Re: Is there a simple way to lay out different camber arcs?

From: William Gowen <wdgowen_at_gmail.com>
Date: Sat, 2 Apr 2016 12:53:34 -0400

In the formula below *s* (the sagitta) is the height of the airfoil at its
midpoint. You can get that by multiplying the percent camber by the chord.
(4% x 4" = 0.16" as an example). *l* is one half the chord (2"). The center
of the circle would be located at *r-s* from the midpoint of the chord.

r
=
s
2
+
l
2
2
s
where: *s* is the length of the sagitta *r* is the radius of the arc *l* is
one *half* of distance across the base of the arc (half the chord length)

On Sat, Apr 2, 2016 at 11:48 AM, dweigt47_at_gmail.com [Indoor_Construction] <
Indoor_Construction_at_yahoogroups.com> wrote:

>
>
> The MASH-UP model design for the EAA weekend used a wing and horizontal
> stabilizer with a 6% camber, a smooth arc of constant radius. The
> downloadable plan had them full size, which was helpful.
>
>
> I spent a long time working through the math to locate the center, to draw
> my own of the proper chord and camber. (It's been more than half a century
> since I had geometry and trigonometry courses!) This simple sounding
> specification isn't that easy to achieve! Is there a simple formula for
> determining the distance from the chord line to the arc's center, to draw
> any chord wing with a wide range of curvature, from flat to say 10%?
>
>
> Don Weigt
>
>
>
>
Received on Sat Apr 02 2016 - 09:53:35 CEST