Astrir turbulator tapes
Istvan Csonka
estimated performance improvement, what is the effect of the flight polar,
etc....
Grob told me that there is something in an old Aerokurier, but
unfortunately I do not have this.
Any help would be appriciated.
Falk Rüth
01c06679$483ce440$282f...@icsonka.hu.ibm.com...
> I would need info about G102 Astir turbulator tapes. How much is the
There was a thread at the segelflug.de-forum:
http://www.e-betteln.de/soaringboard/messages/112.html
Falk
________________
f...@k6-team.de
www.k6-team.de
Istvan Csonka
Falk Rüth <f...@k6-team.de> wrote in article
<91cu06$of9$1...@infosun2.rus.uni-stuttgart.de>...
André Somers
ics...@hu.ibm.com says...
access the service wich can translate webpages and other text for you.
It isn't perfect, but it might help you out.
André
Larry Goddard
48:1. :-)
Larry
hatrim
page 24, titled "Improving the Performance of the Astir
Family Wings," by Deiter Althaus, describes the laminar
separation bubble on the bottom of the E 603 airfoil and the
use of a turbulator to eliminate it and reduce the drag. The
turbulator must be placed at the .65 chord position. The
turbulator is only needed for Reynolds numbers below
1.5 million. Above that, the bubble does not exist on the
unturbulated airfoil. At Reynolds numbers below 1.5 million,
in the lift coefficient range of 0.2 to 1.0 the drag coefficient
is reduced by about .0025 to .0030, and is reduced by a smaller
amount at lift coefficients below 0.2 and above 1.0. At no point
is the drag increased by the turbulator at Reynolds numbers
below 1.5 million. The turbulator used in these tests was a
dimpled mylar strip.
I quote the last paragraph of the article: "On the Astir the
Mylar film should be used along the total span (35% of the
chord from the trailing edge). On the Twin-Astir use of the
film is recommended only on the outer wing up to 4.3 m from
the wingtips inboard." I take this to mean that on the Twin
the turbulators should be used on the part of the wing starting
4.3 m from the root and extending out to the tip.
A quick back-of-the-envelope calculation shows that
for the single seat Astir, if the whole wing benefited from
the turbulator at the speeds for minimum sink and best L/D,
the minimum sink could be reduced by about 8 fpm and the
best L/D increased by about 5 points (!) from 35ish to 40ish.
The benefits of the turbulators will be less with increasing
airspeeds.
Best regards,
Calvin Devries
karls...@my-deja.com
Hi,
I got this Article from Aerokurier 1984 and a desciption of Grob how
and where to fix the turbulator tape. The Author says that it improves
the Astir profile E603 about 5% from epsilon 111 to 116. If you choose
Zick-Zack-Tape the front of the tape should be at 62%. If you like I
can scan the article and the Grob Drawing and mail them to you.
Sent via Deja.com
http://www.deja.com/
Caracole
I'd like to point out a discrepancy.
From the material you quote....
the turbulator for the Twin Astir should be used
from the wingtip for 4.3 meters toward the centerline.
They do not describe the tape as beginning at
the wing root.
Many times, what we want to read is not what
is actually printed.
My only interest here is flight safety.
Cindy
hatrim <hat...@sentex.net> wrote in message
news:3A3A49A4...@sentex.net...
SNIP
> I quote the last paragraph of the article: "On the Astir the
> Mylar film should be used along the total span (35% of the
> chord from the trailing edge). On the Twin-Astir use of the
> film is recommended only on the outer wing up to 4.3 m from
> the wingtips inboard." I take this to mean that on the Twin
> the turbulators should be used on the part of the wing starting
> 4.3 m from the root and extending out to the tip.
>
> Best regards,
> Calvin Devries
>
>
Istvan Csonka
If you could scan and send it for me it would be great.
<karls...@my-deja.com> wrote in message
news:91dlvv$8ob$1...@nnrp1.deja.com...
hatrim
Thanks for your comment. I believe your interpretation
is correct. I attribute my confusion to what appears to be
an awkward translation into English. I quoted the paragraph
so that others might be able to give an althernate reading.
Although it would likely have an effect on performance,
it seems unlikely to me that putting the turbulator on more
of the wing than necessary would have any effect on
flight safety.
Best regards,
Calvin Devries
Istvan Csonka
What does it mean "from epsilon 111 to 116" ?
karls...@my-deja.com
Improving from Epsilon 111 to 116 means that if you consider only the
profile the best L/d improves from 111 to 116 whereas the whole glider
in total has a L/D of about 37.
The improvement for the profile is about 5%, the whole glider will have
much less benefit. So do not expect to much of the tapes, perhaps they
will improve the handling. I don't know because I will fix them this
winter on my CS77 for the first time. Bought it last winter.
By
Ruediger
Istvan Csonka
Thanks for the info, but I have the following problem: I had to remove the
tape from right wing and this tape is not usable again. The questions is for
me buying new tape for the right wing or remove from the left wing ?
karls...@my-deja.com
really I have no Idea by know, as I can not tell the difference before
March 2001 when I have "Roll out" for my tuned CS77 with Zick-Zack Tape.
If you really wan't an opinion on what I expect what will happen, I
guess I will not notice any difference on the L/D, perhaps the handling
will improve, but even If it does not improve I will feel better
(psycho).
The Zick-Zack-Tape will cost about 50 Euro for the glider.
Sorry I cant help you with more information, but perhaps anyone else in
this group can comment.
Wishing you a merry Christmas and a happy 2001
Ruediger
(alias Karlson)
kunac...@gmail.com
I'm interested in this article about Astir turbulators.
Please can You send scan. To josko...@hotmail.com or kunac...@gmail.com
Beet regards from Croatia
Josko
Michael Opitz
Go to the LTB Lindner website and click on SL-12 installation of control
surface seals. The instructions for the Z-Tape are included there:
http://www.ltb-lindner.com/service-letter.html
Good luck,
RO
christoph...@googlemail.com
there is a drawing from Grob, specifying the turbulator location for the single-seaters as follows (distances measured on the pressure side of the wing from the trailing edge to the trailing edge of the tape):
Wing root: 360mm
Inboard end of the aileron: 300mm
Wing tip: 178mm
Twin I and II twoseaters receive the tape only at the ailerons with the following dimensions:
4300mm from the wing tip: 380mm
Inboard end of the aileron: 370mm
Wing tip: 208mm
Unfortunately, these locations are not included in the service letters from LTB Lindner.
The tapes do not significantly improve the performance - perhaps 1 or 2 points, you won't notice that. But they remove the seperation bubble from the ailerons and improve the airflow there. You will notice that the glider becomes more stable in a turn. You will also need less aileron input for corrections and the aileron in general is a bit more responsive.
Best
Christoph
Michael Opitz
>Hi Ruediger,
>
>there is a drawing from Grob, specifying the turbulator location for
the
of the
>
>Wing root: 360mm
>Inboard end of the aileron: 300mm
>Wing tip: 178mm
>
>Twin I and II twoseaters receive the tape only at the ailerons with
the
>4300mm from the wing tip: 380mm
>Inboard end of the aileron: 370mm
>Wing tip: 208mm
>
>Unfortunately, these locations are not included in the service
letters
>
>The tapes do not significantly improve the performance - perhaps
1 or 2
from the
glider
>
>Best
>Christoph
Please re-read Lindner SL-12. It plainly states that all control
surface seals including the rudder may have the Z-Tape installed
just in front of the gap seals. In the case of the rudder, IMO, it
greatly increases the effectiveness of that control surface,
especially at low speeds like on initial take-off roll, etc.. The
drawings you refer to may be for possible increased performance
due to dealing with the laminar separation bubble where the
Z-tape is extended beyond the ends of the ailerons, but it is not
the same as where the service letter basically allows all Grob
glider types to have sealed control surfaces with optional Z-Tape
included.
RO
christoph...@googlemail.com
indeed, SL12 includes a reference to turbulator tape in front of the control surfaces. Especially in case of the rudder, this helps to reduce the lack of rudder authority that most Astir. Turbulators on the suction side in front of the ailerons also seem to improve aileron authority on some gliders, like the ASK21.
However, the drawing that Grob released in the 80s and which the Aerokurier article refers to, includes additional specifications for turbulator tape on the pressure side of the Eppler airfoil. These are not part of SL12. When following these instructions, the tape will not be right in front of the aileron gap as shown in SL12. It will be a few centimetres further upstream.
Regards
Christoph
Michael Opitz
>Hi Michael,
>
>indeed, SL12 includes a reference to turbulator tape in front of the
in
>
>However, the drawing that Grob released in the 80s and which the
tape
SL12.
the
>..
>
>Regards
>Christoph
>
I agree that the additional turbulator tape instructions which the
article refers to may bring some not so noticeable performance
increases. We have underwing turbulators installed in those
positions on our Twin 1's also, and absent side by side glide testing,
there is not much to notice. The handling was always a complaint
with the Twin 1's. and in this case, the addition of turbulators in
front of the control surfaces does help markedly, and the difference
is plain to see and feel. The rudder is most noticeable. Aileron
response is also better. I have even had success using it on the
upper stabilizer to enable more effective high speed nose-down
trim. Operators of Twin 1's that do not have the Z-tape installed
should try it. It doesn't cost much money, and I think the pilots
will be pleasantly surprised.
RO