What is the advantage of a variable pitch propeller?

A variable pitch propeller's key advantage lies in its ability to adjust the blade angle for optimal efficiency during different phases of flight. This adaptability allows the propeller to maintain an ideal angle of attack, which optimizes thrust and fuel efficiency across varying speeds and atmospheric conditions.

For instance, during takeoff, a propeller may adjust to a coarse pitch to generate maximum thrust, while in cruise flight, it can switch to a finer pitch to reduce drag and enhance fuel efficiency. This flexibility significantly improves overall aircraft performance compared to fixed-pitch propellers, which cannot alter their blade angle and are thus limited to one optimal operating condition.

The other options do not represent the true benefits of a variable pitch propeller; a fixed angle of operation is the characteristic of fixed-pitch systems, while general cost considerations and noise levels are not inherent advantages of variable pitch designs.