please de-list me=0AChris Drewett=0A=0A=0A________________________________
=0A From: Europa-List Digest Server <europa-list@matronics.com>=0ATo: Europ
a-List Digest List <europa-list-digest@matronics.com> =0ASent: Sunday, 5 Au
gust 2012, 8:01=0ASubject: Europa-List Digest: 2 Msgs - 08/04/12=0A =0A*=0A
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l Messages Posted Sat 08/04/12: 2=0A- - - - - ------------------
----------------------------------------=0A=0A=0AToday's Message Index:=0A-
---------------------=0A=0A- - 1. 10:06 AM - seals for control surface
s- (Fred Klein)=0A- - 2. 10:52 AM - Re: seals for control surfaces
- (Robert Borger)=0A=0A=0A=0A________________________________- Message
=0AFrom: Fred Klein <fklein@orcasonline.com>=0ASubject: Europa-List: seals
for control surfaces=0A=0AApropos the recent thread on this topic, I found
an old posting by- =0AJohn Lawton which may be enlightening:=0A=0A> In a
message dated 5/9/2007 2:59:30 AM Eastern Daylight Time, europa-list@matron
ics.com=0A=0A>- writes:=0A> My understanding is that preventing the air g
oing over the flap, in=0A> cruise, reduces drag, resulting in higher cruise
speed, which I have=0A> experienced.- I don't have the engineering backg
round to completely=0A> understand what is happening to the wing, in flight
.- That's why I=0A> depend on the guys on the list to keep me straight.
- I'm more of a- =0A> "try=0A> it and see" kinda guy... :)- John's ad
vice is based on the success- =0A> that=0A> the glider guys have had, sea
ling the gaps.- It seems to have worked- =0A> on=0A> Baby Blue, as well
.- Continued testing will tell to what degree of=0A> advantage the seals
make.- It may very well prove that the extra few=0A> knots is not worth t
he float upon landing.- I won't know until I- =0A> satisfy=0A> myself t
hat I've explored all the angles (and strip widths)... ;)=0A>=0A> Hey Jeff,
et al,=0A>=0A> The concept behind seals is pretty simple. In flight the wi
ng- =0A> creates a low pressure area on the top and high pressure on the
- =0A> bottom. (Bernoulli at it again) This pressure differential will tr
y- =0A> to equalize through the gap in the flap area and the hinge line o
f- =0A> the ailerons. This is also true to some extent on the rudder hing
e- =0A> line and the trim tabs when they are deflected. This equalization
- =0A> causes drag, a lot of drag. So, the idea behind seals, both flap g
ap- =0A> and positive seals on ailerons (and rudder and trim tabs), is to
- =0A> prevent this pressure equalization.=0A>=0A> On N245E I used PVC we
ather-strip to create the flap gap seal. The- =0A> size will depend on ho
w big your gap is between the leading edge of- =0A> the flap and the flap
closeout when retracted. Choose a foam that is- =0A> slightly thicker th
an the widest spot in the gap you have. The XS- =0A> flap closeout looks
as if it were designed to be sealed, given the- =0A> flat area at the bot
tom rear of the closeout. If you apply the foam- =0A> strip to the area w
here the flap "noses" into the closeout when up- =0A> it will seal this a
rea for cruise flight, but still allow air to- =0A> flow over the flap wh
en extended. Use a foam that crushes easily- =0A> when the flap comes in
contact with it. You don't want to use a foam- =0A> that is too stiff or
too thick or else your flaps won't fully- =0A> retract. PVC weather-strip
is soft and pliable and works quite well.- =0A> It is also fairly UV res
istant and is very cheap. It's available at- =0A> any hardware store in v
arious thicknesses. We've found that open- =0A> cell foams tend to not la
st very long due to UV and they don't seal- =0A> as well as closed cell f
oams like PVC. I also used weather-strip on- =0A> the ends of my flaps so
that they seal against the side of the- =0A> fuselage when they are in t
he up position. According to Bruce- =0A> Carmichael, renowned Aerodynamic
ist who wrote a book on drag- =0A> reduction in homebuilts, the wing root
/fuselage junction is another- =0A> area of high drag on most airplanes.
Sealing it up helps, too.=0A>=0A> Aileron seals are a bit more tricky to em
ploy. Some folks apply- =0A> Mylar strips over the hinge lines and think
they've sealed their- =0A> ailerons. This is not true. Mylar is not a sea
l, but rather is- =0A> applied to help the boundary flow stay attached ov
er the hinge line.- =0A> Mylar is also somewhat cosmetic in that it hides
the hinge line. At- =0A> high speeds the Mylar will lift up off the wing
due to the pressure- =0A> equalization, thus negating the effects of any
sealing the Mylar- =0A> might be offering. In some cases the Mylar will
"buzz" at high speeds.=0A>=0A> For sealing ailerons you need to install wha
t are known as positive- =0A> seals. These seals go from the leading edge
of the aileron to the- =0A> rear of the closeout. There are commercially
available materials for- =0A> this, including various types of cloth and
Teflon tapes. Some folks- =0A> even use cloth tape along the length of t
he aileron on the- =0A> undersurface. This is fine on low speed gliders,
but I think at the- =0A> speeds we fly this method likely creates more dr
ag. Personally, I- =0A> like parachute cloth for making positive seals. W
hatever you use it- =0A> needs to be zero porosity, i.e., allowing no air
flow through the- =0A> material. Parachute cloth is thin, flexible, zero
porosity and fits- =0A> the bill here perfectly. Here at the 'Possum Werk
s we use Parachute- =0A> cloth almost exclusively to fabricate positive s
eals. (it also helps- =0A> that we have a parachute manufacturer a few mi
les down the road that- =0A> gives us their scraps)=0A>=0A> First remove
the aileron. Then, cut a strip of parachute cloth about- =0A> 3" wide exa
ctly the length of the aileron. The width you use might- =0A> take some t
rial and error to get it right. You don't want it so wide- =0A> the the m
aterial bunches up when the aileron is deflected. 2.5' to- =0A> 3" width
should work on most Europas. Then, yellow contact cement is- =0A> applied
to the leading edge of the aileron, the rear of the closeout- =0A> and t
he mating surfaces of the cloth. We use a brand of glue called- =0A> Plio
-bond. It's handy in that it comes in a small bottle with a- =0A> brush a
pplicator. 3M also makes good contact cement if you can find- =0A> it. Av
oid the water based stuff. It is crap.=0A>=0A> Scuff the area to be glued w
ith 180 to enhance the adhesion. Apply- =0A> the glue in a swath about 3/
8" wide to both the seal, the aileron- =0A> and closeout. Use masking tap
e to keep your glue line to the- =0A> prescribed width and remove the tap
e once the glue is dry.- You can- =0A> also use the masking tape to pro
vide a guide when you scuff the area- =0A> to be glued, but wipe it with
acetone to remove dust before putting- =0A> the glue on. Allow the glue t
o dry, usually about 20 minutes, remove- =0A> the masking tape, then stic
k the seal to the leading edge of the- =0A> aileron first, preferably whi
le on your work bench. If you screw- =0A> something up Xylene will remove
the glue easily without harming your- =0A> paint. The next part takes an
extra set of hands.=0A>=0A> With one person holding the aileron close to t
he wing, attach the- =0A> other half of the cloth to the closeout forming
an "S" pattern.- =0A> Avoid wrinkles. See this drawing for details: http
://wingsandwheels.com/page28.htm=0A>=0A> Then, reattach the aileron as you
would normally do. Check the throw- =0A> and make sure you are not bindin
g! If you apply the seal correctly- =0A> you will not even know it is the
re. I have also sealed my rudder in- =0A> a similar fashion as well as th
e trim tabs. They create similar drag- =0A> when deflected.=0A>=0A> I can
't say specifically what improvements have occurred in N245E as- =0A> a r
esult of the seals since I've not ever flown it without them. I- =0A> can
tell you that I exceed Europas published numbers with a fixed- =0A> pitc
h prop. I can also tell you that on gliders we generally see 2- =0A> to 4
points increase in glide and a noticeable decrease in sink- =0A> rate, e
ven on the old "woodies", after the application of seals. In- =0A> power
planes this translates to faster cruise, better climb rates- =0A> and bet
ter fuel economy.=0A>=0A> Anyway, hope it helps!=0A>=0A> Regards,=0A>=0A> J
ohn Lawton=0A=0A________________________________- Message 2- __________
Europa-List: seals for control surfaces=0AFrom: Robert Borger <rlborger@ma
c.com>=0A=0AFred,=0A=0AThanks for digging this up.- Very informative.-
Now, if I could just get =0Amy 914 running right=85=0A=0ABlue skies & tai
lwinds,=0ABob Borger=0AEuropa XS Tri, Rotax 914, Airmaster C/S Prop.=0ALitt
le Toot Sport Biplane, Lycoming Thunderbolt AEIO-320 EXP=0A3705 Lynchburg D
r.=0ACorinth, TX- 76208-5331=0ACel: 817-992-1117=0Arlborger@mac.com=0A=0A
On Aug 4, 2012, at 12:03 PM, Fred Klein <fklein@orcasonline.com> wrote:=0A
=0AApropos the recent thread on this topic, I found an old posting by John
=0ALawton which may be enlightening:=0A=0A> In a message dated 5/9/2007 2:5
9:30 AM Eastern Daylight Time, =0Aeuropa-list@matronics.com writes:=0A> My
understanding is that preventing the air going over the flap, in =0A> cruis
e, reduces drag, resulting in higher cruise speed, which I have =0A=0A> exp
erienced.- I don't have the engineering background to completely =0A> und
erstand what is happening to the wing, in flight.- That's why I =0A> depe
nd on the guys on the list to keep me straight.- I'm more of a =0A"try
=0A> it and see" kinda guy... :)- John's advice is based on the success
=0Athat =0A> the glider guys have had, sealing the gaps.- It seems to hav
e worked =0Aon =0A> Baby Blue, as well.- Continued testing will tell to w
hat degree of =0A> advantage the seals make.- It may very well prove that
the extra few =0A=0A> knots is not worth the float upon landing.- I won'
t know until I =0Asatisfy =0A> myself that I've explored all the angles (an
d strip widths)... ;)=0A>- =0A> Hey Jeff, et al,=0A>- =0A> The concept
behind seals is pretty simple. In flight the wing creates =0Aa low pressure
area on the top and high pressure on the bottom. =0A(Bernoulli at it again
) This pressure differential will try to equalize =0Athrough the gap in the
flap area and the hinge line of the ailerons. =0AThis is also true to some
extent on the rudder hinge line and the trim =0Atabs when they are deflect
ed. This equalization causes drag, a lot of =0Adrag. So, the idea behind se
als, both flap gap and positive seals on =0Aailerons (and rudder and trim t
abs), is to prevent this pressure =0Aequalization.=0A>- =0A> On N245E I u
sed PVC weather-strip to create the flap gap seal. The =0Asize will depend
on how big your gap is between the leading edge of the =0Aflap and the flap
closeout when retracted. Choose a foam that is =0Aslightly thicker than th
e widest spot in the gap you have. The XS flap =0Acloseout looks as if it w
ere designed to be sealed, given the flat area =0Aat the bottom rear of the
closeout. If you apply the foam strip to the =0Aarea where the flap "noses
" into the closeout when up it will seal this =0Aarea for cruise flight, bu
t still allow air to flow over the flap when =0Aextended. Use a foam that c
rushes easily when the flap comes in contact =0Awith it. You don't want to
use a foam that is too stiff or too thick or =0Aelse your flaps won't fully
retract. PVC weather-strip is soft and =0Apliable and works quite well. It
is also fairly UV resistant and is very =0Acheap. It's available at any ha
rdware store in various thicknesses. =0AWe've found that open cell foams te
nd to not last very long due to UV =0Aand they don't seal as well as closed
cell foams like PVC. I also used =0Aweather-strip on the ends of my flaps
so that they seal against the side =0Aof the fuselage when they are in the
up position. According to Bruce =0ACarmichael, renowned Aerodynamicist who
wrote a book on drag reduction =0Ain homebuilts, the wing root/fuselage jun
ction is another area of high =0Adrag on most airplanes. Sealing it up help
s, too.=0A>- =0A> Aileron seals are a bit more tricky to employ. Some fol
ks apply Mylar =0Astrips over the hinge lines and think they've sealed thei
r ailerons. =0AThis is not true. Mylar is not a seal, but rather is applied
to help the =0Aboundary flow stay attached over the hinge line. Mylar is a
lso somewhat =0Acosmetic in that it hides the hinge line. At high speeds th
e Mylar will =0Alift up off the wing due to the pressure equalization, thus
negating the =0Aeffects of any sealing the Mylar might be offering. In som
e cases the =0AMylar will "buzz" at high speeds.=0A>- =0A> For sealing ai
lerons you need to install what are known as positive =0Aseals. These seals
go from the leading edge of the aileron to the rear =0Aof the closeout. Th
ere are commercially available materials for this, =0Aincluding various typ
es of cloth and Teflon tapes. Some folks even use =0Acloth tape along the l
ength of the aileron on the undersurface. This is =0Afine on low speed glid
ers, but I think at the speeds we fly this method =0Alikely creates more dr
ag. Personally, I like parachute cloth for making =0Apositive seals. Whatev
er you use it needs to be zero porosity, i.e., =0Aallowing no airflow throu
gh the material. Parachute cloth is thin, =0Aflexible, zero porosity and fi
ts the bill here perfectly. Here at the =0A'Possum Werks we use Parachute c
loth almost exclusively to fabricate =0Apositive seals. (it also helps that
we have a parachute manufacturer a =0Afew miles down the road that gives u
s their scraps)=0A>- =0A> First remove the aileron. Then, cut a strip of
parachute cloth about =0A3" wide exactly the length of the aileron. The wid
th you use might take =0Asome trial and error to get it right. You don't wa
nt it so wide the the =0Amaterial bunches up when the aileron is deflected.
2.5' to 3" width =0Ashould work on most Europas. Then, yellow contact ceme
nt is applied to =0Athe leading edge of the aileron, the rear of the closeo
ut and the mating =0Asurfaces of the cloth. We use a brand of glue called P
lio-bond. It's =0Ahandy in that it comes in a small bottle with a brush app
licator. 3M =0Aalso makes good contact cement if you can find it. Avoid the
water based =0Astuff. It is crap.=0A>- =0A> Scuff the area to be glued w
ith 180 to enhance the adhesion. Apply the =0Aglue in a swath about 3/8" wi
de to both the seal, the aileron and =0Acloseout. Use masking tape to keep
your glue line to the prescribed =0Awidth and remove the tape once the glue
is dry.- You can also use the =0Amasking tape to provide a guide when yo
u scuff the area to be glued, but =0Awipe it with acetone to remove dust be
fore putting the glue on. Allow =0Athe glue to dry, usually about 20 minute
s, remove the masking tape, then =0Astick the seal to the leading edge of t
he aileron first, preferably =0Awhile on your work bench. If you screw some
thing up Xylene will remove =0Athe glue easily without harming your paint.
The next part takes an extra =0Aset of hands.=0A>- =0A> With one person h
olding the aileron close to the wing, attach the =0Aother half of the cloth
to the closeout forming an "S" pattern. Avoid =0Awrinkles. See this drawin
g for details: =0Ahttp://wingsandwheels.com/page28.htm=0A>- =0A> Then, re
attach the aileron as you would normally do. Check the throw =0Aand make su
re you are not binding! If you apply the seal correctly you =0Awill not eve
n know it is there. I have also sealed my rudder in a =0Asimilar fashion as
well as the trim tabs. They create similar drag when =0Adeflected.=0A>-
=0A> I can't say specifically what improvements have occurred in N245E as a
=0Aresult of the seals since I've not ever flown it without them. I can
=0Atell you that I exceed Europas published numbers with a fixed pitch =0Ap
rop. I can also tell you that on gliders we generally see 2 to 4 points =0A
increase in glide and a noticeable decrease in sink rate, even on the =0Aol
d "woodies", after the application of seals. In power planes this =0Atransl
ates to faster cruise, better climb rates and better fuel economy.=0A>-
=0A> Anyway, hope it helps!=0A> =0A> Regards,=0A>- =0A> John Lawton=0A=0A
==================
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