Airfoils are divided into three classes: high lift, general purpose, and high speed. High-lift aerofoil sections are normally used on sailplanes and aircraft with short field operations. They have a high thickness chord ratio, a pronounced camber, and well-rounded leading edges. General-purpose airfoil sections employ a lower thickness/chord ratio, less camber, and sharper leading edges. High-speed sections are used for high-speed aircraft. They have a very low thickness/chord ratio, no camber, and sharp leading edges. Their maximum thickness is at about a 50% chord point.
An Illustrated Dictionary of Aviation Copyright © 2005 by The McGraw-Hill Companies, Inc. All rights reserved