into the airflow more aggressively, thus producing a greater amount of thrust. This configuration takes advantage of the high rotational speed of the engine to maximize power output, enhancing the aircraft's performance during this critical phase of flight. This combination is essential because it enables effective acceleration for takeoff. As the aircraft gains speed and altitude, the propeller automatically adjusts its pitch to adapt to changing flight conditions, but during the initial takeoff phase, the priority is on thrust generation rather than efficiency, hence the high-speed, low-pitch angle requirement.