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DG-101 - increase performance/sealing/winglets(?)



 
 
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  #21  
Old July 15th 19, 01:37 PM posted to rec.aviation.soaring
Michael Opitz
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Posts: 318
Default DG-101 - increase performance/sealing/winglets(?)

At 08:44 11 July 2019, Senna Van den Bosch wrote:
I've been flying my DG-101 for a year now and really love it.

However,
there are some gaps which haven't been sealed and I'd like to give

tuning a
shot.

Does anyone have experience using aileron fences? Would it be

worth using
to increase handling?

My rudder has no gap sealing to transition from tail to rudder. Is

this
advised to still have that sealed?

Is turbulator tape something interesting? I have seen some articles

on this
for a Standard Cirrus but can't seem to find a definitive answer.

Last but not least, winglets. I know there are no factory upgrade

winglets
available for a DG-100/101, but could it be possible to add the DG-

300
winglets?

Every % of performance is welcome, feel free to add your options




There is one glaring omission in this discussion, and it that is the
issue of post-mold cure and spar waves on the wing surfaces. DG
was better than most, but most gliders of that generation suffered
from the thick resin in the wing spar caps continuing to cure (and
thus shrink) over a period of ~2 years after manufacture. This
process creates spar waves which will act to trip the laminar
boundary layer to turbulent at a point on the wing chord well before
the intended design transition point, thus significantly reducing
performance. If you have a wave gauge, you can measure the
waviness of the wing profile. If you don't have a wave gauge, you
can simply take a handkerchief, (or paper towel, or a very thin
plastic shopping bag, etc) and use it flat underneath your
outstretched flat hand to rub chord-wise across the wing surface.
Some designers have also commented that spar waves on the under
surface of the wings are at least as important as those on the upper
surfaces, if not more so, due to large lower surface laminar
separation bubbles on that generation of airfoils. You will feel any
significant waves this way. If you want to improve performance and
you have spar waves, then you will need to get rid of them. If the
waves are not too big, and if the gel-coat was applied thick enough
at manufacture, then judicious sanding and polishing might be able
to remove most of them. Probably best to check with your CAMO or
someone who has done this more than a few times already, because
if you are not careful, you can go through the gel-coat. If you are
very lucky, the glider won't have much for spar waves, or a previous
owner had already fixed the issue at another time before you bought
it. While you are at it, make sure the dive brake caps are flush too,
and by all means do seal the glider up... Basic glider tuning course
"101" :-) Smoothing wings that were previously wavy will lead to a
noticeable performance improvement when flying alongside other
similar gliders, like if you were to want to race in Club Class, etc.

RO


  #22  
Old July 15th 19, 01:47 PM posted to rec.aviation.soaring
[email protected]
external usenet poster
 
Posts: 107
Default DG-101 - increase performance/sealing/winglets(?)

I've never tuned a glider, but before I bought my glider I read all of Dick Johnson's test flight reviews. As others have said sealing the control surfaces is where Dick saw some of the biggest returns, but he also would seal the wing roots around the control rods to prevent the (relatively) high pressure air in the fuselage from venting out through the top of the spoiler box and push rod exits. I've seen people do this with cones made of Ceconite and heard of large balloons being cut down and used as well.
DT
  #23  
Old July 15th 19, 03:25 PM posted to rec.aviation.soaring
Tango Whisky
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Posts: 402
Default DG-101 - increase performance/sealing/winglets(?)

Le lundi 15 juillet 2019 14:45:05 UTC+2, Michael Opitz a écritÂ*:
, due to large lower surface laminar
separation bubbles on that generation of airfoils. You will feel any


RO


Profiles of the generation DG100, DG200 don't have laminar separation bubbles at all.
That's why turbulators wouldn't have any effect.
  #24  
Old July 15th 19, 03:59 PM posted to rec.aviation.soaring
Dan Marotta
external usenet poster
 
Posts: 4,601
Default DG-101 - increase performance/sealing/winglets(?)

The glider side.

Twenty-five years ago I sealed the canopy of my LS-6a by wrapping the
fuselage side with cellophane and waxed paper, held down with masking
tape, and then shot a bead of clear silicone sealant along the canopy
sealing surface.Â* Then I locked the canopy down and went away for 24
hours.Â* Upon returning I trimmed the squeeze out inside and out with a
razor blade.

It was unbelievably quiet inside!Â* A minor problem was that, on really
hot days, the silicone expanded enough that locking the canopy was
noticeably stiffer.Â* Still not a problem given the benefit.Â* I imagine
that in Belgium, there aren't that many days hot enough to do that.

On 7/14/2019 5:02 PM, Matt McBee wrote:
Dan, did you apply that to the canopy side or the glider side?

Matt


--
Dan, 5J
  #25  
Old July 15th 19, 04:01 PM posted to rec.aviation.soaring
Dan Marotta
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Posts: 4,601
Default DG-101 - increase performance/sealing/winglets(?)

Good point!Â* My friend's '27 as a very large area along the fuselage
side which is perfect for applying sealing tape.Â* My LS-6, mentioned
above, had a deep groove in the canopy, perfect for the silicone treatment.

On 7/15/2019 6:09 AM, Justin Couch wrote:
On Monday, 15 July 2019 09:02:10 UTC+10, Matt McBee wrote:
Dan, did you apply that to the canopy side or the glider side?

Matt

Canopy side. Most canopies have a concave structure that sits over the lip on the cockpit side. Easier to run this stuff around the concave portion since it won't move then.


--
Dan, 5J
  #27  
Old July 15th 19, 04:11 PM posted to rec.aviation.soaring
Michael Opitz[_2_]
external usenet poster
 
Posts: 1
Default DG-101 - increase performance/sealing/winglets(?)

On Monday, July 15, 2019 at 10:25:29 AM UTC-4, Tango Whisky wrote:
Le lundi 15 juillet 2019 14:45:05 UTC+2, Michael Opitz a écritÂ*:
, due to large lower surface laminar
separation bubbles on that generation of airfoils. You will feel any


RO


Profiles of the generation DG100, DG200 don't have laminar separation bubbles at all.
That's why turbulators wouldn't have any effect.


Hey Bert, I hope that you are not also going to tell me that the flow is supposed to go turbulent at the spar caps too. I would find that very hard to believe.

RO
  #28  
Old July 15th 19, 05:40 PM posted to rec.aviation.soaring
Bob Kuykendall
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Posts: 1,345
Default DG-101 - increase performance/sealing/winglets(?)

I could sell you a good pair of winglets for it, but unfortunately EASA would not be very happy if you installed them.

The first thing I'd do is make sure that cockpit ventilation air has somewhere to escape the fuselage. There is probably a path through the aft fuselage to a vent at the base of the rudder. Make sure that it is not blocked.

Next, I'd check to make sure that air cannot pass between the fuselage and the wings. If air can get drawn into the wing at the root ribs and out through the control connections at the ailerons, it can waste a lot of energy. Check to make sure the controls are sealed at the root ribs.

After doing those, then I'd work on the canopy seal and control surface hinge seals.

--Bob K.
  #29  
Old July 15th 19, 06:33 PM posted to rec.aviation.soaring
Charlie M. (UH & 002 owner/pilot)
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Posts: 1,383
Default DG-101 - increase performance/sealing/winglets(?)

For many ships....the Butler/later Nixon air extractor can suitably vent a cockpit and limit high pressure air not through the wing leaks......
Yes.....various gap seals on wing control surfaces help.
Yes...."boots" of some sort where the wing to fuselage joint is helps.
Yes....many older "glass" ships had shrinkage on spars and dive brake caps....... profiling can help....best profiling won't fix a poor airfoil, but can make a poor airfoil work at max design. Basically, make it work as designed....usually stay away from bugs and rain.....
  #30  
Old July 15th 19, 11:15 PM posted to rec.aviation.soaring
[email protected]
external usenet poster
 
Posts: 2,124
Default DG-101 - increase performance/sealing/winglets(?)

On Monday, July 15, 2019 at 8:45:05 AM UTC-4, Michael Opitz wrote:
At 08:44 11 July 2019, Senna Van den Bosch wrote:
I've been flying my DG-101 for a year now and really love it.

However,
there are some gaps which haven't been sealed and I'd like to give

tuning a
shot.

Does anyone have experience using aileron fences? Would it be

worth using
to increase handling?

My rudder has no gap sealing to transition from tail to rudder. Is

this
advised to still have that sealed?

Is turbulator tape something interesting? I have seen some articles

on this
for a Standard Cirrus but can't seem to find a definitive answer.

Last but not least, winglets. I know there are no factory upgrade

winglets
available for a DG-100/101, but could it be possible to add the DG-

300
winglets?

Every % of performance is welcome, feel free to add your options




There is one glaring omission in this discussion, and it that is the
issue of post-mold cure and spar waves on the wing surfaces. DG
was better than most, but most gliders of that generation suffered
from the thick resin in the wing spar caps continuing to cure (and
thus shrink) over a period of ~2 years after manufacture. This
process creates spar waves which will act to trip the laminar
boundary layer to turbulent at a point on the wing chord well before
the intended design transition point, thus significantly reducing
performance. If you have a wave gauge, you can measure the
waviness of the wing profile. If you don't have a wave gauge, you
can simply take a handkerchief, (or paper towel, or a very thin
plastic shopping bag, etc) and use it flat underneath your
outstretched flat hand to rub chord-wise across the wing surface.
Some designers have also commented that spar waves on the under
surface of the wings are at least as important as those on the upper
surfaces, if not more so, due to large lower surface laminar
separation bubbles on that generation of airfoils. You will feel any
significant waves this way. If you want to improve performance and
you have spar waves, then you will need to get rid of them. If the
waves are not too big, and if the gel-coat was applied thick enough
at manufacture, then judicious sanding and polishing might be able
to remove most of them. Probably best to check with your CAMO or
someone who has done this more than a few times already, because
if you are not careful, you can go through the gel-coat. If you are
very lucky, the glider won't have much for spar waves, or a previous
owner had already fixed the issue at another time before you bought
it. While you are at it, make sure the dive brake caps are flush too,
and by all means do seal the glider up... Basic glider tuning course
"101" :-) Smoothing wings that were previously wavy will lead to a
noticeable performance improvement when flying alongside other
similar gliders, like if you were to want to race in Club Class, etc.

RO


Phase 2 after all the easy stuff has been done.
I agree with checking the drive brakes. Another easy job.
BTDT
UH
 




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