What type of drag is caused by the shape of the aircraft?

Form drag is the type of drag that arises specifically due to the shape or configuration of the aircraft as it moves through the air. It is a consequence of the difference in pressure around the aircraft's surface as it displaces air. When an aircraft takes shape, certain areas, such as the front and leading edges, create a high-pressure zone, while other areas, typically the rear or trailing edges, create low-pressure zones. This differential pressure results in a component of drag opposing the aircraft's motion.

Understanding that form drag is directly influenced by the aircraft's geometry is essential, as it highlights the importance of aerodynamic design. A well-streamlined shape minimizes this form drag, allowing the aircraft to move more efficiently through the air. This contrasts with other types of drag, such as skin friction drag—which primarily relates to the surface texture and the interaction between the air and the aircraft's skin—or induced drag, which is associated with the generation of lift and is more relevant at different angles of attack. Interference drag can occur when airflow around various components of the aircraft affects one another, but it is not directly tied to the basic shape of the aircraft like form drag is.