What is parasite drag primarily caused by?

Parasite drag is primarily caused by the interaction of the aircraft with the air around it, specifically through the disruption of airflow due to the aircraft's components and surface features. This type of drag occurs irrespective of the lift being generated; it is related to the shape and configuration of the aircraft itself.

In this context, the fuselage, along with any protrusions such as antennas, landing gear, and other components, disrupts the smooth airflow over the aircraft's surfaces. These disruptions create turbulence, leading to an increase in drag as the aircraft moves through the air. The design of the fuselage and associated protrusions can significantly affect the overall efficiency and drag characteristics of the aircraft.

While propeller efficiency, wing shape, and aircraft weight also influence the aircraft's performance and drag, they pertain more to other forms of drag or flight dynamics. Propeller efficiency affects thrust and performance but does not specifically pertain to parasite drag. Wing shape may influence lift and induced drag, while weight primarily affects overall performance and climb capability rather than directly contributing to parasite drag.