FAA Powerplant Written Practice Test

A constant-speed propeller provides maximum efficiency by doing what?

1. Maintaining a constant blade angle

2. Adjusting blade angle for most conditions

3. Fixed pitch for all flight conditions

4. Using variable rotational speed

The correct answer is: Adjusting blade angle for most conditions

A constant-speed propeller maximizes efficiency by adjusting the blade angle to optimize performance under varying flight conditions. This capability allows the propeller to change its pitch angle automatically, thereby adapting to the changes in airspeed, engine power, and other factors during flight. By altering its blade angle, the propeller can improve thrust when needed, such as during takeoff or climbing, and then reduce drag during cruise conditions. This dynamic adjustment facilitates the propeller's ability to maintain an optimal angle of attack, which is critical for enhancing efficiency in different phases of flight. Fixed-pitch designs do not have this ability and are unable to optimize performance as conditions change, leading to potential inefficiencies. Additionally, while constant blade angles or variable rotational speeds may play roles in propeller design, it is the ability to actively adjust the blade angle that directly contributes to maximizing efficiency across various operating conditions.