What factors determine the angle of attack of a fixed pitch propeller?

The angle of attack of a fixed pitch propeller is primarily influenced by both forward speed and engine rotational speed. As the aircraft moves forward, the relative wind direction changes, which affects the effective angle that the blades meet this oncoming air. Additionally, the rotational speed of the engine alters the speed at which the propeller blades slice through the air, further impacting the angle of attack.

At low speeds, the blades may experience a higher angle of attack due to the slower relative airflow, which can lead to increased lift but can also risk stalling if the angle becomes too steep. Conversely, as the engine's rotational speed increases, the tips of the blades move faster through the air, which can modify how much lift is generated at a given forward speed. The interplay of these two factors ensures that the angle of attack is dynamic rather than static, making option B the correct choice, as it encompasses the contributions from both forward motion and propeller speed.

The other options do not account for this complexity—forward speed alone does not provide a full picture, nor does engine rotational speed independently determine the angle of attack. As fixed pitch propellers are designed with a specific blade angle that does not change, claiming that the angle is constant ignores the influence of