Woodstock Glider

Thanks Guys

Correct me if I'm wrong, but there is no washout in this design is
there?

On Apr 7, 12:38 pm, wrote:
Thanks Guys

Correct me if I'm wrong, but there is no washout in this design is
there?

Sorry, yet another question, are the Airfoil Data points freely
available?

On Apr 7, 9:50*am, wrote:

Correct me if I'm wrong, but there is no washout in this design is
there?

If there is, it will be shown in the plans. It might also be covered
in _Fundamentals of Sailplane Design_, but my copy is not handy.

Sorry, yet another question, are the Airfoil Data points freely
available?

Probably not. It's not at the UIUC site, so it's probably not freely
available. From what I've heard, it was a one-off profile (OK, two-off
if you count the substantial difference between the root and tip
shapes) that Irv did on a relatively casual basis.

Thanks, Bob K.

I believe the Woodstock has an aerodynamic twist that allows the tip
stall later (slower) then the root. I believe the airfoil was derived
from the Gother 549 (modified by Erv Culver) then it blends into USA
35B at the tip. I flew the prototype and it didn't have a tip stall.
JJ

wrote:
Thanks Guys

Correct me if I'm wrong, but there is no washout in this design is
there?

On Apr 7, 3:03 pm, JJ Sinclair wrote:
I believe theWoodstockhas an aerodynamic twist that allows the tip
stall later (slower) then the root. I believe the airfoil was derived
from the Gother 549 (modified by Erv Culver) then it blends into USA
35B at the tip. I flew the prototype and it didn't have a tip stall.
JJ

wrote:
Thanks Guys

Correct me if I'm wrong, but there is no washout in this design is
there?

I'm looking at the plans, and there is no Washout, that I can detect,
which is why I'm asking.
The spar cutouts are exactly the same relative position on all the
foil profiles, with no twisting.
I am also an Aerospace Engineer, been working mostly mechanical for
the last 8 years so my aerospace brain has cobwebs, but I do know how
to read a drawing, my guess is it was this way for ease of
construction.
I'll re-read the assembly manual again.
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.

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.

Herbie.

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

And I might add that the Woodstock is an amazing sailplane or at least
a simple one that handles well with an amazing wing for a lightweight
glider. It's remarkably fast and surprises me almost everytime I go
somewhere with it. Gary Osoba called it the best kept secret in
soaring.
MM

On Apr 7, 8:51 pm, Bob Kuykendall wrote:
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


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.

Yes, Hence me looking for data points. The chord at root and tip are
known and have hard dimensions for.
I can check that with % chord at root and tip for scaling in that
direction, print off and check over the actual prints I have.
I can also CNC Route some "test ribs" using my CNC router.

On Apr 7, 7:36 pm, wrote:
On Apr 7, 3:03 pm, JJ Sinclair wrote:

I believe theWoodstockhas an aerodynamic twist that allows the tip
stall later (slower) then the root. I believe the airfoil was derived
from the Gother 549 (modified by Erv Culver) then it blends into USA
35B at the tip. I flew the prototype and it didn't have a tip stall.
JJ

wrote:
Thanks Guys

Correct me if I'm wrong, but there is no washout in this design is
there?

I'm looking at the plans, and there is no Washout, that I can detect,
which is why I'm asking.
The spar cutouts are exactly the same relative position on all the
foil profiles, with no twisting.
I am also an Aerospace Engineer, been working mostly mechanical for
the last 8 years so my aerospace brain has cobwebs, but I do know how
to read a drawing, my guess is it was this way for ease of
construction.
I'll re-read the assembly manual again.
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.

The original 12-meter Woodstock wing has no twist. Irv Culver
(Lockheed Skunkworks) did the airfoils at the request of designer Jim
Maupin (both now no longer with us, regrettably). Wingtip/aileron
stall protection was secured via reducing the percent section near the
wingtip. It's in the manual. Woodstock wing stall characteristics (at
least for the original 12 meter wing, which I built and flew) were
absolutely delightful: first time I stalled my n20609, on her maiden
flight, I broke out loud laughing. Perfect stall behavior; as mannerly
as it is possible to be. Despite low wing loading, the Woodstock
feels as much like Libelle as it does a SGS1-26. Easier to keep
rightside up in turbulence than a 1-26 in turbulence to boot,
particularly on aerotow.
Safe soaring,
Bob Wander