What happens to induced drag and parasite drag with increasing speed in straight and level flight?

In straight and level flight, as the speed of the aircraft increases, induced drag and parasite drag behave differently. Induced drag is primarily a byproduct of lift generation and is inversely related to airspeed; as speed increases, the angle of attack required to maintain lift decreases, leading to a reduction in induced drag. This phenomenon occurs because a higher airspeed allows the wings to generate the necessary lift at a lower angle of attack, thus decreasing the vortex strength and subsequently the induced drag.

On the other hand, parasite drag, which encompasses all drag not associated with the generation of lift (such as form drag, skin friction, and interference drag), increases with speed. The faster an aircraft travels through the air, the greater the friction and pressure differential created, resulting in an increase in parasite drag.

Therefore, as speed increases in straight and level flight, induced drag decreases while parasite drag increases. This relationship is foundational in understanding aircraft performance and efficiency at varying speeds.