What is form drag primarily caused by?

Form drag is primarily influenced by the pressure difference generated around the aircraft's surfaces as airflow interacts with its shape. This pressure difference occurs due to the varying velocities of airflow around the object; specifically, there is high static pressure at the leading edge and low static pressure at the trailing edge. The shape of the aircraft causes the airflow to accelerate over the top surface, falling to lower pressure, while the slower flow remains at higher pressure on the underside or leading edge.

This dynamic creates a net force that acts against the motion of the aircraft, contributing to overall drag. While form drag is often associated with the geometry and flow characteristics around the aircraft, it's the pressure differential created in the airflow that primarily defines and contributes to form drag. Understanding this relationship is critical in aerodynamics, as it helps in designing shapes that minimize this type of drag for improved performance and efficiency.