In the answer to this question the author mentions the chord of a wing. What exactly is that, and how is it used in wing design?


1 Answer 1


the Chord is the line stretching from the leading edge of the wing to the trailing edge parallel to the centerline.
Chord diagram from the Pilot's Handbook of Aeronautical Knowledge

There are different variations to describe the chord of the whole wing.

  • The Standard Mean Chord
    Defined as $\frac S b$ with $S$ the surface area and $b$ the span of the wing. This is not used in aerodynamics.

  • The Mean Aerodynamic Chord
    Defined as $\frac2 S \int_0^{\frac b 2} c(y)^2 dy$ with $y$ the coordinate along the wing and $c(y)$ the chord at $y$.
    For swept or delta wings this gives the equivalent chord for a rectangular wing, and is important for placing the Center of Gravity for stability.

  • $\begingroup$ Could you comment on how the chord is considered when creating a wing? Perhaps how it effects lift and stability? $\endgroup$
    – Jae Carr
    May 20, 2014 at 17:57
  • 1
    $\begingroup$ In most caes, the chord is simply the size of the wing in streamwise direction. As this varies over span, there are different ways of computing the average, but for the answer on the X-1 control issue, those differences are academic. If you increase the chord, lift goes up almost linearly and stability decreases, because now the wing's lift force has a longer lever arm in flow direction. By increasing chord, you decrease aspect ratio, but the effect of this is better explained in a full answer to a new question. $\endgroup$ May 20, 2014 at 19:39
  • $\begingroup$ @PeterKämpf I'll be honest, I'm not sure how to even ask that question. Starting to think I just need to pick up a book on aerodynamics and wing design (for dummies, in my case.) $\endgroup$
    – Jae Carr
    May 22, 2014 at 15:15
  • $\begingroup$ @Jay Carr: Yes, that could be a start, but doesn't give you the interactivity you find here. If you think you could annoy the others - if they answer, they clearly are not annoyed. $\endgroup$ May 22, 2014 at 17:52
  • $\begingroup$ @PeterKämpf You should come into the chat at some point, so I can ask you a few questions about it then ;) $\endgroup$
    – Jae Carr
    May 22, 2014 at 18:16

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