Aerodynamic force

Aerodynamic force is the resultant force exerted on a body by the air (or some other gas) in which the body is immersed, and is due to the relative motion between the body and the fluid. An aerodynamic force arises from two causes:

the force due to the pressure on the surface of the body

the force due to viscosity, also known as skin friction

When a body is exposed to the wind it experiences a force in the direction in which the wind is moving. This is an aerodynamic force. When a body is moving in air or some other gas the aerodynamic force is usually called drag.

When an airfoil or a wing or a glider is moving relative to the air it generates an aerodynamic force that is partly parallel to the direction of relative motion, and partly perpendicular to the direction of relative motion. This aerodynamic force is commonly resolved into two components:

Drag is the component parallel to the direction of relative motion.

Lift is the component perpendicular to the direction of relative motion.

The force on a propeller or a jet engine is called thrust and it is also an aerodynamic force. The aerodynamic force on a powered airplane is commonly resolved into three components:
thrust, lift and drag
The only other force acting on a glider or powered airplane is its weight. Weight is not an aerodynamic force.

References

• Hurt, H.H.Jr. Aerodynamics for Naval Aviators. A National Flightshop Reprint, Clearwater, Florida (1979)
• Clancy, L.J. (1975). Aerodynamics. Pitman Publishing Limited, London. ISBN 0 273 01120 0
• Massey, B.S. Mechanics of Fluids, 2nd Edition. Van Nostrand Reinhold Co., London (1970) Library of Congress Catalog Card No. 67-25005

Notes