How much ice on the leading edge of airfoils reduces lift and increases drag?

The correct answer is based on the fact that the accumulation of ice on the leading edges of airfoils significantly affects the aerodynamic performance of an aircraft. Specifically, an accumulation of ice can disrupt the airflow, resulting in reduced lift and increased drag.

When ice builds up to a thickness of 1/2 inch on the leading edge, it alters the shape of the airfoil, which can lead to a higher stall speed and diminished lift capabilities under various flight conditions. The addition of ice creates a harsher transition in airflow over the wing surface, which can lead to flow separation and increased drag. This phenomenon is critical for pilots to understand, as it highlights the importance of removing ice before takeoff and during flight.

While other thicknesses of ice also impact performance, research and practical experience have shown that 1/2 inch is a significant threshold at which the reduction of lift and increase in drag become pronounced enough to pose serious safety concerns for aircraft. This level of ice on an airfoil can drastically hinder an aircraft's ability to maintain flight, making it a crucial consideration in aviation safety protocols.