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

[Senna Van den Bosch]

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 :)

[krasw]

Fences: not worth it

Aileron+rudder sealing: teflon + mylar everywhere

Turbulator: probably not worth it with that profile

Winglets: prepare for long and expensive paper work

Best aerodynamic performance improvement is almost always good electric bugwipers unless you fly over desert.

[Peter F]

Make sure your vario system doesn't leak then spend anything else on
aerotows

PF

[Nick Gilbert]

Rudder, aileron and elevator (or trim tab if all-flying tail) are easy to do and should help. I've heard it said by people who know what they're talking about that with these old profiles it maybe useful to put turbulators on the top surface of the wing - but then it's a pain to clean & the potential difference is negligible anyway.

I've never seen a DG100/101 with winglets - perhaps DG may produce a NEO kit one day?

Something i've always wondered about with mine, there is clearly an extreme amount of washout at the wingtips - at anything above about 80 knots the tips begin to bend downward a large amount. Perhaps winglets might relieve some of the drag caused by the washout at high speed, while still retaining it's good manners?

Nick.

[jpg...@gmail.com]

It is pointless installing turbulator tape or winglets on any glider wing unless you have clear experimental aerodynamic evidence for your glider type that the exact turbulator position and/or the design and installation of the winglets actually does more good than harm - the latter is quite possible in both cases otherwise.

[uncl...@ix.netcom.com]

Sealing will give the best bang for the time and money, after getting the instruments working well and getting the CG in a good place.
Most of the airfoils of that vintage will benefit from turbulators on the bottom to slightly help the high speed portion of the polar.
The key from my experience with unflapped ships is to discipline yourself to not fly too fast and use the better glide angle that results to do less time climbing.
Nothing to do about the twist. Just enjoy the docile handling.
Many of the older ships can't get winglets due to bending issues, and more importantly stiffness in twist.
I say seal it up and enjoy a very nice glider. I had one for a short time.
FWIW
UH

[Martin Gregorie]

On Thu, 11 Jul 2019 14:27:23 -0700, unclhank wrote:

> Most of the airfoils of that vintage will benefit from turbulators on
> the bottom to slightly help the high speed portion of the polar.
> The key from my experience with unflapped ships is to discipline
> yourself to not fly too fast and use the better glide angle that results
> to do less time climbing.
>

Agreed, and I have them fitted on my H.201 Libelle to improve fast
cruise. Other gliders with the same wing section may also benefit -
Glasfaser knows exactly where to put the undersurface turbs on the
Wortmann FX66-17A2-182 section.


--
Martin | martin at
Gregorie | gregorie dot org

[Senna Van den Bosch]

Op donderdag 11 juli 2019 23:27:24 UTC+2 schreef uncl...@ix.netcom.com:

Thanks! I will be contacting DG and SCT Terlet (where I bring my glider for ARC) for advice. I have seen some DG-100 with different wingtips than mine, wingtips more like the LS-4, with a very slight curve and narrowing to the end of the tip, where my DG's wingtips have some sort of block (about 1 inch) with a metal skid. Maybe it would be possible to replace these?

[Martin Gregorie]

On Fri, 12 Jul 2019 02:44:30 -0700, Senna Van den Bosch wrote:

> Thanks! I will be contacting DG and SCT Terlet (where I bring my glider
> for ARC) for advice. I have seen some DG-100 with different wingtips
> than mine, wingtips more like the LS-4, with a very slight curve and
> narrowing to the end of the tip, where my DG's wingtips have some sort
> of block (about 1 inch) with a metal skid. Maybe it would be possible to
> replace these?

About the tip skids: yes, it may be possible to replace them under EASA
rules - I replaced the tip skids on my Libelle without any arguments from
my inspector and Glasfaser, who hold the type certificate, certainly
didn't object. They supplied the new skids.

My original skids were certainly non-standard. They were rectangular
rubber blocks about 15mm thick, 20mm wide and 200mm long. The new ones
are bigger: 50% longer, nearly twice as wide, 50mm deep and a nice
aerodynamic shape. I haven't noticed any handling differences since
fitting them.

But, why do you want to replace yours? IMO ugliness is not a good enough
reason for a job that may be harder than it looks.

I had a good reason for replacing the old skids, which were on the glider
when I bought it. They were far too shallow because they let the aileron
touch the ground at full deflection and, as there was slight abrasion on
the aileron undersurface at the TE, I thought that fitting taller skids
was a good idea. This is why I fitted 50mm skids instead of 30mm.

That solved the aileron abrasion problem, but there are other possible
problems that you need to be aware of. These were my issues:

- the old skids served to keep the tip dollies, needed to guide the wings
into my box trailer, on the wing. These slip over the LE, wrap round the
tip and have a chord-wise extension that passes inside the tip skids and
clips over the TE to hold the dolly in place.

I was careful to position the new skids so that the tip dollies still
fitted correctly.

- my tow-out wing dolly is designed to be put on by sliding it in along
the wing after slipping it over the tip. It is a single airfoil-shaped
loop of fibreglass with carpet inside it and the wheel attached on forks
to the underside.

I completely forgot that it had to pass over the tip skids, and ended up
cutting it's top surface 50mm in front of the TE and fitting over-centre
latches to let it be opened and put round the wing from the front, rather
than passing it over the skid. That now works OK, but I had a fair amount
of fiddling to make the latches work correctly without distorting the
shape of the 'loop' and hurting the wing while still closing firmly
enough to stay in place while the glider is being towed round the
airfield. This involved two visits to the airfield for trial fitting and
adjustment with workshop time after each visit - I live an hour's drive
away from the airfield.

[Nick Hill]

On 12/07/2019 10:44, Senna Van den Bosch wrote:

> Thanks! I will be contacting DG and SCT Terlet (where I bring my glider for ARC) for advice. I have seen some DG-100 with different wingtips than mine, wingtips more like the LS-4, with a very slight curve and narrowing to the end of the tip, where my DG's wingtips have some sort of block (about 1 inch) with a metal skid. Maybe it would be possible to replace these?
>

The different wingtip profile is an official DG mod covered by DG100 TN
301-20. See the DG website for info.

https://www.dg-flugzeugbau.de/en/maintenance-service-aircraft/technical-notes

--

Nick Hill

[Senna Van den Bosch]

Op vrijdag 12 juli 2019 15:13:28 UTC+2 schreef Nick Hill:

That's the tip I was looking for!
Since I'm going to a different trailer instead of my current home-built 30+ year old, I could mount the wings in a different way in my trailer instead of securing it with a hole in the skid.
Thank you!

[cern...@gmail.com]

All good advice.
I only add a very important item IMHO: canopy sealing. Air leaking from the cockpit via the rear canopy gap can create a large "airbrake" always deployed, influencing the airflow over the fuselage and wingroots.

Re. flying conservatively, the IGC traces from current Club Class European Championships seem to show the contrary. They push their Cirri at about 80-90kts when 5kt climbs are expected. That's surprising but effective.

Cheers,
Aldo Cernezzi

[John DeRosa OHM Ω http://aviation.derosaweb.net]

When I bought my DG101 years ago (since sold) I wrote to DG asking if adding turbulators to the wings would help performance. The answer was a clear "no".

[Senna Van den Bosch]

Op vrijdag 12 juli 2019 15:13:28 UTC+2 schreef Nick Hill:

Do you also have any info on handling/performance differences using the new wingtips?

[Senna Van den Bosch]

Op zaterdag 13 juli 2019 15:25:06 UTC+2 schreef John DeRosa OHM Ω http://aviation.derosaweb.net:

> When I bought my DG101 years ago (since sold) I wrote to DG asking if adding turbulators to the wings would help performance. The answer was a clear "no".

That's some work done for me :)
I guess proper sealing and the new wingtips would be the best way to increase performance, will try some proper sealing first.

[Nick Kennedy]

Senna
I'd go with the sealing and make sure the canopy is sealed too.
I would not pay for winglets for that ship.
If you need more go
Look for a ASW 20 or -27 or LS3 with a functioning ballast system
Enjoy your ship for what its worth today
And as Hank said don't try to fly too fast, do less climbing instead, that's some great advice right there.

[Senna Van den Bosch]

Op zondag 14 juli 2019 19:03:17 UTC+2 schreef Nick Kennedy:

Hmm good point.
My maximum speed I usually sustain is 120-130, I do higher if I'm under a street and too high. Higher than 150 feels like going straight down though. Climbs in Belgium average between 1 to 2 m/s with some good spots up to 3 m/s, so not pushing it too far.

Any idea what sealing for canopy works well? There's so much choice. This is where I usually order my gliding needs: http://glider-equipment.nl/catalog/index.php/glider-tuning-tapes-sealings-c-82_86

[Dan Marotta]

Something like THIS works really well.  My friend and I sealed his ASW-27 with it and says the difference was remarkable.  Surely you can find similar in Belgium.

--
Dan, 5J

[Matt McBee]

Dan, did you apply that to the canopy side or the glider side?

Matt

[Justin Couch]

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.

[Michael Opitz]

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

[dtarm...@gmail.com]

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

[Tango Whisky]

Le lundi 15 juillet 2019 14:45:05 UTC+2, Michael Opitz a écrit :
, 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.

[Dan Marotta]

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.  Then I locked the canopy down and went away for 24
hours.  Upon returning I trimmed the squeeze out inside and out with a
razor blade.

It was unbelievably quiet inside!  A minor problem was that, on really
hot days, the silicone expanded enough that locking the canopy was
noticeably stiffer.  Still not a problem given the benefit.  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

[Dan Marotta]

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

--
Dan, 5J

[Dan Marotta]

Shower curtains, too...

On 7/15/2019 6:47 AM, dtarm...@gmail.com wrote:
> 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

--
Dan, 5J

[Michael Opitz]

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

[Bob Kuykendall]

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.

[Charlie M. (UH & 002 owner/pilot)]

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.....

[uncl...@ix.netcom.com]

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

[uncl...@ix.netcom.com]

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

[Glidingstuff]

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

http://ljpanels.co.uk/test/index.php/products/14-extractor-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