Private Pilot License (PPL) Aerodynamics Practice Exam

What effect does frost have on the lift generated by an airplane's wings?

1. It increases the lift significantly

2. It has no effect on lifting performance

3. It decreases the lifting capability

4. It stabilizes the wing's performance

The correct answer is: It decreases the lifting capability

Frost on an airplane's wings can significantly disrupt the airflow over the wing surface, which in turn diminishes the lift generated. When frost forms, it creates a rough surface texture that alters the smooth airflow needed for effective lift. This roughness can lead to earlier airflow separation, increasing drag and reducing the lift that the wings can produce. Since lift is primarily dependent on the shape of the airfoil and the smooth flow of air over it, any condition that disrupts this, such as frost, will negatively impact the wing's performance. Consequently, the presence of frost decreases the lifting capability of the wings, making it harder for the aircraft to achieve the necessary lift for takeoff or stable flight.