Std Libelle Turbulator Tape

[Tim McAllister]

I was looking through old messages on this group and I saw a post
asking for the detailed information on turbulator tape placement for
the Libelle 201B.

Did anyone ever discuss this information? or does anyone know where
one could get the detailed information for exact placement of
turbulator tape on the Libelle 201B?

Any information would be appreciated.

Tim McAllister

[John H. Campbell]

His response [...Streifeneder's] to me was that turbulator tape
provides no benefit to the Std. Libelle wing.
... and he designs, makes, and sells the tape at that. So, it must be
true. You asked for any suggestion... Hazarding a guess that the Huetter
airfoil (?) on that 1960's design might be similar to the Eppler sections on
the contemporary Phoebus and Austria and later Astir, you might try the 60%
(from L.E.) placement suggested by an Althaus paper (famously further
forward than most). Or you can have fun with stethescope rakes or oil
films, probing test placements in flight. Your club will appreciate the
extra tow business. --JHC

[Nick Gilbert]

I have heard (also through Striefeneders) that there may be some merit to
having it on the top of the wing. Either way, Striefeneders are the people
to speak to on matters like this.

Nick.

Tim McAllister wrote in message <39ad508d...@news.cmn.net>...

[Martin]

You still have the option of winglets, looks much cooler than tape!

Martin

O'Neal <bob....@home.net> wrote in message
news:39AD60A6...@home.net...
I asked Hansjörg Streifeneder (.http://www.streifly.de/) the same question.
His response to me was that turbulator tape provides no benefit to the Std.
Libelle wing.
This was disappointing to hear because the tape would look so cool on the
wing.
Bob
Std. Libelle #216

[udor...@my-deja.com]

> You asked for any suggestion... Hazarding a guess that the
Huetter
> airfoil (?) on that 1960's design might be similar to the Eppler
sections on
> the contemporary Phoebus and Austria and later Astir, you might try
the 60%
> (from L.E.) placement suggested by an Althaus paper (famously further
> forward than most).

The Gliders mentioned above have the following airfoils
there is no similarity between them
Std. Austria Naca 65-416
Std. Libelle FX 66-17-182
Libelle H301 Huetter
Astir CS E603
Phoebus E403

The airfoil that could benefit from a turbulator, is the E603
Regards
Udo Rumpf

Sent via Deja.com http://www.deja.com/
Before you buy.

[RFR]

Hey Udo,

Do you happen to know if gap sealing would benefit the 301?

Cheers,
Rod

[udor...@my-deja.com]

> Do you happen to know if gap sealing would benefit the 301?

Rod,
gap sealing is always beneficial

Udo

[Wallace Berry]

301 Libelles came with nylon fabric seals inside the control surface
gaps. These are critical for good performance. However, the external
surfaces of the wing and control surfaces have very small gaps compared
to those on many other sailplanes. I am convinced from experience that
putting mylar seals on the external surfaces don't help performance.
They do serve as places for dirt and water to collect. Seal the inside
and don't worry about the outside is my advice. However, I think now
there are better materials for this than nylon fabric.

Have fun and fly safe.

[RFR]

Hey, the 301's performance in this day and age of Ventus 2's, LS-8's and
ASW-27's is still quite good. In calm, evening air, the 301 can hold even
with an empty LS-8 up to about 120km/h. However, in very weak conditions,
the 301 does not climb as well as the LS-8 or Ventus 2b; something which
really surprised me. Both aircraft were carrying around 40kg. of ballast
and booming thermals were rising at 0.3 - 0.5 m/s.

Sure the gaps on the 301 are not that big, but the space between the flap
and the fuselage is huge. I think it would be interesting an interesting
experiment to try.

The airfoil reminds me very much of the ASH-25, but I find that rain and
bugs do not affect performance as much as they do on the 25 or even a
DG-200.

Regards,
Rod

[Wallace Berry]

In article <8oofov$ksm$1...@pollux.ip-plus.net>, RFR
<XXXroderi...@yahoo.com> wrote:

> Hey, the 301's performance in this day and age of Ventus 2's, LS-8's and
> ASW-27's is still quite good. In calm, evening air, the 301 can hold even
> with an empty LS-8 up to about 120km/h. However, in very weak conditions,
> the 301 does not climb as well as the LS-8 or Ventus 2b; something which
> really surprised me. Both aircraft were carrying around 40kg. of ballast
> and booming thermals were rising at 0.3 - 0.5 m/s.
>
> Sure the gaps on the 301 are not that big, but the space between the flap
> and the fuselage is huge. I think it would be interesting an interesting
> experiment to try.
>
> The airfoil reminds me very much of the ASH-25, but I find that rain and
> bugs do not affect performance as much as they do on the 25 or even a
> DG-200.
>
> Regards,
> Rod

Performance of the 301 does seem to hold up well against the newer
glass, except when it's booming and they are all loaded to the gills
with water. I've not flown one against and LS-8 or Ventus 2b and am
surprised that they outclimb the 301.

You are certainly correct about the flap to fuselage gap. One of the
famous Schuemann modifications for the 301 consists of a fairing on the
fuselage to close that gap. My partner installed mylar "wipers" on the
flap ends to cover the gap, and I've seen foam plugs installed in the
flap ends to close the gap and wipe against the fuselage.

I had a 301 once, I intend to get another in the near future. Best darn
glider for the money. But not for the average low time pilot!

[carl]

Regardless of the "opinion" of respected German designers, trip tapes
indeed enhance the performance of the Standard Libelle airfoil. The
bottom line, so to speak, is 75% of chord.

In February, 1985 I wrote to Prof. D. Althaus asking the same question.
I received his reply in April-- "I made no tests with trip tapes on the
Standard Libelle airfoil and I don't believe that it works."

Well now, that got a chuckle, because I had just spent the intervening
months "making tests" with an integrating drag rake constructed to Dick
Johnson's design specifications. I used bump tape constructed of
"periods" punched into 3/8-inch dymo-label tape. I obtained volumes of
data from over a dozen flights in weak wave or early morning stable air
by using a voice recorder. The chordal position of a three-foot section
of tape in front of the wake probe was varied during these tests, which
included flights with no tape. To reduce the possibility of systematic
errors, the positions of the pitot and statics used for the tests were
varied (e.g., tail-fin pitot and static, nose-pot pitot with tail fin
static, etc.). The net result of all of these tests was that bump-tape
at 75% chord significantly reduced the drag for all speeds from 40 to 85
kt, and did not increase drag above 85 kt.

After these tests, I applied bump-tape punched out in the odd spare
moment (e.g.. while watching the late night news) to the entire wing.
Comparison flights with other Libelles at approximately the same wing
loading confirmed the performance improvement.

Don't rely on opinion, speculation, or theory -- let experimental
evidence be your guide.

Cheers,

Carl Ekdahl (IY -- ASW27)

[Willy]

On Wed, 06 Sep 2000 00:32:16 -0600, carl <ca...@rt66.com> wrote:

>> .. trip tapes indeed enhance the performance of the Standard Libelle airfoil.
>> ... The net result of all of these tests was that bump-tape at 75% chord

>>significantly reduced the drag for all speeds from 40 to 85 kt, and did not
>> increase drag above 85 kt.

>> Carl Ekdahl (IY -- ASW27)

Anyone knows of Std. Cirrus tests?

Willy (C16 -- 00-ZNY)

[F.L. Whiteley]

This is very good information.

Any speculation on whether bump tape would be better than zig-zag in this
application?

Frank Whiteley
Colorado

"carl" <ca...@rt66.com> wrote in message news:39B5E4F0...@rt66.com...

[carl]

Hi Frank,

I didn't test zig-zag, but I would bet that its better than bump ape for
triggering the turbulent flow.

Cheers,

Carl