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

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

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.

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

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

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.

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.....

On Monday, July 15, 2019 at 1:34:00 PM UTC-4, Charlie M. (UH & 002 owner/pilot) wrote:
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.....

Air extractor described can be big improvement but not approved in EASA world for most ships.
UH

Air extractor described can be big improvement but not approved in EASA world for most ships.
UH

http://ljpanels.co.uk/test/index.php...xtractor-ducts

We got his guy to make an extractor for the panel on our ASH 25 M. Works a treat. Really improved the ventilation by dragging air from the cockpit. With vents closed you can feel the air being sucked in through gaps in the canopy frame. We sent him the one on the ASH and he used it as a pattern.

Wings and Wheels sell his ASW 20 and ASW 19 versions.

Cheers

Paul