What happens to parasite drag as the speed of an aircraft decreases?

Parasite drag is primarily influenced by the speed of the aircraft. As the speed decreases, particularly at subsonic speeds, parasite drag generally diminishes. This is because parasite drag is a function of the square of the velocity; thus, when speed is reduced, the drag reduces significantly as well.

In the context of aerodynamics, parasite drag consists of two main components: form drag and skin friction drag. Both of these increase with speed, leading to the conclusion that as aircraft speeds drop, the forces acting against the aircraft (like drag) also lessen. Consequently, as the aircraft slows down, both the form and skin friction drag decrease due to the changing flow conditions over the aircraft’s surface, resulting in reduced total parasite drag.

Understanding this behavior enhances the comprehension of how an aircraft's performance can be optimized during various phases of flight. Therefore, the dynamic relationship between speed and drag is fundamental in aerodynamics.