What type of drag does every part of the aircraft contribute to, regardless of lift?

Every part of the aircraft contributes to parasitic drag because this type of drag is associated with the shape and surface texture of the aircraft and is not dependent on lift. Parasitic drag can be broken down into three components: form drag, interference drag, and skin friction drag, all of which increase as the speed of the aircraft increases. Since parasitic drag is a result of the aircraft's overall design and surface characteristics, it is present regardless of whether the aircraft is generating lift or not.

In contrast, induced drag is directly related to the generation of lift; it arises from the vortex formation that occurs when lift is produced. Therefore, induced drag is not present when lift is absent. Friction drag is a component of parasitic drag specifically related to the surface roughness of the aircraft skin, but it does not encompass all aspects of parasitic drag. Lift drag is not a recognized category of drag in aerodynamics. Thus, parasitic drag represents the drag that every part of the aircraft contributes to irrespective of its lift-generating capability.