LS3A Wing Profile Data

Will be refinishing and profiling a LS3A this winter. Need the wing profile
data which manufacture will not share.
Does anyone out there have tha data they would be willing to share with
me?

email

Bob Fidler

This site, compiled by Dave Lednicer, lists the LS-3 as using the
Wortmann "FX 67-K-170" at the root and a "FX 67-K-150 mod" at the tip.

http://www.ae.uiuc.edu/m-selig/ads/aircraft.html

This agrees with the data in the Thomas book as well as the
directories by Martin Simmons. It was a very popular airfoil on a lot
of gliders from that era.

If you go to this site, you'll find a data file that lists the
coordinates in non-dimensional values.

http://www.ae.uiuc.edu/m-selig/ads/coord_database.html

Now the tricky part....

It may or may not be 17% thick at the root, and typically the airfoils
were scaled in thickness to allow for more uniform spar height
tapering. As a result, you'll probably need to measure the thickness
vs chord ratio at a number of stations and scale appropriately to
match. Also, the tip airfoil is different, and who knows where the
designer started to "blend" into this airfoil along the span...

Now the cool part...and I'm sure I'll get flamed from people who
disagree.... Can't wait....

It really doesn't matter that you get the shape just right for the
full length of the airfoil. The underlying structure is by itself
fairly accurate. You're not going to be sanding away fiberglass. What
does matter is that the profile itself is relatively free of waves and
that the underlying surface quality is quite smooth. Waviness will do
more damage than a slightly in-accurate profile. Hence, you could get
by with just stripping down the gel-coat to the glass, spraying up a
nice uniform thickness of new gel-coat and then spending all of your
time getting rid of chord wise waves. Once that is done, polish up the
final result to a mirror smooth surface and you're done. Technically
you don't even have to polish to mirror smooth, 600 grit sand paper
would yield a smooth enough surface, but your gel coat will last a lot
longer if you go higher. No templates necessary.

-Kevin

On Oct 21, 6:45*pm, Robert Fidler
wrote:
Will be refinishing and profiling a LS3A this winter. Need the wing profile
data which manufacture will not share.
Does anyone out there have tha data they would be willing to share with
me?

email

Bob Fidler

Careful about free advice! It ain't just about waves.
The 67 series is very sensitive to correct profile on the leading
edge.
A few measurements should show linear taper root to tip with airfoil
doing the same thing.
The bad news is that to make templates , you have to plot the airfoil
at each station interpolating between the 67-170 and 67-150.
You don't really want to know how I know this. It's painful.
Look up the series Dick Johnson wrote on improving the PIK-20 which
uses the same series airfoils.
There is much to learn in these articles.
Good luck
UH

You know, I've been flying FX 67-150 and -170 airfoils for years. I've
smashed thousands of bugs, flown through many rain showers and even
collected substantial ice on occasion yet I've not seen any unusual
performance degradation when analyzing flights with SeeYou nor did I feel
any in flight. In fact, those glides with crappy wings often show a
height/distance ratio well above the published L/D. I know Bob Faris gets
great results with his LS-3a in the same conditions. I wonder if these
airfoils are getting a bad rap.

There are PC software programs that will interpolate airfoils and generate
intermediate templates. Just save the results as a .dxf file and email it
to a laser cutting shop so they can make a complete set of templates. I've
had them made out of Plexiglass with laser alignment holes. A complete wing
set should cost no more than a couple of hundred bucks.

In fact, if you just like airfoil shapes as wall hangings, your local
plastic/sign shop can burn them on its laser cutter from .dxf files.

wrote in message
...
On Oct 21, 6:45 pm, Robert Fidler
wrote:
Will be refinishing and profiling a LS3A this winter. Need the wing
profile
data which manufacture will not share.
Does anyone out there have tha data they would be willing to share with
me?

email

Bob Fidler

Careful about free advice! It ain't just about waves.
The 67 series is very sensitive to correct profile on the leading
edge.
A few measurements should show linear taper root to tip with airfoil
doing the same thing.
The bad news is that to make templates , you have to plot the airfoil
at each station interpolating between the 67-170 and 67-150.
You don't really want to know how I know this. It's painful.
Look up the series Dick Johnson wrote on improving the PIK-20 which
uses the same series airfoils.
There is much to learn in these articles.
Good luck
UH

"Bill Daniels" bildan@comcast-dot-net wrote

There are PC software programs that will interpolate airfoils and generate
intermediate templates. Just save the results as a .dxf file and email it
to a laser cutting shop

www.profili2.com would be my first choice: inexpensive, powerful and easy
to learn and use. Once you know chord length and t/c ratio of your wing
creating a DXF for the templates takes less than one hour.

IIRC there were different versions of the FX67 leading edge, see
http://www.gliderforum.com/thread-vi...?threadid=2128 for a start.

Michael

On Oct 21, 11:26*pm, "Bill Daniels" bildan@comcast-dot-net wrote:
You know, I've been flying FX 67-150 and -170 airfoils for years. *I've
smashed thousands of bugs, flown through many rain showers and even
collected substantial ice on occasion yet I've not seen any unusual
performance degradation when analyzing flights with SeeYou nor did I feel
any in flight. *

That's astounding...

I owned an HP-18 for years that made an honest 40:1 clean... and about
7:1 in light rain. I'd feel the ship get draggy with the first tiny
spots on the canopy. In a light rain shower the entire ship hummed
audibly and one had to push the stick forward to maintain 55 kts. The
stall speed went up rather a lot too, but I don't recall any
specifics.

More recently, I watched a Glasflugel (or HPH or whatever they are)
304 -- which has a very similar looking airfoil the root if not
precisely the same airfoil -- get "washed" off a ridge in rain showers
that had little effect on my ASW-20. He might as well have flown into
a net.

I wonder if you have a different leading edge section on your ship, by
happenstance or design. It would be very interesting to discover what
the difference is.

-T8

Been-there-done-that and guess what? Only the first 4 inches are
important. I make up templates before starting, every 24 inches and
then keep everything aft of that dead smooth both cord-wise and span-
wise. Quick and dirty templates can be made from cardboard that is cut
close then crammed over a strip of bondo which is gooped over aluminum
foil every 24" with wing leading edge vertical.
Both Dick Johnson and Allen Bickle made up full scale templates,
worked forever and the bird didn't perform any better than advertised,
except it was a lot heavier because of all that bondo!. Bickle's bird
had a trailing edge that was a good 5mm thick, because that's what the
templates dictated.
Save your time and bondo, concentrate on the first 4".
JJ
When I say bondo, I'm talking about Evercoat Rage Gold, good stuff,
works easy and sticks like mad!


wrote:
On Oct 21, 11:26�pm, "Bill Daniels" bildan@comcast-dot-net wrote:
You know, I've been flying FX 67-150 and -170 airfoils for years. �I've
smashed thousands of bugs, flown through many rain showers and even
collected substantial ice on occasion yet I've not seen any unusual
performance degradation when analyzing flights with SeeYou nor did I feel
any in flight. �

That's astounding...

I owned an HP-18 for years that made an honest 40:1 clean... and about
7:1 in light rain. I'd feel the ship get draggy with the first tiny
spots on the canopy. In a light rain shower the entire ship hummed
audibly and one had to push the stick forward to maintain 55 kts. The
stall speed went up rather a lot too, but I don't recall any
specifics.

More recently, I watched a Glasflugel (or HPH or whatever they are)
304 -- which has a very similar looking airfoil the root if not
precisely the same airfoil -- get "washed" off a ridge in rain showers
that had little effect on my ASW-20. He might as well have flown into
a net.

I wonder if you have a different leading edge section on your ship, by
happenstance or design. It would be very interesting to discover what
the difference is.

-T8

Some thoughts to "muddy" the discussion.
Many years ago, we made leading edge templates of a wing of an undamaged
and relatively new LS sailplane. The templates were made with bondo and
cardboard in the JJ manner. We all know the root is bigger/fatter than
the tip. We would slide the root template from the root to the tip and
observe the changing shape as it neared the tip.
We then took the root template to the other wing and did the same. They
were not same. Not even very close and we found the middle of the other
wing was actually fatter than the root.
This particular LS went we very, very well. It was a winner in many
competitions.
Conclusion?
Bob


"Careful about free advice! It ain't just about waves". (previous
message)

On Oct 21, 9:26*pm, "Bill Daniels" bildan@comcast-dot-net wrote:
You know, I've been flying FX 67-150 and -170 airfoils for years. *I've
smashed thousands of bugs, flown through many rain showers and even
collected substantial ice on occasion yet I've not seen any unusual
performance degradation when analyzing flights with SeeYou nor did I feel
any in flight. *In fact, those glides with crappy wings often show a
height/distance ratio well above the published L/D. *I know Bob Faris gets
great results with his LS-3a in the same conditions. *I wonder if these
airfoils are getting a bad rap.

Bob Faris flies an LS-3, which is rather different than an LS-3a in
the flap/aileron vs flaperon and wing weight areas. Read something in
the past year that suggested that the FX67/170 and 150 did not degrade
on long spans where the thickness was 15%, but can't find it at the
moment.

Frank Whiteley

The LS-3 measured higher in L/D than the 3a according to Dick Johnson's
tests. I actually have a letter from Wolf Lemke that was with papers that
came with my LS-3a assuring owners that there is no difference in
performace from follow-up factory tests of the 3a after Dick's flight
tests??

I also noticed the following quote on wikipedia for the LS-3:
"In spite of its weight the LS3 is a nimble climber. It is also less
sensitive to rain or dirt than other types with the same profile."

I'm not sure who posted this to the Wiki or if this applies only to the 3
or 3a? Was there any change in profile for the 3a?

Matt
LS3-a "RX"

At 15:44 22 October 2008, Frank Whiteley wrote:
On Oct 21, 9:26=A0pm, "Bill Daniels" wrote:
You know, I've been flying FX 67-150 and -170 airfoils for years.
=A0I've
smashed thousands of bugs, flown through many rain showers and even
collected substantial ice on occasion yet I've not seen any unusual
performance degradation when analyzing flights with SeeYou nor did I
feel
any in flight. =A0In fact, those glides with crappy wings often show a
height/distance ratio well above the published L/D. =A0I know Bob
Faris
g=
ets
great results with his LS-3a in the same conditions. =A0I wonder if
these
airfoils are getting a bad rap.

Bob Faris flies an LS-3, which is rather different than an LS-3a in
the flap/aileron vs flaperon and wing weight areas. Read something in
the past year that suggested that the FX67/170 and 150 did not degrade
on long spans where the thickness was 15%, but can't find it at the
moment.

Frank Whiteley