AFOQT Practice Test

What effect does skin friction have on parasite drag?

1. It decreases drag

2. It has no effect

3. It increases drag

4. It alters the shape of the aircraft

The correct answer is: It increases drag

Skin friction is a component of parasite drag that arises from the interaction between the surface of the aircraft and the airflow around it. As air flows over the surface of the aircraft, it experiences resistance due to the viscosity of the air and the texture of the surface. This resistance manifests as drag, which is a force that opposes the aircraft's motion. When skin friction increases, it leads to a greater amount of resistance, thereby increasing the overall parasite drag on the aircraft. This is particularly relevant when the surface of the aircraft has imperfections, is dirty, or has a rough texture, all of which can enhance the skin friction component of drag. In contrast, smoother surfaces tend to minimize skin friction, but once present, skin friction will inevitably contribute to an increase in drag. Consequently, understanding and managing skin friction is crucial in aerodynamic design to optimize performance and fuel efficiency.