CORRECT!

5). What is an advantage of a constant-speed propeller?

a). Permits the pilot to select and maintain a desired cruising speed.
b). Permits the pilot to select the blade angle for the most efficient performance.
c). Provides a smoother operation with stable RPM and eliminates vibrations.
The answer is:
b). Permits the pilot to select the blade angle for the most efficient performance.

A constant-speed (pitch) prop differs from a fixed-pitch prop in that it allows for the pilot to change the pitch angle of the blades. A fixed-pitch prop is essentially a trade-off of performance for simplicity of operation: it is set at a pitch angle that results in acceptable but not great climb performace, and acceptable but not great cruise performance. In order to provide both efficient climb performance and efficient cruise performance, the blades' pitch should be changed to provide high RPMs during climb (when maximum performance is needed to overcome inertia and weight) and a lower RPM setting during cruise (when all that thrust is not required to maintain the desired attitude and cruising speed).

The aircraft's POH is the place to look for manufacturer's recommended procedures to follow when setting the RPMs for a given flight regime. By adjusting the engine RPMs appropriately, the pilot can ensure peak engine performance, including minimizing were-and-tear and optimizing fuel consumption.

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