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drewettcj(at)btinternet.c
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 Posted: Sun Aug 05, 2012 1:00 am Post subject: Europa-List Digest: 2 Msgs - 08/04/12 |
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please de-list me
Chris Drewett
From: Europa-List Digest Server <europa-list(at)matronics.com>
To: Europa-List Digest List <europa-list-digest(at)matronics.com>
Sent: Sunday, 5 August 2012, 8:01
Subject: Europa-List Digest: 2 Msgs - 08/04/12
*
=========================
Online Versions of Today's List Digest Archive
=========================
Today's complete Europa-List Digest can also be found in either of the
two Web Links listed below. The .html file includes the Digest formatted
in HTML for viewing with a web browser and features Hyperlinked Indexes
and Message Navigation. The .txt file includes the plain ASCII version
of the Europa-List Digest and can be viewed with a generic text editor
such as Notepad or with a web browser.
HTML Version:
http://www.matronics.com/digest/digestview.php?Style=82701&View=html&Chapter=2012-08-04&Archive=Europa
Text Version:
http://www.matronics.com/digest/digestview.php?Style=82701&View=txt&Chapter=2012-08-04&Archive=Europa
=======================
EMail Version of Today's List Digest Archive
=======================
----------------------------------------------------------
Europa-List Digest Archive
---
Total Messages Posted Sat 08/04/12: 2
----------------------------------------------------------
Today's Message Index:
----------------------
1. 10:06 AM - seals for control surfaces (Fred Klein)
2. 10:52 AM - Re: seals for control surfaces (Robert Borger)
________________________________ Message 1 _____________________________________
Time: 10:06:37 AM PST US
From: Fred Klein <fklein(at)orcasonline.com (fklein(at)orcasonline.com)>
Subject: Europa-List: seals for control surfaces
Apropos the recent thread on this topic, I found an old posting by
John Lawton which may be enlightening:
| Quote: | writes:
My understanding is that preventing the air going over the flap, in
cruise, reduces drag, resulting in higher cruise speed, which I have
experienced. I don't have the engineering background to completely
understand what is happening to the wing, in flight. That's why I
depend on the guys on the list to keep me straight. I'm more of a
"try
it and see" kinda guy...  John's advice is based on the success
that
the glider guys have had, sealing the gaps. It seems to have worked
on
Baby Blue, as well. Continued testing will tell to what degree of
advantage the seals make. It may very well prove that the extra few
knots is not worth the float upon landing. I won't know until I
satisfy
myself that I've explored all the angles (and strip widths)... 
Hey Jeff, et al,
The concept behind seals is pretty simple. In flight the wing
creates a low pressure area on the top and high pressure on the
bottom. (Bernoulli at it again) This pressure differential will try
to equalize through the gap in the flap area and the hinge line of
the ailerons. This is also true to some extent on the rudder hinge
line and the trim tabs when they are deflected. This equalization
causes drag, a lot of drag. So, the idea behind seals, both flap gap
and positive seals on ailerons (and rudder and trim tabs), is to
prevent this pressure equalization.
On N245E I used PVC weather-strip to create the flap gap seal. The
size will depend on how big your gap is between the leading edge of
the flap and the flap closeout when retracted. Choose a foam that is
slightly thicker than the widest spot in the gap you have. The XS
flap closeout looks as if it were designed to be sealed, given the
flat area at the bottom rear of the closeout. If you apply the foam
strip to the area where the flap "noses" into the closeout when up
it will seal this area for cruise flight, but still allow air to
flow over the flap when extended. Use a foam that crushes easily
when the flap comes in contact with it. You don't want to use a foam
that is too stiff or too thick or else your flaps won't fully
retract. PVC weather-strip is soft and pliable and works quite well.
It is also fairly UV resistant and is very cheap. It's available at
any hardware store in various thicknesses. We've found that open
cell foams tend to not last very long due to UV and they don't seal
as well as closed cell foams like PVC. I also used weather-strip on
the ends of my flaps so that they seal against the side of the
fuselage when they are in the up position. According to Bruce
Carmichael, renowned Aerodynamicist who wrote a book on drag
reduction in homebuilts, the wing root/fuselage junction is another
area of high drag on most airplanes. Sealing it up helps, too.
Aileron seals are a bit more tricky to employ. Some folks apply
Mylar strips over the hinge lines and think they've sealed their
ailerons. This is not true. Mylar is not a seal, but rather is
applied to help the boundary flow stay attached over the hinge line.
Mylar is also somewhat cosmetic in that it hides the hinge line. At
high speeds the Mylar will lift up off the wing due to the pressure
equalization, thus negating the effects of any sealing the Mylar
might be offering. In some cases the Mylar will "buzz" at high speeds.
For sealing ailerons you need to install what are known as positive
seals. These seals go from the leading edge of the aileron to the
rear of the closeout. There are commercially available materials for
this, including various types of cloth and Teflon tapes. Some folks
even use cloth tape along the length of the aileron on the
undersurface. This is fine on low speed gliders, but I think at the
speeds we fly this method likely creates more drag. Personally, I
like parachute cloth for making positive seals. Whatever you use it
needs to be zero porosity, i.e., allowing no airflow through the
material. Parachute cloth is thin, flexible, zero porosity and fits
the bill here perfectly. Here at the 'Possum Werks we use Parachute
cloth almost exclusively to fabricate positive seals. (it also helps
that we have a parachute manufacturer a few miles down the road that
gives us their scraps)
First remove the aileron. Then, cut a strip of parachute cloth about
3" wide exactly the length of the aileron. The width you use might
take some trial and error to get it right. You don't want it so wide
the the material bunches up when the aileron is deflected. 2.5' to
3" width should work on most Europas. Then, yellow contact cement is
applied to the leading edge of the aileron, the rear of the closeout
and the mating surfaces of the cloth. We use a brand of glue called
Plio-bond. It's handy in that it comes in a small bottle with a
brush applicator. 3M also makes good contact cement if you can find
it. Avoid the water based stuff. It is crap.
Scuff the area to be glued with 180 to enhance the adhesion. Apply
the glue in a swath about 3/8" wide to both the seal, the aileron
and closeout. Use masking tape to keep your glue line to the
prescribed width and remove the tape once the glue is dry. You can
also use the masking tape to provide a guide when you scuff the area
to be glued, but wipe it with acetone to remove dust before putting
the glue on. Allow the glue to dry, usually about 20 minutes, remove
the masking tape, then stick the seal to the leading edge of the
aileron first, preferably while on your work bench. If you screw
something up Xylene will remove the glue easily without harming your
paint. The next part takes an extra set of hands.
With one person holding the aileron close to the wing, attach the
other half of the cloth to the closeout forming an "S" pattern.
Avoid wrinkles. See this drawing for details: http://wingsandwheels.com/page28.htm
Then, reattach the aileron as you would normally do. Check the throw
and make sure you are not binding! If you apply the seal correctly
you will not even know it is there. I have also sealed my rudder in
a similar fashion as well as the trim tabs. They create similar drag
when deflected.
I can't say specifically what improvements have occurred in N245E as
a result of the seals since I've not ever flown it without them. I
can tell you that I exceed Europas published numbers with a fixed
pitch prop. I can also tell you that on gliders we generally see 2
to 4 points increase in glide and a noticeable decrease in sink
rate, even on the old "woodies", after the application of seals. In
power planes this translates to faster cruise, better climb rates
and better fuel economy.
Anyway, hope it helps!
Regards,
John Lawton
|
________________________________ Message 2 _____________________________________
Time: 10:52:40 AM PST US
Subject: Re: seals for control surfaces
From: Robert Borger <rlborger(at)mac.com (rlborger(at)mac.com)>
Fred,
Thanks for digging this up. Very informative. Now, if I could just get
my 914 running right=85
Blue skies & tailwinds,
Bob Borger
Europa XS Tri, Rotax 914, Airmaster C/S Prop.
Little Toot Sport Biplane, Lycoming Thunderbolt AEIO-320 EXP
3705 Lynchburg Dr.
Corinth, TX 76208-5331
Cel: 817-992-1117
rlborger(at)mac.com (rlborger(at)mac.com)
On Aug 4, 2012, at 12:03 PM, Fred Klein <fklein(at)orcasonline.com (fklein(at)orcasonline.com)> wrote:
Apropos the recent thread on this topic, I found an old posting by John
Lawton which may be enlightening:
| Quote: | My understanding is that preventing the air going over the flap, in
cruise, reduces drag, resulting in higher cruise speed, which I have
|
| Quote: | experienced. I don't have the engineering background to completely
understand what is happening to the wing, in flight. That's why I
depend on the guys on the list to keep me straight. I'm more of a
"try
|
| Quote: | it and see" kinda guy... John's advice is based on the success
that
|
| Quote: | the glider guys have had, sealing the gaps. It seems to have worked
on
|
| Quote: | Baby Blue, as well. Continued testing will tell to what degree of
advantage the seals make. It may very well prove that the extra few
|
| Quote: | knots is not worth the float upon landing. I won't know until I
satisfy
|
| Quote: | myself that I've explored all the angles (and strip widths)...
Hey Jeff, et al,
The concept behind seals is pretty simple. In flight the wing creates
a low pressure area on the top and high pressure on the bottom.
|
(Bernoulli at it again) This pressure differential will try to equalize
through the gap in the flap area and the hinge line of the ailerons.
This is also true to some extent on the rudder hinge line and the trim
tabs when they are deflected. This equalization causes drag, a lot of
drag. So, the idea behind seals, both flap gap and positive seals on
ailerons (and rudder and trim tabs), is to prevent this pressure
equalization.
| Quote: |
On N245E I used PVC weather-strip to create the flap gap seal. The
size will depend on how big your gap is between the leading edge of the
|
flap and the flap closeout when retracted. Choose a foam that is
slightly thicker than the widest spot in the gap you have. The XS flap
closeout looks as if it were designed to be sealed, given the flat area
at the bottom rear of the closeout. If you apply the foam strip to the
area where the flap "noses" into the closeout when up it will seal this
area for cruise flight, but still allow air to flow over the flap when
extended. Use a foam that crushes easily when the flap comes in contact
with it. You don't want to use a foam that is too stiff or too thick or
else your flaps won't fully retract. PVC weather-strip is soft and
pliable and works quite well. It is also fairly UV resistant and is very
cheap. It's available at any hardware store in various thicknesses.
We've found that open cell foams tend to not last very long due to UV
and they don't seal as well as closed cell foams like PVC. I also used
weather-strip on the ends of my flaps so that they seal against the side
of the fuselage when they are in the up position. According to Bruce
Carmichael, renowned Aerodynamicist who wrote a book on drag reduction
in homebuilts, the wing root/fuselage junction is another area of high
drag on most airplanes. Sealing it up helps, too.
| Quote: |
Aileron seals are a bit more tricky to employ. Some folks apply Mylar
strips over the hinge lines and think they've sealed their ailerons.
|
This is not true. Mylar is not a seal, but rather is applied to help the
boundary flow stay attached over the hinge line. Mylar is also somewhat
cosmetic in that it hides the hinge line. At high speeds the Mylar will
lift up off the wing due to the pressure equalization, thus negating the
effects of any sealing the Mylar might be offering. In some cases the
Mylar will "buzz" at high speeds.
| Quote: |
For sealing ailerons you need to install what are known as positive
seals. These seals go from the leading edge of the aileron to the rear
|
of the closeout. There are commercially available materials for this,
including various types of cloth and Teflon tapes. Some folks even use
cloth tape along the length of the aileron on the undersurface. This is
fine on low speed gliders, but I think at the speeds we fly this method
likely creates more drag. Personally, I like parachute cloth for making
positive seals. Whatever you use it needs to be zero porosity, i.e.,
allowing no airflow through the material. Parachute cloth is thin,
flexible, zero porosity and fits the bill here perfectly. Here at the
'Possum Werks we use Parachute cloth almost exclusively to fabricate
positive seals. (it also helps that we have a parachute manufacturer a
few miles down the road that gives us their scraps)
| Quote: |
First remove the aileron. Then, cut a strip of parachute cloth about
3" wide exactly the length of the aileron. The width you use might take
|
some trial and error to get it right. You don't want it so wide the the
material bunches up when the aileron is deflected. 2.5' to 3" width
should work on most Europas. Then, yellow contact cement is applied to
the leading edge of the aileron, the rear of the closeout and the mating
surfaces of the cloth. We use a brand of glue called Plio-bond. It's
handy in that it comes in a small bottle with a brush applicator. 3M
also makes good contact cement if you can find it. Avoid the water based
stuff. It is crap.
| Quote: |
Scuff the area to be glued with 180 to enhance the adhesion. Apply the
glue in a swath about 3/8" wide to both the seal, the aileron and
|
closeout. Use masking tape to keep your glue line to the prescribed
width and remove the tape once the glue is dry. You can also use the
masking tape to provide a guide when you scuff the area to be glued, but
wipe it with acetone to remove dust before putting the glue on. Allow
the glue to dry, usually about 20 minutes, remove the masking tape, then
stick the seal to the leading edge of the aileron first, preferably
while on your work bench. If you screw something up Xylene will remove
the glue easily without harming your paint. The next part takes an extra
set of hands.
| Quote: |
With one person holding the aileron close to the wing, attach the
other half of the cloth to the closeout forming an "S" pattern. Avoid
|
wrinkles. See this drawing for details:
http://wingsandwheels.com/page28.htm
| Quote: |
Then, reattach the aileron as you would normally do. Check the throw
and make sure you are not binding! If you apply the seal correctly you
|
will not even know it is there. I have also sealed my rudder in a
similar fashion as well as the trim tabs. They create similar drag when
deflected.
| Quote: |
I can't say specifically what improvements have occurred in N245E as a
result of the seals since I've not ever flown it without them. I can
|
tell you that I exceed Europas published numbers with a fixed pitch
prop. I can also tell you that on gliders we generally see 2 to 4 points
increase in glide and a noticeable decrease in sink rate, even on the
old "woodies", after the application of seals. In power planes this
translates to faster cruise, better climb rates and better fuel economy.
| Quote: |
Anyway, hope it helps!
Regards,
John Lawton
|
--> p; -Matt Dralle, Libution" =======
| | - The Matronics Europa-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?Europa-List |
|
|
|
| Back to top |
|
 |
klinefelter.kevin(at)gmai
Guest
|
| Posted: Sun Aug 05, 2012 5:10 am Post subject: Europa-List Digest: 2 Msgs - 08/04/12 |
|
|
Chris, go all the way down to the end any list message and you will find a link for list un/subscription.
Do not archive
On Aug 5, 2012, at 1:59 AM, C DREWETT <drewettcj(at)btinternet.com (drewettcj(at)btinternet.com)> wrote:
[quote]please de-list me
Chris Drewett
From: Europa-List Digest Server <europa-list(at)matronics.com (europa-list(at)matronics.com)>
To: Europa-List Digest List <europa-list-digest(at)matronics.com (europa-list-digest(at)matronics.com)>
Sent: Sunday, 5 August 2012, 8:01
Subject: Europa-List Digest: 2 Msgs - 08/04/12
*
=========================
Online Versions of Today's List Digest Archive
=========================
Today's complete Europa-List Digest can also be found in either of the
two Web Links listed below. The .html file includes the Digest formatted
in HTML for viewing with a web browser and features Hyperlinked Indexes
and Message Navigation. The .txt file includes the plain ASCII version
of the Europa-List Digest and can be viewed with a generic text editor
such as Notepad or with a web browser.
HTML Version:
http://www.matronics.com/digest/digestview.php?Style=82701&View=html&Chapter=2012-08-04&Archive=Europa
Text Version:
http://www.matronics.com/digest/digestview.php?Style=82701&View=txt&Chapter=2012-08-04&Archive=Europa
=======================
EMail Version of Today's List Digest Archive
=======================
----------------------------------------------------------
Europa-List Digest Archive
---
Total Messages Posted Sat 08/04/12: 2
----------------------------------------------------------
Today's Message Index:
----------------------
1. 10:06 AM - seals for control surfaces (Fred Klein)
2. 10:52 AM - Re: seals for control surfaces (Robert Borger)
________________________________ Message 1 _____________________________________
Time: 10:06:37 AM PST US
From: Fred Klein <fklein(at)orcasonline.com (fklein(at)orcasonline.com)>
Subject: seals for control surfaces
Apropos the recent thread on this topic, I found an old posting by
John Lawton which may be enlightening:
| Quote: | writes:
My understanding is that preventing the air going over the flap, in
cruise, reduces drag, resulting in higher cruise speed, which I have
experienced. I don't have the engineering background to completely
understand what is happening to the wing, in flight. That's why I
depend on the guys on the list to keep me straight. I'm more of a
"try
it and see" kinda guy... John's advice is based on the success
that
the glider guys have had, sealing the gaps. It seems to have worked
on
Baby Blue, as well. Continued testing will tell to what degree of
advantage the seals make. It may very well prove that the extra few
knots is not worth the float upon landing. I won't know until I
satisfy
myself that I've explored all the angles (and strip widths)...
Hey Jeff, et al,
The concept behind seals is pretty simple. In flight the wing
creates a low pressure area on the top and high pressure on the
bottom. (Bernoulli at it again) This pressure differential will try
to equalize through the gap in the flap area and the hinge line of
the ailerons. This is also true to some extent on the rudder hinge
line and the trim tabs when they are deflected. This equalization
causes drag, a lot of drag. So, the idea behind seals, both flap gap
and positive seals on ailerons (and rudder and trim tabs), is to
prevent this pressure equalization.
On N245E I used PVC weather-strip to create the flap gap seal. The
size will depend on how big your gap is between the leading edge of
the flap and the flap closeout when retracted. Choose a foam that is
slightly thicker than the widest spot in the gap you have. The XS
flap closeout looks as if it were designed to be sealed, given the
flat area at the bottom rear of the closeout. If you apply the foam
strip to the area where the flap "noses" into the closeout when up
it will seal this area for cruise flight, but still allow air to
flow over the flap when extended. Use a foam that crushes easily
when the flap comes in contact with it. You don't want to use a foam
that is too stiff or too thick or else your flaps won't fully
retract. PVC weather-strip is soft and pliable and works quite well.
It is also fairly UV resistant and is very cheap. It's available at
any hardware store in various thicknesses. We've found that open
cell foams tend to not last very long due to UV and they don't seal
as well as closed cell foams like PVC. I also used weather-strip on
the ends of my flaps so that they seal against the side of the
fuselage when they are in the up position. According to Bruce
Carmichael, renowned Aerodynamicist who wrote a book on drag
reduction in homebuilts, the wing root/fuselage junction is another
area of high drag on most airplanes. Sealing it up helps, too.
Aileron seals are a bit more tricky to employ. Some folks apply
Mylar strips over the hinge lines and think they've sealed their
ailerons. This is not true. Mylar is not a seal, but rather is
applied to help the boundary flow stay attached over the hinge line.
Mylar is also somewhat cosmetic in that it hides the hinge line. At
high speeds the Mylar will lift up off the wing due to the pressure
equalization, thus negating the effects of any sealing the Mylar
might be offering. In some cases the Mylar will "buzz" at high speeds.
For sealing ailerons you need to install what are known as positive
seals. These seals go from the leading edge of the aileron to the
rear of the closeout. There are commercially available materials for
this, including various types of cloth and Teflon tapes. Some folks
even use cloth tape along the length of the aileron on the
undersurface. This is fine on low speed gliders, but I think at the
speeds we fly this method likely creates more drag. Personally, I
like parachute cloth for making positive seals. Whatever you use it
needs to be zero porosity, i.e., allowing no airflow through the
material. Parachute cloth is thin, flexible, zero porosity and fits
the bill here perfectly. Here at the 'Possum Werks we use Parachute
cloth almost exclusively to fabricate positive seals. (it also helps
that we have a parachute manufacturer a few miles down the road that
gives us their scraps)
First remove the aileron. Then, cut a strip of parachute cloth about
3" wide exactly the length of the aileron. The width you use might
take some trial and error to get it right. You don't want it so wide
the the material bunches up when the aileron is deflected. 2.5' to
3" width should work on most Europas. Then, yellow contact cement is
applied to the leading edge of the aileron, the rear of the closeout
and the mating surfaces of the cloth. We use a brand of glue called
Plio-bond. It's handy in that it comes in a small bottle with a
brush applicator. 3M also makes good contact cement if you can find
it. Avoid the water based stuff. It is crap.
Scuff the area to be glued with 180 to enhance the adhesion. Apply
the glue in a swath about 3/8" wide to both the seal, the aileron
and closeout. Use masking tape to keep your glue line to the
prescribed width and remove the tape once the glue is dry. You can
also use the masking tape to provide a guide when you scuff the area
to be glued, but wipe it with acetone to remove dust before putting
the glue on. Allow the glue to dry, usually about 20 minutes, remove
the masking tape, then stick the seal to the leading edge of the
aileron first, preferably while on your work bench. If you screw
something up Xylene will remove the glue easily without harming your
paint. The next part takes an extra set of hands.
With one person holding the aileron close to the wing, attach the
other half of the cloth to the closeout forming an "S" pattern.
Avoid wrinkles. See this drawing for details: http://wingsandwheels.com/page28.htm
Then, reattach the aileron as you would normally do. Check the throw
and make sure you are not binding! If you apply the seal correctly
you will not even know it is there. I have also sealed my rudder in
a similar fashion as well as the trim tabs. They create similar drag
when deflected.
I can't say specifically what improvements have occurred in N245E as
a result of the seals since I've not ever flown it without them. I
can tell you that I exceed Europas published numbers with a fixed
pitch prop. I can also tell you that on gliders we generally see 2
to 4 points increase in glide and a noticeable decrease in sink
rate, even on the old "woodies", after the application of seals. In
power planes this translates to faster cruise, better climb rates
and better fuel economy.
Anyway, hope it helps!
Regards,
John Lawton
|
________________________________ Message 2 _____________________________________
Time: 10:52:40 AM PST US
Subject: Re: Europa-List: seals for control surfaces
From: Robert Borger <rlborger(at)mac.com (rlborger(at)mac.com)>
Fred,
Thanks for digging this up. Very informative. Now, if I could just get
my 914 running right=85
Blue skies & tailwinds,
Bob Borger
Europa XS Tri, Rotax 914, Airmaster C/S Prop.
Little Toot Sport Biplane, Lycoming Thunderbolt AEIO-320 EXP
3705 Lynchburg Dr.
Corinth, TX 76208-5331
Cel: 817-992-1117
rlborger(at)mac.com (rlborger(at)mac.com)
On Aug 4, 2012, at 12:03 PM, Fred Klein <fklein(at)orcasonline.com (fklein(at)orcasonline.com)> wrote:
Apropos the recent thread on this topic, I found an old posting by John
Lawton which may be enlightening:
| Quote: | My understanding is that preventing the air going over the flap, in
cruise, reduces drag, resulting in higher cruise speed, which I have
|
| Quote: | experienced. I don't have the engineering background to completely
understand what is happening to the wing, in flight. That's why I
depend on the guys on the list to keep me straight. I'm more of a
"try
|
| Quote: | it and see" kinda guy... John's advice is based on the success
that
|
| Quote: | the glider guys have had, sealing the gaps. It seems to have worked
on
|
| Quote: | Baby Blue, as well. Continued testing will tell to what degree of
advantage the seals make. It may very well prove that the extra few
|
| Quote: | knots is not worth the float upon landing. I won't know until I
satisfy
|
| Quote: | myself that I've explored all the angles (and strip widths)...
Hey Jeff, et al,
The concept behind seals is pretty simple. In flight the wing creates
a low pressure area on the top and high pressure on the bottom.
|
(Bernoulli at it again) This pressure differential will try to equalize
through the gap in the flap area and the hinge line of the ailerons.
This is also true to some extent on the rudder hinge line and the trim
tabs when they are deflected. This equalization causes drag, a lot of
drag. So, the idea behind seals, both flap gap and positive seals on
ailerons (and rudder and trim tabs), is to prevent this pressure
equalization.
| Quote: |
On N245E I used PVC weather-strip to create the flap gap seal. The
size will depend on how big your gap is between the leading edge of the
|
flap and the flap closeout when retracted. Choose a foam that is
slightly thicker than the widest spot in the gap you have. The XS flap
closeout looks as if it were designed to be sealed, given the flat area
at the bottom rear of the closeout. If you apply the foam strip to the
area where the flap "noses" into the closeout when up it will seal this
area for cruise flight, but still allow air to flow over the flap when
extended. Use a foam that crushes easily when the flap comes in contact
with it. You don't want to use a foam that is too stiff or too thick or
else your flaps won't fully retract. PVC weather-strip is soft and
pliable and works quite well. It is also fairly UV resistant and is very
cheap. It's available at any hardware store in various thicknesses.
We've found that open cell foams tend to not last very long due to UV
and they don't seal as well as closed cell foams like PVC. I also used
weather-strip on the ends of my flaps so that they seal against the side
of the fuselage when they are in the up position. According to Bruce
Carmichael, renowned Aerodynamicist who wrote a book on drag reduction
in homebuilts, the wing root/fuselage junction is another area of high
drag on most airplanes. Sealing it up helps, too.
| Quote: |
Aileron seals are a bit more tricky to employ. Some folks apply Mylar
strips over the hinge lines and think they've sealed their ailerons.
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This is not true. Mylar is not a seal, but rather is applied to help the
boundary flow stay attached over the hinge line. Mylar is also somewhat
cosmetic in that it hides the hinge line. At high speeds the Mylar will
lift up off the wing due to the pressure equalization, thus negating the
effects of any sealing the Mylar might be offering. In some cases the
Mylar will "buzz" at high speeds.
| Quote: |
For sealing ailerons you need to install what are known as positive
seals. These seals go from the leading edge of the aileron to the rear
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of the closeout. There are commercially available materials for this,
including various types of cloth and Teflon tapes. Some folks even use
cloth tape along the length of the aileron on the undersurface. This is
fine on low speed gliders, but I think at the speeds we fly this method
likely creates more drag. Personally, I like parachute cloth for making
positive seals. Whatever you use it needs to be zero porosity, i.e.,
allowing no airflow through the material. Parachute cloth is thin,
flexible, zero porosity and fits the bill here perfectly. Here at the
'Possum Werks we use Parachute cloth almost exclusively to fabricate
positive seals. (it also helps that we have a parachute manufacturer a
few miles down the road that gives us their scraps)
| Quote: |
First remove the aileron. Then, cut a strip of parachute cloth about
3" wide exactly the length of the aileron. The width you use might take
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some trial and error to get it right. You don't want it so wide the the
material bunches up when the aileron is deflected. 2.5' to 3" width
should work on most Europas. Then, yellow contact cement is applied to
the leading edge of the aileron, the rear of the closeout and the mating
surfaces of the cloth. We use a brand of glue called Plio-bond. It's
handy in that it comes in a small bottle with a brush applicator. 3M
also makes good contact cement if you can find it. Avoid the water based
stuff. It is crap.
| Quote: |
Scuff the area to be glued with 180 to enhance the adhesion. Apply the
glue in a swath about 3/8" wide to both the seal, the aileron and
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closeout. Use masking tape to keep your glue line to the prescribed
width and remove the tape once the glue is dry. You can also use the
masking tape to provide a guide when you scuff the area to be glued, but
wipe it with acetone to remove dust before putting the glue on. Allow
the glue to dry, usually about 20 minutes, remove the masking tape, then
stick the seal to the leading edge of the aileron first, preferably
while on your work bench. If you screw something up Xylene will remove
the glue easily without harming your paint. The next part takes an extra
set of hands.
| Quote: |
With one person holding the aileron close to the wing, attach the
other half of the cloth to the closeout forming an "S" pattern. Avoid
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wrinkles. See this drawing for details:
http://wingsandwheels.com/page28.htm
| Quote: |
Then, reattach the aileron as you would normally do. Check the throw
and make sure you are not binding! If you apply the seal correctly you
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will not even know it is there. I have also sealed my rudder in a
similar fashion as well as the trim tabs. They create similar drag when
deflected.
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I can't say specifically what improvements have occurred in N245E as a
result of the seals since I've not ever flown it without them. I can
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tell you that I exceed Europas published numbers with a fixed pitch
prop. I can also tell you that on gliders we generally see 2 to 4 points
increase in glide and a noticeable decrease in sink rate, even on the
old "woodies", after the application of seals. In power planes this
translates to faster cruise, better climb rates and better fuel economy.
| Quote: |
Anyway, hope it helps!
Regards,
John Lawton
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--> p; -Matt Dralle, Libution" =======
| Quote: |
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