# How is the camber calculated?

In this picture, how do you determine the amount of the camber? Is it the average difference in the distances between the mean camber line and the chord line from the leading edge all the way down to the trailing edge?

## 1 Answer

The mean camber line is the locus of points halfway between the top surface and the bottom surface (which are sometimes referred as upper and lower cambers). For a symmetrical airfoil, it is merged with the chord line.

This curve is described by a polynomial function at each point along the chord axis. An airfoil may have a camber line which changes direction at one or more point, and which possibly crosses the chord.

All measures are taken perpendicular to the chord which is considered having a length of 1 or 100%.

Adapted from Wikipedia.

What you ask for is the maximum camber, which is determined by the value of the maximum difference between chord and mean camber line, and the distance from the leading edge.

Adapted from Wikipedia.

• So it looks like there is no such thing as the "average camber." Then, when deployed flaps are said to increase the camber, what exactly does it mean? Does it mean the maximum camber increases? – lemonincider Mar 6 '17 at 7:15
• @lemonincider: The "average" camber is likely the "mean" camber. when flaps are extended, the chord line changes because the trailing edge is lowered, this increases the maximum camber. – mins Mar 6 '17 at 7:22
• Is the mean camber different from the mean camber line? Then, is it the "mean camber" that is referred to when the flaps are commonly said to increase the camber? – lemonincider Mar 6 '17 at 7:31
• @lemonincider: No, this is a shortcut, like chord line and chord. – mins Mar 6 '17 at 7:53
• ... The more the airfoil is cambered, the more it is asymmetric , at some point the bottom face becomes concave (by definition of the mean line) and the chord is outside of the airfoil. So yes, when the camber is not reflexive (no inflection point), this is a measure of the difference with the chord. – mins Jul 12 '17 at 0:18