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Old April 8th 08, 01:51 AM posted to rec.aviation.soaring
Bob Kuykendall
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Posts: 1,345
Default Woodstock Glider

On Apr 7, 4:44 pm, wrote:
Sorry, I just clued in on the aerodynamic twist.
The tip foil should stall later, right.
I got confused with the %18 vs %13, which is just the thickness and
I wouldn't have thought the difference would have been significant,
but if what Mr. Sinclair is saying, they are actually different foils then
there would be some form of washout. Thanks guys.


Yup, that's the way I understand it - there's no angular difference
between the chord lines of the root and tip sections, but the profile
differences between the root and tip airfoils make the wing act as if
there are.

Here's a couple of pictures from the Les Sparks site that shows the
Woodstock wing profiles:

http://members.aol.com/lessparks/clint20.jpg

http://members.aol.com/woodglider/clint25t.jpg

It's kind of hard to see in the photos, but if you look closely you
can see that the profile goes from sort of flat-bottomed at the tip to
a deeper-bellied (for lack of a better term) section at the root.

Here's the home page for the site those photos are from:

http://members.aol.com/woodglider/index.htm

I haven't heard from Les for a while, I wonder what's up with his
project.

I scanned sheet one of the 13M drawings and have the foils
now in a DWG format.
What I'll do is use Pro/E to loft between foil 1 and 20, then insert
each foil from 1 to 20 at station, then generate cross sections at
each station to see if they all meet up.


That sounds like a good plan, that ought to work great. The main
gotcha, and you've probably already thought of this, is that old
blueprints tend to shrink and warp a bit as they age. Also, sometimes
scanners add their own scaling errors. So its possible to accumulate a
bunch of little errors that add up to something substantial. The plans
probably have some key dimensions that you can use to correct the
scaling of your DWGs; if you keep an eye on them you'll be fine.

Thanks, Bob K.
http://www.hpaircraft.com/hp-24