Understanding Drag ©


DRAG, the arch enemy of THRUST

Drag is related to friction but is slightly more complex. Its effect, however, is identical to friction. Drag opposes the motion of an object as it moves through a fluid (liquid or gas).

The most important factors that affect drag on an airplane are:

  1. the frontal shape of the object
  2. the frontal area of the object
  3. the speed of the object through the air

SHAPE FLOW PATTERN COMMENTS
Blunt rectangleThe square corners and blunt face cause the air to become turbulent as it tries to flow around the object. The drag created by this shape is very large.
Smooth Curve Smoothing the edges improves the air flow around the object and therefore the amount of drag is reduced.
Long smooth
curve		Making the curve longer so that the air flow can change direction less radically further reduces the drag. Unfortunately the length of the curve has practical limits.
Needle

Transparency Master

 When the aircraft is expected to fly at speeds greater than the speed of sound ( i.e. supersonically ), a needle shape turns out to have the minimum drag.

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