# What is the chord of a wing?

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?

the Chord is the line stretching from the leading edge of the wing to the trailing edge parallel to the centerline. 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.

• Could you comment on how the chord is considered when creating a wing? Perhaps how it effects lift and stability? – Jay Carr May 20 '14 at 17:57
• 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. – Peter Kämpf May 20 '14 at 19:39
• @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.) – Jay Carr May 22 '14 at 15:15
• @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. – Peter Kämpf May 22 '14 at 17:52
• @PeterKämpf You should come into the chat at some point, so I can ask you a few questions about it then ;) – Jay Carr May 22 '14 at 18:16