angle of attack for infinite aspect ratio

effective angle of attack

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That part of a given angle of attack that lies between the chord of an airfoil and a line representing the resultant velocity of the disturbed flow. This angle is measured on a finite wing, but it has the same effective magnitude as that of an angle of attack for the infinite aspect ratio measured on a theoretical airfoil between the chord and the direction of the undisturbed airflow. To produce the same amount of lift, an airfoil of finite span must be set at a greater angle of attack than would be necessary if the airfoil were of infinite span, because the downwash velocity produced by the airfoil tip vortices of the finite airfoil tend to reduce the lifting effectiveness of its angle of attack. Also called an angle of attack for infinite aspect ratio.
An Illustrated Dictionary of Aviation Copyright © 2005 by The McGraw-Hill Companies, Inc. All rights reserved