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VIKING SQUADRON |
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Airplanes |
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Airfoil design: An airfoil is designed specifically to cause a dynamic reaction from the air through which it moves. Those parts of the airplane specifically designed to react with the air include the wing and tail surfaces. Likewise, propellers are airfoils, by design, and their rotation through the relative wind creates a “forward lift.” The illustration below shows the cross section of a wing, but it could be a tail surface or a propeller, because they are all essentially the same.
Leading Edge. The leading edge of an airfoil meets relative wind, first. The shape at this location depends upon the intended use of the airfoil. If the airfoil is designed to be flown at high speeds, its leading edge will be sharp such as those found on the wings of jet fighters. The leading edges of the wings on slower training and pleasure-type aircraft (such as the single-engine trainers and gliders) are more rounded and thicker.
Camber. Immediately behind the leading edge, there is the upper and lower camber. This curvature determines the airfoil’s thickness. Camber can be either positive or negative. Positive camber curves away from the centerline while negative camber moves toward the centerline of the airfoil.
Trailing Edge. Whether the camber is pronounced, thin, positive, or negative, the upper and lower surfaces must come together at the rear of the wing. This thin junction is called the trailing edge. The trailing edge area is where the air stream rejoins after having been separated at the leading edge and directed over, and under the airfoil surface. Chord. A very important part of an airfoil is its chord. This imaginary line is shown in the illustration above. It connects the leading with the trailing edge. It is used in the scientific explanation of several aerodynamic functions. One of the most important is the concept of angle of attack. |
