Plain English Meaning

The simple, thin, curved wing shape used on the earliest airplanes, before engineers learned how to design more efficient wings.

Full Definition

An early airfoil refers to the wing cross-section shapes used on the first powered aircraft, characterized by a thin, highly curved (cambered) profile with the upper and lower surfaces nearly parallel. These shapes were developed before the systematic aerodynamic research of the 1920s and 1930s and produced relatively low lift, high drag, and poor structural depth compared to later designs.

Context Anchor

Seen in the Pilot’s Handbook of Aeronautical Knowledge in a figure comparing different airfoil designs.