What distinguishes a controllable-pitch propeller from a constant-speed propeller?

The distinction between controllable-pitch propellers and constant-speed propellers primarily lies in the method of adjusting the blade angle in relation to engine RPM. A controllable-pitch propeller allows a pilot to adjust the blade angle manually during flight, enabling more tailored engine performance under varying conditions. However, a constant-speed propeller incorporates a governor system that automatically adjusts the blade angle to maintain a preset RPM, irrespective of the engine power output.

In the context of this question, the function of the constant-speed propeller is what makes it distinct. It continuously reads the engine speed and makes the necessary adjustments to the blade angle to keep the RPM constant, thereby optimizing performance during different flight phases without pilot intervention. This automatic adjustment reduces pilot workload and enhances efficiency across various flight conditions.

The other options illustrate misunderstandings regarding the functionality of these propellers. For instance, while a controllable-pitch propeller allows for manual adjustments by the pilot, this does not accurately describe the constants of a constant-speed propeller as being governed independently of pilot input. Similarly, the statement about constant-speed propellers not requiring engine power for adjustments misrepresents how they function, as they still rely on engine power for effectiveness. Ultimately, the clarity in understanding these differences aids