Turbulator Tapes, Mylars to a lesser extent Winglets
Jon Dixon
I am enquiring as to what sources of information regarding the accurate
placement of Turbulator tapes on sailplanes (mine is an ASTIR CS). So far I
have seen that generally the Turbulators for the underside of the wings are
at approximately 65% of the chord for the astir. I have also read that the
tapes can be applied somewhere on the upper surface of the wings.
Where do I find out about this? My interest at this time is specifically for
the Astir, however, I am generally interested in all types.
I am also interested in fittment of Mylar seals and possibly at a later date
winglets.
Basically, I'm trying to get the Astir to fly at her best (pilot skills will
be handled by time in the air).
Please feel free to email me j...@swd.com.au direct with information as well
as to the group. I am not monitoring the group daily and would not like to
miss out on any relevant messages on this topic.
Regards
Jon Dixon
Ruediger
we had this thread a few weeks ago and I offered to mail an image of the
original article from Aerokurier 1984 about the effect of tape / Zick-zack
on the E603 profil and a letter from Grob where the right position is shown
(it differs from "Noppen-" at 65% to "ZICK-ZACK-" at 63% turbulators). The
Article says that if you only consider the profile E603 the L/D improves
from 111 to 116, so for the whole glider you can expect about 5%
improvement. If you are interested you can have these files. Concerning the
Mylar seals I think everything will help to improve the L/D. In the
"segelflug.de" we had a similar thread and I learned that the seals / and
turbulators eg. at the vertikal stabalizer will also help to improve the
handling. Turbulators on outer three meters ot the upperside of of the wing
were advised for improving the handling as well (a ASK21 specially used for
aerobatics was given as an example).
Ruediger (Astir CS 77)
"Jon Dixon" <j...@swd.com.au> schrieb im Newsbeitrag
news:3aa6...@usenet.per.paradox.net.au...
Robertmudd1u
writes:
>Turbulator tapes on sailplanes (mine is an ASTIR CS).
Grob published something on this. Contact Mike Shade in Bluffton, Oh. He is of
course the Grob aircraft rep in the States.
As I remember the Boeing Glider Club did some studies on dimple tape placement
on a Astir CS in the 1980s. Anyone remember that?
Robert Mudd
Former CS owner.
Paul Alan Sponagle
reduce the L/D. I thought the whole idea of achieving the highest L/D was
to stay in the laminar bucket.
I have a pretty good idea how roll control woould improve with turbulent
flow over the ailerons but this increased L/D is bothering me. L/D will
should go down in a turbulent flow unless there are some separation
problems.
Where can turbulator tape be purchased. I'm doing some wind tunnel
testing and it might come in handy.
_______________________
Paul Alan Sponagle
4th year aerospace engineering
Carleton University
Ottawa, Ontario
J.A.M.
In laminar wings, near the trailing edge the flow separates from the
surface, thus creating induced drag, and loss of control over the ailerons.
With the turbulator tape, or blow holes the effect is create a turbulent
flow that stays 'glued' to the wing surface, increasing flow over the
aileron. This creates drag, but it's lower than the drag flow separation
creates. The lower drag you get, the best L/D!
Corrections expected...
Good landings,
Jose Manuel Alvarez.
"Paul Alan Sponagle" <pspo...@lager.engsoc.carleton.ca> escribió en el
mensaje news:9897eo$d8m$1...@bertrand.ccs.carleton.ca...
Don
>snip.
> I'm doing some wind tunnel
> testing and it might come in handy.
>
You might like to look at :
http://beadec1.ea.bs.dlr.de/Airfoils/turbulat.htm - this site deals with
turbulation at Reynolds numbers applicable to model aircraft sizes but it
explains the principles and requirements very well.
Don B.
North Wales
UK
Udo Rumpf
Todd Pattist wrote:
>
> You hit the nail on the head. The flow naturally wants to
> separate near where the tape is applied. Turbulating the
> flow allows it to stay attached longer. Often the tape is
> applied after the natural separation point is identified
> experimentally with an oil flow test (paint the wing with
> used motor oil and go fly).
The turbulator is attached ahead of the the point of transition.
It has to be applied were the laminar flow is still energetic
enough to allow for a positive transition to turbulent flow.
The idea is to transition into turbulent flow without a
bubble and stay attached with turbulent flow to the trailing
edge. All Airfoils develop bubbles some are separation
and others are transition bubbles. The difference is, as the
name implies. When the transition is near the trailing edge
at the bottom of the airfoil, this could become a separation
bubble and the flow leaves the wing, it never has a chance
to reattach. In the second case the flow attaches again as
turbulent flow. In either case the drag increase can be
substantial.
Some bubbles are smaller then others, the question is, does
the bubble develop more drag then the turbulator. If the
bubble is of the critical size then a turbulator will help. A
turbolator prevents a separation bubble in the case of the
separation bubble being near the trailing edge at the bottom
of an airfoil.
Regards
Udo
--
http://www.wingdolly.reach.net
George Emsden
only one who has forgotten.......
--
George
"Don" <donald...@virgin.net> wrote in message
news:Ie7q6.6478$t1.4...@news6-win.server.ntlworld.com...
Jon Dixon
It would be good to get this information. I dont suppose that Mike Shade has
an email??? Do you have any contact info for this person.
Regards
Jon
Perth, Western Australia
"Robertmudd1u" <robert...@aol.comnojunk> wrote in message
news:20010308221830...@nso-mh.aol.com...
F.L. Whiteley
"Todd Pattist" <pat...@DONTSPAMME.snet.net> wrote in message
news:k0thatoi4vcgpotd1...@4ax.com...
> Paul Alan Sponagle <pspo...@lager.engsoc.carleton.ca>
> wrote:
>
> >Can I get someone to explain to me how turbulator tape is upposed to
> >reduce the L/D.
>
> perhaps this is just a typo
>
> > I thought the whole idea of achieving the highest L/D was
> >to stay in the laminar bucket.
>
>
> >I have a pretty good idea how roll control woould improve with turbulent
> >flow over the ailerons but this increased L/D is bothering me. L/D will
> >should go down in a turbulent flow unless there are some separation
> >problems.
>
> separate near where the tape is applied. Turbulating the
> flow allows it to stay attached longer. Often the tape is
> applied after the natural separation point is identified
> experimentally with an oil flow test (paint the wing with
> used motor oil and go fly).
>
> >testing and it might come in handy.
>
> dressmaker's pinking shears. I've also seen zig-zag and
> dotted varieties. The sailplane manufacturer's reps and
> sailplane suppliers probably have it too.
>
Dimpled tape has been made using a broken needle in a sewing machine to
dimple, rather than puncture, tapes. Zig-zag may be made as Todd descibes.
Or they may be purchased. Some gliders have dimples at the flying controls
and zig-zag elsewhere. Tapes and internal sealing as well as mylar seals
can provide significant improvement. The Grobs could use fillets at the
wing root also, where I suspect that separation is significant (See
Johnson's Russia fillets). Oil or tuft tests may reveal this. All of these
will be easier, and less pricey, than winglets.
Frank Whiteley
Don
"When comparing the characteristics of wing sections, it is important to
do so at the correct Reynolds Number.
Mention of Reynolds Number is inclined to excite some alarm in gliding
circles, and statements which say that it is `a non-dimensional measure of
aerodynamic scale' or `represents the ratio of the inertia forces to the
viscous forces in the fluid' are rarely greeted with a display of
enthusiastic comprehension. In reference books it usually either appears as
an austere mathematical conception or surrounded by such a haze of verbiage
that even more confusion is produced. Not wishing to join the latter
category, it is simplest to state a fact: if one wishes to apply the results
of a wind tunnel test to, say, the design of a glider wing, the Reynolds
Number of the tests must be roughly the same as the Reynolds Number which
will occur in flight. "
In an appendix he writes
"Reynolds Number is a dimensionless quantity which expresses the ratio of
the inertia forces to the viscous forces in the flow of a fluid. It is an
important parameter in determining the behaviour of the boundary layer on
the surface of a wing or body. In the case of a wing section, the curve of
drag coefficient against lift coefficient depends on the Reynolds Number, as
do various other section properties such as the maximum lift coefficient.
When considering wing section data, it is therefore essential to use figures
relating to the correct Reynolds Number. Unfortunately, glider wings operate
in the range 0.5 x 10(power6) to 5 x 10(power6), where the section
characteristics are often fairly sensitive to Reynolds Number."
Reynolds Number is defined as Re = pVl/q
where p = air density (in slugs/ft3). V = true airspeed (in ft/sec),l = a
characteristic length in ft. ( the chord in the case of wings, q = viscosity
of the air (in slugs/ft.sec)
Don B.
North Wales
UK
George Emsden <yq...@dial.pipex.com> wrote in message
news:98bne0$dd6$1...@lure.pipex.net...
Jon Dixon
of turbulator placement for the Eppler 603 as fitted to an ASTIR CS?
Regards
Jon
"Jon Dixon" <j...@swd.com.au> wrote in message
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